WALT
• Name additional structures in the cell and
explain their function
• Watch:
http://www.youtube.com/watch?v=vCqQLo
RaTNA&feature=plcp
• Then Bozeman biology tour of the cell
http://www.youtube.com/watch?v=1Z9pqS
T72is&feature=plcp
vesicle
Golgi apparatus
cytoskeleton
Smooth
endoplasmic
reticulum
Nuclear membrane
pore
cilia
Plasma
membrane
centrioles
lysosome
ribosome
mitochondrion
nucleolus
Rough endoplasmic
reticulum
nucleus
cytoplasm
Cell animation
• http://www.cellsalive.com/cells/cell_model.
htm
• A tour of the cell – Bozemanbiology
• http://www.youtube.com/watch?v=1Z9pqS
T72is&feature=related
• The cell song – Sciencemusicvideos
http://www.youtube.com/watch?v=rABKB5
aS2Zg&feature=fvwrel
Structure
Function
Nucleus
Contains DNA
Nucleolus
Controls the synthesis of RNA and
components needed to build ribosomes.
Smooth ER and rough ER
Endoplasmic
Reticulum (ER)
Ribosome
Lysosome
Place where protein is synthesised.
Mitochondria
Contains enzymes that digest worn-out
organelles and microbes.
Site of aerobic respiration
Centriole
Needed for cell division
Golgi Body
Processes and packages molecules
ready for discharge from cell.
Controls what enters and exits the cell.
Plasma Membrane.
Quiz time!!
• http://www.teachersdirect.co.uk/resources/quiz-busters/quizbusters-game.aspx?game_id=76982
WALT
• Revise the features of enzymes
• Revise their response to temperature and
pH and explain how this occurs
• Describe enzyme activity illustrated
graphically
• Using illustrations, explain competitive and
non competitive inhibitors
• Explain enzyme activity with inhibitors
drawn graphically
• Bozeman biology enzymes:
• http://www.youtube.com/watch?v=ok9esg
gzN18&feature=plcp
Characteristics of Enzymes
• They are proteins
• They are biological
catalysts
• They are sensitive to
temperature changes
being denatured at high
temperatures
• They are sensitive to pH
• They are substrate
specific
• Enzymes possess an
active site within which
chemical reactions take
place
Substrate
molecule in
the ACTIVE
SITE
Enzyme molecule
Temperature and Enzyme Activity
This is the maximum rate of the
reaction (37oC)
This is the optimum temperature.
Rate of
Reaction
As the temperature
increases, the
reaction rate
increases
As the temperature increases
beyond the optimum,
the active site is altered.
Substrate can no longer bind
to the enzyme. The enzyme
has been DENATURED
Temperature (oC)
Enzymes and pH
Each specific enzyme can only work
over a particular range of pH
B
A
Each enzyme has its own optimum pH
where the rate of reaction is maximum
C
Enzyme A = amylase
optimum pH = 7
Enzyme B = pepsin
optimum pH = 2.5
Enzyme C = lipase
optimum pH = 9.0
Extremes of pH denature the enzyme
Enzymes Place
Substrate Product
Amylase Mouth
Starch
Maltose
Conditions
37°C
pH7
Pepsin
Stomach Protein
Peptones/ 37°C
Amino
Ph 2.5
acids
Lipase
Small int. Fats
Fatty acids 37°C
and
Neutral
glycerol
Ph9
Catalase Body
Hydrogen Water and 37°C
cells
peroxide oxygen
pH9
• Enzyme reactions can occur inside cells
(intracellular) or outside cells
(extracellular).
• Bozeman biolgy enzyme rates of
reactions:
• http://www.youtube.com/watch?v=LicEaaX
hlEY&feature=plcp
The Effect Of Substrate Concentration
On The Rate Of Enzyme - Catalysed Reactions
Rate of Rate of reaction reaches
reaction a maximum at substrate
concentration A
Rate of reaction
increases as the
substrate
concentration
increases
All the active sites of the
enzymes are occupied Enzyme concentration
is the limiting factor
A
Increasing concentration of substrate
copy
• At low substrate concentrations,
reaction rate is low as too few
substrate molecules present to use all
the active sites. An increase in
substrate concentration causes
increased reaction rate as more active
sites become used until the graph levels
off when all the active sites are
occupied.
The effect of enzyme concentration
on rate of reactions
Enzyme
concent
-ration
(%)
Height of
foam
Exp 1
(mm)
Height of
foam
Exp 2
(mm)
Average
height of
foam
(mm)
2cm ³ catalase enzyme:
2%
1%
0.5%
0.1% 0%
0
0.1
0.5
1
2
5cm³ hydrogen
peroxide
1 drop detergent
Enzyme reactions animation
• http://www.kscience.co.uk/animations/enz
yme_model.htm
The Effect Of Enzyme Concentration
On The Rate Of Enzyme - Catalysed Reactions
Rate of Rate of reaction reaches
reaction a maximum at enzyme
concentration A
Rate of reaction
increases as more
active sites used
All the active sites of the
enzymes are occupied substrate concentration
is the limiting factor
A
Increasing concentration of enzyme
Competitive Inhibitors
The presence of competitive inhibitor molecules decreases the rate
of enzyme reactions by reversible combination with the enzyme.
Normal substrate
Molecule similar
in shape to the
normal substrate
The inhibitor
competes
with the normal
substrate
for the active site
This molecule
is an example of
a COMPETITIVE
INHIBITOR
%
80
20
%
14
12
10
8
6
4
2
0
0%
• As the concentration
of the inhibitor
increases the rate of
reaction slows.
rate of reaction
Effect on rate of reaction
percentage of
inhibitor
rate of
reaction
Effect of increasing the concentration of
a competitive inhibitor on the rate of
enzyme action.
• Copy:
• At low inhibitor concentration, reaction rate
is high since few active sites are blocked by
the inhibitor and substrates easily find free
active sites.
• As the inhibitor’s concentration increases,
the reaction rate decreases as less unblocked
active sites are available to the substrate.
Non-competitive Inhibitors
This inhibitor molecule does not bind to the active
site but attaches to the enzyme at another region.
The active site shape is altered indirectly. Eg cyanide and
lead.
The substrate
molecule cannot
bind to the active
site
Substrate cannot
be converted into
product. The
inhibitor molecule
changes the shape of
the active site
This inhibitor
is not competing
for the active
site
Effect of Inhibitors
No inhibitor
Rate of
reaction
1
Competitive
inhibitor
2
Non-competitive
3
inhibitor
Increasing substrate conc
copy
1. An
in substrate concentration (SC)
causes an in reaction rate until all the
active sites are occupied and then the
graph levels off as the reaction can’t
happen any quicker.
copy
• 2. An
in SC causes a slower increase
in reaction rate as the competitive
inhibitor occupies some of the active
sites. As SC , more active sites
become occupied by substrates rather
than inhibitors. The reaction rate
continues to until all active sites
become occupied and graph levels off.
copy
• 3. Most of the enzymes are altered by
the non-competitive inhibitor and left
inactive. However a few enzyme
molecules remain unaffected, so the
reaction proceeds at a slow rate.
• copy
• Many enzymes require the presence
of a non protein substance called a
cofactor which allows the substrate
to fit the enzyme’s active site.
Examples are minerals such as zinc,
iron and copper.
Activators
• Some enzymes are inactive until they
are converted into their active form by
enzyme activators.
enteropeptidase
trypsinogen
trypsin
Hydrochloric acid
pepsinogen
pepsin
Both trypsin and pepsin are kept inactive until needed so they don’t
digest the cells where they are made.
Coenzymes
• Copy
• Some co-factors are called co-enzymes.
Many of these contain a vitamin as the
main part of their molecular structure.
E.g. vit B which is required to make the
co-enzyme involved in the transfer of
hydrogen during aerobic respiration.
Metabolism
• Metabolism is the sum of all the chemical
reactions in the body.
• Some chemical reactions are involved in
breaking down molecules, others are involved
in building up (synthesis)
• A metabolic pathway consists of SEVERAL
STAGES involved in the conversion of one
metabolite to another.
Metabolic Pathway
Enzyme 1
Metabolic A
Enzyme 2
Metabolic B
Metabolic C
Each stage in the pathway is controlled by an enzyme.
Errors in Metabolism
• If a fault occurs in the gene that codes for
the enzyme, it can’t be made
• This fault is caused by a mutation in the
genetic code.
• If the enzyme is not produced and the
pathway breaks down.
• These are called INBORN ERRORS OF
METABOLISM.
copy
• Each stage in a metabolic reaction is
controlled by an enzyme which is coded
for by a gene. If a mutation (change)
occurs in that gene, the enzyme will not
be produced.
• Thus part of the pathway can’t be
complete and this causes a build up of
an intermediate metabolite which
causes problems.
Phenylketonuria
• Usually:
Phenylalanine
Enzyme A
Enzyme B
Tyrosine
Melanin
Enzyme C
Phenylpyruvic acid
Phenyketonuria (PKU) occurs when the enzyme phenylalanine hydroxylase
(enzyme A) is absent. Phenylalanine accumulates and undergoes alternative
metabolic pathways which produces toxins which affect brain cells.
Quiz time!!
• http://www.teachersdirect.co.uk/resources/quiz-busters/quizbusters-game.aspx?game_id=76986
Protein Structure
• Copy
• Proteins are organic compounds which
contain carbon, hydrogen, oxygen and
nitrogen (CHON). Many also contain
sulphur.
• Proteins consist of amino acids joined
by peptide bonds to form polypeptides.
• There are 20 different amino acids.
A.A.1
A.A.2
A.A.3
A.A.5
A.A.4
A.A.20
• These amino acids are joined by
peptide bonds to form polypeptides.
A.A.1
A.A.4
A.A.2
Peptide bond
Polypeptide
A.A.20
Primary Structure
• The primary structure of a protein is the
sequence of amino acids within the
polypeptide.
A.A.1
A.A.4
A.A.2
A.A.20
Secondary Structure
• Hydrogen bonds form between certain
amino acids and the chain becomes a
spiral.
Hydrogen bond
Amino
acids
Tertiary Structure
• Copy
• Established when
its peptides become
further linked
together by bridges
between sulphur
atoms and
additional hydrogen
bonding.
Types of proteins
• Fibrous – Polypeptide chains become arranged
in long parallel strands
• Globular – Polypeptide chains become folded
together into a spherical shape
• Conjugated – Polypeptide chains become folded
together into a spherical shape (globular protein)
and contains non-protein parts
Fibrous Protein Examples
• ELASTIN found in artery walls to provide flexible
support.
• COLLAGEN found in bones, tendons and
ligaments which provides rigid support.
• KERATIN found in hair which has the function
of protection.
• ACTIN + MYOSIN which is found in muscles
providing movement.
Globular Protein Examples
• ENZYMES which control chemical reactions.
• HORMONES such as insulin and glucagon
which regulate blood glucose levels along with
growth hormone (somatotrophin).
• ANTIBODIES which are involved in cell defence
• STRUCTURAL protein which make up the cell
membrane.
Conjugated Protein Examples
• HAEMOGLOBIN pigment used to transport
oxygen. Contains the non-protein part iron.
• LIPOPROTEINS which coat the products of fat
digestion before they are absorbed.
• CYTOCHROME which is involved in aerobic
respiration
Functions of Protein
•
Protein
Type
Function
collagen
fibrous
Bone,tendon,ligaments.
actin
fibrous
muscles
myosin
fibrous
muscles
enzymes
globular
Catalyse reactions
hormones
globular
Chemical messengers
membrane
globular
Cell membrane structure
lipoprotein
conjugated
Transports fat products
haemoglobin conjugated
Transport of oxygen
cytochrome
Used in respiration
conjugated
Chemiluminescence
• http://www.youtube.com/watch?v=hbEHvR
rfqrc
Quiz time!!
• http://www.teachersdirect.co.uk/resources/quiz-busters/quizbusters-game.aspx?game_id=77037
Muscular system
• Bozeman biology:
• http://www.youtube.com/watch?v=mejCXr
7p37U&feature=plcp
Myofibrils
muscle
myofibril
sarcomere
• http://www.youtube.com/watch?v=XoP1di
aXVCI&feature=plcp
Sarcomere
Thin actin filament
Thick myosin filament
light band medium
band
dark band
Muscle
• Copy
• Skeletal muscle consists of fibres containing
many smaller myofibrils. Each myofibril is
divided into compartments called sarcomeres.
Each myofibril contains 2 different types of
filament:
• Thick filament made of myosin and found in
the centre
• Thin filament made of actin and found at the
sides.
• When a muscle fibre contracts, each of its
sarcomeres becomes shorter. This reduction
in length is brought about by the actin
filaments sliding over the myosin and moving
towards the centre of the sarcomere.
WALT
• Explain the basic structure and
components of DNA
• Name the 4 nucleotide bases and explain
which ones match up in pairs
• DNA intro- gd!:
• http://www.glowscience.org.uk/mindmap#!/biology/cells_
and_dna/dna or found at
http://www.twigonglow.com/mindmap/#205/dna?&_suid=13463252177810749224693863
6337
• DNA rap: http://www.youtube.com/watch?v=wdhLT6tQco
• What is DNA – Bozemanbiology:
• http://www.youtube.com/watch?v=q6PPC4udkA&list=UUEikU3T6u6JA0XiHLbNbOw&index=90&feature=plpp_video
Deoxyribonucleic Acid (DNA)
• Copy
• Chromosomes are thread like structures
found inside the nucleus of a cell. They
contain deoxyribonucleic acid (DNA).
The DNA codes for different genes
which are inherited characteristics.
DNA
• The basic building blocks of DNA are
nucleotides.
Phosphate
Deoxyribose sugar
Organic base
• There are 4 different organic bases :
adenine - A
thymine - T
cytosine -C
guanine - G.
A
T
Nucleotides join
along their sugar
phosphate backbones
with strong chemical bonds
C
G
Hydrogen bonds
A
T
T
A
C
G
G
C
Double Helix
• DNA fingerprinting – Bozemanbiology
• http://www.youtube.com/watch?v=DbR9x
MXuK7c&list=UUEikU3T6u6JA0XiHLbNbOw&index=1&feature
=plpp_video
Importance of replication
• In order to continue life, cells must
constantly replicate themselves to grow
and replace worn out cells.
• For the cell to be able to function, it must
contain an EXACT copy of the information
present in its parent cell. Without the full,
correct information contained within the
DNA, the cell will not be viable and
therefore not be able to form.
• DNA and RNA – Bozemanbiology
• http://www.youtube.com/watch?v=qoERVSWKm
Gk&list=UUEikU3T6u6JA0XiHLbNbOw&index=130&feature=pl
pp_video
• DNA replication – Bozemanbiology
• http://www.youtube.com/watch?v=FBmO_rmXxI
w&list=UUEikU3T6u6JA0XiHLbNbOw&index=28&feature=plp
p_video
DNA replication animation!
• Also:
http://www.lpscience.fatcow.com/jwanama
ker/animations/DNA%20Lecture.html
DNA untwists and
unzips. Free
nucleotides slot in
and combine with
their corresponding
base.
The nucleotides
join up to form 2
identical strands enough for the 2
new cells.
Replication
• Copy
• When 1 cell is dividing to form 2 cells
the DNA untwists and unzips exposing
the bases. Free nucleotides slot in and
combine with their corresponding bases.
The nucleotides join up along their sugar
phosphate backbone to form identical
strands- enough for 2 new cells.
Protein synthesis
• There are two phases to protein
synthesis:
1. Transcription – where the DNA inside
the nucleus makes a copy of itself
2. Translation – where the copy is ‘read’
to make the correct protein
Overview of Protein Synthesis
• How does DNA make protein?:
http://www.twigonglow.com/mindmap/#205/dna?&_suid=13463252177810749224693863
6337
• DNA transcription and translation – Bozemanbiology
• http://www.youtube.com/watch?v=h3b9ArupXZg&list=U
UEikU3T6u6JA0XiHLbNbOw&index=27&feature=plpp_video
•
• DNA RNA
• http://www.youtube.com/watch?v=xZaMi6OhsS
U&feature=plcp
Transcription
•DNA cannot itself leave the cell’s nucleus. It overcomes
this by making a copy of itself, called messenger RNA
(mRNA).
• The basic building blocks of RNA are still nucleotides.
Phosphate
Ribose sugar
Organic base
(A,G,U,C)
RNA Structure
• RNA also consists
of nucleotides.
The sugar is
ribose and it is 1
stranded. The
base thymine is
replace by uracil.
RNA is made in
the nucleus.
RNA vs DNA
• RNA is similar to DNA in that it is made
up of 4 bases, except the base thymine
(T) is replaced by another base, uracil
(U)
• mRNA is only one strand thick
• Instead of a deoxyribose sugar, RNA
contains a ribose sugar.
• TRY A VENN DIAGRAM!
Venn diagram
DNA
both
RNA
Protein synthesis animation
• http://www.lpscience.fatcow.com/jwanama
ker/animations/Protein%20%20lecture.html
• Bozeman biology:
• http://www.youtube.com/watch?v=h3b9Ar
upXZg&feature=plcp
Transcription
• Copy:
• DNA can’t get out of the nucleus so it needs a
messenger mRNA. The DNA unzips exposing
the bases. Free RNA nucleotides slot in
opposite their corresponding bases. The RNA
nucleotides join up along their sugar
phosphate backbone using the enzyme RNA
polymerase to form a strand of mRNA. Each
triplet of bases on the mRNA is called a
codon. The DNA zips back up. The mRNA
codons move out through a pore in the nucleur
membrane into the cytoplasm and travel to
the ribosomes.
Transcription animation EdScot
• Can you provide the commentary for this?
• http://www.educationscotland.gov.uk/highe
rsciences/biology/animations/transcription.
asp
Translation
• The mRNA moves to the ribosome. Free
ribosomes make proteins for the cell itself,
whereas ones attached to the ER make
proteins to be excreted from the cell.
mRNA
U A
A C
G
G C U
• Six bases (2 codons) are
exposed at a time
A
Ribosome (+ enzymes)
tRNA
• Transfer RNA (tRNA) is present in the
cytoplasm. Each tRNA carries one amino acid
to the ribosome.
• tRNA has a base triplet
(anticodon) at the bottom. Amino Acid 1
The anticodon decides which
amino acid is carried.
• There are 20 different
A
U
U
tRNAs - one for each
amino acid.
Translation
• tRNA carries the amino acid to the
ribosome.
Amino Acid 1 Amino Acid 2
A
U
U
U
A A
G
C
Amino Acid 3
C
C
G
G
G
C
A
U
U
A
Translation (p25/26)
Translation
• Copy:
• Translation causes alignment of amino
acids in a certain order. The order
which the amino acids join up makes a
specific protein.
• Peptide bonds join the amino acids into
a polypeptide chain which is released
into the endoplasmic reticulum.
Translation animation Ed Scot
• Can you provide the commentary for this?
• http://www.educationscotland.gov.uk/highe
rsciences/biology/animations/translation.a
sp
Protein synthesis animation!
• Have a go yourself:
• http://learn.genetics.utah.edu/content/begi
n/dna/transcribe/
• Or Google ‘transcribe and translate a
gene’
Golgi body animation
• http://www.kscience.co.uk/animations/golg
i.htm
Golgi Body
Endoplasmic reticulum
A vesicle full of protein is formed
Protein passed into the Golgi
Protein processed in
Golgi body
Vesicle fuses
with membrane
and processed protein
excreted from cell
Vesicle with
processed
protein
The golgi body processes and packages the
protein e.g. adds carbohydrates to make
glycoprotein.
1. vesicle containing freshly synthesised
protein pinched off from rough ER.
2.vesicle joins up with golgi body.
3. protein processed in golgi body.
4. vesicle containing finished protein nipped
off.
5. vesicle moves towards cell membrane
6.vesicle fuses with cell membrane
7. protein secreted.
• Bozeman biology respiratory system:
• http://www.youtube.com/watch?v=MrDbiK
QOtlU&feature=plcp
Alveoli
The Lungs
• The respiratory system – Bozemanbiology
• http://www.youtube.com/watch?v=MrDbiK
QOtlU&list=UUEikU3T6u6JA0XiHLbNbOw&index=52&featur
e=plpp_video
Breathing
Inspiration
Expiration
Intercostal
muscles
Diaphragm
Contracts
Relaxes
Contracts
Relaxes
Lung volume
Increase
Decrease
Lung pressure
decrease
Increase
Air movement
inhaled
exhaled
Gas Exchange and Respiration
• Copy
• The lungs are a mammals organ of gas
exchange. Air entering by the nose and
mouth then the trachea, bronchus, and
bronchioles which end in tiny air sacs
called alveoli. The alveoli are so
numerous that they provide a large
surface area for gas exchange and give
the lungs a sponge like texture.
Primary Sources
• The primary sources of energy are the
carbohydrates.
• Carbohydrates contain carbon, hydrogen
and oxygen.
• Examples of carbohydrates are sugar,
starch and glycogen.
• Carbohydrates can be monosaccharides,
disaccharides or polysaccharides.
Monosaccharides
6 carbon ring
These are simple
sugars.
Examples are glucose
and fructose.
They are soluble in
water and have
reducing
properties.
They are reducing sugars.
Disaccharides
These are sugars made up of 2
monosaccharide units joined together. They
are soluble in water. Examples are maltose
and sucrose.
Maltose is a reducing sugar. Sucrose is not.
Polysaccharides.
Polysaccharides are made up of many
monosaccharide units joined together.
They are large and insoluble. Examples
are starch and glycogen.
Monosaccharides can release energy but
disaccharides and polysaccharides have
to be broken down before they can
release energy
Secondary Sources
• Lipids
glycerol
3C sugar
Pyruvic acid
Fatty acids
Acetyl Co A
proteins
• Copy
• Excess amino acids are deaminated into
urea and organic acids such as pyruvic
acid and kreb cycle intermediates.
Copy
• Starvation- Tissue protein is used after the
reserves of glycogen and fat have been used
up.
• Marathon running- in the first few mins muscle
glycogen is used, then liver glycogen and fatty
acids are used for 30 mins. As supplies of
glycogen decreases fat tissue is used.
• Efficiency of lipids as an energy store- lipids
liberate more than double the quantity of energy
released by the same mass of carbohydrates.
Other Roles of Lipids
TYPE
ROLE
Subcutaneous fat
Thermal insulation
Fat pads
Cushions and protects
Sebum
Waterproofs skin
Phospholipid
Cell membranes
Cholesterol
Cell membranes
Myelin
Nerve insulation
Lipoprotein
Transport of vitamins
Steroids
Sex hormones
• Cellular respiration – Bozemanbiology
• http://www.youtube.com/watch?v=Gh2P5
CmCC0M&list=UUEikU3T6u6JA0XiHLbNbOw&index=33&featur
e=plpp_video
Adenosine Triphosphate
• Copy
• When the energy sources e.g. glucose is
broken down during respiration it
releases energy. This energy is used to
produce a chemical called adenosine
triphosphate (ATP). This is an energy
store.
ATP
• Adenosine Triphosphate
• Molecule able to provide energy
immediately.
•Adenosine Triphosphate
adenosine
Pi
Pi
Pi
ATP song
• http://www.youtube.com/watch?v=V_xZuC
PIHvk
Phosphorylation
breakdown releasing energy
ATP
ADP + Pi
build up requiring energy
When the cell activity rises there is an increase demand on the
supply of ATP to break down and release energy.
• Respiration- is the process by which chemical
energy is released from a food stuff by oxidation.
• Oxidation is the removal of electrons (hydrogen)
from a substance.
• Reduction is the addition of electrons (hydrogen)
to a substance.
• OIL RIG!!!!!!
• Bozeman biology:
• http://www.youtube.com/watch?v=Gh2P5
CmCC0M&feature=plcp
Glycolysis song!
• http://www.youtube.com/watch?v=evYmy
Hgj550&feature=plcp
• Glycolysis
• http://www.youtube.com/watch?v=nGRDa
_YXXQA&feature=plcp
Glycolysis 2
GLUCOSE
C C C C C C
2ATP
2ADP + 2Pi
Required
to start
the
process
C C C C C C
4ADP + 4Pi
C C C
C C C
PYRUVIC ACID
4ATP
• 6 carbon glucose is broken down in a
series of reactions to form 2 molecules
of Pyruvic Acid (3C).
Glycolysis
• Copy
• 6C glucose is broken down by a series of
enzyme controlled reactions to form 2
molecules of 3C pyruvic acid. 2ATP are
needed to start the process but 4 are
generated to produce a net gain of 2
ATP molecules.
• Occurs in the cytoplasm.
Kreb’s Cycle
PYRUVIC ACID
C
C
Carbon dioxide
C
C
C
C
C
C
ACETYL COENZYME A
TRICARBOXYLIC ACID
C C C C C C
C
Carbon dioxide
C
C
C
C
C
Carbon dioxide
Krebs Cycle
• Copy
• Pyruvic acid moves into the central
matrix of the mitochondria and is
converted into 2C acetyl coenzyme A
(acetyl CoA). This joins with a 4C
compound called tricarboxylic acid. This
is gradually converted back into a 4
carbon compound by a series of
reactions which release carbon dioxide.
Enzymes controlling the release of
carbon to form carbon dioxide are
called decarboxylases.
Mitochondria
• Krebs Cycle takes
place in the matrix.
• Electron Transfer
System takes place
on the cristae.
Oxidative Phosphorylation
WATER
NH2
CYTOCHROME SYSTEM
OXYGEN
N
ADP+Pi
ADP+Pi
ADP+Pi
ATP
ATP
ATP
Cytochrome System
• Copy
• The cytochrome system is carried out
on the cristae of the mitochondria.
• At various points thought the pathway
hydrogen is removed by the enzyme
dehydrogenase and bound to a coenzyme
called NAD (N).
NAD + H²
NADH²
• Copy
• NADH² transfers the hydrogens to a chain of
carriers called cytochrome system. The
transfer of the 2 hydrogens through the
carriers releases enough energy to generate
3ATP. This is called oxidative
phosphorylation. The final hydrogen acceptor
in the chain is oxygen which combines with
hydrogen to form water.
• There are 6 points in the pathway were
hydrogen are removed- 6x3 = 18ATP but are
2 pyruvic acids from each glucose and
therefore 2x18 =36. 2ATP molecules formed
during glycolysis and so the total production
of ATP from the breakdown of 1 molecule of
glucose is 38.
GLUCOSE (6C)
2 ATP
PYRUVIC ACID (3C) x2
CO2
ACETYL COENZYME A (2C)
4 C COMPOUND
CO2
TRICARBOXYLIC ACID
6C
5C COMPOUND
CO
2
NH2
WATER
CYTOCHROME
OXYGEN
N
3 ATP
Mitochondrion
Outer membrane
Inner membrane
Crista
Matrix
Enzymes
copy
• Glycolysis- occurs in the cytoplasm
• Krebs cycle- occurs in the central matrix of
the mitochondria
• Cytochrome- occurs in the crista of the
mitochondria
Anaerobic Respiration
• In the absence of oxygen the cytochrome
system and the krebs cycle cannot occur.
glucose
2ADP + Pi
Pyruvic acid
Lactic acid
2ATP
For each molecule of glucose broken down 2 ATP are
produced. Anaerobic respiration occurs in the cytoplasm.
Oxygen Debt
• Copy
• During lactic acid formation, the body
accumulates an oxygen debt. This is
repaid when oxygen becomes available
and lactic acid is converted back to
pyruvic acid which then enters the
aerobic pathway.
Quiz time!
• http://www.teachersdirect.co.uk/resources/quiz-busters/quizbusters-game.aspx?game_id=3594
• http://www.youtube.com/watch?v=CscrXm
3LG98&feature=plcp
• Cell membrane – Bozemanbiology
http://www.youtube.com/watch?v=S7CJ7x
ZOjm0&list=UUEikU3T6u6JA0XiHLbNbOw&index=64&featur
e=plpp_video
carbohydrate
protein
protein
Phosholipid
bi-layer
glycoprotein
protein
copy
• Phospholipids- have a water loving head and a
water hating tail. Therefore the phospholipids
form a double layer with its tails together. The
phospholipids form a fluid but stable layer.
• Protein- provides structural support, contains
channels (pores) to allow small molecules
through, act as carriers that pump molecules
across , act as receptors for hormones and
serve as antigenic markers to identify the cells
type.
• Fluid mosaic model- proposes that the plasma
membrane consists of a fluid bilayer of
constantly moving phospholipid molecules
containing a patchy mosaic of protein molecules.
• Membranes are also found around the
nucleus, mitochondria, endoplasmic
reticulum, golgi apparatus and lysosomes.
• Transport across the cell membrane
http://www.twigonglow.com/mind-map/#208/thecell?&_suid=1346325399625077875273972405
46
• Bozeman biology transport across cell
membrane:
• http://www.youtube.com/watch?v=RPAZvs4hvG
A&feature=plcp
Diffusion
• Net movement of molecules/ions from a
region of high conc to a region of low
conc along the conc gradient.
• It does not require energy so is a
passive process.
glucose
Amino acids
oxygen
urea
water
Carbon
dioxide
Osmosis
• Net movement of WATER molecules from
a region of high water conc (HWC) to a
region of low water conc (LWC) through a
selectively permeable membrane along a
conc gradient.
Hypotonic
Solution
Hypertonic
Red Blood
Solution
Cell.
Isotonic
Solution
Water moves from a high concentration
outside the cell to a low concentration
inside the cell. The cell swells up and
bursts.
Water moves from a high concentration
inside the cell to a low concentration
outside the cell. The cell loses water
and shrivels up.
The water concentrations are equal inside and outside the cell.
There is no net movement of water.
Active Transport
copy
• Active transport is movement of
molecules from a region of low
concentration to a region of high
concentration against the concentration
gradient. Proteins in the membrane act
as carriers and transfer the molecules
across the membrane. It is an active
process and requires energy from ATP.
The rate of active transport is affected
by temperature, oxygen availability and
the concentration of the respiratory
substrate glucose.
Active transport –
sodium potassium pump
• Active transport often involves ions
(charged atoms)
• The sodium – potassium pump actively
transports sodium ions out of the cell and
potassium ions into the cell.
Phagocytosis animation
• http://www.kscience.co.uk/animations/pha
gocyte.htm
Endocytosis
• The cell membrane engulfs material and
takes it into the cell.
a) Phagocytosis solids are engulfed.
b) Pinocytosis liquids are engulfed.
Exocytosis
• Inside the cell, substances
become surrounded by
membrane. This “bubble”
of membrane fuses with
the cell membrane and the
substance is excreted from
the cell.
• Bacteria:
http://www.twigonglow.com/mindmap/#207/immunedefence?&_suid=13463256600310729821
9281124401
copy
• Diseases- are caused by pathogens e.g.
bacteria, viruses and fungi. When
foreign particles enter the body they
are detected due to their antigens
which act as a signature. In response to
foreign antigens antibodies are
produced by the body which will make
the pathogen harmless.
copy
• Common antigens- which are recognised
as non-self are microbes, pollen, blood
cells and transplanted organs.
• Spread of disease- disease is spread
through the air (e.g. flu), by contact
(e.g. measles), through food and drink
(e.g. salmonella) and through wounds
(e.g. rabies).
• Immune defence (lhs)
http://www.twigonglow.com/mindmap/#207/immunedefence?&_suid=134632566003107298219281
124401
• Cell defence – Bozemanbiology
• http://www.youtube.com/watch?v=z3M0vU3Dv8
E&list=UUEikU3T6u6JA0XiHLbNbOw&index=50&feature=plp
p_video
copy
• First Line of Defence- skin, cilia and
mucus, stomach acid, body secretions
(tears which contain lysozyme), coughing,
sneezing, vomiting, ear wax and clotting of
the blood.
• Immune defence (rhs)
http://www.twigonglow.com/mindmap/#207/immunedefence?&_suid=13463256600310729821
9281124401
Second Line of Defence
• Individual cells respond to invasion by
becoming inflamed. The cells release
histamine which increases blood supply to
the area. The infected area becomes hot,
looks red and swells. The blood brings
extra white blood cells and chemicals to
fight the infection. The infection produces
a fever. The white blood cells (aka
leucocytes) engulf antigens and produce
antibodies.
• Granulocyte- engulfs pathogens
• Monocyte- engulf pathogens
- when they move into tissues from the blood
they become bigger and are known as
macrophages.
• Lymphocyte- produce antibodies.
Non
specific –
attack any
pathogen
Specific –
attacks only
certain
pathogens
Phagocytosis
Phagocytosis animation
• http://www.kscience.co.uk/animations/pha
gocyte.htm
•Granulocytes, monocytes and macrophages
all engulf bacteria when it enters the body.
This process is called phagocytosis.
Once the bacteria is
inside the blood cell,
enzymes from
lysosomes digest
the bacteria.Dead
bacteria and blood
cells form pus at the
injury site.
• Bozeman biology immune system:
• http://www.youtube.com/watch?v=z3M0vU
3Dv8E&feature=plcp
Third Line of Defence
• Copy
• Antibodies are proteins that are made in
response to foreign substances.
Antibodies are specific and therefore the
body has thousands of lymphocytes, each
of which can only make one type of
antibody. Antibodies are Y shaped, each
arm has a receptor site which is specific to
a particular antigen. When the antibody
binds to the antigen the pathogen
becomes harmless.
Lymphocyte animation
• http://www.kscience.co.uk/animations/lym
phocyte.htm
Action of Lymphocytes
Lymphocytes are made in bone marrow.
Some pass into the lymph glands and
replicate to form B cells.
B cells - B cells are stimulated by the
presence of antigens and multiply rapidly.
Some mass produce the antibody (neutralise
the antigen) while others become memory
cells. If the pathogen attacks again the
memory cells produce B and T cells.
Lymphocytes
lymphocytes made in bone marrow
pass into lymph gland
and replicate
become B cells
stimulated by presence
of antigens, replicate and either:
mass produce
antibodies
become
memory cells
(will produce correct B and
T cells if pathogen attacks again)
Other lymphocytes pass into the thymus gland
and replicate to become T cells. There are 2
types of T cells:
Killer T cells - When a virus enters a body
cell the killer T cells destroy that infected cell.
Helper T cells – look out for foreign antigens in
the body. When an antigen is spotted they
activate B cells, Killer T cells and
macrophages.
Lymphocytes
lymphocytes made in bone marrow
pass into thymus
gland and replicate
become T cells
killer T cells
identify viruses
and destroy the
infected cell
helper T cells
look out for
foreign
antigens and
respond by
activating B
cells, killer T
cells and
macrophages
AKA cell mediated response
pass into lymph gland
and replicate
become B cells
stimulated by presence
of antigens, replicate and either:
mass produce
antibodies
become
memory cells
(will produce correct B and
T cells if pathogen attacks again)
AKA humeral response
Disease prevention
Give 3
reasons
why the
disease is
usually
prevented
the second
time around
Disease prevention
• A disease is usually prevented the second
time around because:
- Memory cells have the required
antibodies already so they are produced
i) much quicker and ii) in greater numbers
- Higher numbers of antibodies remain
for longer
Types of immunity
• When the body is able to acquire the
specific antibodies to fight a certain
pathogen, it is said to have become
‘immune’.
• This means that it can fight and destroy
the pathogen immediately, therefore we do
not become ill by it again.
• Smallpox vaccine:
http://www.twigonglow.com/mindmap/#207/immunedefence?&_suid=13463256600310729821
9281124401
Acquired / Active Immunity
- the body actively acquires immunity to a
disease, either:
• Natural- when attacked, T and B cells are made which
produce the required antibodies. Memory cells are also
produced and recognise and produce the correct
antibodies quicker.
• Artificial- through a vaccine which contains a harmless
form of the pathogen (the antigens remain unaltered).
The body reacts to the foreign antigen in the normal way
without the person suffering from the disease and will
have developed memory cells for future use.
Passive immunity
-the body receives ‘outside’ antibodies, either:
• Natural passive immunityi)antibodies given to developing foetus through
the placenta, or
ii) antibodies given to the baby in the mothers
milk.
• Artificial passive immunity- injection of
antibodies. e.g. tetanus The effect is short lived
but gives the person high temporary levels of
antibodies
Allergy
• This is when the immune system over-reacts
and responds to a harmless substance.
• E.g. pollen, feathers, dust, penicillin
• The cells over-react by producing histamine
which causes nasal congestion, constriction of
bronchioles etc…
• It can be relieved by anti-histamine drugs.
Autoimmune Response
• Copy
• Normally the immune system doesn’t
attack its own cells. If it does, it is
called autoimmunity. Autoimmune
diseases are rheumatoid arthritis (
cartilage attacked) and multiple
sclerosis ( myelin sheath on nerve
attacked).
Self & Non-self
• Human body can recognise it’s own cells
(SELF) and attack cells which do not
belong to it (NON-SELF).
• Blood types – Bozemanbiology
• http://www.youtube.com/watch?v=KXTF7
WehgM8&list=UUEikU3T6u6JA0XiHLbNbOw&index=14&featur
e=plpp_video
ABO Blood System
There are 4 blood groups - A, B, AB and O.
Red blood cells have antigens on their
surface. There are also antibodies present in
the plasma.
Whenever incompatible antigens and
antibodies are mixed agglutination or clotting
results.
BLOOD GROUP ANTIGEN
(RBC)
A
B
AB
O
A
B
AB
None
ANTIBODIES
PLASMA
B
A
None
AB
BLOOD
GROUP
A
B
AB
O
CAN
CAN
DONATE TO RECEIVE
FROM
A
A
AB
O
B
B
AB
O
AB
A
B
AB O
A
B
O
AB O
Transplants
• Transplants are recognised as non self
and are attacked by the body’s immune
system. This is called tissue rejection. The
transplant tissue is typed and matched to
be as close as possible to self. The
problem of rejection is overcome by giving
immunosuppressor drugs which inhibit the
immune system.
Virus
• http://www.youtube.com/watch?v=U2h0E
CyMWhE&feature=plcp
• HIV virus
http://www.twigonglow.com/mindmap/#207/immunedefence?&_suid=13463256600310729821
9281124401
Viruses
• Viruses – Bozemanbiology
• http://www.youtube.com/watch?v=L8oHs7G_syI
&list=UUEikU3T6u6JA0XiHLbNbOw&index=35&feature=plp
p_video
• Viral replication simulation – Bozemanbiology
• http://www.youtube.com/watch?v=4ow6XEwZVz
k&list=UUEikU3T6u6JA0XiHLbNbOw&index=74&feature=plp
p_video
Structure
• A virus is not a cell. It consists of 1 type of
nucleic acid (DNA or RNA) surrounded by
a protective coat (capsid) normally made
of protein.
• Size- 20-300(nm) (1nm = 1*10¯9m)
Replication
• Copy
• Its genetic material carries the information
necessary for viral multiplication but lacks
the biochemical machinery to carry this out
on its own.
• BBC Horizon Whyd o viruses kill? ¼ series
http://www.youtube.com/watch?v=1a4fzxS_i
pg
Viral Diseases
• Small pox- infectious disease which caused a
fever and was fatal in 1 in 5 cases. Survivors
were left permanently scarred. A vaccine was
developed using cow pox.
• Polio- poliomyelitis virus is found in faeces and
can be passed onto food by flies. A vaccine has
eradicated polio in developed countries.
• Aids- Acquired Immune Deficiency Syndrome is
caused by the retrovirus called Human
Immunodeficiency Virus (HIV). HIV attacks
helper T lymphocytes.
WALT
• Explain the importance of correct cell
replication.
• Describe the stages and processes which
occur during mitosis
• BBC horizon the DNA years
http://www.youtube.com/watch?v=FCzWd
9dXURM
• Mitosis: http://www.twigonglow.com/mindmap/#208/thecell?&_suid=13463253996250778752739
7240546
Cell
division
All complex organisms
originated from a single
fertilised egg.
Every cell in your body
started here, through cell
division the numbers are
increased
Cell then specialise and
change into their various
roles
Mitosis
• Mitosis is the process by which new body
cell are produced for:
– Growth
– Replacing damaged or old cells.
This is a complex process requiring different
stages
Observing Chromosomes
• All the cells of an organism have a certain
number of chromosomes
• E.g.
– Onion – 8 pairs
– Man – 23 pairs
– Chimp – 24 pairs
– Dog – 39 pairs
Privet hedge – 23 pairs
* This is called the ‘chromosome complement’ *
Introduction
• Each species has a specific number of
chromosomes called the ‘chromosome
complement’. The appearance of the
chromosome complement is called the
karyotype.
• Human body cells contain 46 chromosomes (23
‘homologous’ pairs).
• 23 pairs = 22 pairs of autosome chromosomes
+ 1 pair of sex chromosomes
(female = XX, male = XY)
Cell Division - Mitosis
• When 1 body cell divides into 2 for
either growth or repair it is important
that there are enough chromosomes for
the 2 new cells.
46
chromosomes
46
chromosomes
46
chromosomes
Parent cell
Chromosomes are
copied and double
in number
Chromosomes
now split
2 daughter cells
identical to original
• Mitosis – Bozemanbiology
• http://www.youtube.com/watch?v=1cVZBV
9tD-A&list=UUEikU3T6u6JA0XiHLbNbOw&index=22&featur
e=plpp_video
• The DNA has to replicate (make a copy
of itself) to provide enough
chromosomes for the 2 new cells.
A
C
T
G
A
C
T
G
T
G
A
C
T
G
A
C
A
C
T
G
T
G
A
C
• Energy, enzymes, DNA nucleotides and
a DNA template are needed
Mitosis animation
• http://www.cellsalive.com/mitosis.htm
• During mitosis each parent cell
produces 2 daughter cells which are
identical to each other and the parent
cell. Each cell has the diploid number of
chromosomes (2 sets).
• The DNA replicates.
• The chromosomes
become visible.
• The chromosomes can be
seen to consist of 2
chromatids joined at the
centromere.
• DNA replication
caused the formation centromere
of these 2 chromatids.
chromatid
Chromosome
• A spindle forms in
the cell. The
spindle
chromosomes move
on to the equator of
the spindle.
The spindle fibres
contract and pull
chromatids from
each pair to opposite
ends of the cell
• The cytoplasm starts
to divide to form 2
cells.
• The 2 new cells are identical to each
other and to the original cell
Can you think of how to remember
the order????
•
•
•
•
•
I
P
M
A
T
WALT
• Name of the process whereby sex cells
(gametes are produced)
• State the number of pairs of
chromosomes present at the beginning
and in the new cells produced.
• Give the correct names for these
numbers
• Explain the process by which
chromosomes move and separate
• Inheritance 1:
http://www.twigonglow.com/mindmap/#206/genetics?&_suid=13463263811
2507263694461188228
• Bozeman biology genetics intro:
http://www.youtube.com/watch?v=Xk0bnJ
PtsrI&feature=plcp
Meiosis
• Diploid haploid cells:
• http://www.youtube.com/watch?v=MU83V
WAvUf4&feature=plcp
Meiosis
Normal adult cell
containing 46
chromosomes (23 pairs)
Sperm containing
23 chromosomes (half the
number)
• Meiosis – Bozemanbiology
• http://www.youtube.com/watch?v=rB_8dTuh73c
&list=UUEikU3T6u6JA0XiHLbNbOw&index=16&feature=plp
p_video
• Mitosis and meiosis – Bozemanbiology
• http://www.youtube.com/watch?v=pOROHmEm
qmU&list=UUEikU3T6u6JA0XiHLbNbOw&index=61&feature=plp
p_video
Maintaining chromosome complement
(number) during reproduction
46
23 23
23
46
MEIOSIS
23
23
23
23 23
Add these labels:
Egg mother cell
Male gamete
46
Female gamete
zygote
Sperm mother cell
fertilisation
Maintaining chromosome number
during reproduction
Egg mother cell
23 23
46
23
46
MEIOSIS
23
23
Female gamete
23
Sperm mother cell
23 23
Male gamete
fertilisation
46
Zygote
Cell Division - Meiosis
• Cell division must also occur to produce sex
cells, known as _________. Each sperm or
egg mother cell contains ___ chromosomes,
or 2 sets (2n) known as a ________
number, however each sperm / egg cell
must only contain ______ chromosomes, or
1 set (1n) known as a _______ number.
• These sex cells are different from the parent
cell so meiosis allows variation.
• Adult cells have half / double the
chromosomes complement of gametes.
• Zygotes have half / double the
chromosome complement of gametes.
Meiosis animation
• http://www.cellsalive.com/meiosis.htm
• Meiosis: http://www.twigonglow.com/mindmap/#208/thecell?&_suid=13463253996250778752739
7240546
Chromosome becomes
visible.
First Division
• The chromosomes become
visible and can be seen
to consist of 2 chromatids
joined at the centromere.
DNA replication has
already occurred.
• The homologous pairs
of chromatids lie
alongside each other.
Chromatids from each
may cross over and join
to form chiasmata.
These chiasmata hold
the pair together and
as pieces of chromatid can swap
between the chromosomes they allow
variation.
• The homologous
pairs of chromosomes
align up along the
equator of the spindle
• The spindle fibre
contracts and pulls
each chromosome
(of the pair) to
opposite ends of
the cell.
• The spindle fibre
contracts and pulls
each chromosome
(of the pair) to
opposite ends of
the cell.
• The cytoplasm divides
to form 2 cells.
Each cell goes through
the second division
Second Division
• The chromosomes
align themselves
along the equator
of the spindle
• The spindle fibres
contract and pull
each chromatid to
opposite ends of
the cell.
• The cytoplasm
divides.
• 4 sex cells are
formed. Each
has the haploid
number of
chromosomes.
• Meiosis occurs in the testes and the
ovaries to form 4 cells which have half
the number of chromosomes. It is a
reduction division which forms 4 cells.
• Bozeman biology mechanisms that
increase variation:
http://www.youtube.com/watch?v=UjMn4o
HfYL4&feature=plcp
Independent Assortment
During the first meiotic division the homologous
pairs of chromosomes can be arranged in 2
different ways on the spindle.
Or
This option is available to all of the homologous
pairs of chromosomes so there are many
possible combinations of chromosomes in the
sex cells.
Fertilisation
Fertilisation is a random process which increases
J.Wallace2003
variation.
Crossing over
These “cross overs” occur when the
homologous chromosomes lie together
and the chromatids cross over and join.
When the pairs of chromosomes are
pulled apart the “joins” break and
pieces of chromosome are swapped.
• http://www.twigonglow.com/mindmap/#206/genetics?&_suid=13463263811
2507263694461188228
• Bozeman biology review of terms:
http://www.youtube.com/watch?v=fPCtvQI
StSg&feature=plcp
Phenotype
An organisms appearance resulting from its
parents.
Genotype
Alleles of genes a person has
Dominant
Allele that is always expressed in the phenotype
if it is present.
Recessive
Is masked by the presence of a dominant allele.
Heterozygous
2 different alleles present
Homozygous
2 of the same alleles present
F1
First generation
F2
Second generation
Haploid
One set of chromosomes
Diploid
Double set of chromosomes
Gene
A unit of heredity which controls a genetically
inherited characteristic.
Allele
Different forms of the gene.
• Mendel and inheritance:
http://www.twigonglow.com/mindmap/#206/genetics?&_suid=13463263811
2507263694461188228
• Bozeman biology Mendelian genetics:
http://www.youtube.com/watch?v=NWqgZ
UnJdAY&feature=plcp
Forms of a Gene
• Genes control a characteristic e.g. hair
colour.
• There are two forms of a gene called
ALLELES e.g. Brown, blonde.
• Genotype – the alleles a person has. This
can be represented by different symbols (e.g.
a gene for Brown hair form both parents B
from mother, B from father = BB)
• Phenotype – the observable characteristics of
an individual.
• If the alleles are the same e.g BB or bb the
gene is said to be homozygous or true
breeding.
• If the alleles are different e.g. Bb the gene
is said to be heterozygous.
Dominant/Recessive
• Dominant alleles mask the other allele and
are always shown in the person’s
phenotype. (BB or Bb = Brown hair)
• Recessive alleles only show in the
phenotype if both alleles are recessive.
(bb = blond hair)
Parents
Roller
(Pure breeding)
X Non roller
Genes
TT
X
tt
Gametes
T
X
t
F1
Tt
(First set of offspring)
Rollers
• A beginner’s guide to punnett squares –
Bozemanbiology
• http://www.youtube.com/watch?v=Y1PCw
xUDTl8&list=UUEikU3T6u6JA0XiHLbNbOw&index=86&featur
e=plpp_video
Parents
Tt
X
Gametes
T or t X
Tt
T or t
Gametes
T
t
T
TT
Tt
t
Tt
tt
• Genotype expression – Bozemanbiology
• http://www.youtube.com/watch?v=fPCtvQI
StSg&list=UUEikU3T6u6JA0XiHLbNbOw&index=82&featur
e=plpp_video
• A black male mouse and a white female mouse
produced a black mouse offspring. What allele
is dominant and which one is recessive?
• What letters could you use to represent each
allele?
• What allele would the offspring mouse have?
• What colour would the mouse be?
• If the offspring mouse was to reproduce with a
black mouse (Bb) would all of their offspring be
black?
Extra Practise
• If mum has blue eyes (bb) and dad has
brown eyes (BB), what colour eyes would
the first and second generation have?
Write down the genotypes, gametes etc.
Incomplete Dominance
•One allele of a gene is not completely
dominant over the other. There is an in
between state in the heterozygote e.g. sickle
cell anaemia.
A mutation causes the formation of
haemoglobin S which is an inefficient oxygen
carrier. When this mutation is homozygous
(SS) haemoglobin S is formed and the red
blood cells are sickle shaped (interferes with
the circulation and causes death). If the
mutation is heterozygous (HS) there are no
sickle shaped red blood cells (sickle cell trait).
Parents
HS
Gametes
F1
X
H or S X
HS
H or S
Gametes
H
H
HH
S
HS
S
HS
SS
Genotypes
HH
2HS
SS
Phenotypes 1 Normal 2 sickle cell trait
( Sickle cell anaemia dies).
1 sickle cell anaemia
Co-Dominance
• One allele is not dominant over the other
and both genes are expressed e.g. MN
blood system.
Genotype
Blood Group
MM
M
NN
N
MN
MN
Parents
Gametes
F1
MM
M
X
X
MN
NN
N
Multiple Alleles
• This occurs when more than 2 alleles can
occupy the same spot on the chromosome
e.g. ABO blood system.
O
O
A
A
Group O Group A
B
B
Group B
A
O
Group A
B
O
Group B
A
B
Group AB
A and B are co-dominant to each other
and are both dominant over O.
Parents
Gametes
F1
Gametes
B
O
AO
X
BO
A or O
X
B or O
A
AB
AO
O
BO
OO
Phenotypes AB, A, B, O
Gamete Production
23 chromosomes
23 chromosomes
46 chromosomes
Sex Chromosomes
XY
XX
X
X
X
XX
XY
Y
• Humans have 22 pairs of autosomes and
1 pair of sex chromosomes. In the
females sex chromosomes are XX and in
male they are XY. Sex linked genes are
carried on the sex chromosomes ( on
the X chromosome as the Y chromosome
is very small) e.g. colour blindness
The X chromosome
is much larger than
the Y chromosome
and can carry more
genes. These genes
are said to be SEX
LINKED.
If the X and Y chromosome
meet during fertilisation the
genes on this part of the X
chromosome are always
expressed as the smaller Y
chromosome does not
possess alleles for this gene
Colourblindness, haemophilia and muscular
dystrophy are caused by sex linked genes.
Haemophilia (blood doesn’t clot) is caused by a
recessive sex linked gene.
Parents Carrier female X Normal male
XHXh
X
XHY
Gametes
XH or Xh X XH or Y
F1
Gametes XH
Xh
XH
Y
XHXH
XHY
XHXh
XhY
Phenotypes Normal female, Carrier female,
Normal male, Haemophiliac male
Parents
XHXH
Gametes
XH or XH X
F1
Gametes
Xh
Y
Phenotypes
males
XhY
X
Xh or Y
XH
XHXh
XH
XHXh
XHY
XHY
Carrier females, Normal
XHXh
X
XhY
XH or Xh
X
Xh or Y
Parents
Gametes
F1
Gametes
Xh
Y
XH
XHXh
XHY
Xh
XhXh
XhY
Phenotypes: Carrier female,
Haemophiliac female, Haemophiliac
male, Normal male.
DISCONTINUOUS
VARIATION – single gene
inheritance
• Earlobe shape –
detached or attached
• Blood groups - A, B, AB
or O
DISCONTINUOUS VARIATION
Characteristics which fall into distinct, separate categories are said to
show discontinuous variation. (remember variation simply means
differences)
They would be represented in bar graphs, as below:
CONTINUOUS VARIATION
• Characteristics which show a
range of differences on a
continuous scale are said to show
continuous variation.
• They are described as showing
continuous variation and are
therefore drawn as a line graph
• E.g. Skin tone
• Continuous variation is always
controlled by more than one
gene, known as polygenic
inheritance.
Polygenic inheritance
• http://www.youtube.com/watch?v=gouqTq
5p168
• Chromosomal genetics (polygenics) –
Bozemanbiology
• http://www.youtube.com/watch?v=rIe7mP
XkYhs&list=UUEikU3T6u6JA0XiHLbNbOw&index=17&featur
e=plpp_video
Polygenic Inheritance
• There are 2 types of inheritancediscontinuous and continuous. In discontinuous
variation there are distinct groups e.g. tongue
rolling (either you can or you can’t). The
characteristic is usually controlled by a single
gene. In continuous variation there are no
distinct groups e.g. height. The characteristic
is controlled by more than one gene, this type
of inheritance is called polygenic.
Single gene
polygenic inheritance
1 gene
2 genes
as every gene has 2 alleles:
Genotype
2 alleles
4 alleles
Skin Colour
• Skin colour is controlled by several genes but
let’s imagine that it is controlled by 2 genes
represented by the letter R: R1 and R2.
The dominant form of both genes is black – R
The recessive form of both genes is white - r
•
Skin colour
• The homozygous dominant (black) genotype would
look like this: R1R1R2R2
R1R1R2R2
first gene second gene
• The homozygous recessive genotype r1r1r2r2 is
white.
• All the other genotypes are different shades,
e.g.R1r1R2r2
R1R1R2R2
R1r1R2R2
R1R1R2r2
r1r1R2R2
R1r1R2r2
R1R1r2r2
R1r1r2r2
r1r1R2r2
r1r1r2r2
- black
- dark brown
- dark brown
- brown
- brown
- brown
- light brown
- light brown
- white
Parents
Black
R1R1 R2R2
X
X
White
r1r1 r2r2
Each gamete will have one allele from each gene
passed on:
R2
R1
R1R2
R1
R1R2
R2
R1R2
R1R2
Gametes
F1
R1R2
X
r1
r2
r2
r1
r1r2 R1r2
r1r2 r1r2
r1r2
R1r1R2r2 (brown)
Parents
R1r1R2r2
X
R1
r1
R2
R1R2
r1R2
r2
R1r2
r1r2
Gametes
R1R2, R1r2
r1R2, r1r2
X
R1r1R2r2
R1
r1
R2
R1R2
r1R2
r2
R1r2
r1r2
R1R2, R1r2
r1R2, r1r2
Gametes
R1R2
R1r2
r1R2
r1r2
R1R2
R1R1R2R2
R1R1R2r2
R1r1R2R2 R1r1R2r2
R1r2
R1R1R2r2
R1R1r2r2
R1r1R2r2 R1r1r2r2
r1R2
R1r1R2R2
R1r1R2r2
r1r1R2R2 r1r1R2r2
r1r2
R1r1R2r2
R1r1r2r2
r1r1R2r2
Black
Dark brown
Light brown
White
r1r1r2r2
Brown
Polygenic inheritance
• I cross two parents:
male
r1R1r2R2
x
female
R1R1R2r2
1. Which parent will be lighter coloured?
2. What are the possible genotypes of the male and
female gametes? (Hint – do punnet squares for both,
each gamete should contain 2 alleles )
3. What are the possible genotypes of the F1 offspring?
(Hint- do a large punnet square, each offspring should
contain 4 alleles)
4. What % could turn out i) pure black ii) pure white?
• Huntingdon’s and cystic fibrosis:
http://www.twigonglow.com/mindmap/#206/genetics?&_suid=13463263811
2507263694461188228
Mutations
• A mutation is a change in the structure
or amount an organism’s DNA.
• This can be a tiny change where only
one base is altered or a change in the
number of chromosomes.
• An individual is called a mutant if a
change in the genotype is expressed in
the phenotype
• Watch:
• http://www.youtube.com/watch?v=efstlgoy
nlk&feature=plcp
• Bozeman biology mutations:
http://www.youtube.com/watch?v=OaovnS
7BAoc&feature=plcp
Mutations
SUSBSTITUTION OF A NUCLEOTIDE
GGCCTCCTC
GGCCACCTC
CCGGAGGAG
CCGGUGGAG
PRO – GLU - GLU
PRO – VAL - GLU
INVERSION OF TWO OR MORE NUCLEOTIDES
AGAGTCT TC
AGATGCTTC
UCUCAGAAG
UCUACGAAG
SER –GLUN - LYS
SER – THR - LYS
Mutations
INSERTION OF A NUCLEOTIDE
GGCCTCCTC
GGCCCTCCT
CCGGAGGAG
CCGGGAGGA
PRO – GLU - GLU
PRO – GLY - GLY
T deleted
DELETION OF A NUCLEOTIDE
AGAGTCT TC
AGA G CTTCG
UCUCAGAAG
UCU C GAAGC
SER –GLUN - LYS
SER – ALA - SER
• Mutations arise spontaneously and at
random but only occur rarely.
• The mutation rate can be increased by
mutagenic agents such as X-rays, UV
light.
• BBC Horizon the ghost in your genes:
http://www.youtube.com/watch?v=Q6cQS
R3mPm8
Chromosomal Abnormalities
• Chromosomes can be affected by
mutations where unusual gametes are
formed.
• Zygotes with abnormal chromosome
complements such as 47 chromosomes
can be produced due to NONDISJUNCTION during meiosis.
Non-Disjunction
• Homologous
chromosomes fail to
separate because a
spindle fibre fails.
• This results in extra or
missing
chromosomes in the
gametes.
Non-Disjunction
Extra copy of chromosome 21
Down’s Syndrome
• copy
• If non-disjunction of chromosome 21 occurs in
the egg mother cell then one or more
abnormal eggs may be formed. If this egg
becomes fertilised than a zygote is formed
containing 47 chromosomes.
• Down’s syndrome is characterised by mental
retardation and distinctive physical features.
• non-disjunction of the egg mother cell is
related to age therefore pregnant women
over the age of 35 are routinely offered a
fetal chromosome analysis.
Lacks a second sex chromosome causing infertility
Turner’s Syndrome
• Copy
• If a gamete which posses no sex chromosomes
fuses with an normal X gamete then a zygote is
formed with 45 chromosomes.
• The sufferer is always female and short. Since
their ovaries do not develop secondary sexual
characteristics also fail to develop (e.g. breasts,
menstruation ect).
• Occurs 1 in 2500 live female births.
Extra X chromosome causing infertility
Klinefelter’s Syndrome
• Copy
• If an XX egg is fertilised by a normal Y sperm or
a normal egg is fertilised by an XY sperm then
the zygote formed has 47 chromosomes (44 +
XXY).
• The sufferer is always male but are infertile
since their testes only develop to about half their
normal size and fail to produce sperm. The small
testes fail to produce testosterone which results
in the failure to produce secondary
characteristics (e.g. facial hair, deepening of the
voice etc)
Genetic Screening
Pedigree
• Family trees (pedigree) can be used to
construct a pattern of inheritance.
• Once the phenotypes are known, most
of the genotypes can be deduced.
• It can then be used to work out the
possibility of passing on a genetic
disorder.
• This form of genetic counselling allows
people to make informed decisions
based on the information available and
the risks of passing on a disorder.
Cystic fibrosis: recessive
autosomal condition
• http://www.youtube.com/watch?v=zzhmr1
qom3Q&feature=channel&list=UL
Autosomal Recessive Inheritance
• The trait is rare
• The trait tends to skip generations
• Both males and females are affected
equally
• All sufferers of the trait are homozygous
recessive.
Autosomal Dominant Inheritance
• The trait appears in every generation
• Each sufferer of the trait has an affected
parent
• Males and females are affected in equal
numbers
• All non sufferers are homozygous
recessive
• http://www.twigonglow.com/mindmap/#209/usinggenetics?&_suid=1346327368421067314
60647874807
• Bozeman biology genetics review:
http://www.youtube.com/watch?v=xUf2PJ
ugr-U&feature=plcp
Sex Linked Recessive
• More males are affected than females
• None of the sons of an infected male show
the trait
• All sufferers are homozygous recessive
Pre-natal Screening
• Two methods that require foetal
material to be taken to obtain a
karyotype;
• Amniocentesis – removal of amniotic
fluid containing foetal cells using a
needle placed into the womb.
• Chorionic Villus Sampling – small
sample of placental cells are taken
using a tube inserted into the mother’s
reproductive tract. Cells examined.
Higher risk of miscarriage.
Post-natal screening
• PKU can be tested for after the baby is
born and if discovered PKU sufferers can
be fed a low phenylalanine diet to prevent
mental retardation.