GENETICS
1
LEVELS OF ORGANIZATION TO LIFE
 Nonliving Levels
1.
Atom (elements)
2.
Molecule (compounds like
carbohydrates and proteins)
3.
Organelles (parts of the cell: nucleus,
cytoplasm, etc…)
2
LEVELS OF ORGANIZATION TO LIFE
 Living Levels
1.
Cell (makes up ALL organisms)
2.
Tissue (cells working together)
3.
Organ (a group of tissues. Heart, brain,
stomach, etc…)
4.
Organ System (A group of organs that
work together)
5.
Organism
3
THE CELL
 Cells are the basic
structure of all living
beings, from singlecell bacteria to giant
sequoias, flies to
elephants, fungi to
human organisms.
The CELL is the
basic unit of
life.
4
THE CELL THEORY
The cell theory describes the basic
properties of all cells.
1. All living things are composed of one
or more cells.
2. The cell is the basic unit of life.
3. All new cells arise from existing cells
5
THE STRUCTURE AND FUNCTION OF
THE HUMAN CELL
 MOST cells are so small they can only be observed under a
microscope.
 The average sized human has an estimated 100,000
BILLION cells
 An optical microscope allows us to distinguish Four cell
components:
 The cell membrane
 The cytoplasm
 The nucleus
 The nuclear membrane
6
THE
STRUCTURE
AND
FUNCTION
OF THE
HUMAN
CELL –
GRADE 9
REVIEW
7
THE CELL
MEMBRANE
 The CELL
MEMBRANE is
a flexible
barrier that
surrounds the
cell contents,
allowing the
cell to interact
with its
environment.
8
THE CYTOPLASM
 The CYTOPLASM is all of
the material within the
cell membrane and
outside the nucleus.
 The two major
components of
cytoplasm
 Cytosol
 Organelles
9
THE NUCLEUS
 The NUCLEUS, easily recognizable by its darker
colour, is the cell’s control center.
 It contains a molecule that controls all cell activity:
DNA – Deoxyribonucleic Acid
10
THE
NUCLEUS
11
THE NUCLEUS – NUCLEAR MEMBRANCE
 The NUCLEUS, contains
and protects individual
genetic information.
 The outer layer of the
nucleus is called the
NUCLEAR MEMBRANE.
Much like the cell
membrane it

forms a barrier and protects
the nucleus and

Enables certain exchanges
with the rest of the cell
12
ORGANELLES – OTHER CELL STRUCTURES
 Organelles are
structures that
enable the cell
to live, grow
and reproduce
13
MITOCHONDRIA
 The
MITOCHONDRIA
converts energy
stored in food into
usable energy,
through cellular
respiration
 It is considered the
powerhouse of the
cell
14
MITOCHONDRIA
GOLGI APPARATUS
 The GOLGI
APPARATUS
stores material
produced by the
cell and
transports it to
the cell
membrane and
outside the cell
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GOLGI APPARATUS
17
ENDOPLASMIC RETICULUM
The ENDOPLASMIC
RETICULUM produces
some of the material
necessary for cell
activities
 Transports material
from one part of the
cell to another.
 There is rough and
smooth ER
 Rough ER is
characterized by the
presence of Ribosomes

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ENDOPLASMIC RETICULUM
19
RIBOSOMES
 RIBOSOMES
produce some of
the material
necessary for cell
activities.
 They are
responsible for
making proteins
(protein synthesis)
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RIBOSOMES
CYTOSOL
 CYTOSOL is the
gelatinous liquid
found inside the cell.
produce some of the
material necessary
for cell activities.
 The cytoplasmic
organelles are within
the cytosol.
22
LYSOSOMES
 Lysosomes contain
molecules known as
enzymes that help
digest materials
brought into the cell.
 They also help
breakdown and
recycle organelles.
23
LYSOSOMES
FACTORS RESPONSIBLE FOR CHARACTER
TRAITS AMONG LIVING ORGANISMS
•The similarities and difference amongst a species
are known as CHARACTER TRAITS.
•Character traits are the physical, psychological
and physiological attributes that vary from
individual to individual.
•How is it that individual have different character
traits?
fere
A LOOK INSIDE THE NUCLEUS CHROMOSOMES
•
Most eukaryotic cells contain a nucleus holding a person’s
basic genetic information.
•
The main component of the nucleus is CHROMATIN, made
up of a molecule of DNA, combined with PROTEINS.

•
CHROMATIN is a mass of DNA and proteins within the
nucleus of most cells not undergoing division.
When the cells are about to divide, chromatin contracts
forming visible rods called CHROMOSOMES
CHROMOSOMES
Is the DNA in the nucleus just free
floating all over the place?


YES AND NO!

Each DNA molecule inside the
nucleus is partially uncoiled.
HOWEVER! During cell division, the
DNA becomes compact and forms
into CHROMOSOMES

A CHROMOSOME is a
that is formed when chromatin
contracts. It is visible under the
microscope.
29
CHROMOSOMES
The nucleus of each human cell (except for red blood cells
and reproductive cells (sperm and ova)) contains 23 PAIRS
of CHROMOSOMES.


23 PAIRS = 46 chromosomes.

Where do we get our chromosomes from?

In EACH PAIR of chromosomes, one comes from your
mother and the other from your father.

22 pairs are made up of homologous (similar)
chromosomes in both males and females.


They share a similar size and shape
The 23rd pair is the SEX CHROMOSOME
30
CHROMOSOMES

KARYOTYPE: is an ordered
representation of an individual’s
chromosomes, obtained by
grouping them into pairs according
to SIZE.

NOTICE the 23rd Chromosome
difference between males and
females

Females have TWO “X”
chromosomes

Males have ONE ”X”
chromosome and ONE “Y”
chromosome.
31
DNA AND GENETIC MATERIAL
 The nucleus contains the cell’s genetic material,
which is responsible in part for our physical
appearance.
 This genetic material also contains all
the necessary instructions for the cell to
function properly.
 The instructions for the manufacturing of substances
the cell needs to produce for life.
32
CHROMOSOMES

The number of chromosomes varies between different species
and the more one has, does not mean complexity
33
Number of Chromosomes
34
SEX CHROMOSOMES
• Normally, only one pair can contain chromosomes
of different sizes, the pair of SEX
CHROMOSOMES.
• As with most animals, two sex chromosomes are
the same for females (XX pair), while in the
male, one of the two chromosomes is smaller
(XY pair).
THE NUCLEUS – REVISITED!
 The NUCLEUS, easily recognizable by its darker
colour, is the cell’s control center.
 It contains a molecule that controls all cell activity:
DNA – Deoxyribonucleic Acid
36
DNA D e ox y r i b o nu c l e i c A c i d
Found inside the cell nucleus in long chains that
are coiled like telephone cord to form a
DOUBLE HELIX. It consists of a series of
chemical units called nucleotides.
 Every cell in your body has the same
DNA, with few exception.
 Red Blood Cells being an exception since they
do not contain a nucleus.
 DNA forms the basis of life on Earth.
 DNA molecules contain instructions for
building every living organism from the tiniest
bacterium to a massive blue whale.

37
THE COMPONENTS OF DNA

DNA is a long molecule made up of repeating
individual units of monomers called nucleotides.

Nucleotides are made up of three parts that are held
together by bonds:
1. A sugar: DEOXYRIBOSE (sides of the
ladder)
2. A PHOSPHATE group (sides of the
ladder)
3. One of 4 nitrogenous bases:
ADENINE (A), THYMINE (T),
GUANINE (G) or CYTOSINE (C)
(rungs of ladder)
A nucleoside is just the sugar and Nitrogenous base
DNA

When you uncoil the double
helix structure DNA has the
appearance of a ladder with
millions of rungs.

Two chains linked by pairs of
molecules (the rungs of the
ladder) called (nitrogenous)
bases.

Adenine (A)

Guanine (G)

Cytosine (C)

Thymine (T)
39

BASE PAIRING
Binding of the bases from one side of
the ladder to the other is very
specific!

Adenine (A) ALWAYS binds
thymine (T)

Guanine (G) ALWAYS binds
cytosine (C)
 Humans have about 3 billion
base pairings

DNA is made of 2 long strands of
nucleotides arranged in a specific
way called the “Complementary
Rule”
42
STRUCTURE OF DNA
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
GENES
 In the discussion of genetics and
DNA you most definitely have heard
of the term GENE.
 A GENE is a DNA segment that
contains information for making
proteins.
 Genes contain the information for
protein making.
 Proteins determine character traits
and body functioning.
45
GENES
 Our genes are the blueprint for our biology. They
contain the instructions for things like the shape of
our nose and the size of our feet. It is estimated that
we have approximately 25, 000 different genes in
our body.
 Genes code for the manufacturing of proteins in our
cells, such as enzymes and hormones that not only
aid in the function of the cell, but to also give us our
characteristic features.
46
THE GENOME
 The entire base-pair sequencing in an individual
or species makes up the individuals GENOME.
 A GENOME is the complete set of
information
 It includes all the genetic information that codes
our genes but there is also a huge percentage of
DNA that does not code for anything! –
“JUNK DNA”
47
PROTEINS
• A PROTEIN is a molecule that plays a specific
role in the functioning of an organism and in
the expression of its character traits.
• The human body has more than 100,000
proteins each with a specific role.
• Genes provide the information to make
proteins.
• Proteins account for more than 50% of the dry
mass in a cell.
PROTEIN FUNCTIONS
• SUPPORT: Elastin is a protein that make our skin
firm yet elastic.
• TRANSPORT OF SUBSTANCES: Hemoglobin is
a protein that carries O2 in the blood.
• IMMUNITY: Antibodies are proteins that protect
us from disease.
• CONTROL AND MESSAGE RELAY: Hormones
are proteins that help make the body develop
properly.
• CATALYSIS: Enzymes are proteins that speed up
biochemical reactions in the body.
AMINO ACIDS
• Proteins are made up of one or more chains of
small units called amino acids.
• An AMINO ACID is a molecule that can combine
with other amino acids to form proteins.
• There are 20 different amino acids.
• Some chains are very long, containing 600 amino
acids.
• Usually proteins have an average of 100-200
amino acids.
AMINO ACIDS
• The sequence of amino acids
determines the shape of the protein.
The shape of the protein is the biggest
factor that determines its function.
PROTEIN SYNTHESIS
• PROTEIN SYNTHESIS is the
creation of proteins by cells
• Usually carried out by the
ribosomes
PROTEIN SYNTHESIS - RNA
• Since DNA cannot leave the nucleus, a messenger must carry the
information from the DNA to the ribosomes: RNA (mRNA)
• An RNA molecule is very similar to a DNA molecule with a few
important differences:
DNA
RNA
Double Stranded
Single Stranded
Thymine base pair
Uracil base pair
Sugar is deoxyribose
Sugar is ribose
TWO TYPES OF RNA
• Messenger RNA (mRNA) is the
messenger for carrying the instructions
from the gene to the ribosome.
• Transfer RNA (tRNA) transfers the
amino acid in the cell’s cytoplasm to the
ribosomes in order to make proteins.
DNARNA  PROTEIN: AND OVERVIEW
OF INFORMATION FLOW IN A CELL
• Making a protein
from the
instructions in the
DNA is a two step
process:
• Transcription
• Translationad
p.358-359
Process of Protein synthesis
PROTEIN SYNTHESIS
https://www.youtube.com/watch?v=NJxobgkPE
Ao
https://www.youtube.com/watch?v=gG7uCskU
OrA
GENETIC DIVERSITY

Every gene that codes for proteins that
make you into the individual that you
are came from your parents.

Every gene can exist in different
variations and forms.

Example

Genes responsible for eye colour can
render the eyes blue, green, brown
and so on, while the genes for hair
colour produce hair that is a
particular shade of blond, brown, red,
or black.
62
GENETIC DIVERSITY

With 25,000 Genes in each of
our cells, each with their own
variations, it is virtually
impossible for two individuals to
possess the same genetic
information.

THE EXCEPTION:


Identical Twins
GENETIC DIVERSITY is
achieved by all the possible
genetic variations of a
particular specie.
63
GENETIC DIVERSITY

Sexual reproduction increases the genetic diversity of a species.

You get one copy of a particular gene from EACH parent.

Each birth is therefore a new opportunity to combine the genes of two
parents

Allows for new variations in the population

The greater the number of individuals in a population, the greater the genetic
diversity
INBREEDING!


Offspring with members of your family

Can lead to a higher expression of a defective gene than one would
normally expect.

Less genetically diverse!
64
INBREEDING

Queen Victoria - Hemophilia – Close intermarriages
65
SICKLE-CELL DISEASE
A slight change in primary structure can drastically
change the entire shape of the protein.
When a protein changes shape, it will not work the
same.
Sickle-cell anemia is a genetic disease that occurs when
red blood cells are shaped like crescents or sickles
instead of saucers.
 Result: Not enough oxygen gets through the body, making
the person become tired very easily.
•
The single gene that is affected changes one single
amino acid in the primary structure of hemoglobin.
10 µm
Red blood Normal cells are
cell shape full of individual
hemoglobin
molecules, each
carrying oxygen.
10 µm
Red blood
cell shape
Fibers of abnormal
hemoglobin deform
cell into sickle
shape.
• This affects the secondary structure, which affects
the tertiary structure, which affects the quaternary
structure.
PROTEIN
SYNTHESIS
THE PROTEIN-MAKING PROCESS
Protein Synthesis
(Gene Expression)
Notes
Proteins (Review)
 Proteins make up all
living materials
• Proteins are composed of amino acids – there are 20
different amino acids
• Different proteins are made by combining these 20
amino acids in different combinations
PROTEINS ARE MANUFACTURED
(MADE) BY THE RIBOSOMES
MAKING
PROTEINS
STEP 1: TRANSCRIPTION
Making a Protein—
Transcription
 First Step: Copying of
genetic information
DNA to RNA is called
Transcription
 Why? DNA has the
genetic code for the
protein that needs to be
made, but proteins are
made by the
ribosomes are outside
nucleus in the
cytoplasm.
 DNA is too large to
leave the nucleus
stranded), but RNA can
leave the nucleus (single
stranded).
• Part of DNA temporarily unzips and is used as a
template to assemble complementary nucleotides
into messenger RNA (mRNA).
STEP 1½: RNA EDITING
•
•
An mRNA molecule has to be “edited” in
order to be useful. There’s a lot of
unnecessary information that needs to be
removed.
An mRNA sequence that does NOT code for
protein is called an interon. A sequence that
is useful in making a protein is called an
exon.
STEP 1½: RNA EDITING
DNA
transcription
pre-RNA (in nucleus)
exon 1
interon
RNA editing
exon 2
interon
interon
interon
RNA (in cytoplasm)
exon 1
exon 2
exon 3
exon 3
 mRNA then
goes through
the pores of
the nucleus
with the DNA
code and
attaches to the
ribosome.
MAKING
PROTEINS
STEP 2: TRANSLATION
Making a Protein—
Translation
 Second Step:
Decoding of mRNA
into a protein is
called Translation.
 Transfer RNA (tRNA)
carries amino acids
from the cytoplasm
the ribosome.
These amino
acids come from
the food we eat.
Proteins we eat
are broken down
into individual
amino acids and
then simply
rearranged into
new proteins
according to the
needs and
directions of our
DNA.
•A series of three adjacent bases
in an mRNA molecule codes for
a specific amino acid—called a
codon.
•Each tRNA has 3 nucleotides
that are complementary to the
codon in mRNA.
•Each tRNA codes for a different
amino acid.
Amino acid
Anticodon
 mRNA
carrying the
DNA
instructions
and tRNA
carrying
amino acids
meet in the
ribosomes.
• Amino acids are joined together to make a protein.
Polypeptide = Protein
Use one of the codon charts on the next page to find the amino acid
sequence coded for by the following mRNA strands.
CAC/CCA/UGG/UGA
___________/___________/___________/____________
AUG/AAC/GAC/UAA
___________/___________/___________/____________
CAC/CCA/UGG/UGA
___________/___________/___________/____________
3rd Base
1st Base
2nd Base
AUG/AAC/GAC/UAA
___________/___________/___________/____________
Protein Synthesis