2.7 Gene Expression
WHAT YOU SHOULD ALREADY KNOW FROM YEAR 11 FOR THIS.
DNA
Structure – Double helix, phosphate-sugar backbone,
Base parings A-T, C-G. Nucleotide monomer
(Phosphate, Sugar & Base)
Gene
A section of DNA that codes for a particular protein/trait
(ie. Hair type)
Allele
An alternative form of a gene (ie. Straight hair vs Curly
Hair)
The specific pair of alleles (on homologous
chromosomes) that the organism carries for a particular
trait.
The physical expression of the alleles an organism
carries.
A DNA molecule that is coiled up tightly (around
histones – packaging proteins).
Genotype
Phenotype
Chromosome
Mutation
A permanent change in the DNA base sequence (this
may result in a new allele).
DNA
DNA
• DNA stands for Deoxyribose nucleic acid
• DNA is a very large molecule
• It is made two strands of molecules which are
twisted together in the shape of a Double
Helix.
• The two strands of DNA are called the
backbone
• Each strand is made up of alternating
molecules of sugar and phosphate
DNA
• The strands are joined by molecules called
nitrogen bases.
• DNA is described as a large polymer.
• A polymer is made up of repeating units called
monomers.
• The monomers of DNA are called nucleotides
• Nucleotides are made up of a sugar,
phosphate and base.
DNA Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Sugar
(deoxyribose)
C3
C2
Nitrogenous base
(A, G, C, or T)
6
Bases
Weak hydrogen bonds
hold the bases together.
Nitrogenous Bases
• Double ring PURINES
Adenine (A)
Guanine (G)
A or G
• Single ring PYRIMIDINES
Thymine (T)
Cytosine (C)
T or C
8
Base-Pairings
• Purines only pair with
Pyrimidines
• Three hydrogen bonds
required to bond Guanine
& Cytosine
3 H-bonds
G
C
9
•Two hydrogen bonds are
required to bond Adenine &
Thymine
T
A
10
DNA
5
O
3
3
P
5
O
O
C
G
1
P
5
3
2
4
4
2
3
P
1
T
5
A
P
3
O
O
P
5
O
3
5
P
11
• It is called Deoxyribose Sugar
• Deoxy means one oxygen atom less (than RNA)
• Ribose is a 5 Carbon Sugar Molecule
• The carbon atoms are numbered in a particular
way from (1-5, see diagram above)
Phosphate
Functions of DNA
• Describe the functions of DNA
• DNA contains the Genetic Code (in its base
sequences to make proteins).
• DNA is able to replicate itself and therefore
pass on the genetic code from one generation
to the next.
Antiparallel DNA
RNA
RNA stands for Ribonucleic Acid
RNA is called a Nucleic Acid
RNA and DNA are both involved
with making proteins.
Functions of RNA
1. Together with DNA, makes proteins.
2. Contains the genetic code in some viruses
eg. HIV (these do not have DNA)
Comparison of DNA and RNA
Gene
GENE
• A gene is a section of DNA on a chromosome,
that has a specific base sequence that codes
for a protein.
PROTEINS
• video's for 2.7\How Genes Work Hand-MeDown Genes Series - DNA and Proteins Part 1 How Genes Work.wmv
Basic Gene Protein
A gene on DNA codes for a particular
protein, which, together with other
compounds/molecules makes up a
characteristic eg. Eye Colour.
Name the following?
A
Cytoplasm
Ribosome
B
C
Nucleus
Cell Organelles
Cell
Organelles
DNA
• http://www.youtube.com/watch?v=qy8dk5iS1
f0
DNA Structure & Purpose.
• DNA is a double helix, with a phosphate-sugar
backbone and bases paired by hydrogen bonds
(Adenine with Thymine and Cytosine with
Guanine).
• It holds the genetic code in it’s base order. DNA is
found in the nucleus of eukaryotic cells
• (NB. It is also in the cytoplasm of prokaryotic
cells) but eukaryotic vs Prokaryote comparisons
are not needed at Level 2.
THE GENETIC CODE
Amino Acids
NUCLEIC ACIDS
• These are the biochemical macromolecules
involved with the transmission of inherited
information. There are two main types: DNA&
RNA. Nucleic acids are polymers made up of
many units called monomers.
DNA differences
Similarities
RNA differences
Long – many genes
Nucleic Acids
Short – one gene
Thymine
Bases: Adaneine,
Uracil.
Deoxyribose Sugar
Cytosine & Guanine.
Ribose Sugar
Stable
Carry Genetic code in
Less Stable
Double stranded
base sequence.
Single Stranded
In Nucleus
Have Sugar-phosphate
Can go to nucleus &
backbones.
Cytoplasm.
AMINO ACIDS
Redundancy vs Degeneracy
• Redundancy refers to the many ways that one
Amino Acid can be coded for by various codon
combinations.
• Whereas Degeneracy refers to the third position
in the codon and that in most cases, if it were to
change, the Amino Acid coded for would still be
the same.
• Both redundancy and degeneracy protect against
mutations, because most times the Amino Acid
sequence and therefore protein will remain un
affected.
PROTEINS
Hydrogen Bonds
Disulfide Bonds
Proteins
• Why can proteins be
described as an amino acid
chain and as a polypeptide
chain?
• What are some of the
functions of proteins?
Protein Synthesis –simple overview of
mRNA and tRNA
• http://www.metacafe.com/watch/319359/hu
man_genome/
Gene Expression outline
This unit is entitled Gene Expression. It covers some
basic aspects of how the information encoded in
our genome (by the order of nucleic bases), are
expressed.
Remember a gene codes for a specific protein.
So the basic process of going from
Gene  Protein
What is needed and how it can be influenced will
be covered.
Extract from Campbell & Reece
1. Copying of Genes
• This is transcription when a section of DNA is
copied to RNA.
• This occurs in the nucleus.
1. Copying of Genes
What is RNA?
• It is a single stranded Nucleic Acid.
There
types of
ofT)RNA
• Bases used
(A,are
G, Cthree
& U instead
• Messenger RNA (mRNA)
• Small & Short (one gene only)
• Transfer RNA (tRNA)
• Unstable (easily
brokenRNA
down
& bases
• Ribosomal
(rRNA)
recycled)
1. Copying of Genes
Transcription:
• Occurs in the Nucleus.
• DNA is unzipped by Helicase
• RNA Polymerase then uses the DNA as a
template to make a complementary strand of
mRNA.
• Once the gene has been copied, the mRNA
can then move outside the nucleus.
SEM
The banding on this chromosome is
thought to correspond to groups of
genes. Regions of chromosome
puffing are occur where genes are
being transcribed into mRNA.
A polytene chromosome showing
localized regions that are uncoiling to
expose their genes (puffing) to allow
transcription. Polytene chromosomes are
giant chromosomes formed by multiple
DNA replications.
Transcription
• http://www.stolaf.edu/people/giannini/flasha
nimat/molgenetics/transcription.swf
Translation
• http://www.stolaf.edu/people/giannini/flasha
nimat/molgenetics/translation.swf simple
• http://207.207.4.198/pub/flash/26/transmen
u_s.swf complex
Protein Synthesis
• http://www.teachersdomain.org/resources/td
c02/sci/life/gen/proteinsynth/assets/tdc02_vi
d_proteinsynth/tdc02_vid_proteinsynth_56_
mov.html
Protein synthesis
http://www.youtube.com/watch?v=983lhh20rG
Y
Where & How mRNA is translated into a protein.
• Translation is where the code sequence carried on the mRNA is used to
create a functional protein.
• First, mRNA has to leave the nucleus via pores in the nucleus.
• mRNA forms a complex with a ribosome, which is close to the nucleus
(usually on the endoplasmic reticulum).
• The ribosome is an organelle, which ‘reads’ mRNA bases in a code of three
bases at a time. This is known as a codon.
• tRNA brings in amino acids – there is a different kind of tRNA for each
amino acid
• Three unpaired bases on the tRNA are known as an anticodon. They are
complementary to a codon on the mRNA Codon–anticodon ‘matches’
combine with base pairing thus bringing the correct amino acid to the next
part of the sequence.
• A start codon initiates the translation.
• Peptide bonds form between amino acids building a polypeptide chain.
• A stop codon ends translation.
• The polypeptide chain is released from the ribosome and ‘folds’ into a
three-dimensional structure, becoming a functional protein.
2.
Copying
of
Genes
Transcription and Translation
Transcription and Translation
A
cellcall
may
require
a particular
protein to be translation.
produced. They
coded
We
the
next stage
of protein-synthesis
Onceare
the
mRNA
A cell may require a particular __________(1) to be produced. They are coded by a particular sequence of
by
awhich
particular
sequence
of bases
we
call aof
gene.
These
code
has
leftwethe
it attaches
towhich
ribosome.
The
molecules
that for
bases
call nucleus,
a __________(2).
These
code for
aaspecific
sequence
__________(3)
__________(4)
which
form thesequence
protein. RNA differs
from __________(5)
in three
important
ways:
the sugarRNA
molecules
in an
aRNA
specific
of
amino
acids
which
form
the
protein.
differs
attach
to
the
mRNA
are
called
transfer
RNA
(tRNA).
At
one
end
of
the
nucleotide is __________(6), the nitrogenous base is __________(7) instead of __________(8), and the
from
DNA
ingene
three
important
ways:
the
sugar
molecules
in anOn
RNA
tRNA
molecule
are
bases
which
we
callprotein
an anticodon.
the
polynucleotide
chain
for RNA
is three
usually
__________(9).
The
specific
that
codes
for
the
required
is exposed
by
The
specificend
geneis
that
codestRNA
for the
the required
proteinisis a
exposed
by
the
__________(10)
bonds that
nucleotide
ribose,
nitrogenous
base
issplitting
uracil
instead
of thymine,
other
ofhydrogen
the
molecule
specific
amino
acid.together
The
distance
splitting
the
bonds
that
holds
the
double
helix
in
holds the double __________(11) together in that region. Free RNA __________(12) bind to the
and
the
polynucleotide
chain
for
RNA
isto
usually
single-stranded.
between
the
anticodon
andTheamino
acid
isthe
always
theofsame.
__________(13)
bases
on the
DNAnucleotides
strand.
sugar-phosphate
__________(14)
the RNA isThe
formed
that
region.
Free
RNA
bind
complementary
basesby a
__________(15)
reaction
occurs binds
betweento
thethe
sugarcomplementary
of one nucleotide and the
__________(16)
group of
anticodon
of
thethattRNA
bases
on the
on
the
DNA
strand.
The
sugar-phosphate
backbone
of
the
RNA
is
another. The strand of RNA that is formed is a copy of the DNA and we call this __________(17) RNA
mRNA.
The
tRNA
brings
the
acids
together
into athe
specific
(mRNA).
Theby
mRNA
peels away
from the
DNAamino
and leaves
the nucleus
viabetween
a __________(18)
__________(19).
formed
a condensation
reaction
that
occurs
sugarorder.
of
We
call this first
stage of form
protein-synthesis
__________(20).
Peptide
bonds
between
the amino
acids
and this
forms
the
one
nucleotide
and
the
phosphate
group
of
another.
The
strand
of
We call the next stage of protein-synthesis __________(21). Once the mRNA has left the nucleus, it attaches
polypeptide
with
aisspecific
primary
structure.
The
then goes
RNA
that is formed
a copy
of the
we__________(23)
callprotein
this messenger
to a __________(22).
The molecules
that attach
to theDNA
mRNA and
are called
RNA (tRNA). At one
end
the be
tRNAfolded,
molecule are
__________(24)
basesto
which
wesecondary
call an __________(25).
On the other end of
onof to
which
gives
rise
the
and leaves
tertiary
RNA
(mRNA).
The
mRNA
peels
away
from
the
DNA
and
the
the tRNA molecule is a specific __________(26) __________(27). The distance between the __________(28)
structures.
nucleus
via a nuclear
pore.
We the
callsame.
thisThefirst
stage
of tRNA
protein-synthesis
and __________(29)
__________(30)
is always
anticodon
of the
binds to the
complementary __________(31) on the mRNA. The tRNA brings the amino acids together into a
transcription.
__________(32) order. __________(33) bonds form between the amino acids and this forms the
__________(34) with a specific __________(35) structure. The protein then goes on to be folded, which
gives rise to the __________(36) and __________(37) structures.
Mutations
Definition
• Any permanent change to the DNA.
Since DNA carried the genetic code that has all
the instructions for the normal functioning of
life processes, a change to this could have
significant effects on the organism.
Mutations cont.
• Mutations are the only new source of genetic
information. Therefore by providing more
variety in the base sequences it can
eventually lead to different proteins being
produced, and if the mutations is not
harmful, and occurs in the gametes it can
enter the gene pool providing more genetic
diversity in the population.
Mutagens
• A mutagen is a physical or chemical agent
that changes the genetic material, usually
DNA, of an organism and thus increases the
frequency of mutations above the natural
background level, eg:
• radiation
• toxins
• Viruses
Point Mutations
• Where a base is
changed through
substitution,
addition or
deletion.
Sickle Cell Anaemia
– CH 11
– Substitution (A instead of T)
– Missense Mutation.
Mutations
There are three types of point mutations
1. Missense
•
The change will result in a different amino acid
coded for.
2. Silent
•
The same amino acid is coded for – the protein
amino acid sequence is the same.
3. Nonsense
• The change causes a stop codon to be produced; the
protein is shorter.
Ie.
Ie.
Ie.
Ie.
Ie.
FRAMESHIFT
Frameshift mutations
(caused by base addition or
deletion) are the most
detrimental. They effect
every triplet and therefore
codon downstream from
where the mutation
occurred. Therefore
changing the amino acid
sequence significantly.
Explain the effects of each type of
mutation & how it could affect the
organism it occurs in.
• Substitution mutations could have a variety of effects. They could occur
and not affect the organism via a silent mutation (usually in the 3rd
position of the codon) until perhaps another mutation occurs (in the 2nd or
1st position) and this changes the amino acid produced making it a
missense mutation. Rarely this will be beneficial and selected for in an
environment, it increases the genetic diversity of a population.
Furthermore if a substitution mutation occurs to make the codon a stop
codon it would be a nonsense mutation and render the gene nonfunctional as the full polypeptide chain would no longer be made and
hence no functional protein.
• Lastly there are the addition and deletion mutations these have the most
severe effects, especially if they occur towards the start of the gene. This is
because a frameshift mutation will cause all the codons downstream from
it to be read differently and significantly change the Amino Acid sequence
coded for, so a nonfunction protein is produced.
• If the gene in which the mutation occurs produces proteins essential for
life the individual will die, however if the protins produced are not
essential for life the individual could live but perhaps be limited by not
certain proteins produced.
Explain the effects of each type of mutation &
how it could affect the organism it occurs in.
• Substitution mutations could have a variety of effects.
They could occur and not affect the organism via a silent
mutation (usually in the 3rd position of the codon) until
perhaps another mutation occurs (in the 2nd or 1st
position) and this changes the amino acid produced
making it a missense mutation. Rarely this will be
beneficial and selected for in an environment and
increases the genetic diversity of a population.
Furthermore if a substitution mutation occurs to make
the codon a stop codon it would be a nonsense mutation
and render the gene non-functional as the full
polypeptide chain would no longer be made and hence
no functional protein.
Explain the effects of each type of mutation &
how it could affect the organism it occurs in.
• Lastly there are the addition and deletion
mutations these have the most severe effects,
especially if they occur towards the start of the
gene. This is because a frameshift mutation will
cause all the codons downstream from it to be
read differently and significantly change the
Amino Acid sequence coded for, so a
nonfunction protein is produced.
Explain the effects of each type of mutation &
how it could affect the organism it occurs in.
• If the gene in which the mutation occurs
produces proteins essential for life the
individual will die, however if the protins
produced are not essential for life the
individual could live but perhaps be limited by
not certain proteins produced.
Redundancy & Degeneracy
Define:
• Redundancy in the Genetic Code.
• When some amino acids are coded for by
more than one codon.
• Degeneracy in the Genetic Code.
• When a change in the third position of a
codon will still code for the same Amino Acid.
• Explain how redundancy and degeneracy of the code mean that
in many cases a mutation does not have an effect on the protein
produced?
• The genetic code is protected against mutation by having
redundancy and degeneracy built into it. Therefore if a mutation is
to occur that does not cause a frameshift, it is likely that this
mutation could still result in the same amino acid being coded for
and therefore there is no phonotypical change for the individual.
• Degeneracy allows substation mutations that occur in the 3rd
position of a codon to be (most likely) harmless. While redundancy
also allows this as most Amino Acids are coded for by more than
one codon, and some have different 1st position codons different
but result in the same amino acid.
• So both redundancy and degeneracy minimise the effects of
mutations and protect the genetic code so that the same amino
acid sequence can still be produced, and life processes for that
individual can still occur as normal.
Metabolic Pathways
Metabolic Pathways
•
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/12
0070/bio09.swf::A%20Biochemical%20Pathway
Metabolic Pathway
• Definition:
– A metabolic pathway is a series of biochemical
reactions that are connected by their
intermediates: The reactants (or substrates) of
one reaction are the products of the previous one,
and so on.
• A metabolic pathway requires a series of biochemical
reactions in which the product form one reaction is used as
the reactant for the next. It also requires a number of
enzymes to facilitate the pathway so each reaction can occur.
g
• Should any of the enzymes in the pathway be non-functional
(ie, as a result from a mutation) this would cause a build up of
the precursor substance (reactant) and none of the products
needed further down the pathway.
g
• For example people with the condition PKU do not have a
functional Phenylalanine Hydroxylase enzyme, therefore
there is a build up of any Phenylaline taken in from the diet
and a lacking of Tyosine (however some Tyosine can be
gained from other sources). The build up of Phenylalanine
caused a build up of Phenylpyruvic Acid which can cause brain
damage and the conditions associated with the condition
PKU. The lack of Tyrosine in their diet leads to a lack of
melanin production and these individuals will also have a
lighter skin colour.
Albinism
• To produce the final product melanin in which
gives skin colour, there are a series of
biochemical reactions that occur.
• So should the enzymes be non-function for any
of these reactions, the final product of melanin
will not be produced and the condition Albinism
will result.
• Furthermore there will be a build-up of primary
or intermediate products depending on which
enzymes is unable to convert the substrate into a
product.
Dominant vs Recessive Metabolic
Pathways & Inheritance (1/2)
Dominant condition
In this case both parents would have to be heterozygous for the
condition otherwise it would be impossible to avoid the effect of the
dominant allele.
Both parents could have more than 1 point in the pathway affected so
long as they were heterozygous at that point, eg
Rr
Rr
parent 1 A--------->B---------->C
Rr
Rr
parent 2 A--------->B---------->C
rr
rr
Offspring A--------->B---------->C
Dominant vs Recessive Metabolic
Pathways & Inheritance (2/2)
There are a number of possible combinations to the way in which a condition can be
inherited because the metabolic pathway has at least two points where different genes are
controlling the outcome.
Recessive condition
Both parents have the condition so they must both have recessive alleles for one of the
genes controlling one of the points of the pathway.
One of their offspring can be normal because if the points which are affected in the parents
are different, then each one of those can be dominated by an allele inherited from the
other,
Eg:
rr
Rr or RR
parent 1 A--------->B---------->C
Rr or RR
rr
parent 2 A--------->B---------->C
Rr
Rr
Offspring A--------->B---------->C
The Environment & Genes
• Define Environmental Factor. (Biozone:
sources of genetic variation)
• Any internal or external factors that influence
the expression of the genotype.
• External factors can include: temperature,
light intensity, and competition. While internal
factors can include: presence or absence of
Hormones and/or growth factors during
development.
Genotype
• Genotype is genetic constitution (the genome)
of a cell or an organism.
Or
• The Allele combinations an organism has at a
particular locus.
Environment & Genotype
• Environmental mutagens
can affect genotype for
the next generation
should the mutation
occur in the gametes.
Explain how the environment can affect the genotype, give
specific examples.
• The environment can effect genotype via mutagenic
agents increasing the likelihood of mutations to occur. If
the mutation causes a change in the protein, it becomes a
new allele and can change the genotype for some cells in
that individual, and if the mutation occurred in the gametic
cells the new allele can enter the gene pool.
• For example those who smoke may develop lung cancer,
which affects the lung cells in the body as they have come
into contact with the mutagen, however if the cancer
spread and the poisonous chemicals breathed in from
tobacco smoking caused a mutation to occur in that
individuals gametes that caused a new allele, then their
offspring can be affected and have the new allele in every
cell of their body.
Temperature & Phenotype
• Dark pigment produced only in cooler parts of
the body.
• Ie. Ice pack on Himalayan rabbit = Black Hair.
Explain how the environment can affect the phenotype, give
specific examples.
• The environment can affect the way the genes are
expressed without changing the alleles or genotype of an
individual. For example if someone were to plant tall beans
that say the grow over 2 meters tall but, fail to water them
regularly, space them out and weed the soil around them,
the plants may be stunted in their growth through lack of
water, nutrients and sunlight availability.
• Another example could be human skin colour, if there were
identical twins with light skin colour, but one twin did a lot
of sport and work outside while the other was mainly
indoors, then the outdoor twin would build up more of a
tan and melanin in their skin as protection against the sun’s
rays and therefore look different than their twin.
Epigenetics
http://www.youtube.com/watch?v=LcaRTDsLmiA
Epigenetics
Life Processes Pgs. 229-231.
Define Epigenetics
• The study of the factors that activate and
silence gene expression.
• Epi means ‘in addition too’, therefor the
study of epigenetics is looking at the
factors that affect an individual in addition
to normal genetics.
Agouti Gene
• http://learn.genetics.utah.edu/content/epige
netics/nutrition/
Explain how these above example of ‘Agouti’ mice can be
genetically identical and yet look so different.
• The Agouti Mice from the example have ideantical DNA, but
different epigenomes. This means that agouti gene is silenced
in one mouse (small brown) while it is expressed in the other
mouse (large yellow).
• The expression of the Agouti gene is linked with various
methylation sources. So while the mice were developing in
the womb, if the diet of the mother was high in methyl
groups, it caused the agouti gene so be methylated and
therefore silenced, giving a slim, healthy brown mouse.
• While if the mothers diet was low in methyl groups, then the
Agouti gene would be expressed resulting in the mouse being
obese, prone to cancer and diabetes and yellow in coat
colour. This explains why the appearance can be so different
while the gene’s still identical.
What is the significance of DNA methylation? What
effect does this have on Gene Expression?
• DNA methylation determines if the genes are
expressed or silenced. When DNA is methylated it is
tightly coiled up and cannot be unwound for
protein synthesis, therefore the gene is not
expressed. Gene silencing can have significant
effects as the protein produced from on gene can
change the balance of a metabolic pathway and
prevent various products being made and cause a
build-up of some precursors.
The Bible & Epigenetics
•
•
•
•
Daniel 1:1-21
New International Version (NIV)
Daniel’s Training in Babylon
1 In the third year of the reign of Jehoiakim king of Judah, Nebuchadnezzar
king of Babylon came to Jerusalem and besieged it. 2 And the Lord delivered
Jehoiakim king of Judah into his hand, along with some of the articles from the
temple of God. These he carried off to the temple of his god in Babylonia[a] and
put in the treasure house of his god.
• 3 Then the king ordered Ashpenaz, chief of his court officials, to bring into the
king’s service some of the Israelites from the royal family and the nobility— 4
young men without any physical defect, handsome, showing aptitude for every
kind of learning, well informed, quick to understand, and qualified to serve in
the king’s palace. He was to teach them the language and literature of the
Babylonians.[b] 5 The king assigned them a daily amount of food and wine from
the king’s table. They were to be trained for three years, and after that they
were to enter the king’s service.
• 6 Among those who were chosen were some from Judah: Daniel, Hananiah,
Mishael and Azariah. 7 The chief official gave them new names: to Daniel, the
name Belteshazzar; to Hananiah, Shadrach; to Mishael, Meshach; and to
Azariah, Abednego.
•
•
•
•
•
•
8 But
Daniel resolved not to defile himself with the royal food and wine, and he asked
the chief official for permission not to defile himself this way. 9 Now God had caused
the official to show favor and compassion to Daniel, 10 but the official told Daniel, “I
am afraid of my lord the king, who has assigned your[c] food and drink. Why should he
see you looking worse than the other young men your age? The king would then have
my head because of you.”
11 Daniel then said to the guard whom the chief official had appointed over Daniel,
Hananiah, Mishael and Azariah, 12 “Please test your servants for ten days: Give us
nothing but vegetables to eat and water to drink. 13 Then compare our appearance
with that of the young men who eat the royal food, and treat your servants in
accordance with what you see.” 14 So he agreed to this and tested them for ten days.
15 At the end of the ten days they looked healthier and better nourished than any of
the young men who ate the royal food. 16 So the guard took away their choice food
and the wine they were to drink and gave them vegetables instead.
17 To these four young men God gave knowledge and understanding of all kinds of
literature and learning. And Daniel could understand visions and dreams of all kinds.
18 At the end of the time set by the king to bring them into his service, the chief official
presented them to Nebuchadnezzar. 19 The king talked with them, and he found none
equal to Daniel, Hananiah, Mishael and Azariah; so they entered the king’s service. 20
In every matter of wisdom and understanding about which the king questioned them,
he found them ten times better than all the magicians and enchanters in his whole
kingdom.
21 And Daniel remained there until the first year of King Cyrus.
The Bible & Epigenetics
• Genesis 30:37-40 (NIV)
• 37 Jacob, however, took fresh-cut branches from poplar,
almond and plane trees and made white stripes on them
by peeling the bark and exposing the white inner wood
of the branches. 38 Then he placed the peeled branches in
all the watering troughs, so that they would be directly in
front of the flocks when they came to drink. When the
flocks were in heat and came to drink, 39 they mated in
front of the branches. And they bore young that were
streaked or speckled or spotted. 40 Jacob set apart the
young of the flock by themselves, but made the rest face
the streaked and dark-colored animals that belonged to
Laban. Thus he made separate flocks for himself and did
not put them with Laban’s animals.
The Bible & Epigenetics
• Proverbs 23:7
• King James Version (KJV)
• 7 For as he thinketh in his heart, so is he: Eat
and drink, saith he to thee; but his heart is not
with thee.
The Bible & Epigenetics
• Romans 12:2
• New International Version (NIV)
• 2 Do not conform to the pattern of this world,
but be transformed by the renewing of your
mind. Then you will be able to test and
approve what God’s will is—his good, pleasing
and perfect will.
• http://jbq.jewishbible.org/assets/Uploads/36
4/364_sheep.pdf
EXTRA ACTIVITIES
• The base sequence can be used to make up the
amino acid chain. Can this be done in the
reverse, having an amino acid chain translated
back into RNA and reverse Transcribed into the
same DNA that coded for it? Explain your
answer.
• No it cannot give the same DNA that coded for
the Amino Acid sequence. This is because there
are many codons that code for an amino acid,
therefore there is no way of ensuring that a DNA
sequence produced is the same as the original
due to redundancy and degeneracy in the genetic
code.
(c)
Describes how mRNA is Explains how mRNA is
processed.
processed.
Eg non coding regions /
introns are removed.
Eg mRNA / Primary transcript
produced by transcription has
both coding regions / exons
and non-coding regions /
introns of RNA. These non
coding regions / introns are
removed to leave only the
coding regions / exons.
CGA
TCA
GCT
ACC
TCT
GCU
AGU
CGA
UGG
AGA
ala
ser
arg
trp
arg
Achievement
Achievement with Merit
Achievement with Excellence
Any TWO of:
Any TWO of:
Discusses how DNA sequence results in the
formation of a protein.
•
Transcription is described. •
Eg: Production of mRNA
copy of DNA / genetic
material
•
Explains the roles of
transcription.
Eg: Transcription is the process
where mRNA is manufactured by
attaching free nucleotides to
complementary DNA strand.
Translation is described.
E.g. information from mRNA
•
Explains the role of translation.
is used to join amino acids
into a polypeptide.
Eg: Translation is the process
happening at the ribosome, where
RNA codons are matched with tRNA
•
A role of RNA is
anti codons, resulting in the joining
described.
of amino acids.
Eg: mRNA carries the code
Each amino acid is specific to an
from a gene to / site of
anticodon / codon.
synthesis / ribosome.
Eg: tRNA carries an amino
acid which connects with the
codon of mRNA at the
ribosome.
•
Explains a link between amino
acids and protein folding
Eg: The interactions between amino
acids sequence can affect the final
shape / folding of the protein.
Eg: During transcription, mRNA is produced
through complementary base pairing with
exposed bases on DNA. mRNA is read via
translation at the site of the ribosome (rRNA),
where codon sequences are translated via tRNA
into a chain of amino acids. tRNA attach to
specific amino acids and contain an anti codon,
complementary to the codons of the mRNA.
AND
The final protein / order in which the amino
acids are joined is a result of the DNA sequence
/ genetic code.
OR
The order of amino acids affects the folding of
the protein structure due to the interactions
between them. Sulfur bridges / bonds between
cysteines / hydrophobic / hydrophilic
interactions / will lead to folding of the
polypeptide / protein chain.