Download Ch 12/13 Notes

DNA and Protein Synthesis
CH 12/13 NOTES
Genes
SECTION 12.1
ANSWER QUESTIONS BELOW IMAGE…
GRIFFITH QUESTIONS

What happened when Griffith combined harmless
heat-killed S and harmless live R?


What was found in the dead mouse?


Live S strain.
What process occurred?


The mouse died.
Transformation
Did Griffith know what was being picked up to
transform/change the live harmless R strain into
the disease-causing S strain?

NO!
GRIFFITH’S EXPERIMENTS / TRANSFORMATION
In 1928, a man named Griffith was trying to
determine how bacteria make people sick with
a serious immune disease known as
pneumonia.
 He isolated two different strains of bacteria.
The S strain (smooth edged) and the R strain
(rough edged).

GRIFFITH’S EXPERIMENTS / TRANSFORMATION

Of the two strains, the S strain caused
pneumonia in mice due to the smooth edges
not allowing the mice’s immune system to
destroy it.

Griffith ran four different tests to see what
happened when different strains of bacteria
were put in the mouse.
GRIFFITH CONTINUED

Griffith called what happened in his fourth
experiment TRANSFORMATION because the
harmless bacteria, the R strain, had been
changed permanently into the S strain.
AVERY’S EXPERIMENT

In any given cells you have the four
macromolecules which are?
 Proteins,

What type of macromolecule are enzymes?
What are their role?
 Proteins

lipids, carbohydrates, nucleic acids
and they speed up the rate of reactions
What are the two types of nucleic acids?
 DNA
and RNA
AVERY’S EXPERIMENT
In 1944 Canadian biologist Oswald Avery, and
his team, set out to discover what molecule in
the heat-killed bacteria was most important for
transformation.
 Look at the table and try to answer why the
mouse lived given the experiments ran.

AVERY’S EXPERIMENT
WHY????DNA must have been the transforming
molecule.
 His theory was not accepted at that time. Why
do you think that is?

THE HERSHEY-CHASE EXPERIMENT
In 1952 American Scientists, Alfred Hershey
and Martha Chase, worked to prove it was DNA
causing the transformation by making use of
bacteriophage.
(see the images of them to the right)

HERHSEY-CHASE EXPERIMENT
A bacteriophage is a virus that infects bacteria.
 When it enters a bacterium, it attaches to the
surface of the cell and injects its genetic info
into it which acts to produce new
bacteriophages that will kill the bacterium.
 When the cell splits open, hundreds of new
viruses burst out.

BACTERIOPHAGE
fills up cell
bursts free to infect
other cells
HERSHEY-CHASE EXPERIMENT
Hershey-Chase wanted to determine what part
of the bacteriophage was injected into the
bacterium. What is the protein coat or the DNA
core?
 They created viruses that were tagged with
certain chemicals. One where DNA was tagged
with phosphorus-32 and the protein was
tagged with sulfur-35. Whichever was found
inside determined what was being injected.

HERSHEY-CHASE EXPERIMENT
After running through the experiment only
phosphorus-32 was found in the cell. What
were the viruses injecting into the cell?
 DNA
 Therefore that must be the genetic material of
the bacteriophage.
 This convinced scientists that DNA was the
genetic material for all living things, not just
viruses and bacteria.

The structure of DNA
12.2 NOTES
WHAT SCIENTISTS KNEW

DNA and RNA were both nucleic acids. They
also knew they were made up of the monomers
nucleotides.
ROLES OF DNA

The three roles of DNA are
 Storing
information
 Copying information
 Transmitting information
WHAT SCIENTISTS KNEW

They knew the parts of the nucleotide were
Simple
pentose sugar (deoxyribose)
Nitrogeneous base
(aka N-base)
Phosphate group
NITROGENEOUS BASES
There are four different nitrogeneous bases
 A = adenine
 T = thymine
 C = cytosine
 G = guanine

CHARGAFF’S RULE
Chargaff’s rule stated that the amount of A
always equals the amount of T and the amount
of C always equals the amount of G.
 Example:
DNA strand 1
% A = 20
%T =
% G=
%C =
DNA strand 2
% A=
%T =
% G =15.5 %C =

CHARGAFF’S RULE

Using the image of the nucleotides in your
notes answer the four questions below it. And
please note that these are chemical rings not
perfectly round rings they are talking about.
CHARGAFF’S RULE
What group of compounds do A and G belong to?
 Purines
 What group of compounds do C and T belong to?
 Pyrimidines
 How many rings are purines?
2
 How many rings are pyrimidines?
1

WHAT WASN’T KNOWN ABOUT DNA?

What the structure of DNA was.

Who would solve this mystery? In 1953, James
Watson (an American biologist) and Francis
Crick (a british physicist) solved the DNA
structure mystery.
DNA STRUCTURE MYSTERY

How did they do it? By looking at the x-ray
image of the DNA taken by a woman named
Rosalind Franklin it became clear that DNA
resembled a spiral staircase.

What did they call this structure? A double
helix.
DNA STRUCTURE MYSTERY
In 1962, Watson and Crick received the Nobel
prize in science for this discovery (along with a
colleague of Franklin), but Franklin did not
receive the prize because she was no longer
alive.
 HW due Monday: 12/13 vocab, 12.1 # 7-8,
12.2 #1- 7

DNA STRUCTURE

The backbone of DNA is
made up of alternating
sugars and phosphate
groups, while the steps
of the DNA ladder are
made up of the 4
alternating nitrogeneous
bases.
DNA STRUCTURE


Chargaff’s rules were
also proven correct, in
that A always pairs up
with T, and C always
pairs up with G.
These are
complementary bases.
DNA STRUCTURE


In other words, the
complement of A is T
and the complement of
C is G.
Use the image in your
notes to answer the
following questions.
DNA STRUCTURE
What is the complementary strand of
CGTATAGCA?
 GCATATCGT
 What is the name of the simple sugar found in
DNA?
 Dexoyribose

DNA STRUCTURE
What does the N-base connect directly to, the
sugar or the phosphate?
 Sugar
 What type of bonds are found between the Nbases?
 Hydrogen bonds
 What type of bonds are found along the backbone
of DNA?
 Phosphodiester bonds.

DNA STRUCTURE
One half of the DNA molecule is upright, the other
half is flipped the opposite direction, what is the
term for this?
 Antiparallel
 DNA’s charge is negative, what part of the DNA
molecule makes it negative?
 Phosphate group
 What are the three roles of DNA in the body?
 Store, copy, and transmit information

DNA replication
12.3 NOTES
WHO NEEDS DNA?
All organisms use the four nitrogenous bases A,
T, G, and C.
 While all life on earth uses this coding it is the
sequence/order of these N-bases that differs
between organisms.

DNA INFORMATION
Location of DNA?
 Nucleus (eukaryotes) and cytoplasm (prokaryotes)
 The DNA gets replicated during what stage of the
cell cycle?
 S phase (during interphase)
 What does DNA stand for?
 Deoxyribonucleic acid

DNA INFORMATION
What is the weak bond that holds the N-bases
together?
 Hydrogen bonds
 DNA looks like a spiral staircase also known as
what?
 Double helix

DNA INFORMATION
What bases are complements?
 A and T
C and G
 What is the complement of this strand of DNA?
CCAGTAATTCCGG
 GGTCATTAAGGCC

STEPS OF DNA REPLICATION
1.
2.
Break the weak hydrogen bond. DNA helicase,
an enzyme, unwinds and unzips the double
helix.
DNA polymerase, another enzyme, brings in
the correct nucleotides to pair with their
complements to make two exact copies of
DNA. It is also responsible for proof-reading
the cell at the end to make sure it has made
an exact copy.
END RESULT OF DNA REPLICATION
Two exact copies of DNA each with an original
strand a new strand.
Original strand splits and is filled with
complementary nucleotides to create two exact
copies of strands.
A-T
A-T
A-T
C-G

C-G
C-G
G-C
G-C
G-C

PROKARYOTIC REPLICATION

Due to one circular DNA strand there is only
one point of origin and it will replicate out in
opposite directions until it meets on the other
side.
EUKARYOTIC REPLICATION

Replication will start in dozens or even
hundreds of different locations so there will be
several DNA polymerases working on it to
speed up the replication.
TELOMERES
The tips of chromosomes are known as
telomeres.
 The ends of DNA molecules, located at the
telomeres, are hard to copy. So difficult at
times that over time DNA may actually be lost
from telomeres each time a chromosome is
replicated.

TELOMERES

An enzyme called telomerase compensates for
this problem by adding short, repeated DNA
sequences to telomeres, lengthening the
chromosomes slightly and making it less likely
that important gene sequences will be lost
from the telomeres during replication.
POST REPLICATION
After replication the cell will move into the G2
phase and will prepare for mitosis.
 During interphase DNA is present as chromatin
then when it condenses it becomes
chromosomes during cell division.

13.1 NOTES
RECAPPING DNA

Griffith coined the term transformation
because he noticed that in his experiment that
something was changing his bacteria from live
R strain to a live S strain.
STEPS OF DNA REPLICATION
 Break
the Hydrogen- bonds
 DNA Helicase an enzyme, unwinds and unzips the
double helix.
 DNA Polymerase, another enzyme, fills in the
missing nucleotides to create a complementary
strand. Then it proof reads it to make sure it has
created two exact copies.
COMPARING DNA AND RNA

Like a construction job DNA is the original
blueprint kept in the office while RNA are
disposable copies that are sent out in the field.
Name
DNA
Deoxyribonucleic Acid
Made up of
nucleotides?
Yes
# of strands?
2
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Complements
Name of 5
carbon sugar
deoxyribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
RNA
Name
DNA
Deoxyribonucleic Acid
Made up of
nucleotides?
Yes
# of strands?
2
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Complements
Name of 5
carbon sugar
deoxyribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
RNA
Ribonucleic Acid
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Name
Complements
Name of 5
carbon sugar
deoxyribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
1
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Name
Complements
Name of 5
carbon sugar
deoxyribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
1
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Adenine (A), Uracil (U), Guanine
(G), Cytosine (C)
Name
Complements
Name of 5
carbon sugar
deoxyribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
A and U
G and C
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
1
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Adenine (A), Uracil (U), Guanine
(G), Cytosine (C)
Name of 5
carbon sugar
deoxyribose
ribose
Made from?
Another dna strand
Role in the cell
Store, copy, and
transmit information
Name
Complements
A and U
G and C
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
1
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Adenine (A), Uracil (U), Guanine
(G), Cytosine (C)
Name of 5
carbon sugar
deoxyribose
ribose
Made from?
Another dna strand
Another dna strand
Role in the cell
Store, copy, and
transmit information
Name
Complements
A and U
G and C
DNA
Deoxyribonucleic Acid
RNA
Ribonucleic Acid
Made up of
nucleotides?
Yes
Yes
# of strands?
2
1
Names of
N-bases
Adenine (A), Thymine
(T), Guanine (G),
Cytosine(C)
A and T
G and C
Adenine (A), Uracil (U), Guanine
(G), Cytosine (C)
Name of 5
carbon sugar
deoxyribose
ribose
Made from?
Another dna strand
Another dna strand
Role in the cell
Store, copy, and
transmit information
To create proteins
Name
Complements
A and U
G and C
THREE TYPES OF RNA
Messenger RNA (mRNA)
 Transfer RNA (tRNA)
 Ribosomal RNA (rRNA)

MESSENGER RNA



Made up of four Nbases A, U, C, and G.
Made up of only a single
strand.
Created in the nucleus
from a strand of DNA
through the process of
transcription.

It carries instructions for
protein (aka polypeptide)
synthesis from the
nucleus to ribosomes
outside of the nucleus.
RIBOSOMAL RNA


The “ribbon” in the
ribosome to the right.
Location where proteins
are assembled.
RIBOSOMAL RNA

The two subunits of a
ribosome are made up
of several rRNA
molecules and as many
as 80 different proteins.
TRANSFER RNA


Transfers the amino
acid to the ribosome by
matching up
complementary
segments, called
anticodons with the
mRNA.
Anticodons are always
grouped in threes.
RNA TRANSCRIPTION



In transcription, segments
of DNA serve as
templates to produce
complementary mRNA
molecules.
In prokaryotes the
process of transcription
takes place in the
cytoplasm.
In eukaryotes the process
of transcription takes
place in the nucleus.
STEPS OF RNA TRANSCRIPTION
First
RNA Polymerase, an enzyme, binds to the DNA
and separates the DNA strand.
* important to put the RNA in front of the enzyme
so as to distinguish it from DNA polymerase.
STEPS OF RNA TRANSCRIPTION
SECOND
RNA Polymerase creates a
strand of
complementary RNA
nucleotides (to the
strand of DNA) to create
a single stranded
mRNA.
STEPS OF RNA TRANSCRIPTION

END RESULT A single
strand of mRNA that is
now encoded with
instructions for protein
synthesis and will travel
to other parts of the cell
where it will meet up
with tRNA and rRNA.
LET’S PRACTICE
Remember that mRNA does not use the N-base T
but uses the N-base U instead. This is what will
attach to A.
Example 1
DNA Strand:
AATGC
mRNA Strand: UUACG
LET’S PRACTICE
Example 2
 DNA strand
GTAGC
 mRNA strand CAUCG

Example 3
 mRNA strand UUACG
 DNA strand
AATGC

PROMOTERS
How does a RNA polymerase known where to
start copying?
 It will bind to regions on the DNA called
promoters that have a specific base sequence
to indicate that is where to start.
 Similarly there are promoters that tell RNA
polymerase where to stop transcription.

RNA EDITING


Before it is officially
considered to mRNA the
newly created strand
must be edited.
Unnecessary pieces,
introns, will be cut out
and the remaining
exons will be spliced
together.
RNA EDITING
Biologists are still unsure as to why a cell
expands so much energy to make a large
mRNA molecule and then throw parts away.
 They do know however that this process allows
a single gene to produce several forms of RNA.

Ribosomes and Protein Synthesis (translation)
13.2 NOTES
TRANSCRIPTION RECAP
The enzyme RNA polymerase binds to the DNA
and separates the DNA strand. It then uses
one strand of DNA as a template to assemble
nucleotides into a complementary strand of
mRNA.
 Three types of RNA: mRNA, rRNA, and tRNA

TRANSCRIPTION RECAP

The monomers of nucleic acids are nucleotides
and the monomers of proteins are amino acids.
nucleotide structure
PROTEINS
There are 23 different amino acids. Your body
is mostly protein.
 Protein synthesis is known as translation
because you are translating the codons (bases)
on the mRNA to create proteins.

PROTEIN SYNTHESIS (TRANSLATION)
First:
mRNA is made in the nucleus through the
process of transcription. The mRNA is made up
of codons. It moves to a ribosome where
proteins are made.

PROTEIN SYNTHESIS (TRANSLATION)
Second:
Translation begins at the codon AUG (met). Met
is the amino acid methionine.
tRNA arrive at the ribosome carrying an amino
acid and it will match up to its anticodons
(bases) with the mRNA codon.

PROTEIN SYNTHESIS
Third:
Covalent bonds will form between each amino
acid and after losing its amino acid the tRNA
will release from the codon. This will continue
until it reaches one of the three codons that
mean “stop”. Protein will then break free and
be released from the ribosome.
http://youtu.be/Ikq9AcBcohA

QUICK QUESTIONS
Codons are grouped in how many bases?
3
 Anticodons are grouped in how many bases?
3
 Anticodons are on what type of rna?
 tRNA
 Codons are on what type of rna?
 mRNA

QUICK QUESTIONS
The process of creating mRNA is called what?
 transcription
 The process of creating proteins is called what?
 Protein synthesis aka translation
 The monomer of proteins are called what?
 Amino acids.

HOW TO READ CODONS
First: need the mRNA strand (codons).
 Second: always read from the left to the right in
groupings of three.
 Note:the amino acid is attached to the tRNA
that has the anticodons but it is the codons
that determines what amino acid will connect
at that location.

CODON CHART
First lets do some work on finding out
complements: fill in the following
 DNA:
CGATAA
 mRNA:
 tRNA:

CODON CHART
First lets do some work on finding out
complements: fill in the following
 DNA:
CGATAA
 mRNA: GCUAUU
 tRNA:
CGAUAA

What codes for the amino acid? The mRNA or
the tRNA?
The mRNA brings in the right tRNA so the
mRNA (codons) code for the amino acid. It is
read from left to right in groupings of 3.
 DNA:
CGATAA
 mRNA: GCU AUU
1 2
Now lets read the codon chart for each grouping
of three to find the amino acids.

DNA:
CGATAA
 mRNA: GCU AUU
1 2
Amino acids
Ala - Ile

So this protein would be made of the two amino
acids Alanine and Isoleucine.
QUESTION:
Using the same chart fill in the blanks of this
example:
 DNA:
TAC GGG ATT
 mRNA:
 tRNA:
 Amino acids:

QUESTION:
Using the same chart fill in the blanks of this
example:
 DNA:
TAC GGG ATT
 mRNA:
AUG CCC UAA
 tRNA:
UAC GGG AUU
 Amino acids: Met – Pro
Note: if you reach a stop amino acid it just
breaks off what has already formed.

NEW CODON CHART





Read this chart from the
inside out:
DNA: GCA CAT
mRNA:
tRNA:
Amino Acid:
NEW CODON CHART





Read this chart from the
inside out:
DNA: GCA CAT
mRNA: CGU GUA
tRNA: GCA CAU
Amino Acid:
Arginine - Valine
3RD CODON CHART
Delete out the third codon chart. You will not
need this one. Know how to use the first two.
QUESTION: DETERMINE THE AMINO ACIDS
DNA
TAC
ATA
ACT
mRNA
tRNA
Amino acid
QUESTION: DETERMINE THE AMINO ACIDS
DNA mRNA
TAC AUG
ATA UAU
ACT UGA
tRNA Amino
acid
UAC Met
AUA Tyr
ACU stop

Note the first amino acid
in every true protein is
methionine coded by
mRNA as AUG.
THE MOLECULAR BASES OF HEREDITY
the central dogma (belief) of molecular bio is
that info is transferred from DNA to RNA to
proteins.
 Although some organisms show slight
variations in their amino acids the code is
always read in the same direction and three
bases at a time. This shows remarkable unity
at life’s most basic level, the molecular biology
of the gene.

13.3
MUTATIONS
WHAT IS A MUTATION?

A mutation occurs when there is a change in
the DNA sequence.

Why are they important? Because they are the
cause behind genetic diversity!
TYPES OF MUTATIONS
Non-disjunction
 Chromosomal
 Point

NON-DISJUNCTION

This occurs when whole chromosomes do not
separate properly during meiosis 1 or meiosis 2
resulting in gametes with too many or too few
chromosomes.
NON-DISJUNCTION
If an organism gets extra sets of chromosomes
it is called being polyploidy. In
humans/animals this is rare but in plants this
is common. Humans are diploid (two sets),
apples and carrots are triploid (three sets) and
strawberries are octaploid (eight sets).
 Example: Down’s syndrome (trisomy 21) where
there is one too many 21st chromosomes.

CHROMOSOMAL MUTATIONS
Involves small “segments” of chromosomes
 This occurs when these segments get broken
off and maybe even shifted around.
 Four types: deletion, duplication, inversion, and
translocation.
 These changes can create a change in the
amino acids that the mRNA will code for and
eventually the protein.

CHROMOSOMAL MUTATIONS
EXAMPLE OF DELETION

Cri du chat (cry of the
cat): A specific deletion
of a small portion of
chromosome 5; these
children have severe
mental retardation, a
small head with
unusual facial
features, and a cry that
sounds like a
distressed cat.
EXAMPLE OF DUPLICATION

Example - Fragile X: the most
common form of mental
retardation. The X
chromosome of some people
is unusually fragile at one tip
- seen "hanging by a thread"
under a microscope. Most
people have 29 "repeats" at
this end of their Xchromosome, those with
Fragile X have over 700
repeats due to duplications.
Affects 1:1500 males,
1:2500 females.
EXAMPLE OF TRANSLOCATION

Acute Myelogenous
Leukemia is caused by
this translocation:
EXAMPLE OF INVERSIONS
The most common inversion seen in humans is
on chromosome 9. This inversion is generally
considered to have no deleterious or harmful
effects, but there is some suspicion it could
lead to an increased risk for miscarriage or
infertility for some affected individuals.
 An inversion does not involve a loss of genetic
information, but simply rearranges the linear
gene sequence.

POINT (OR GENE) MUTATIONS
Involves changes in one or a few genes.
 Three types of point mutations

Substitution, insertion, and deletion
POINT (OR GENE) MUTATIONS

Insertion and deletion are also known as
frameshift mutations because they shift the
reading frame of the genetic message.
Substitution however only have the possibility
of changing one amino acid.
SUBSTITUTION
INSERTION
FRAMESHIFT MUTATIONS

Frameshift mutations are dangerous in that
they can alter a protein to the point where it is
unable to perform its normal function.
FRAMESHIFT MUTATIONS

Ex: Sickle cell disease is caused by a point
mutation specifically a substitution mutation
which changes the type of amino acid it codes
for. This will change the type of protein,
changing the shape of hemoglobin on red
blood cells causing them to carry less oxygen to
the cells of the body.
ACCURACY AND REPAIR

Mutations are rare where there are only 1
errors in a BILLION nucleotides due to how well
the enzyme DNA Polymerase proof reads the
DNA.
WHAT CAN CAUSE MUTATIONS?
They are called mutagens.
 Examples of these are:

 Radiation
 Chemical
exposure
 Extreme heat/sun

When mutations go unchecked disease and
even cancer can result.
HOW COMMON ARE MUTATIONS?

The most common place where there are
mutations….?
Bacteria.
Why do you think that is?