Biology Notes
Topic: Protein Synthesis
Objective: Alabama Course of Study #8
Glencoe High School
Meredith Barkley
List of Note-Cards (AL COS #8)
 #8-1 What is relationship between chromosomes, DNA, & genes?
 #8-2 Notable Scientists
 #8-3 Simplified Structure of DNA
 #8-4 DNA Replication
 #8-5 DNA versus RNA
 #8-6 Protein Synthesis
 #8-7 Protein Synthesis Practice Problems
 #8-8 Genetic Variation
 #8-9 Examples of Biotechnology
 #8-10 Types of Mutations
 #8-11 Genetic Disorders
#8-1 What is the relationship between
chromosomes, DNA, and genes?
 Chromosomes unravel into
strand of DNA…
 Segments or sub-units of
DNA are called genes.
 The human genome
contains ~ 20,000 genes
that codes for proteins,
such as enzymes (biological
catalysts) within your
body!
What kind of genes do you have???
 Remember that genes are
basically coded information
cells use in order to produce
proteins, like enzymes, that
are responsible for important
jobs within your body. For
example, the BRCA 1 and
BRCA 2 genes are found on
human chromosomes 13 and
17. These genes act as
tumor suppressors,
preventing uncontrolled cell
growth that could lead to
malignant tumors.
#8-2 Notable Scientists
(1928)
Griffith
1900
1915
(1949)
Chargaff
1930
1945
(1944)
Avery
(1952)
Hershey
& Chase
1960
1975
1990
(1952)
Wilkins &
Franklin
(1953)
Watson & Crick
2005
2020
#8-2 Notable Scientists
(1928)
Griffith
1900
1915
(1949)
Chargaff
1930
1945
(1944)
Avery
(1952)
Hershey
& Chase
1960
1975
1990
(1952)
Wilkins &
Franklin
(1953)
Watson & Crick
2005
2020
#8-2 Notable Scientists
Scientist(s)
Griffith (1928)
Avery (1944)
Chargaff (1949)
Hershey and
Chase (1952)
Wilkins and
Rosalind Franklin
(1952)
Watson and Crick
(1953)
Contributions to Genetics
#8-2 Notable Scientists
Scientist(s)
Contributions to Genetics
Griffith (1928)
Discovered process of transformation, which is a change in the genotype of an
individual and is caused when cell take up foreign genetic material.
Avery (1944)
Demonstrated the DNA was responsible for transformation.
Chargaff (1949)
Developed “base-pairing” rules for nitrogen bases within DNA: The amount of
adenine is equal to the amount of thymine, and the amount of cytosine is equal to
the amount of guanine. (Amounts of A=T and C=G)
Hershey and
Chase (1952)
Reaffirmed discovery made by Avery , reproving DNA was the genetic material
within cells by experimenting with bacteriophages.
Wilkins and
Rosalind Franklin
(1952)
They developed x-ray diffraction photographs of strand of DNA. Rosalind
Franklin died of ovarian cancer due to the nature of their work at the age of 37.
Watson and Crick Built 3-D model of DNA in the form of a double helix.
(1953)
Griffith’s Experiment Illustrated
Griffith’s Experiments Summarized
 Made accidental discovery while preparing vaccines against the
bacteria Streptococcus pneumoniae
 Griffith worked with 2 strains of pneumoniae:
1. S. pneumoniae (enclosed in capsule & forms smooth colonies)
2. R. pneumoniae (no capsule & forms rough-edged colonies)
 Bacterial colonies with capsules were protected against the bodies
immune system and were considered virulent, or able to cause
disease.
 Through a series of 4 experiments he discovered the process of
transformation (change in genotype caused when body takes up
foreign genetic DNA)
Hershey and Chase’s Experiment
Illustrated
Hershey and Chase’s Experiments
Summarized
 Question: What is the genetic material within cell?
 Answer: DNA
 Experiments were used to prove this concept involved “T2





bacteriophages”
bacteriophage : virus that infects bacteria
T2 bacteriophages have phosphorus in their DNA.
T2 bacteriophages have sulfur in their protein coat.
They labeled both phosphorus and sulfur with radioactive
isotopes in order to track their location.
After the phages infected E. coli bacteria, the radioactive
phosphorus moved into the cell, while the sulfur remained
within the phage.
#8-2 Notable Scientists
 Match each scientists name
with the illustrations
provided:
A. Griffith
B. Avery
C. Chargaff
D. Hershey & Chase
E. Wilkins & Rosalind
Franklin
F. Watson & Crick
#8-3 Simplified Structure of DNA
Component
Description
DNA
Shape
Sub-Units
Organization
(Sides of Ladder)
Organization
(Rungs of Ladder)
Student Skills
Needed
#8-3
Simplified
Structure of
DNA
#8-3 Simplified Structure of DNA
Component
Description
DNA
Deoxyribose (sugar) nucleic acid: genetic info within cells
Shape
Spiral ladder called a “double helix”
Sub-Units
Nucleotides (sugar, phosphate, and base)
Organization (Sides Each side is made up of alternating sugars and phosphates,
of Ladder)
and the sides are anti-parallel in nature (one strand will be
shown from 5 prime (5’) to 3 prime (3’) and the other strand
will be shown from 3’ to 5’
Organization
(Rungs of Ladder)
Made up of complementary nitrogen base pairs (based on
Chargaff’s Rule)
Student Skills
Needed
•Be able to record complementary strands of DNA, based on
sequence given.
•Be able to draw or identify the components of DNA.
#8-3 Simplified Structure of DNA
Draw sketches as needed to accompany your notes!
Nucleotide
Practice Problems
 Record the complementary strand of DNA that corresponds
to the sequence given.
1. AGG TCA
TCC AGT would be the complementary DNA strand.
2. GTT ACC
CAA TGG would be the complementary DNA strand.
3. GCA TAC
CGT ATG would be the complementary DNA strand.
#8-4 DNA Replication
 Refer to this diagram as you go through your notes,
remembering there is more detail here than you will be
responsible for… Don’t get overwhelmed!!!
#8-4 DNA Replication
Prokaryotes
 Before we talk about the
copying / replication of
DNA, it’s helpful to
remember that DNA
within prokaryotes will be
found within the cell’s
cytoplasm in a single loop.
 Prokaryotic cells may also
contain plastids with
additional DNA.
Picture
#8-4 DNA Replication
Picture
Eukaryotes
 Before we talk about the
copying / replication of
DNA, it’s helpful to
remember that DNA within
eukaryotes will be found
within the cell’s nucleus.
 Extra-nuclear DNA can also
be found within the
mitochondria and
chloroplasts of eukaryotic
cells. (connection to
EndosymbioticTheory)
#8-4 DNA Replication
 Prior to all forms of cell division, DNA is replicated/copied.
 DNA Replication occurs during the S Phase (synthesis) of
Interphase within the cell cycle for eukaryotic cells. Remember,
this is why a typical cell spends 90% of its life in interphase…takes
time to copy DNA and other cellular components.
 DNA replication involves a series of complex processess that we
can simply summarize into the following steps.
1. DNA is unwound/unzipped.
2. New nucleotide sequences are added.
3. The end result of DNA replication is that two DNA molecules
have been formed, each composed of a new strand and an
original strand. (semi-conservative model)
#8-4 DNA Replication: Initiation



DNA replication will
take place at certain
points called origins.
This process is aided by
special proteins.
Remember all enzymes
are classified as proteins.
These enzymes speed up
biological processes.
 This picture represents the
semi-conservative model of
DNA replication, meaning
each DNA molecule will
be made of one new and
one original stand.)
#8-4 DNA Replication: Elongation
 The enzyme DNA helicase
opens up / unzips the double
helix of DNA by breaking the
hydrogen bonds that linked
the complimentary nitrogen
bases between the strands.
 The areas where the DNA
separates are called
replication forks because
of their y-shape.
Prokaryotic and Eukaryotic DNA have a
different number of replication forks…
Prokaryotes
Eukaryotes
 Remember, DNA within
 The replication of a human
prokaryotes is found within a
nucleoid (nucleus like region)
in a single loop.
chromosome with only one
pair of replication forks from
a single origin would take 33
days!!! Therefore, a human
chromosome is replicated in
~100 sections, reducing the
time to replicate the DNA to
about 8 hours.
#8-4 DNA Replication: Elongation
 As DNA helicase
unwinds/unzips DNA… a
replication bubble is formed.
This bubble is where DNA
will be copied.
 Single stranded binding
proteins help hold and
temporarily separate each
original strand of DNA.
#8-4 DNA Replication: Elongation
 As the double helix is
pulled apart, the enzyme
DNA polymerase adds
new nucleotides to the
exposed nitrogen bases,
according to base-pairing
rules. DNA polymerase
also functions in
proofreading in an attempt
to correct any incorrect
sequences.
#8-4 DNA Replication: Elongation
 One strand will work ahead of the other, because of the
structure of the strand. The one that works at a quicker pace
is known as the leading strand. The lagging strand works like
a sewing machine back-stitching…
#8-4 DNA Replication
 This process produces two
DNA molecules, each
made up of a new strand
and an original strand.
 This is referred to as the
semi-conservative model of
DNA replication.
 Simple, right?? 
#8-5 RNA versus DNA
Characteristic
Type of Sugar
Structure
Nitrogen Bases
RNA
DNA
#8-5 RNA versus DNA
#8-5 RNA versus DNA
Characteristic
Type of Sugar
Structure
Nitrogen Bases
RNA
Ribose
Single Strand
A, U, C, G
DNA
Deoxyribose
Double Strand
A, T, C, G
Adenine
Uracil
Cytosine
Guanine
Adenine
Thymine
Cytosine
Guanine
Why is RNA important?
RNA plays an essential role in protein synthesis within your body.
#8-6 Protein Synthesis
Protein
Synthesis
Description
AKA
Process in which proteins are made from info encoded
within DNA
Gene expression
Steps
1. Transcription
2. Translation
Location (for
eukaryotes)
1. Transcription takes place in nucleus.
2. Translation takes place in the cytoplasm.
Analogy
Imagine there is a Spanish reference book (master code) that cannot leave the library
that contains info you would like to use to build your research paper… You could
copy info from the book within the library and then take the temporary copy to your
Spanish teacher’s classroom where it can translated and used to construct your final
research paper…
#8-6 Protein Synthesis
Transcription
 The instructions for making a protein are
transferred from a gene in DNA to a RNA
molecule called mRNA (messenger RNA).
 The RNA instructions are written as a series
of three-nucleotide sequences on the mRNA
called codons.
 This messenger RNA will carry the
instructions for making the protein from a
gene and deliver it to a site of translation.
#8-6 Protein Synthesis
 Notice that during transcription, DNA within the nucleus is used
as a template to make mRNA. DNA temporarily elongates and
unwinds. After the mRNA has been made, the double helix
reforms, and mRNA leaves the nucleus with its copy of the
instructions to make a protein written in RNA code.
#8-6 Protein Synthesis
Ribosomes Function in
Synthesizing Proteins
Translation
 The information to make
proteins is transferred from
the language of RNA
(nucleotides) to the
language of proteins (amino
acids).
 This takes place in
cytoplasm where ribosomes
are located.
 There are 64 possible codon
sequences that can be
translated into 20 different
amino acids.
#8-6 Protein Synthesis
 Translation of codons into amino acids
Interpreting the Genetic Code of Codons into Amino Acids,
the Building blocks of Proteins (pg 211)
Notice the Codon sequences that will START or STOP the process of protein synthesis!
#8-7 Protein Synthesis Practice
Example 1
Example 2
Example 3
DNA
mRNA
codon
Amino Acid
(Protein)
*Remember, you will need a table (like the one found on page 211
of your Holt Biology textbook) in order to complete “translation”
which involves recording the name of the amino acid that
corresponds to the mRNA codon you recorded/transcribed.
#8-7 Protein Synthesis Practice
DNA
mRNA
codon
Amino Acid
(Protein)
Example 1
ACC
Example 2
TTA
Example 3
AAA
*Remember, you will need a table (like the one found on page 211
of your Holt Biology textbook) in order to complete “translation”
which involves recording the name of the amino acid that
corresponds to the mRNA codon you recorded/transcribed.
#8-7 Protein Synthesis Practice
DNA
mRNA
codon
Amino Acid
(Protein)
Example 1
ACC
UGG
Example 2
TTA
Example 3
AAA
*Remember, you will need a table (like the one found on page 211
of your Holt Biology textbook) in order to complete “translation”
which involves recording the name of the amino acid that
corresponds to the mRNA codon you recorded/transcribed.
#8-7 Protein Synthesis Practice
Example 1
DNA
ACC
mRNA codon UGG
Amino Acid
Tryptophan
(Protein)
Click here for
info about this
amino acid
found in protein
supplements!
Example 2
TTA
AAU
Asparagine
Example 3
AAA
UUU
Phenylalanine
Click here for
info about this
amino acid
found in protein
supplements!
Click here for
info about this
amino acid
found in protein
supplements!
Do you know what
PKU is?
Gene Regulation and Structure
 This section will be added later for Pre-AP Bio Students 
#8-8 Genetic Variation



Genetic variation describes
naturally occurring genetic
differences among individuals
of the same species
This variation permits
flexibility and survival of a
population in the face of
changing environmental
circumstances.
Consequently, genetic
variation is often considered
an advantage, as it is a form of
preparation for the
unexpected.
Genetic variation may increase
through the following
processes
1. Independent Assortment
2. Crossing Over
3. Random Fertilization
4. Genetic Engineering /
Biotechnology
5. Mutation
#8-9 Examples of Biotechnology
 Biotechnology (AKA
 Human Genome Project
genetic engineering):
process of manipulating
genes for practical
purposes
 This may involve building
recombinant DNA: DNA
made from 2 or more
different organisms
 Genetically engineered
drugs and vaccines
 DNA fingerprinting
 Agriculture
 Animal Farming
#8-10 Mutations within DNA
What is a mutation and
who can it affect???
 Mutation: change in DNA
 Mutation to somatic cells
(body cells) affect only the
individual in which they
occur.
 Mutations to gametes (sex
cells) can be passed on to
the offspring of an affected
individual.
Major Types of Mutation
1. Point Mutation: changes a
single nucleotide within a
DNA sequence. This may or
may not affect function of the
gene in regards to protein
synthesis. (Ex: inversion)
2. Reading Frame Shift
Mutation: alters entire
reading frame of DNA
sequence, affecting function in
protein synthesis. (Example:
addition, deletion) pg.220
Case Study: Knowing Your Genome
 Actress Angelina Jolie
announced in a New York Times
op-ed article on Tuesday that she
underwent a preventive double
mastectomy after learning that
she carries a mutation of
the BRCA1 gene, which sharply
increases her risk of developing
breast cancer and ovarian
cancer.
 (2013 CNN) "My doctors
estimated that I had an 87
percent risk of breast cancer
and a 50 percent risk of
ovarian cancer, although the
risk is different in the case of
each woman…Once I knew
that this was my reality, I
decided to be proactive and
to minimize the risk as much
I could. I made a decision to
have a preventive double
mastectomy.“ – Angelina Jolie
Case Study: Knowing Your Genome
Additional Information
 Read this Reader’s Digest
article 5 Surprising Facts You
Didn’t Know About the
Breast Cancer Gene, to find
out more about Angelina
Jolie’s decision.
 KEY QUESTION: What are
potential benefits AND
drawbacks of having your
genome screened for
potential disease???
BRCA 1 and 2 Genes:
Mutation to These Genes
Associated With Increased
Risk of Breast Cancer…
#8-11 Genetic Disorders
Disorder
Sickle cell anemia
Tay-Sachs disease
Cystic fibrosis
Hemophilia A
Huntington’s
Colorblindness
Inheritance
Pattern
Characteristics
(*denotes group that is at increased risk)
#8-11 Genetic Disorders
Disorder
Inheritance
Pattern
Characteristics
(*denotes group that is at increased risk)
Sickle cell anemia
recessive
Poor blood circulation (*African Americans)
Tay-Sachs disease
recessive
Deterioration of CNS, causes death (*Jewish)
Cystic fibrosis
recessive
Excessive mucus production (*Caucasians)
Hemophilia A
Sex-Linked rec.
Failure of blood to clot (*men)
Huntington’s
Dominant
Deterioration of brain in mid-life, eventually death
Colorblindness
Sex-Linked rec.
Defective color vision (*men)
Sickle Cell Anemia
 Recessive disorder
 Produces a defective form of hemoglobin, which bends the red
blood cells (RBCs) into a sickle shape
 Why do people with sickle cell anemia have poor blood
circulation? Normal RBCs live ~120 days, while sickle cells live
~10-20 days…Sickle shaped RBCs rupture easily and tend to get
stuck in blood vessels which is painful and cuts off blood supply to
organs and decreases oxygen carrying capacity
 People with Sickle Cell Anemia, as well as carriers (heterozygous
individuals) are resistant to Malaria! (Malaria is caused by a
protozoan that invades RBCs.)