CH 13: DNA, RNA & PROTEINS STUDY GUIDE
I. Section 1: The Structure of DNA
A. DNA: The Genetic Material
1. In the 1800’s, Mendel showed that
2. We now know that the instructions for inherited traits are called
__________.
3. Before the 1950’s scientists did NOT know what genes were made
of. Since then, we now know that genes are made of
________________________________________ or DNA.
4. Prior Knowledge: What are the building blocks/monomers of
DNA called?
B. Searching for the Genetic Material – DNA was discovered in 1869 by
a Swiss doctor named Miescher, but he did not know that it was the
hereditary material. By the 1900’s scientists knew that hereditary
material was in the cell but they didn’t know exactly where in the cell
it was located. Three major experiments helped scientists figure out
that DNA is the hereditary material located in the nucleus of all
eukaryotic cells. DESCRIBE EACH SCIENTIST’S
EXPERIMENT.
1. Griffith Discovers Transformation - 1928
a. Identify the 3 types of organisms Griffith worked with.
b. What disease was Griffith working with?
c. Griffith’s 4 Experiments:
1. Injects mice with the R strain (rough pneumonia bacteria):
What happened to the mice?
2. Injects mice with the S strain (has the polysaccharide capsule
covering it): What happened to the mice?
3. Injects mice with heat-killed S strain bacteria: What
happened to the mice?
4. Injects mice with harmless R strain bacteria mixed with
harmless DEAD/heat-killed S strain bacteria: What happened to
the mice? How does Griffith explain these results?
d. What is Griffith’s conclusion regarding his experiment?
2. Avery’s Experiments with Nucleic Acids – 1940’s
a. What was Avery trying to figure out?
b. Identify the organisms Avery was working with.
c. Which organic molecule (carbohydrate, lipid, protein, or nucleic
acid) caused the harmless R strain bacteria to transform into
disease-causing S strain?
d. Do you think all scientists were convinced that DNA was the
hereditary material?
3. Hershey-Chase Experiment – 1952
a. What were Hershey & Chase trying to determine?
b. Identify the organisms Hershey & Chase were working with.
c. What 2 organic molecules are viruses like the bacteriophage
made of?
d. Explain Hershey & Chase’s conclusions.
e. So, is it the protein or the DNA that carries our hereditary
information/genes?
f. By the early 1950’s, most scientists were convinced that DNA
is the hereditary material.
C. The Shape of DNA
1. Name the 2 scientists that discovered the structure of the DNA
molecule.
2. Describe the shape of the DNA molecule & give its scientific name.
3. Identify the monomers/building blocks of nucleic acids.
4. Notice the 3 parts of a nucleotide on the labeled diagram below.
NOTE: You may be asked to label a nucleotide sometime in the future.
5. Name the 5-carbon sugar in the DNA nucleotide.
Use the diagram of the DNA molecule to answer the following 3 questions:
6. What are the “sides” of the DNA molecule made of?
7. What are the “rungs” of the DNA molecule made of?
8. What connects the 2 strands together?
D. The Information in DNA
1. The order of the nitrogen bases determines the information in the
DNA molecule while the paired nitrogen bases allow the DNA
molecule to be copied.
2. Name the 4 nitrogenous bases in DNA.
3. Which nitrogen bases are single rings/pyrimidines?
4. Which nitrogen bases are double rings/purines?
5. How do the nitrogen bases pair up & what type of bond holds them
together?
6. If the one side of the DNA molecule has the sequence
TATGAGAGTCTG what is the sequence of nitrogen bases on
the complimentary strand?
E. Discovering DNA’s Structure – Identify each scientist’s contribution
to the discovery of DNA’s structure.
1. In 1949 this scientist’s research showed that no matter what
organism’s DNA he studied the amount of adenine always equaled
the amount of thymine & the amount of cytosine always equaled
the amount of guanine. Name the scientist.
2. In 1952 these 2 scientists used x-ray diffraction to photograph
DNA. Name the scientists.
3. In 1953 these 2 scientists used Chargaff’s data & Franklin’s x-ray
data to build a 3-D model of the DNA molecule. Name the 2
scientists.
4. What happened in 1962 & why wasn’t Franklin part of the group?
F. Key Ideas – use the information in this section to answer these
questions.
1. What is genetic material composed/made of?
2. List the experiments & the scientists that helped identify the role of
DNA as the hereditary material.
3. What is the shape of the DNA molecule?
4. How is genetic information organized in a DNA molecule?
5. What scientific investigations led to the discovery of DNA’s
structure? Identify the scientists involved.
II. Section 2: Replication of DNA
Check out this web site: http://www.pbs.org/wgbh/aso/tryit/dna/# - DNA Replication
A. DNA Replication - When cells divide, each new cell contains a
____________________________ of the original cell’s DNA.
DNA is made of 2 strands of complementary base pairs. If the 2
strands are separated, each strand serves as a pattern (template) for
making a new complementary strand of DNA. The end result is
the formation of 2 exact copies of DNA from the original DNA.
STEP 1: UNWINDING & SEPARATING DNA STRANDS
The DNA double helix ____________ & enzymes/proteins called
_________________ separate the 2 original DNA strands. The
Y-shaped areas of separation are called _____________________.
STEP 2: ADDING COMPLEMENTARY BASES
______________________ nucleotides are added to each strand
by enzymes called ________ _____________________. The
addition of the complementary nucleotides occurs at the Y-shaped
___________________ __________.
NOTE: Where do the nucleotides we need to build new DNA
come from?
STEP 3: FORMATION OF 2 IDENTICAL MOLECULES
______ DNA molecules are formed. They are identical to each
other and to the original _______ ____________________. Each
double-stranded DNA helix is made of one _______ strand of DNA
& one _________________ strand of DNA. The nucleotide
sequence of both these DNA molecules is _______________ to
each other & to the ______________ DNA molecule.
B. Replication Proteins – involved in replicating DNA.
1. DNA Helicase – discuss this enzyme’s function in the space
below.
2. DNA Polymerase – discuss this enzyme’s 2 functions in the space below.
a.
b.
NOTE: Why is proofreading the new DNA strands so important?
(THINK: Why should you proofread your work before turning it in?)
C. Prokaryotic & Eukaryotic Replication
1. Prokaryotic DNA Replication – occurs in bacteria cells.
a. Describe the shape of the bacterial chromosome.
b. What 2 organic molecules make up the bacterial chromosome?
c. How many chromosomes does a bacterial cell have?
d. Explain how the bacterial chromosome replicates.
2. Eukaryotic DNA Replication – occurs in protist, fungi, plant, & animal
cells.
a. Describe the shape of the eukaryotic chromosome.
b. What 2 organic molecules make up the eukaryotic
chromosome?
c. How many chromosomes can a eukaryotic cell have?
d. Explain how our eukaryotic chromosomes replicate.
e. How long does it take to replicate an entire human
chromosome?
f. Size of Eukaryotic DNA
 Which chromosomes are smaller; prokaryotic or
eukaryotic?
 How many chromosomes are in the nucleus of the cell of
a normal human being?
 If all 46 of your chromosomes were lined up end to end,
how long a line would you have?
III. Section 3: RNA & Gene Expression
A. Introduction
1. What organic molecules perform most of the functions of the cell?
2. What molecule carries the code or information for the making of
proteins?
3. Which nucleic acid takes the information for making a protein from
DNA?
4. Define the following terms:
 Gene Expression –
 Transcription –
 Translation –
B. RNA: A Major Player
1. List the 3 differences between DNA & RNA below.
DNA
RNA
2. Name the 3 main types of RNA
a.
b.
c.
C. Transcription: Reading of the Gene on DNA
1. What happens during transcription?
2. Description of transcription.
a. Step 1 – Enzyme ______ ________________ binds/attaches to a
specific area of DNA in the gene called the ________________.
The promoter acts as the “__________” location.
b. Step 2 – Enzyme ______ _______________ untwists/unwinds &
separates the 2 strands on the double helix exposing the ______
nitrogen bases on each strand.
c. Step 3 – RNA polymerase adds & links/joins complementary
_____ bases/nucleotides as it “_______” the gene on DNA.
Whenever the RNA polymerase reads an adenine on the DNA
molecule a _____________ nucleotide pairs with the adenine
rather than a thymine. A _____________ strand of RNA is
formed. Eventually, the RNA polymerase reaches a “_______”
location on the DNA molecule & transcription ends. The DNA
re-twists into the double helix & the single strand of mRNA can
now leave the nucleus & enter the cytoplasm of the cell.
D. Transcription Versus Replication
TRANSCRIPTION
REPLICATION
E. The Genetic Code: Three-Letter “Words”
1. Each group of 3 nitrogen bases on the m-RNA is called a
________________.
2. Each codon (aka: triplet codon) codes for 1 of 20
__________ __________ or acts as a ____________ or ________
signal for translation (making a protein).
3. Previous Knowledge: Amino acids are the monomers/
building blocks of ___________ __________.
4. _______________ amino acids have more than one
_______________. Example: UCU, UCC, UCA, UCG all code
for the amino acid _________________.
5. The codon AUG is a ______________ codon. The codons
UAG, UAA, & UGA are ____________ codons & signal the
ribosome to stop reading the code on the m-RNA &
protein synthesis/translation stops.
6. The matching of codons & amino acids is known as the
______________ __________.
F. Translation: RNA to Proteins
1. What is the cell making during the process of translation?
2. Previous Knowledge: What is a polypeptide?
3. Description of Translation – the building of a protein
a. Step 1: The ribosome attaches to the ________ at the
_____________ codon AUG. A ________ with the
anticodon _______ and carrying the amino acid
methionine binds to the m-RNA.
b. Step 2: The ribosome reads the next codon on the
m-RNA & another t-RNA brings another ___________
_________ which binds to the first amino acid in the
protein chain. A ______________ bond joins the
amino acids together.
c. Step 3: The first t-RNA detaches from the ribosome &
goes back into the cytoplasm to pick up another
____________ __________. The ribosome continues
reading the codons on the m-RNA, the t-RNA’s
continue bringing & adding ___________ _________
to the protein/polypeptide chain.
d. Step 4: When the ribosome reads a _________ codon
the process of translation or _____________ synthesis
stops.
e. Step 5: The protein chain/____________________ is
released into the cytoplasm, & the ribosome
separates from the m-RNA.
4. Several _______________ can translate the same piece of m-RNA
at the same time, which allows _____________copies of the same
protein to be made very rapidly.