Download Unit 7 (Molecular Biology - DNA) Study Guide KEY

Pre-AP DNA and Protein Synthesis Review - KEY
1. Describe the experimental procedure and conclusion for each of the following scientists:
a. Griffith
Conclusion: Transformation (The transfer of genetic material from one cell to another cell or from one
organism to another organism) can occur
b. Chargaff (tell only his conclusion, not the procedure)
In all living organisms, % of A=% of T and % of C=% of G
c. Hershey and Chase
DNA, and not proteins, is the hereditary material.
d. Watson and Crick (tell only their conclusion, not their procedure)
Double Helix
2. What is the monomer of a nucleic acid? Nucleotide
3. What 3 parts make up a nucleotide? nitrogenous base, 5 carbon sugar, phosphate
4. Draw a nucleotide, label each part, and tell what parts would be different if it were a DNA
nucleotide vs. an RNA nucleotide.
Phosphate
Nitrogenous base
(DNA – A, T, C, G)
(RNA – U instead of T)
Deoxyribose Sugar
(Would be ribose for RNA)
5. List by order of size the following: gene, cell, chromosome, atom, nucleus of a cell, base,
nucleotides, DNA molecule.  (Important note: The only difference between a DNA molecule
and a chromosome is that a DNA molecule refers only to a strand of DNA while a chromosome is
a strand of DNA AND the histone proteins it is associated with).
atom, base, nucleotide, gene, chromosome, nucleus, cell
6. What are pyrimidines and what are the examples?
Single ringed bases; C, T, and U
7. What are purines and what are the examples?
Double ringed bases; A and G (Purines Are Good)
8. What is the bond between two bases?
Hydrogen (very weak, can be broken – MUST UNZIP DNA TO USE IT)
9. Write all of the complementary base pairs.
A to T (or A to U if it’s RNA)
C to G
10. Answer all of the following questions concerning DNA replication.
a. What is it? copying DNA (during S phase of interphase)
b. Where does it happen? nucleus (everything that involves DNA must occur in the
nucleus)
c. Why does it happen? So that we have 2 sets of DNA and we can perform mitosis (with
each new cell getting a complete set of DNA)
11. What is the difference in the leading and lagging strand of DNA replication?
Both are involved in DNA replication. Leading strand adds continuously to the 3’ end toward
the replication fork. The lagging strand must add to the 3’ end away from the replication fork;
therefore, it is built in segments that are then joined together by DNA ligase.
12. What is the function of each of the following enzymes?
a. DNA Polymerase
build new DNA
b. RNA Polymerase
build new RNA
c. Helicase
separates strands of DNA by breaking hydrogen bonds between bases
d. Primase
adds primer so that polymerase can build a new DNA strand
e. Ligase
closing gap between Okazaki fragments on lagging strand
Questions 13-16 should be answered together
13. What is the complementary strand of DNA for the following template of DNA?
a. CGC TAT CCG
GCG ATA GGC
14. What would be the mRNA for the template above?
GCG AUA GGC
15. What would be the tRNA for the template above? BONDS WITH MRNA
CGC UAU CCG
16. What amino acids are produced from the process described in questions 13-15?
ALA, ILE, GLY
USE MRNA
17. Answer all of the following questions concerning transcription.
a. What is it? DNA to mRNA (just a cheap copy of DNA)
b. Where does it happen? nucleus (because DNA is involved)
c. Why does it happen? DNA is too important to take out of the nucleus and risk it getting
messed up. Also, DNA is too big to get out of the nucleus.
18. Answer all of the following questions concerning translation.
a. What is it? mRNA to proteins
b. Where does it happen? ribosomes (in the cytoplasm or rough ER)
c. Why does it happen? to make proteins that do all of the work in the cell
19. Answer the following questions concerning codons
a. Where are they located? mRNA
b. How many bases are they made of? 3
c. What do they “code” for? amino acid (monomer of protein)
d. Using the answer given in part c, how many of they does each codon “code” for? 1
20. What is an anticodon?
3 bases on tRNA that are complementary to codon on mRNA
21. Draw the generic shape of a tRNA and label the amino acid, the tRNA, and the anticodon. (What
does the t in tRNA stand for? What are they transferring?)
22. What kind of bond forms between amino acids? peptide (covalent bond)
23. If the DNA analysis of a gene shows 20% adenine bases, what would be the percentage of
Thymine, Cytosine, Guanine, and Uracil?
T = 20% percent, C = 30%, G = 30%, U = 0%
24. Draw a double helix and indicate the location of each of the following:
b. Phosphate group
c. Sugar (deoxyribose)
d. Hydrogen bond
e. Covalent bond
f.
g.
h.
i.
Adenine
Thymine
Cytosine
guanine
H-Bond
Covalent Bond
(phosphodiester
bond)
Biotechnology = using our knowledge of life for our own benefit (cloning, recombinant DNA,
GM food, etc)
25. Prokaryotic genes are expressed in groups using an operon. Draw an operon (ONLY IN
BACTERIA) below and label the following: promoter, operator, structural genes. We modeled
this using straw, noodle, paper clip, etc.
26. All of the following terms apply to the usage of operons drawn above. Define each of the
following terms:
a. Operon – A group of prokaryotic genes with a related function that are often grouped and
transcribed together.
b. Promoter-The nucleotide sequence that can bind with RNA polymerase to start
transcription. This sequence also contains the operator region.
c. Operator-The nucleotide sequence that can bind with repressor protein to inhibit
transcription. ON/OFF SWITCH
d. Structural genes- genes that are related and code for related enzymes in a biochemical
pathway.
e. RNA Polymerase – enzymes that reads DNA and makes mRNA
f. Regulatory Gene – Gene that lies outside the operon region and produces a protein called a
repressor that can inhibit the transcription of an operon by attaching to the operator.
27. What is the difference in an inducible operon and a repressible operon? (Hint: The lac operon is
an example of an inducible operon and the trp operon is an example of a repressible operon).
Inducible = usually off but can be turned on (induce labor)
repressible = normally on but can be turned off
28. Define the following terms.
a. Plasmid –
i. These are small, circular, exchangeable pieces of DNA.
ii. These are in addition the main large circular DNA strand.
iii. These help to increase variation and survival.
b. Restriction Site – site where a restriction enzyme MUST cut
c. Restriction Enzyme – enzyme found in bacteria used to cut specific DNA sequences
d. Recombinant DNA – DNA from 2 different sources (Remember spider-goats?). Use
restriction enzyme to cut DNA from one source and insert it into another.
TRANSFORMATION - GRIFFITH
29. What are the 4 steps to bacterial cloning? (Hint: Be sure to understand the purpose of the ampR
gene on the plasmid as well as placing the bacteria in an antibiotic.)
a. The first step in this process uses restriction enzymes to create “Sticky Ends” on a
plasmid and DNA from another source. This plasmid will also have a gene for antibiotic
resistance on it.
b. The second step is to introduce the fragments to the “open” plasmids for
recombination to occur.
i. Recombination – This is the DNA of the plasmid recombining to contain both
the original plasmid DNA and the new DNA.
ii. The “sticky ends” base pairs will match allowing for recombination to occur.
iii. The third step uses the enzyme Ligase to seal the DNA fragments together.
c. The third step is to introduce the recombined plasmids back into the bacteria. The
bacteria are also called a Cloning Vector. A vector is a carrier organism.
d. The fourth step is to identify the bacteria that took the plasmid up by putting them on
ampicillin. The bacteria that took up the plasmid will have antibiotic resistance and will
live. The bacteria that did not will not have antibiotic resistance and will die.
Then let the bacteria reproduce, by binary fission, to achieve a large working
population.
30. What is Gel Electrophoresis used for?
Use Restriction enzymes to chop up DNA. Separate DNA fragments based on size