Download Exam II Review - Iowa State University

Exam II Review
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Safwan Elkhatib
BIO 212 (6)
Coffman
02/19/2014
This worksheet is designed to help you review for exam II. This is not all-inclusive, and
attempts to encourage recall. For each concept, you should help you develop a more holistic
understanding of each idea as well as how we can relate them to one another.
Interpret the classical experiments that identified DNA as the genetic material in bacteria.
1. Describe the central finding of each classical DNA experiment, as well a short summary of
their methods.
I. Griffith (R & S type bacterial “transformation”):
II. Avery, Macleod, McCarty (Preparation of DNA from S-type bacteria, addition of
various enzymes):
III. Hersey-Chase (Labeled phages):
IV. Meselson & Stahl (Use of Nitrogen isotope to understand mechanism of replication):
Describe DNA structure (the sugar-phosphate backbone, nucleotide bases, and the doublestranded helix structure.)
2. What are four bases contained with DNA, and how can we classify them into groups? Which
base pairing are you likely to find in a thermophilic bacterium? Why?
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3. Using Chargaff’s Rules, how much Adenine is contained within the DNA of a turtle,
knowing that Guanine makes up 22.0% of its nucleotide bases?
4. Given the sequence 5’-ATGAGCGACCCC-3’, the reverse complement is…
5. What is the backbone of a DNA molecule composed of? The linkage exists between a
______________ and a ___________ of the next deoxyribose (within the same strand). This
gives rise to the 3’ and 5’ polarity on a strand. The two strands of the helix are
_____________ to each other.
Know that DNA replication is carried out by DNA polymerase and describe the mechanism
of DNA replication.
6. DNA Replication—these simple words strike fear into the bones of many BIO 212
students. Using the word bank below, draw this process and explain the function of
each enzyme along the way: [Double helix strand, single-strand binding proteins, DNA
topoisomerase, Replication fork, DNA helicase, DNA ligase, DNA Polymerase, Okazaki
fragments, Leading strand, Lagging strand, DNA Primase, RNA Primers]
Understand that DNA is folded into chromosomes in eukaryotes and describe how chromosome
numbers are maintained through mitosis and meiosis.
7. DNA folding and compaction is a field of biology still containing many unknowns. We do
know that…(Buzzwords: nucleosome, histones)
8. A chromosome is just a long molecule of _____. Chromosomes are most compact during
___________.
9. What purpose do telomeres serve during DNA replication?
10. Chromosome number can help you understand organismal complexity. T / F
Learning Goals: Describe the following:
(1) the major components of a gene,
(2) Transcription of DNA into RNA by RNA polymerase
(3) The processing of RNA.
(4) The translation of RNA into the amino acid sequences of proteins.
11. What is the “central dogma” of molecular biology?
12. What are the three stages of transcription? What key enzyme facilitates this process?
I.
II.
III.
13. In prokaryotes, translation at the 5’ of mRNA will often begin as is still being transcribed in
the 3’ region. Eukaryotic cells cannot do this for two reasons. Name the two reasons—there
are three specific types under one of these.
I.
II.
i.
ii.
iii.
14. mRNA is the end product of transcription. We then begin translation, which takes place in
the ___________ within the ____________.
15. mRNA is read in groups of three bases, known as _______.
16. Draw the general structure of an amino acid. If you had multiple amino acids bonded
together, draw and name the type of bond that would exist between the two. Looking at the
structure you have drawn, how can we label the C and N terminus?
17. The end production of translation is a chain of amino acids, also known as a __________.
Once the mRNA enters the ribosome, we have another three step process that begins (same
three words as transcription). Explain what happens in each of these steps—and how does
tRNA tie it all together?
I.
II.
III.
18. Now to summarize it all graphically draw a general step-wise outline of this “central dogma”
in eukaryotes.
(Think: DNA → pre-mRNA → mRNA → tRNA → amino acids)
Describe the regulation of gene expression in prokaryotes (using lac operon as an example).
Know that gene expression is regulated by transcription factors, which bind to regulatory
elements in promoter regions of genes.
Know that gene expression is affected by chromatin structure.
Understand that gene expression can be regulated at the post-transcriptional level (e.g.
alternative splicing & microRNA).
19. The Lac operon allows for transcriptional regulation; this is accomplished by regulating the
initiation of transcription at the promoter site. The two types discussed in lecture were…
I. Repressor protein—what does it do?
i. When Lactose is ________, lac operon is induced because (think side rxn)…
II. Activator—cAMP binding to CAP. When glucose is _________, the CAP activator is
binded by cAMP which allows for the more efficient expression of the lac operon.
20. MicroRNAs are 21-22 NT RNAs that bind to specific target mRNAs. This mRNA is changed
in one of two ways.
I.
II.
21. Due to alternative splicing in mRNA, different exons can be included. This means that…