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Leader: Tiffany
Exam 2 review
Supplemental Instruction
Iowa State University
Course: Biol 212 (1)
Instructor: Powell-Coffman
Date: 02/20/2011
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
1. Non-coding sequences of DNA can be defined as:
a. exons
b. operons
c. introns
d. both a and b
2. Solar energy is used to split _________ to produce oxygen
a. electrons
b. water
c. carbon dioxide
d. b and c
e. none of the above
3. Which of the following is NOT an input of the calvin cycle?
a. carbon dioxide
b. ATP
c. NADH
d. G3P
e. c and d
4. A mutation that stops translation early is called
a. missense mutation
b. frame shift
c. silent mutation
d. nonsense mutation
5. What is the basis for the difference in how the leading and lagging strands of DNA replication?
a. a single polymerase can only work on one strand at a time
b. the origins of the replication are only at the 5’ end
c. helicase damages the replication fork
d. polymerase can only add nucleotides to the 3’ end
e. a and d are true
6. Which of the following mends the fragments of the lagging strand together in DNA transcription?
a. helacase
b. DNA polymerase III
c. ligase
d. primase
7. What is not true of an operon?
a. usually present in prokaryotes
b. regulates gene expression rates
c. usually present in eukaryotes
d. use RNA polymerase to start
e. none of the above
8. DNA can be found in which of the following?
a. nucleus of a eukaryotic cell
b. mitochondria
c. chloroplast
d. nucleus of a prokaryotic cell
e. a and b
f. a, b and c
g. a and d.
Leader: Tiffany
Exam 2 review
Supplemental Instruction
Iowa State University
Course: Biol 212 (1)
Instructor: Powell-Coffman
Date: 02/20/2011
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
1.Describe where the light reactions and the calvin cycle take place in a plant cell
and what the inputs and outputs are of the two stages.
The light reactions occur in the thylakoid membranes of chloroplasts.
The inputs are H2O and light energy and the outputs are NADPH,
ATP, and oxygen.
The calvin cycle in an anabolic process which occurs in the stroma of
chloroplasts. It uses ATP and NADPH from the light reactions to
convert CO2 into sugar. Each cycle of the Calvin Cycle starts with a
5C sugar and with the aid of rubisco (an enzyme) will add a C from
CO2 to create sugar molecule containing 3 C’s (it must go through the
cycle 2 times to make one sugar molecule).
2. How are C3 and C4 plants different/similair?
In C3 plants, fixation of carbon occurs via rubisco, which adds CO2 to ribulose
biphosphate during the calvin cycle. The product of carbon fixation is a 3-carbon
compound.
In C4 plants, PEP carboxylase adds CO2 to PEP to make a 4 carbon compound (in
the mesophyll cells), the 4-C compound is then exported to the bundle-sheath cells
through plasmodesmata. In the bundle-sheath cells, the 4C compound breaks up
into CO2 and pyruvate. In this way, C4 plants maintin a concentrtation of CO2 in
their bundle sheath cells as an adaption to hot, dry climates. If they were to open
their stomata to take in CO2 during the day, they would also lose too much water.
This way, they can keep their stomata partially closed during the day and use CO2
that is concentrated in bundle-sheath cells to generate sugar.
3. How is energy conserved in an ecosystem? Discuss the role of photosynthetic
organisms.
By using the energy from the sun, CO2, and H2O, photosynthesis in chloroplasts of
photosynthetic organisms produces organic molecules (sugars) and oxygen, which
organisms that contain mitochondria (animals) can use during cellular respiration
to create ATP, which powers cell work.
In other words, the outputs that photosynthetic organisms generate through
photosynthesis are used by animals as the inputs of cellular respiration to create
ATP and power cell work.
DNA structure and Replication
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
1.
Draw two complementary strands of DNA. Label the 5’ and 3’ ends of both strands and
indicate what type of bonds are between the base pairs and what type of bonds hold together
the sugar-phosphate backbone.
Covalent bonds hold together the sugar-phosphate backbone
2.
DNA
type of sugar
nitrogenous bases used
single/double stranded?
where can be found in
cell?
deoxiribose
ATCG
double
Mitochondria, chloroplasts,
nucleus
RNA
Ribose
AUCG
Single
Nucleus, cytosol,
3. General steps of DNA replication (It will be helpful if you draw it )
1) At the ____origin_____ __of__ __replication_____, __hydrogen____
bonds are broken between the two strands by __Helicase___.
2) ______RNA____ __primers______ are added to both strands
3) DNA polymerase makes a new strand in the ____5’-->3’________ direction.
For the ____leading_____ _____strand____, synthesis occurs toward the
replication fork. For the ____lagging________ _____strand_______,
synthesis occurs toward the origin of replication
4) _______DNA polymerase______ removes the _____RNA primers_______
and replaces them with dNTPs. DNA ligase joins together the
______okazaki________ _____fragments________ of the lagging strand.
4. Compare the two processes to amplify a DNA sequence of interest.
Bacterial DNA cloning (in _____)
Polymerase chain reaction (in ____)
How hydrogen bonds are Helicase
High temperature
broken
Primers?
Are RNA
Are DNA, must know sequence
How are dNTP monomers By DNA polymerase
By Taq polymerase, which won’t
added?
denature at high temps
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1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
Fast/slow?
slow
faster
5. What is the difference between a haploid and a diploid cell? In a haploid cell is DNA double
stranded? In a diploid cell?
A haploid cell has one copy of each chromosome. A diploid cell has two copies of each
chromosome. Both haploid and diploid cells have dsDNA! (chromosomes are made of DNA
packaged into chromatin (chromatin is dsDNA wrapped around histones))
DNARNA (_______transcription_________________)
1.
True or False
T or F The origin is the place on DNA where transcription starts (the promoter)
T or F During transcription, transcription factors bind to the promoter and recruit
RNApolymerase
T or F During transcription, ribose nucleotide monomers are 5’3’ direction
T or F Thymine has a methyl group (CH3), which Uracil lacks.
T or F All RNA that is transcribed must undergo processing in the nucleus
(only in eukaryotic cells)
T or F During RNA processing, introns are removed be the splicesome complex.
2. What mRNA would be transcribed from the following DNA sequence?:
5’ACTCGTCGA 3’
a.
b.
c.
d.
e.
f.
3.
5’ACGACGAGT3’
5’TGAGCAGCT 3’
5’ UGAGCAGCU 3’
5’UCGACGAGU 3’
3’TGAGCAGCT 5’
3’UGAGCAGCU 5’
Pre-mRNA processing includes:
Addition of 3’ poly-A tail 2) addition of 5’cap of modified guanine nucleotides
3) removal of introns by RNA splicing to form coding segment
Leader: Tiffany
Exam 2 review
Supplemental Instruction
Iowa State University
Course: Biol 212 (1)
Instructor: Powell-Coffman
Date: 02/20/2011
mRNAprotein (_____TRANSLATION______)
1. Describe the role of each of the following in translation:
a. Ribosomes- translate mRNA into protein
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1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
b. tRNA- has a stem-loop structure, the 3’ end is covalently attached to a specific amino
acid, it has an anticodon with base-pairs with the corresponding triplet codon in
mRNA, transfers amino acids 1-by-1to growing polypeptide chain
c. mRNA- what is translated by ribosomes into a polypeptide chain
d. amino acids- make up protein, transferred to growing chain by tRNA
e. aminoacyl-tRNA synthetase- enzyme that attaches an amino acid to a specific tRNA,
so that the tRNA will be “charged” and ready to be used for translation
2. Discuss the steps of translation
a. Intiation- the small ribosomal subunit binds to the mRNA, the anticodon of a charged
tRNA base-pairs with start codon AUG, and then the large ribosomal subunit binds
b. Elongation- the mRNA is pulled through the ribosome so a new codon is exposed in
the A site and a charged tRNA docks in the A site. The mRNA will be pulled through
again, which will make the first bound tRNA in the P site. Then, another charged
tRNA whose anticodon corresponds to the codon in the A site will bind in the A site.
The amino acid on the tRNA in the P site is then transferred to the amino acid on the
tRNA in the A site ( they bind together in a covalent peptide bond formed by a
dehydration reaction). Then, the mRNA with be “ratcheted” through, exposing a
codon in the A site again, and the tRNA which was previously bound to the growing
polypeptide (now unbound) will be released from the E site.
c. Termination- a stop codon is reached in the A site. A release factor comes into the A
site causing the tRNA and polypeptide to be released. GTP is then used to break up
the ribosomal subunits, mRNA, and release factor.
3. Provide a few examples of post-translational modifications
Phosphorylation (such as with the sodium/potassium pump), glycosylation (protein is
covalently linked to a carbohydrate), degradation of proteins by proteasomes, localization
of proteins (for example cell surface proteins internalized in an endocytosed vesicle
Regulation of gene expression
1. Define and explain the theory of genomic equivalence
The theory of genomic equivalence states that in a multicellular organism, each nucleus
in the adult cell has the same genomic content as that present in the original zygote
Known exceptions in humans- b cells and t cells, malignant cancer cells, haploid germ
cells
2. What is a gene? What is differential gene expression? How is this achieved pretranscription or post-translation?
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
A gene is a region of DNA that codes for a specific RNA molecule. This includes the region
that will be transcribed to RNA and regions that will regulate transcription.
Differential gene expression is how cells with the same genome can adopt very different cell
fates.
Pre-transcription: Activators promote transcription and repressors inhibit transcription.
Post-translation: Phosphorylation (such as with the sodium/potassium pump), glycosylation
(protein is covalently linked to a carbohydrate), degradation of proteins by proteasomes,
localization of proteins (for example cell surface proteins internalized in an endocytosed
vesicle
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu