Download Exam 3 Review -Key - Iowa State University

Exam 3 Review - Key
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Brandon
Biol 212
Dr. Coffman/Manz
3/26/2017
1. __Asexual__ reproduction is based on __mitosis__ and results in offspring that are
__genetically__ identical to their __parents__.
2. __Sexual__ reproduction is based on __meiosis__ and fusion of __gametes__, resulting
in offspring that are genetically __identical__ from each other and from their
__parents__.
3. Spermatogenesis can be defined as:
a. The formation of spermato’s
b. The degradation of sperm
c. The formation of sperm
d. The formation of oocytes
4. Oogenesis can be defined as:
a. The formation of oogonia
b. The formation of the fetus
c. The degradation of oocytes
d. The formation of eggs
5. Starting with a spermatogonium, what events take place to produce a mature sperm?
The spermatogonium divides
by ___mitosis___ and
produces what is known as a
___primary spermatocyte___.
The ___primary___
___spermatocyte___
undergoes ___meiosis I___
and produces __two__
___secondary___
___spermatocytes___.
Each ___spermatid___
matures into a ___sperm
cell___.
Each ___secondary___
___spermatocyte___
undergoes ___meiosis II___,
and produces __two__
___spermatids___ (giving a
total of __four__
___spermatids___).
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6. Starting with an oogonium, what events take place to produce a mature egg (ovum)?
The oogonium undergoes
__mitosis__ to produce
what is known as a
__primary__ __oocyte__.
The __primary__
__oocyte__ undergoes
__meiosis I__ and
produces a __secondary__
__oocyte__ and a
__polar__ __body__.
The __secondary__
__oocyte__ undergoes
__meiosis II__ and
produces an __ootid__
and a __polar__
__body__.
The __ootid__ matures
into an __egg cell__
(__ovum__).
The __polar__ __body__
produced from meiosis I
also undergoes __meiosis
II__, and produces two
more __polar__
__bodies__.
7. Label the: nucleus, acrosome, centriole, mitochondria, vacuole, plasma membrane,
flagellum, head, midpiece, neck, and tail of the sperm cell.
8. How does the structure of a sperm cell aid in fertilization and the development of the
zygote?
Head region:
- Nucleus – contains DNA
Acrosome – enzyme-filled structure; enzymes stored in acrosome allow the sperm to
penetrate the barriers surrounding the egg.
Neck region:
- Centriole – the centriole from the sperm will combine with the centriole from the egg to
form a centrosome.
o The centrosome is required for spindle formation during mitosis.
-
Midpiece region:
- Mitochondria – produce the ATP required to power movement.
Tail region:
- Flagellum – whips back and forth to make swimming possible.
9. External fertilization most commonly occurs in animals that live in which type of
environments?
a. Terrestrial
b. Aquatic
c. Microscopic
d. Savannah
10. How is external fertilization done?
a. Males deposit sperm directly into the female reproductive tract with the aid of a
copulatory organ.
b. Males package their sperm into a spermatophore, which is picked up and placed into
the female’s reproductive tract.
c. Individuals release their gametes into their environment synchronously.
d. Females package their eggs into an oogoniaphore, which is picked up and placed into
the male’s reproductive tract.
11. Which of the following best describes an ovoviviparous organism?
a. The embryo develops inside the mother’s body, but is nourished by the nutrient-rich
yolk stored in the egg instead of directly by the mother.
b. The embryo develops inside the mother’s body, attaching to the mother’s
reproductive tract and receiving direct nutrition via diffusion from the mother’s
circulatory system.
c. The majority of embryonic development takes place inside an egg that is laid in the
environment.
d. Offspring are raised by a guy named ovoviviparous.
12. What are the main functions of the male reproductive system?
- Spermatogenesis and sperm storage
- Production of accessory fluids
- Transport and delivery
13. Where does spermatogenesis and sperm storage take place in the male reproductive
system?
a. Cervix
b. Urethra
c. Epididymis
d. Vas deferens
14. What anatomical features of the male reproductive system contribute to the production of
accessory fluids and what do these accessory fluids do?
- Seminal vesicles
o Fructose – source of chemical energy for sperm movement
o Prostaglandins – stimulate smooth muscle contractions in uterus
- Prostate gland
o Antibiotic compounds – prevent urinary tract infections in males
o Citric acid – nutrient used by sperm
- Bulbourethral gland
o Alkaline mucus – lubricate tip of penis; neutralize acids in urethra
15. What are the main functions of the female reproductive systems?
- Production and transport of eggs
- Development of offspring
16. Describe the transportation of eggs to the uterus?
- During ovulation, a secondary oocyte is expelled from the ovary and enters the oviduct
(fallopian tube) where fertilization may take place. Fertilized eggs are then transported
through the oviduct to the uterus.
17. The sex hormones testosterone and estradiol play a key role in what three events?
Development of the
reproductive tract in
embryos.
Maturation of the
reproductive tract during the
transition from childhood to
adulthood.
Regulation of
spermatogenesis and
oogenesis in adults.
18. What is the function of Gonadotropin-Releasing Hormone (GnRH)?
a. Stimulates sperm production in the testis in males.
b. Stimulates estrogen production, ovulation, and formation of the corpus luteum in
females and testosterone production in males.
c. Stimulates growth of eggs and follicles in the ovaries for females.
d. Stimulates release of follicle-stimulating hormone (FSH) and luteinizing hormone
(LH) from the pituitary gland.
19. What is progesterone?
- A steroid hormone produced and secreted by the corpus luteum in the ovaries after
ovulation and by the placenta during gestation; protects uterine lining.
20. What process leads to an increase in testosterone and estradiol?
The release of
the chemical
signal
Gonadotropinreleasing
hormone (GnRH)
from the
hypothalamus
leads to the
release of two
regulatory
hormones (LH
and FSH) from
the pituitary
gland
These hormones
trigger the
release of
testosterone
from the testis
(male) and
estradiol from
the ovary
(female)
21. What are the two phases of the female menstrual cycle? Describe what occurs during
each phase.
- Follicular phase – stage where follicle matures
- Luteal phase – degeneration of corpus luteum
22. How do the following contraceptive methods work:
a. Hormone based methods – provides continuous or cyclical delivery of
progesterone, or progesterone plus estradiol.
b. Barrier methods – Covers sex structure (penis, vagina, cervix, etc.) and prevents
sperm from entering uterus.
c. Behavioral methods – Not having sex, withdrawing before ejaculation.
d. Fertilization prevention –
i. IUD – inserted into uterus, induces uterus to produce substances hostile to
sperm and eggs.
ii. Emergency contraception – delivers progesterone or progesterone and
estradiol after unprotected vaginal intercourse.
e. Pregnancy termination –
i. Mifepristone – blocks progesterone receptors so menstruation occurs even
after fertilization and implantation.
23. In what ways does the mother’s respiratory and circulatory systems change during
pregnancy?
- Changes in ways that increase the efficiency of nutrient transfer and gas exchange with
the fetus.
24. Which of the following is an example of a change that would occur as a result of the
change in the mother’s respiratory and circulatory systems?
a. A woman’s total blood volume expands by as much as 50% during pregnancy.
b. To accommodate the increase in blood volume, maternal blood vessels constrict and
blood pressure increases.
c. The mother’s heart enlarges and beats slower, decreasing her total cardiac output by
almost 50%.
d. The mother’s breathing rate and breathing volume decrease to accommodate the
fetus’s demand for oxygen and its production of carbon dioxide.
25. Describe the birthing sequence process.
- Dilation of cervix
o Cervical canal at base of uterus begins to open/dilate. Once cervix is fully dilated,
uterine contractions become more forceful, longer, and more frequent.
- Expulsion: delivery of infant
o The fetus is expelled through the cervix and into the vagina.
- Delivery of placenta
o After baby is delivered, the placenta remains attached to the uterine wall. When
the mother delivers the placenta and accompanying membranes, birth is complete.
26. Nucleic acids form when nucleotides:
a. Synthesize
b. Catalyze
c. Replicate
d. Polymerize
27. Given the following DNA strand what will its complementary DNA strand look like?
5’-AGCCAGAAGGC-3’
a. 5’-GCCTTCTGGCT-3’
b. 5’-TCGGTCTTCCG-3’
c. 5’-UCGGUCUUCCG-3’
d. 5’-AGCCAGAAGGC-3’
28. What was the purpose of the Hershey-Chase experiment?
- To test if genes were made up of DNA or protein
o This would tell what the hereditary material was.
29. What was the purpose of the Meselson-Stahl experiment?
- To test if DNA replication is semiconservative, conservative, or dispersive.
30. How do DNA polymerase and mismatch repair reduce errors during DNA synthesis?
- DNA polymerase proofreads the growing strand.
o If the wrong base is added during DNA synthesis, the enzyme pauses, removes
the mismatched deoxyribonucleotide that was added, and then proceeds with
synthesis.
- If DNA polymerase leaves a mismatched base behind, mismatch repair will correct the
base.
o Mismatch repair occurs after DNA synthesis.
31. What pathway describes how genetic information is converted into the production of
proteins? Draw this pathway.
- Central dogma of molecular biology
32. Given the following DNA sequence, what will be the subsequent sequences?
DNA
5’
3’
ATG
TAC
CTA
GAT
GCC
CGG
TAT
ATA
TCG
AGC
AGG
TCC
TGA
ACT
3’
5’
CUA
GCC
UAU
UCG
AGG
UGA
3’
mRNA
5’
AUG
Amino acids
Met
Leu
Ala
Tyr
Ser
Arg
STOP
33. Given the following DNA sequence, what will be the subsequent sequences?
DNA +
1
5’
3’
TGC
ACG
GAA
CTT
TGG
ACC
CCA
GGT
AGT
TCA
AGT
TCA
AUG
GCC
AAG
UAG
UGC
CGG
UUC
GC
CG
3’
5’
mRNA
5’
CGA
3’
tRNA anticodons
3’
UAC
5’
Amino acids
Met
Ala
Lys
34. All of the following are accurate descriptions of the genetic code except:
a. “The genetic code is redundant”
b. “The genetic code is ambiguous”
c. “The genetic code is non-overlapping”
d. “The genetic code is nearly universal”
e. “The genetic code is conservative”
35. Given the following mRNA sequence, what type of point mutation occurred?
5’
Original mRNA sequence:
CCA
CAU
AUU
a. Silent
5’
CCA
GGA
UUU
3’
CAU
AUU
GGG
UUU
3’
b. Nonsense
CCA
CAU
UAA
GGA
UUU
3’
c. Missense
5’
CCA
CAA
AUU
GGA
UUU
3’
d. Frameshift
5’
CCA
CAA
UUG
GAU
UU
3’
5’
36. How does transcription differ in eukaryotes in comparison to bacteria?
-
-
-
Eukaryotes
Eukaryotes have three polymerases – RNA
polymerase I, RNA polymerase II, RNA
polymerase III
o Each polymerase transcribes only certain
types of RNA in eukaryotes.
o RNA polymerase II is the only
polymerase that transcribes proteincoding genes.
Promoters in eukaryotic DNA are more diverse.
o Eukaryotic promoters include the TATA
box and other important diverse
sequences.
Eukaryotic RNA polymerases recognize
promoters using basal transcription factors.
Contain RNA processing mechanisms.
-
-
Bacteria
Bacteria have one polymerase – RNA
polymerase
Bacterial promoters less diverse.
o Bacteria promoters contain a -35 box
and a -10 box.
Bacteria recognize promoters using a sigma
protein.
No RNA processing mechanisms present.
37. True or False: the process of transcription and translation occur at the same time and in
the same location.
- True - this happens because there is no nuclear envelope to separate the processes.
- In eukaryotes, translation and transcription occur at separate times and in separate
locations.
o Transcription is conducted in the nucleus to produce a mature mRNA; the
mRNA is then exported to the cytoplasm of the cell where translation occurs.
38. What is the function of tRNAs?
- Transfer amino acids from the RNA to a growing polypeptide.
- tRNAs act as an interpreter during translation
o This allows amino acids to interact with an mRNA template.
39. What allows the correct amino acid for a particular tRNA to be attached?
- Aminoacyl-tRNA synthetases = Catalyze the addition of amino acids to tRNAs.
- ATP = Required to attach an amino acid to a tRNA.
- *Each aminoacyl-tRNA synthetase has a binding site for a particular amino acid and
a particular tRNA; so small differences in the shape and the base sequence of tRNAs
allow aminoacyl-tRNA synthetases (enzymes) to recognize the correct tRNA for the
correct amino acid.
40. Describe the three step protein synthesis sequence by ribosomes?
An aminoacyl tRNA diffuses into the A site; if its anticodon
matches a codon in mRNA, it stays in the ribosome.
A peptide bond forms between the amino acid held by the
aminoacyl tRNA in the A site and the growing polypeptide,
which was held by a tRNA in the P site.
The ribosome moves down the mRNA by one codon, and all
three tRNAs move one position within the ribosome. The
tRNA in the E site exits; the tRNA in the P site moves to the E
site; and the tRNA in the A site switches to the P site.
41. Which of the following best describes post-translational control?
a. Regulation of gene expression by modification of proteins; necessities for proteins to
be activated are inhibited.
b. Regulatory molecules alter the length of time an mRNA survives, or affect translation
initiation or elongation.
c. Regulatory proteins affect RNA polymerase’s ability to bind to a promoter.
d. Regulatory molecules affect the inducers ability to synthesize proteins after (post)
translational processes.
42. Among the mechanisms of gene regulation, what trade-off is present?
- Speed of response and the conservation of resources (efficiency of resource use)
43. Which of the regulation methods is exhibited in the lactose metabolism model system?
a. Positive control
b. Negative control
c. Translational control
d. Post-translational control
44. What are two ways that transcription can be regulated? Describe what happens during
each method.
- Negative control: occurs when a regulatory protein called a repressor binds to DNA
and shuts down transcription.
- Positive control: occurs when a regulatory protein called an activator binds to DNA
and triggers transcription.
45. Which of the following is not an example of one of the six levels at which eukaryotes can
control gene expression.
a. RNA splicing
b. Synthesis of polypeptides from information in codons of messenger RNA.
c. Phosphorylation
d. Packing DNA into a bundle to allow from transcription.
e. Addition of a 5’ cap and a 3’ poly (A) tail
46. How does alternative splicing allow different proteins to be produced from the same
gene?
- When splicing occurs, selected exons are removed from the primary transcript along
with the introns; however, the same primary RNA transcript can yield more than one
kind of mature, processed mRNA, consisting of different combinations of exons.
- If you have a different combination of exons, therefore different combinations of
mRNA, then the polypeptides translated will be different.
- So splicing the same primary RNA transcript in different ways will produce different
mature mRNAs, and therefore produce different proteins; and this is what is known as
alternative splicing.
47. What is RNA interference and what happens during this process?
- RNA interference is a form of gene regulation that directly prevents mRNA from
undergoing translation.
- RNA polymerase is going to transcribe genes that code for RNAs that double back on
themselves to form a hairpin structure.
- The double stranded hairpin is going to be moved outside of the nucleus and into the
cytoplasm.
- In the cytoplasm, an enzyme is going to cut the hairpin loop, forming a doublestranded RNA molecule.
- The double-stranded RNA is going to bind to a group of proteins called the RISC
protein complex (RNA induced silencing complex) and one strand of the RNA is
going to be degraded.
o This is called a microRNA (miRNA)
- The miRNA is going to bind to the complementary sequences of the target mRNA.
- If the match between the miRNA and the target mRNA is perfect, then the target
mRNA will be destroyed by being cut in half by an enzyme from the RISC protein
complex.
- If the match between the miRNA and the target mRNA is not perfect, then the mRNA
will not be destroyed, but translation will be inhibited.
48. Chemical modification is an example of what type of gene regulation mechanism?
a. Transcriptional control
b. Post-transcriptional control
c. Translational control
d. Post-translational control
49. If lactose is present and glucose is absent, will transcription occur if there is a mutation in
the promoter of the lac operon? Why?
- No, the promoter is responsible for allowing RNA polymerase to bind, and RNA
polymerase is responsible for synthesizing mRNA. So if there is a mutation in the
promoter, that means that RNA polymerase will not be able to bind, therefore, mRNA
will not be able to be synthesized.
50. If lactose is present and glucose is absent, will transcription occur if there is a mutation in
the operator of the lac operon? Why?
- Yes, the operator is responsible for allowing the repressor to bind; so if the repressor
cannot bind, then transcription will occur.
51. Will transcription occur if there is a mutation in the lacI gene? Why?
- Yes, the lacI gene is responsible for synthesizing the repressor; therefore, a mutation
would mean that the repressor is not synthesized, so transcription will occur.
52. If a mutation occurs that prevents the binding of the inducer, will transcription be able to
occur?
- No, an inducer is a small molecule that triggers transcription of a specific gene; so if
the inducer is unable to bind, then transcription cannot be initiated.
53. If there is a mutation of the lacY gene encoding galactoside permease that causes
galactoside permease to be unrecognized and inactivated in the presence of glucose, will
transcription occur if:
f. Lactose is absent and glucose is absent? Why?
- No, there is nothing present to remove the repressor.
-
-
g. Lactose is present and glucose is absent? Why?
Yes, lactose can come into the cell and remove the repressor.
h. Lactose is present and glucose is present? Why?
Yes, even though glucose is present, the mutation allows for lactose to pass into the
cell unnoticed and remove the repressor.