Final Exam Flashcards
A particular eukaryotic protein is 300 amino acids long. Which of the following could be the maximum number of nucleotides in the DNA that codes for the amino acids in this protein?
900
Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?
the phosphate bonds in the nucleotide triphosphates that serve as substrates
Oxidation of water occurs
Photosynthesis
Reduction of NADP+
Photosynthesis
Electrons flow along a Transport Chain
Both Photosynthesis and Respiration
Oxidative phosphorylation and/or photophosphorylation occurs
Both Photosynthesis and Respiration
Generation of proton gradients occurs
Both Photosynthesis and Respiration
In which stage of the cell cycle are sister chromatids separated and pulled to the opposite poles of the cell?
Anaphase
In which direction are nucleotides laid down in the new strand while DNA is being synthesized?
5’—>3‘
Codons are sets of three _____ that encode a protein.
RNA nucleotides
According to the central dogma, what molecule should go in the blank?
mRNA
What is NOT synthesized from a DNA template?
amino acids
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called:
Cyclins
How can one eukaryotic gene lead to one transcript, but multiple different proteins?
Alternative Splicing
What type of hypothesized replication results in one duplex containing both parental strands and the other duplex containing two new strands of DNA after the two parental strands had served as templates for the two daughter strands?
conservative replication
The specific site on the bacterial chromosome at which replication begins is called the ________.
origin
n an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5’ cap and poly-A tail. Which of the following would you expect her to find?
The molecule is digested by enzymes because it is not protected at the 5’ end.
What is the first event to take place in translation in eukaryotes?
the small subunit of the ribosome recognizing and attaching to the 5’ cap of mRNA
Ribosomes can attach to prokaryotic messenger RNA ________.
before transcription is complete
What occurs in prokaryotes but not in eukaryotes?
concurrent transcription and translation
Put the events of elongation in prokaryotic translation in chronological order.
- Binding of mRNA with small ribosomal subunit
- Recognition of initiation codon
- Complementary base pairing between initiator codon and anticodon of initiator tRNA
- Attachment of the large subunit
- Base pairing of the mRNA codon following the initiator codon with its complementary tRNA
What are the differences between prokaryotic and eukaryotic transcription?
The processing of RNA.
The promoter sequences used.
The area within the cell in which transcription occurs.
place the events of protein synthesis in the proper order.
- A small ribosomal subunit binds with mRNA, the tRNA for methionine (in the P site), and a large ribosomal subunit
- An amino-acyl tRNA binds to the A site
- A peptide bond forms between the new amino acid and a methionine amino acid.
- The ribosome moves so that the “empty” tRNA moves from the P site to the E site and the amino-acyl tRNA moves from the A site to the P site.
- tRNA in the E site disassociates from the complex.
What level of gene expression allows the most rapid response to environmental change?
post-translational control
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?
Allolactose binds to the repressor protein.
The greatest expression of the lac operon occurs when lactose levels are ________.
high and glucose levels are low
The product of the lacI gene is ________.
the repressor
DNA is undamaged, therefore DNA will be allowed to replicate.
G1
Chromosomes have replicated correctly and MPF is present.
G2
Spindle fibers are properly attached to sister chromatids at the kinetochore.
M
Why might a point mutation in DNA make a difference in the level of a protein’s activity?
It might substitute a different amino acid in the active site.
RNA is created in a ________ fashion, which means DNA is read from ______.
5’ to 3’ / 3’ to 5’
In which direction do the DNA strands grow during replication?
one toward the replication fork and one away from the replication fork
Codes for a protein.
mRNA
Is a carrier for amino acids and has an anticodon.
tRNA
Along with proteins, makes up a ribosome.
rRNA
Strand initiation in DNA replication is accomplished when an enzyme lays down a primer. Of what molecule is that primer composed?
RNA
Transcription and translation happen______ in prokaryotes.
almost simultaneously
If you wanted to prevent a regulatory protein from changing gene expression, you would have to prevent physical contact between the protein and ________.
DNA
According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?
The lac operon would be transcribed continuously.
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome.
If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following would be likely?
Beta galactosidase will not be produced.
Ribosomes can attach to prokaryotic messenger RNA ________.
before transcription is complete
As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they discovered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can the genes-in-pieces hypothesis be explained?
Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.
How does termination of translation take place?
A stop codon is reached.
How can one eukaryotic gene lead to one transcript, but multiple different proteins?
Alternative Splicing
The statement “DNA → RNA → Proteins” ________.
is known as the central dogma
Strand initiation in DNA replication is accomplished when an enzyme lays down a primer. Of what molecule is that primer composed?
RNA
Why might a point mutation in DNA make a difference in the level of a protein’s activity?
It might substitute a different amino acid in the active site.
The mutation resulting in sickle cell disease changes one base pair of DNA so that a codon now codes for a different amino acid, making it an example of a ________.
missense mutation
What mutations would be most likely to have a harmful effect on an organism?
a single nucleotide insertion downstream of, and close to, the start of the coding sequence
What type of hypothesized replication results in one duplex containing both parental strands and the other duplex containing two new strands of DNA after the two parental strands had served as templates for the two daughter strands?
conservative replication
The specific site on the bacterial chromosome at which replication begins is called the ________.
origin
RNA polymerase needs additional proteins to tightly bind a gene’s promoter.
Transcriptional
mRNA is quickly degraded by an enzyme in the cell’s cytoplasm before a protein can be made.
Translational
A protein needs to have a phosphate group added to its structure before it can perform its function.
Post-Translational
What process is central to the initiation of transcription in bacteria?
binding of sigma to the promoter region
Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?
the phosphate bonds in the nucleotide triphosphates that serve as substrates
In eukaryotic cells, chromosomes are composed of ________.
DNA and proteins
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
The first gap in the cell cycle (G1) corresponds to ________.
normal growth and cell function
What happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis.
When does the synaptonemal complex disappear?
late prophase of meiosis I
How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have ________.
half the number of chromosomes and one-fourth the amount of DNA.
Methylation of histones makes DNA
more “loose” or less condensed.
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This ratio suggests that ________.
the parents were both heterozygous for the particular trait
The greatest expression of the lac operon occurs when lactose levels are ________.
high and glucose levels are low
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?
Allolactose binds to the repressor protein.
Which of the following levels of gene expression allows the most rapid response to environmental change?
post-translational control
Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?
Cells would expend significantly more energy.
Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?
the phosphate bonds in the nucleotide triphosphates that serve as substrates
You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?
a bacterial promoter sequence
In eukaryotic cells, transcription cannot begin until ________.
several transcription factors have bound to the promoter
Put the events of bacterial transcription in chronological order.
- Sigma binds to RNA polymerase.
- Sigma binds to the promoter region.
- The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.
- Transcription begins.
- Sigma is released.
A mutation that results in premature termination of translation ________.
is a nonsense mutation
What mutations would be most likely to have a harmful effect on an organism?
a single nucleotide insertion downstream of, and close to, the start of the coding sequence
The mutation resulting in sickle cell disease changes one base pair of DNA so that a codon now codes for a different amino acid, making it an example of a ________.
missense mutation
The predominant mechanism driving cellular differentiation is the difference in gene ________.
expression
In a nucleosome, the DNA is wrapped around ________.
histones
What is true about the DNA in one of your brain cells?
It is the same as the DNA in one of your heart cells.
If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis.
After telophase I of meiosis, the chromosomal makeup of each daughter cell is ________.
haploid, and the chromosomes are each composed of two chromatids
What happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have ________.
half the number of chromosomes and one-fourth the amount of DNA.
Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?
Cells would expend significantly more energy.
The predominant mechanism driving cellular differentiation is the difference in gene ________.
expression
In a nucleosome, the DNA is wrapped around ________.
histones
Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria?
control of both RNA (alternative) splicing and chromatin remodeling
A cell in late anaphase of mitosis will have ________.
no chromosomes in the center of the cell
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
The first gap in the cell cycle (G1) corresponds to ________.
normal growth and cell function
A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?
Albino is recessive; black is dominant.
Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that ________.
traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1 generation
When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
50 percent
In eukaryotic cells, transcription cannot begin until ________.
several transcription factors have bound to the promoter
What process is central to the initiation of transcription in bacteria?
binding of sigma to the promoter region
A frameshift mutation could result from ________.
either an insertion or a deletion of a base
The mutation resulting in sickle cell disease changes one base pair of DNA so that a codon now codes for a different amino acid, making it an example of a ________.
missense mutation
What mutation would be most likely to have a harmful effect on an organism?
a single nucleotide insertion downstream of, and close to, the start of the coding sequence
Transcription and translation of a gene composed of 30 nucleotides would form a protein containing a maxim of ___ amino acids
90
What are the differences about Eukaryotes?
- has introns
- undergoes RNA editing
- transcription occurs in the nucleus
- translation occurs in the cytoplasm
What are the differences about Prokaryotes?
- don’t have introns
- no RNA editing
- Transcription and translation occurs in cytoplasm
- Transcription and translation occur simultaneously
makes mRNA from DNA template
RNA polymerase
What does RNA polymerase do in prokaryotes?
uses sigma bound to -35 -10 promoter region to find a place to begin transcription
What does RNA polymerase do in eukaryotes?
uses TATA box to find a place to begin transcription
What are the features of RNA synthesis?
- RNA is synthesized in 5’ to 3’
- RNA polymerase reads DNA 3’ to 5’
- RNA polymerase reads the Template Strand
What are the steps of Bacterial Transcription?
- ) Initiation- RNA polymerase finds sigma and attaches to DNA and breaks hydrogen bonds between nucleotides
- ) Elongation- RNA polymerase adds complementary base pairs to DNA template strand
- ) Termination- RNA polymerase reads a termination sequence, stops transcribing RNA and releases it
How does RNA polymerase know where to start transcription on the DNA in prokaryotes?
RNA polymerase binds to sigma which is bound to -35 -10 box
What are the two exceptions of eukaryotic transcription?
- ) RNA polymerase starts at after the TATA box, not the -35 -10 box
- ) RNA must undergoes editing before being translated
Where does RNA editing occur?
in the nucleus
How do you get mature RNA?
take the introns out of pre-mRNA
What are added to the mRNA molecule for stability?
5’ cap and poly (A) tail
How is pre-mRNA edited?
- ) snRNPs (small nuclear ribomucleoproteins) gather on the intron
- ) snRNP’s pinch pre-mRNA and splice together exon
In prokaryotes and eukaryotes this process is nearly identical
translation
what drives translation?
tRNA
on tRNA there is an _______ and a ____ _____ on the __ end
anticodon
amino acid
3’
What is tRNA primed with?
Aminoacyl-tRNA synthase (ATP dependent process)
What do ribosomes do?
synthesize proteins from mature mRNA
What are the two subunits of a ribosome?
small-attaches to mRNA first
large- begins translation once it binds to small subunit
What do initiation factors do?
recruit mRNA and first tRNA to the small ribosomal subunit
The first mRNA codon to specify an amino acid always ____
AUG
The first mRNA codon is AUG so the anticodon sequence that would bring in the MET is ____
UAC
What are the three sites of translation elongation?
E site-“Exit” site
P site- “Passing” site
A site- new tRNAs enter
What bond do the amino acids form at the ribosomes active site?
Peptide
What are the steps of translation termination?
- Release factor binds to stop codon
- Polypeptide is released
- Ribosome subunits separate
How is transcription different in prokaryotes?
Transcription and translation happens almost simultaneously in prokaryotes
What are polyribosomes?
clusters of ribosomes that translate the same piece of mRNA at the same time in prokaryotes
What are the three types of gene regulation for prokaryotes?
- Transcriptional
- Translation
- Post-transaltional
Which type of gene regulation allows for the most rapid response to the environment?
post-translational
Which type of gene regulation is the most energy efficient?
transcriptional
What is transcriptional control?
- Prevents the transcription of DNA to mRNA
- most energy efficient
What is translation control?
-mRNAs aren’t translated to proteins
What is post-translational control?
- prevents the activation of proteins by chemically adding or taking away a molecule
- fastest response
Which type of control prevents chemical modification of proteins so that they stay inactive?
post-translational control
What is a monosaccharide that is readily used by E. coli for cellular respiration?
glucose
What happens once glucose is taken in by the cell?
it directly undergoes glycolysis
What is a disaccharide that and must be broken down before being used?
Lactose
What can lactose be broken down into?
glucose and galactose
Why must lactose be broken down?
it is a disaccharide
What two proteins are required to break down lactose?
B-Galactosidase
Galactoside permease
a set of genes that are regulated by the same promoter and are transcribed together
operon
codes for the repressor of the Lac operon (responds to lactose concentration)
LacI
where the LacI repressor will bind to prevent transcription
operator
codes for B-galatosidase (the enzyme that breaks lactose into glucose and galactose)
LacZ
Codes for Galactoside permerase (transmembrane protein that transports lactose into the cell)
LacY
When does the negative control of lac operon occur?
when a regulatory protein binds to the DNA and prevents transcription
-determined by presence of lactose
How does lactose being absent affect negative control?
- LacI repressor is produced and binds to operator
- repressor blocks RNA polymerase and leads to infrequent transcription
How does lactose being present affect negative control?
- LacI repressor is produced but releases from operator when bound to lactose
- RNA polymerase can bind to DNA and frequently transcribe the Lac operon
How does the pretense of both lactose and the repressor affect the outcome of negative gene control?
Transcription occurs
Would bacteria keep breaking down lactose even in the presence of high glucose?
no
When does the positive control of lac operon occur?
when a regulatory protein binds to the DNA and triggers transcription
-not determined by presence of lactose (uses CAP as regulatory protein instead)
What is CAP?
(catabolite gene activator protein) is a protein regulator
What is cAMP?
(cyclic Adenine MonoPhosphate) binds to and activates CAP
-regulated by glucose concentration
What is the status of CAP and cAMP when glucose concentrations are high?
cAMP concentrations are low so so the cAMP/CAP complex will not form and bind to Lac operon
What happens when the cAMP/CAP complex doesn’t form?
RNA polymerase will only loosely bind to DNA
-infrequent transcription
What is the status of CAP and cAMP when glucose concentrations are low?
cAMP concentrations are high so the cAMP/CAP complex forms and binds to Lac operon
What happens when the cAMP/CAP complex forms?
RNA polymerase can tightly bind to DNA
-frequent transcription
What gene codes for the Lac operon repressor and where does the repressor bind?
LacI, operator
If an E.coli cell is currently in an environment that is abundant in both lactose and glucose will transcription of the Lac operon be:
infrequent
What if the E. coli is only abundant in lactose?
frequent
In the function of the lac operon in E. coli, the lac genes are transcribed in the presence of lactose because
a molecule of lactose binds to the repressor
Different genes are turned on and off to_______
make different proteins
When can even expression be controlled?
- Before transcription
- chromatin remodeling - During transcription
- regulatory sequences - During RNA processing
- splicing
- stability - During translation
- Regulatory proteins - After translation
- Chemical modification
- Protein folding
DNA forms _____ bonds with _____ ______ to provide structure
ionic
histone proteins
What does DNA wrap itself around?
histone beads
What does DNA wrapping allow for?
protein scaffolding
DNA is ___ while histones are _____
negative
postive
What are histones full of?
lysine and arginine
Euchromatin is ______ packed making it _______ to transcription proteins
loosely
accessible
Heterochromatin is ________ packed making it __________ to transcription proteins
tightly
inaccessible
If a region of DNA were to become more condensed, how would the expression of that gene be affected?
Gene expression would decrease
have N-terminus tails that can be modified covalently
histones
Adding and removing ______ groups changes the ________ charge of the ______
functional
postive
histone
Changing the charge strengthens the bonds between
histones and DNA
Addition of a methyl group
methylation
Addition of an acetyl group
acetylation
removal of an acetyl group
Deacetylation
- Restores + charge
- Tightens chromatin
- Turns genes “off”
histone deacetylase
- Neutralizes + charge
- Loosens chromatin
- Turns genes “on”
Histone Acetyl Transferase
- Opposite of acetylation
- Silences gene expression by condensing DNA
Histone Methylation
How would gene expression be affected if the concentration of HAT was increased?
Gene expression would increase
HAT acetylates histones —> chromatin decondenses —> trasncription is induced
How would gene expression be affected if the concentration of DNA Methyltransferase was decreased?
Gene expression would increase
DNA methyltransferase doesn’t methylate histones —> chromatin decondendses —> transcription is induced
DNA methyltrasnferase binds a ______ group to a _____ at a ____ site
methyl
cytosine
CpG
heritable control of gene expression without changing DNA sequences
Epigenetics
Impreinted genes are ___
permanently off and heritable
A silenced gene will be ____
passed down in its inactive form
Inherited genes ____
may not be functional
Methylation is also used to ________
permanently silence genes during certain stages of development
In comparative genomic hybridization_____
methylated fragments match up with complementary sections of DNA
The _____ of the resulting chromosomes indicates which ____ are present
color
tags
Yellow means
equal parts from each person
Green means
comes primarily from person 1
-increase in methylation
Red means
comes primarily from person 2
-decrease methylation
For transcriptional regulation, eukaryotes have ____
regulatory sequences within their DNA
- proteins recongnize and bind to these sites
- –leads to increase or decrease of transcription
The 3D structure of DNA changes when
distal promoters are used
In the presence of corresponding regulatory proteins, a regulatory sequence causes the rate of transcription to decrease. When the 3D configuration of the DNA changes, the sequence has not effect on transcription. What type of regulatory sequence is this?
A silencer sequence
Premature mRNA gets
spliced to make mature mRNA, which gets translated
What is alternative splicing?
2+ mature mRNAs are made from the eons and code for 2 different proteins
Introns get
removed
Exons are
left in
The longer mRNA exists in the cytoplasm,
the more it can be translated
Greater stability leads to
greater expression
Enzymes in the cytoplasm _______
break down mRNA
mRNA has to be protected so _____
it can be transcribed
________ and _____ block the enzymes from the RNA
Poly-A tail
5’ cap
mRNA can be broken down using
RNA interference
RISC protein complex does what?
- Binds to a single strand of mRNA
- Brings target mRNA, miRNA, and enzymes together
miRNA:
- made solely for mRNA regulation
- serves as a template
What is Dicer?
Enzyme that cuts mRNA
Suppose there is a mutation in the gene that codes for Dicer, which causes the protein to be non-functional. How would this effect the expression of other genes?
Gene expression would increase
Translation can be stopped by
preventing the binding of mRNA and ribosomes
How does preventing the binding of mRNA and ribosomes stop translation?
- mRNA binds to ribosome and translation starts
- Regulatory proteins bind to mRNA
- —-Ribosome and initiation factors are blocked
- Ribosome is phosphorylated
- —-Chemical modification prevents initiation
Proteins may be ________, but can still be ________.
synthesized
non-functional
Proteins must be ______ to function
properly
these proteins help other proteins to fold correctly
chaperone
Chemical modification can also
change protein functionality
- -phosphorylation
- -formation of quaternary structures
What is evolution?
a change in population over time
What is not a form of evidence used to investigate evolution?
anthropological studies
What are the five important types of evidence used to investigate evolution?
- fossils
- biogeography
- comparative anatomy
- comparative embryology
- molecular studies
Do fossils reveal extant organisms?
no
What provide physical evidence of change in living things over time?
fossils
Fossils tend to be from _____
extinct organisms
What are the age of fossils determined with?
Isotope Analysis
Where are newer rock layers found?
closer to the surface (the top)
Dr. Navaratnam found a Mesosaurus fossil: this freshwater reptile was only native to South America and Africa during the Permian period. Which concept provides rationale to this discovery?
Continental drift
deals with geographic distribution of species at given points in time
biogeography
Structures that come from the same common ancestor and are similar regarding form or function
homologous structures
species with structures sharing the same form or function, but lacking a common ancestor
analogous structures
What is an example an analogous structure?
bird and insect wings
Is a turtle shell a vestigial trait?
no
structures that are no longer functional for the organism
vestigial traits
The comparison of the developmental stages of different species
comparative structure
similar developmental stages between species provide
evidence of a common ancestor
What are molecular studies?
DNA similarities (genetic homology)
Protein similarities
mutations vs time
What is the evolutionary driving force proposed by Jean-Baptiste de Lamarck?
Inner need to change
Lamarck:
- made the first formal theory of evolution
- believed that evolution can span across a lifetime
The process by which populations change over time
natural selection
natural selection provides an explanation for
evolution
the ________ drives natural selection
environment
Natural selection requires
diversity within the population
–so genetic variability and external factors affect an organism’s level of fitness
regards the organism’s ability to reach maturation and successfully reproduce
fitness
natural selection acts on
the individual
–this can result in evolutionary change in the population
The gene coding for this species coloration also affects fertility. If black coloration results from mutation making the organism infertile, which would have the higher level of fitness the black or white bugs in the given environment?
this species is fucked
Natural selection DOES NOT
create new traits or alleles
Carrying capacity clearly provides
evidence of the environment driving natural selection
Population growth is
naturally exponential
Exponential growth can only be seen when
resources are abundant
marks the point of growth where resources are no longer abundant (population saturation point)
carrying capacity
crossing the carrying capacity line results in
increased death rate
a type of membrane transport that does not require the usage of ATP.
simple diffusion
Does facilitated diffusion require ATP?
no
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome.
If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following would be likely?
Beta galactosidase will not be produced.
If you wanted to prevent a regulatory protein from changing gene expression, you would have to prevent physical contact between the protein and ________.
DNA
The product of the lacI gene is ________.
the repressor
Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?
Cells would expend significantly more energy.
The greatest expression of the lac operon occurs when lactose levels are ________.
high and glucose levels are low
The driving force behind natural selection is:
the environment
Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower color trait in radishes is an example of which of the following?
incomplete dominance
In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?
0
In humans, male-pattern baldness may be assumed to be controlled by an autosomal gene that occurs in two allelic forms. Allele B determines nonbaldness, and allele b determines pattern baldness. In males, because of the presence of testosterone, allele b is dominant over B. If a man and woman both with genotype Bb have a son, what is the chance that he will eventually be bald?
75 percent
Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white.
(a) What is the most probable genotype of each parent?
(b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.)
Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1
In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
tortoiseshell females; black males
What is not necessary for natural selection to occur?
Characteristics acquired by individuals over the course of their lifetime, i.e. big muscles from weight lifting, are passed on to their offspring.
Placing a cell in a hypotonic solution will cause it to
swell
What are the molecules that go into (are the “inputs” for) the light-independent reactions of photosynthesis?
NADPH
ATP
CO2
Bipasha is studying a new drug, Calcigro, that is suspected to improve bone density. The drug has made it through animal testing and into human trials. Two groups of females have been matched for age, race and health status. Group A is given a pill containing starch and 1000 mg of Calcigro while Group B is given a pill containing starch only. Both groups are following a diet regimen with an intake of 1000 mg of calcium daily.
What is the dependent variable?
Bone density
The type of chemical reaction responsible for linking monomers into polymers is known as a
dehydration reaction
Two atoms are bonded together when valence electrons are shared between the two. The electrons spend more time circulating around the nucleus of the first atom than the second.
What type of bond is described above?
Polar Covalent
Fur thickness in dogs is inherited via three different genes (each with two possible alleles). The addition of dominant alleles makes the fur more thick. The addition of recessive alleles makes the fur thinner. The majority of dogs have a median fur thickness. What inheritance pattern best describes the above scenario?
Quantitative Trait
What will most easily pass through a semipermeable membrane?
Small Polar Molecules
What are the final products (or “outputs”) of glycolysis?
Pyruvate
NADH
ATP
What does it mean when we say the genetic code is redundant?
More than one codon can specify the addition of the same amino acid.
What mutation would be most likely to have a harmful effect on an organism?
a single nucleotide insertion downstream of, and close to, the start of the coding sequence
The mutation resulting in sickle cell disease changes one base pair of DNA so that a codon now codes for a different amino acid, making it an example of a ________.
missense mutation
Antibiotic resistance occurs because of
the presence of a chance mutation in an individual bacteria’s genome, not due to the presence of an antibiotic.
An individual has the genotype of rrYy for two Mendelian genes. Select all of the following that are possible gametes from this individual:
rY
ry
What is a capability of natural selection?
Allows for the fittest individuals to produce more offspring.
Homologous chromosomes ________.
carry information for the same traits
What makes sexually reproduced offspring genetically different from their parents?
genetic recombination during meiosis
What are similarities between mitosis and meiosis?
- Process begins with a single, diploid cell.
- DNA replication occurs once before cell division begins.
- Separation of sister chromatids.
If you were to observe the activity of methylated DNA, you would expect it to ________.
have turned off or slowed down the process of transcription
If a cell were unable to produce histone proteins, which of the following would be a likely effect?
The cell’s DNA couldn’t be packed into its nucleus.
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
In one set of experiments she succeeded in increasing acetlylation of histone tails. Which of the following results would she most likely see?
decreased chromatin condensation
Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria?
control of both RNA (alternative) splicing and chromatin remodeling
Gene expression can be altered more easily at the level of post-transcriptional processing in eukaryotes than in prokaryotes because ________.
eukaryotic exons may be spliced in alternative patterns
The children of athletes tend to be much more athletic, on average, than other children because the physical characterics their parents built up over their lifetimes have been passed on to their children.
This statements is more:
Lamarckian
A cell biologist has developed a new drug that will block the cis face of the Golgi apparatus. The cis face of the Golgi apparatus is the “receiving” or “incoming” face of the Golgi. If eventually approved by the FDA, she wants to use this new drug to aid cancer patients. What specifically will this drug prevent from happening inside a cancer cell?
the movement of the lipids and proteins synthesized in the endoplasmic reticulum to the Golgi apparatus
The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does NOT happen, cells would most likely be arrested in ________.
metaphase
What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are in G2?
The cells enter mitosis.
In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.
incorporates the entire template molecule in the product
Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?
Codons are a nearly universal language among all organisms.
The same basic internal organs (kidneys, stomach, heart, lungs) are found in frogs, birds, snakes, and rodents. This is primarily an example of ________.
structural homology
Similar gill pouches in embryos of a chick, human, and cat are an example of ________.
developmental homology
Biological fitness is best defined as
the ability of an individual to produce offspring that survive and reproduce, relative to other individuals in the population.
Given a population that contains genetic variation, what is the correct sequence of the events under the influence of natural selection?
- A change occurs in the environment.
- Poorly-adapted individuals have decreased survivorship.
- Well-adapted individuals leave more offspring than do poorly-adapted individuals.
- Poorly-adapted individuals have decreased survivorship.
What is the best example of fitness trade-off (compromise)?
Turtle shells provide protection but are heavy and burdensome when moving.
Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must ________.
be removed before sister chromatids can separate
Kinetochore microtubules assist in the process of splitting centromeres by ________.
creating tension by pulling toward opposite poles
If meiosis produces haploid cells, how is the diploid number restored for those organisms that spend most of their life cycle in the diploid state?
fertilization
When we first see chiasmata under a microscope, we know that ________.
prophase I is occurring
Sexual reproduction ________.
can produce diverse phenotypes that may enhance survival of a population in a changing environment
What is the smallest unit containing the entire human genome?
one male somatic cell
A bacterial cell suddenly stops creating protein, even though the DNA is still present and in working order. Which organelle’s malfunction would be responsible for this result?
Ribosomes
In a nucleosome, the DNA is wrapped around ________.
histones
Imagine that you have isolated a yeast mutant that contains a constitutively (constantly) active histone deacetylase. What phenotype do you predict for this mutant?
The mutant will show low levels of gene expression.
What allows more than one type of protein to be produced from one gene?
alternative forms of RNA splicing
The predominant mechanism driving cellular differentiation is the difference in gene ________.
expression
What are the final products (or “outputs”) of the light-independent reactions of photosynthesis?
ADP + P
Water
Sugar
NADP
If a cell has accumulated DNA damage, it is unlikely to ________.
pass the G2 checkpoint
What does NOT occur during mitosis?
replication of the DNA
Fur thickness in dogs is inherited due to a single gene with two possible alleles. When two copies of the dominant gene is present, the fur is very thick. When two copies of the recessive gene is present, the fur is very thin. Heterozygous individuals have a median fur thickness phenotype. What inheritance pattern best describes the above scenario?
Incomplete dominance
What are the molecules that go into (are the “inputs” for) the light-dependent reactions of photosynthesis?
ADP + P
NADP+
Light
Water
Sister chromatids separate from each other during ________.
mitosis and meiosis II
Two atoms are bonded together when a valence electron is donated from one atom and received by the second. The resulting charge of the two atoms leads to their attraction to one another.
What type of bond is described above?
Ionic
What are the final products (or “outputs”) of the Electron Transport Chain and Chemiosmosis?
Water
NAD
ATP
FAD
Which of the following modifications would allow for DNA to become less condensed (more loosely coiled)?
Remove methyl groups from DNA bases.
Add acetyl groups to histones.
Remove methyl groups from histones.
Which of the following modifications would allow for DNA to become more condensed (more tightly coiled)?
Add methyl groups to DNA bases.
Add methyl groups to histones.
Remove acetyl groups from histones.
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to ________.
disruption of mitotic spindle formation
Colony collapse disorder is an issue facing America’s honey bee population. It is not known exactly what causes the death of honey bees, but it is thought to be due to either one, or a combination, of three factors: insecticides building in the wax of the hive, mites, and/or a virus known as KBV. To conduct an experiment to determine the effect of these factors on honey bee survival, which groups of bees will be needed?
Bees treated with high levels of insecticide
Bees exposed to mites
Bees exposed to KBV virus
Bees exposed to combinations of all three factors
Healthy honey bees
If you wanted to prevent a regulatory protein from changing gene expression, you would have to prevent physical contact between the protein and ________.
DNA
The product of the lacI gene is ________.
the repressor
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?
Allolactose binds to the repressor protein.
What level of gene expression allows the most rapid response to environmental change?
post-translational control
Translation requires ________.
mRNA, tRNA, and rRNA
There should be a strong positive correlation between the rate of protein synthesis and ________.
the number of ribosomes
Ribosomes can attach to prokaryotic messenger RNA ________.
before transcription is complete
What is the first event to take place in translation in eukaryotes?
the small subunit of the ribosome recognizing and attaching to the 5’ cap of mRNA
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?
roan × roan
In humans, male-pattern baldness may be assumed to be controlled by an autosomal gene that occurs in two allelic forms. Allele B determines nonbaldness, and allele b determines pattern baldness. In males, because of the presence of testosterone, allele b is dominant over B. If a man and woman both with genotype Bb have a son, what is the chance that he will eventually be bald?
75 percent
What are the molecules that go into (are the “inputs” for) the Citric Acid Cycle?
FAD
NAD
Acetyl CoA
ADP + P
A frameshift mutation could result from ________.
either an insertion or a deletion of a base
Placing a cell in a hypertonic solution will cause it to
shrink
Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?
Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.
Similar gill pouches in embryos of a chick, human, and cat are an example of ________.
developmental homology
