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Worksheetsgenetics exam
Total questions: 91
Worksheet time: 3hrs 2mins
Because DNA polymerase at a replication fork occurs as a dimer
Only one strand serves as a template during DNA replication
Both strands at one fork are lagging, and both strands at the other fork are leading
the lagging strand template loops out so both strands can be synthesized in the same direction
Nucleotides are added to the 5' end of DNA on the lagging strand and the 3' end on the leading
What is the major enzyme that drives transcription
RNA polymerase
DNA polymerase
protein polymerase
reserve transcriptase
Which of the following statements about promoters is true?
promotors are proteins
the location of the promoter is usually described by a negative number
the promotor sequences are the first to be transcribed into RNA
Every chromosome contains only a single promoter
In bacteria, the function of 3' to 5' exonuclease activity of DNA polymerase 3 is
to remove RNA nucleotides in primers
to relieve supercoiling tension ahead of the replication fork
to bind Okazaki fragments together
to proofread, removing nucleotides that were not paired correctly
When nucleotides are added to a growing strand of DNA during DNA replication
adenine pair with cytosines on the template strand
uracil bases are converted to thymines
helicase reforms hydrogen bonds between phosphate groups
two phosphate groups are removed
DNA replication occurs during the G0 phase of the cell cycle
true
false
which of the following is a true statement about proteins
the function of all proteins is to catalyze (speed up) chemical reactions
the information needed to create proteins is contained in DNA
proteins are made up of long chains of nucleotides
All amino acids are made up of protein subunits
The protein component of telomerase serves what primary function?
replaces the enzyme primase and creates DNA primer at the telomere
breaks phosphodierster bonds at the telomere, causing it to shorten
acts as a reverse transcriptase, making a DNA copy of the RNA template
causes a protein to separate from the DNA template strand
because telomerase is not expressed, or expressed at very low levels, in most somatic cells
their telomere length is maintained during cell division
cells can divide an infinite # of times
#of times the cell can divide is limited
the mutation rate is kept at a low level
The 3' C of the pentose sugar in nucleic acids
covalently bonded to an amino acid
forms a hydrogen bond with a nucleoside
involved in the formation of a phosphodiester bond
cleaved during the polymerization of DNA
the basic function of mitosis is to
create a haploid gamete or sex cell
two haploid daughter cells from one diploid cell
two diploid daughter cells from one diploid cell
a molecule of RNA from a DNA template
The function of a kinetochore is to attach
sister chromatids to each other
spindle fibers to the centromere
centriole to the centromere
transcription start site to the promoter
A metacentric chromosome is defined as one that
is found on the metaphase plate
has a centromere located in the middle
is more than 1000 base pairs long
does not contain any genes
For bacterial transcription to begin
the initiator protein must bind to the oriC region
primers must first be removed from the promoter
DNA must separate from RNA in the replication bubble
sigma factor must bind to RNA poymerase to form the holoenzyme
Which of the following is typical of most bacterial chromosomes?
only 1 strand of each fork is replicated during DNA replication
there is a single origin of replication
DNA is always single stranded
All of the above
The short, discontinuous pieces of DNA on the lagging strand are referred to as
obama fragments
Chargaff fragments
Watson fragments
Okazaki fragmens
Which of the following occurs during anaphase of mitosis
Nuclear envelope begins to condense
chromnosomes begin to condense
the sister chromatids separate from each other
homologous chromosomes separate from each other
which of the following list sequences elements in the correct order reading in the 5' to 3' direction along the non-template strand of a transcription unit
Termination, transcription start site, promotor
transcription start site, Termination, promotor
promotor, transcription start site, Termination,
primers are necessary for DNA replication because
RNA polymerase cannot carry out proofreading to remove errors
DNA is always replicated in a 3' to 5' direction, whereas RNA is replicated in the 5' to 3' direction
DNA polymerase cannot "start from scratch" it can only add to the 3' end of an existing strand
they seal up breaks in the sugar-phosphate backbone
For a species of turtle, the value of N is 20, Which of the following statements is true?
The value of N for turtle sperm will be 10
each chromosome has 20 genes
During prophase of mitosis, 40 chromosomes will be presented in a cell
The two daughter cells of mitosis will contain 20 chromosomes
What function does the helicase activity of the rho factor serve in rho-dependent termination of transcription?
Creates hydrogen bonds between RNA and a protein
opens up a fork in a replication bubble
releases the RNA molecule from the DNA template strand
removes two phosphate groups
The term "polymer" refers to
linear molecule composed of many similar subunits
an enzyme that binds many DNA fragments together
a small organic molecule with hydroxyl group
an enzyme that catalyzes the addition of nucleotides to the 3' end of a DNA strand
A sequence of DNA is transcribed to produce the following RNA sequence
5' AACGUCGG 3'
What sequence of the non-template strand in the DNA that produced it?
3' AACGUGG 5"
3' TTGCAGCC 5'
5' GTTCCGAC 3'
5' AACGTCGG 3'
Chromatin is
a complex composed of DNA wrapped around histones proteins
a highly condensed form of DNA that is present only during mitosis
found only in bacteria
all of the above
A cell is diploid. This means that
the cell is in the process of diving into two
2 members of each homologous pairs are present
2 sister chromatids are presented for each chromosome
the cell has two nuclei
which of the following occurs during prophase of mitosis
two daughter cell undergo cytokinesis
homologous pairs line up along the central plate
sister chromatids separate from each other
Chromatin condenses and spindle fibers begin to form
How do structures of DNA and RNA differ?
RNA, but not DNA, has a hydroxyl group on the 2'C of the pentose sugar
DNA is double stranded, and RNA is generally single stranded
DNA contains thymine, RNA contains uracil
all of the above
promoters contain a "consenus sequence". this means that
their sequences are indentical in all organisms
their sequences are similar but not always identical in different organisms
scientists have reached a consensus that an enzyme binds to them
they contain many errors
the purpose of translation is to
produce RNA copy of a gene
synthesized a protein or polypeptide using information in a codon sequence
produce two identical molecules of DNA before cell divison
generate genetic variation resulting in new alleles
the 5' and 3' of an intron can be recognized by the presence of
amino acids
7-methyl guanosine cap
consensus sequences
hairpin loops
which of the following are typically NOT found in eukaryotes?
poly A tail
polycistronic mRNAs
promoters
spliceosomes
The degeneracy of the genetic code refers to the fact that
a codon can code for multiple amino acids
there is more than one start codon
mRNAs are easily degraded
multiple codons can code for the same amino acid
Before newly transcribed tRNA can serve its function at the ribosome
it must fold up and form double-stranded loops
some nucleotides are chemically modified to rare bases
it must be charged with an amino acid
all of the above
When a glucose is present at high levels, the rate of transcription of structural genes in the lac operon is reduced because
binds to a repressor, causing the repressor to bind near the promoter
inhibits the production of cAMP, which must be present for CAP to bind
unwinds the chromatin structure of DNA
Binds to a regulatory element, preventing a repressor from binding there
A regulatory element is
always found in the termination sequence of a transcription unit
sequence of nucleotides where a regulatory protein binds
protein that turns on or off translation
gene that codes for a structural protein
Alternative splicing creates
most of the known genetic diseases
several different protein products from the same gene
mRNAs that are unstable
homologous chromosomes with different alleles
During the elongation phase of translation, transfer RNAs will move from
The A site to the P site to the E site of the ribosome
The P site to the E site to the A site of the ribosome
The E site to the P site to the A site of the ribsome
the promoter to the termination sequence
Gene A encodes Enzyme A, which converts Molecule B to Molecule C. When molecule B is present, it binds to an activator protein which then binds to a site near the promoter of Gene A, turning on transcription of the gene. This is an example of
Positive inductible control
Negative inductible control
positive repressible control
negative repressible control
In which of the following are features of a eukaryotic transcription unit for a protein-coding gene arranged in the correct order from 5' to 3' on the coding strand? The gene contains a single intron.
Promoter, start codon, +1 site , intron , termination sequence, stop cofon
Promoter, +1 site, start codon, intron, stop codon, termination sequence
+1 site , start codon, promoter, stop codon, termination sequence
shine- Dalgarno sequence, start codon, +1 , stop codon, termination sequence
A key step in the post-transcriptional modification of messenger RNA in Eukaryotes is
addition of a 5' cap
termination of the anti-codon
rho-dependent termination
formation of many hairpin loops to form a clover leaf structurr
which of the following is an example of a regualator gene
the binding site for an activator protein
gene that is always expressed
a gene that codes for a tRNA
gene that codes for a repressor protein
The results of the experiment suggest that K is a binding site for a regulatory protein. What kind of protein binds there
repressor
activator protein
helicase
ribosome
What part of the reported gene is inserted, is an experiment such as this one
the upstream regulatory region only
both the regulatory region and the coding region
introns
coding region only
A tRNA contains the anticodon: 5' CGA 3'. What amino acid would be carried by the tRNA that binds to this anticodon?
Arg
ser
ala
histidine
A spliceosome is
binding site for histone proteins that regulates gene expression in eukaryotes
found only in bacteria
a structure composed of RNA and protein that removes introns
an enzyme that adds a poly A tail to a messenger RNA in bacteria
The molecule GTP is the primary source of energy that drives what process?
translation
transcription
DNA replication
charging of rRNAs
Transfer RNA genes are transcribed and then translated
true
false
N-formly fmet is always found
at the amino or N terminus of a newly translated bacterial gene
at the carboxyl or C terminus of a newly translated eukaryotic gene
bound to a tRNA with the anti-codon CCC
at the 3' end of a strand of DNA
Proteins are composed of , attached to each other by __ to form a polymer
nucleotides / phosphodiester bonds
amino acids / peptide bonds
nucleotides / hydrogen
amino acids / phosphodiester
the acetylation of histones is thought to have what effect
prevent ribosomes from splicing out introns
catalyzes the charging of ribosomes
it causes DNA to be less tightly bound to histones
it breaks hydrogen bonds between DNA and RNA in the replication bubble
besides their roles in stabilizing RNA, the 5' cap and poly A tail are known to play a role in
transcription of polycistronic mRNA
DNA proofreading
the processing of glucose by E. coil cells
initiation of translation
in the lac operon of E. coil, when lactose is present
binds to the repressor, changing the repressor's shape and removing it from the operator
binds to CAP, changing CAP's shape and removing from the CAP binding site
binds to RNA polymerase, causing the enzyme to be removed from the repressor
it causes the spliceosome to break down into several subunits
chromatin remodeling takes place in and is a mechanism of ___
bacteria/ regulation of gene expression
euk / reg of gene express
bacteria / posttranslational proofreading
euk / DNA synthesis
which of the following would NOT be found in a pre-mRNA transcribed from a eukaryotic gene for a protein
a start codon
poly A tail
promoter
both B and C
in E. coil, the rate of transcription of the B galatosidase gene is highest when
lactose is absent and glucose is present
lactose and glucose are both absent
the messenger RNA exits from the nucleus
lactose is present and glucose is absent
DNA of bacteria is single stranded
True
False
in the classic mendelian expectation of 9/16, 3/16, 3/16, 1/6 (9:3:3:1), the "9/16" refers to the expected fraction of
phenotypes that express both recessive traits in the F2 generation of a dihybrid cross
phenotypes that express both dominant traits in the F2 generation of a dihybrid cross
genotypes that heterozygous for both genes in the f2 generation of a dihybrid cross
dominant phenotypes in the f2 generation of a monohybrid cross
you cross YYRR x yyrr parents to produce an F1 generation. According to mendelian principles individuals in the f1 generation will be heterozygous and express he dominant phenotype
true
false
boveri and sutton are most famous for
the molecular basis of crossing over
all cells come from preexisting cells
meiotic events are the biological basis of mendelian segreagation
barr bodies and X-inactivation
What is the mode of inheritance of the disease
autosomal dominant
autosomal recessive
cannot be determined
what is the genotype of the female indicated by an arrow
homozygous for the normal allele
heterozygous
homozygous
transition from diploid to haploid occurs during
1st cell divison of meiosis
second cell division of meiosis
mitosis
the S phase of the cell cycle
An AaBb individual undergoes meiosis and produces only 2 kinds of gametes: AB and ab. Which of the mendels four major principles appears to be violated
principle of segregation
principle of independent assortment
two factors control each trait
principle of epistatasis
in what model organism was genetic linkage first studied?
polar bears
mice
peas
fruit flies
(1 out of 2 ) in a crossing experiment with fruit flies, you do a chi sqaure test to determine whether a model of simple mendelian inheritance fits your data. Your test returns X^2 value of 12.3 and a p value of 0.013. What do you conclude
mendelian model of inheritance provides a good fit to your data
you should reject a mendelian model of inheritance and look for another explanation
you do not have enough data to test the model
( 2 out of 2) a second trial of the same experiment yields a somewhat larger x^2 value of 15.4. The P value for the second trail would be
greater then 0.013
less than 0.013
greather than 1
You do a trihybrid cross between a homozygous tall, purple-flowered plant with yellow pollen and a homozygous short, white-flowered plant with grey polle. Tall , purple, and yellow are all dominant. What fraction of the f2 generations do you expect to be short, purple-flowered with grey pollen
1/4
1/64
9/16
3/64
A man with type AB blood and a women with type O blood have children. What possible phenotypes could the children have?
Type AB only
Type B only
Type O or type AB
Type A or Type B
a plant with leaves that are 4 cm long is corssed with a plant whose leaves are 2 cm long. The f1 generation has leaves that are 3 cm long. The most likely explanation for this result is
incomplete dominance
epistasis
sex-linkage
non-recombinant crossing over
when one trait is epistatic over another, the F2 phenotypic ratios in a dihydbrid cross differ from mendel expectations because
the two genes do not assort independently
alleles at the two genes do not segregate
one gene affects the expression of another
all of the above
If a a gamete contains 10 picograms of DNA, how many picograms of DNA are present in a cell of the same species at prophase 1 of meiosis
20
40
10
100
the function of meiosis is to
produce two diploid cells from one diploid cell for somatic growth
replace diploid somatic cells that are damaged
produced gametes
repair DNA
During anaphase of meiosis 2
sister chromaids separate and migrate to opposite poles
homologous chromosomes separate and migrate to opposite poles
homo chromo find each other and pair up
sister chromatid line up together and undergo crossing over
the allele for sickle cell anemia is thought to be particularly common in some regions because
sickle cell allele is dominiant there and common
homoz dor the sickle cell have higher reproductive rates
heteroz are resistance to malaria, which is common there
heteroz in those regions express a more severe form of disease
name the phase and cell divison type of each
anaphase of mitosis, prophase of meiosis 1b
anaphase of meosis 1 , anaphase 1 of meiosis
mendels result were
first published in 1412 in an obscure italian journal
rediscovered by the broader scientific community in about 1900
never published
published after the structure of DNA had already been described
you carry out a dihydrid cross of a plant. you should conclude that the genotype of f2 plants are
TtRr
TTRR
TTRr
TtRR
crossing over occurs
during metaphase of mitosis
during prophase of meosis 1
when gamates fuse to form a zygote
during the S phase of the cell
The synaptonemal complex has what function?
attaches spindle fibrs to the homologous chromosomes to pull them apart during anaphase 1
it binds two homologous chromosomes to each other during prophase of meosis 1
it condenses and inactivates one X-chromosome
it turns on genes that produce male characteristics
when two genes are on different chromosomes, a testcross of the f1 of a dihybrid cross will produce
4 different offspring phenotypes, half recombinant and half non-recombinant
two different offsprings phenotypes, all non-recombinant
offsprings that all express both dominant traits
offsprings that all express both recessive traits
a dominant allele is an allele that
always is found in homozygous genotype
has the highest fitness and is therefore selected for
is expressed in heterozgote and hides the effect of the recessive allele
it is the most common
homozygous and heterozygous are words used to describe a
phenotype
genotype
allele
all of the above
calico cat coloration is caused by random x-inactivation. the coat color gene is located on the X chromosome. If a black boy cat and orange female cat have kittens, what will be the phenotypes of the kittens
1/2 orange males, 1/2 black females
1/2 orange males , 1/2 calico females
1/2 black males, 1/2 calico females
both males and females will be calico
which of the follow is often true in inheritance of X-linked traits, but typically not true with autosomal traits?
females are always homozygous
males are always homozygous for the recessive allele
males always show an intermediate phenotype between the two homozygotes
phenotypes produced can depend on the direction of the cross
in the formation of a holliday junction the heteroduplex DNA that forms is composed of
one strand of DNA from each of the 2 homo chromo
one sister chromatid of each homologous chromosome
1 recessive snd 1 dominant allele
one strand of DNA and one strand of RNA
a tetrad consist of
4 pairs of homologous chromosome
4 cell produced by the second meiotic division
pair of homo chromo assembled during meiosis 1
pair of centrioles that has divided once
slipper limpets and jack in the pulpits show sequential hermaphroditism in which
individuals reproduce clonally, producing genetically identical offsprings
male and females both produce Y chromosomes
males and females take turns caring for offspring
individuals change from one sex to another in the course of their life
how does gamate production differ in male and female mammals
the two meiotic cell divisions produce 4 gametes in males but only 1 gamete in females
males produce diploid gametes, but females produce haploid gametes
females produce gametes containing both X and Y, while male gametes contain only Y
male gametes are larger than female gametes
you use a testcross to determine the gentoype of a dominant phenotype. to do so, you would cross it with a
homozygous recessive individual
heterozygous individual
homozygous dominant individual
individuals of a different species
the pseudoautosomal region or PAR of the mammalian Y chromosomes play what essential role
produces all of the male characteristics
it contains most of the functional genes in the Y chromosome
it causes the Y to pair with another Y to create a male gamete
it allows X and Y chromosomes to pair up during meiosis
the basic principle underlying genetic mapping is that the frequency of crossing over increases
as the distance between genes decrease
as the distance genes increase
in genes that are involved in epistatic interactions
the closer they are to the centromere of a chromosome
