Genetics Exam 3
The lygaeus mode of sex-determination is the _______
XY/XX scheme
Autopolyploidy
an individual that has more than two chromosome sets that are all derived from a single species
A mutation in the O region of the lac operon would most likely result in ______
constitutive expression of lac operon, whether or not lactose was present, as the repressor cannot bind
Genes that are continually being expressed in most cells are referred to as
constitutive genes
In the lactose operon, the product of structural gene lacZ is capable of
converting lactose to glucose and galactose
In the lactose operon, the product of structural gene lacZ is capable of _____.
converting lactose to glucose and galactose
Bar bodies
during embryonic development, one of your X chromosomes are inactivated so that gender characteristics can be established
Base-pair additions and deletions that alter the reading frame of all subsequent base-pair triplets are collectively referred to as:
frameshift mutations
Point Mutations
gene mutations involving changes in one or a few nucleotides
The process of turning on the expression of a gene in response to a substance in the environment is called:
induction
Hfr mapping
is carried out using interrupted mating experiments
An E. coli trp- auxotroph can grow on:
minimal medium plus the AA trp
The mutation which will not affect the length of a protein is
missense mutation
frameshift mutation
mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide
Individuals with Klinefelter syndrome are
phenotypically male and usually 47, XXY
Name the general category into which double-stranded circular extrachromosomal DNA elements such as F factors, ColE1, and R would fall.
plasmid
allopolyploidy
polyploidy resulting from contribution of chromosomes from two or more species
Wild type bacteria are _________ and can synthesize everything they need for growth; mutant bacteria are _______ and require chemicals to be added to the media in order to grow.
prototrophic; auxotrophic
NER system
recognizes damage, its enzyme then removes the single strand DNA in the damaged section Cuts out the segment on the new strand and inserts the corresponding segment on the old strand
BER system
repairs damage done to single base by comparing old and new strands Damaged base can be removed and inserted through translation.
Mutations that arise in nature, from no particular artificial agent, are called
spontaneous mutations
The condition that exists when an organism gains or loses one or more chromosomes but not a complete haploid set is known as ________.
Aneuploidy
Polyploids created by chromosome duplication within a species are known as:
Autopolyploids
Transduction is a form of recombination in bacteria that involves ________.
Bacteriophages
_______ excision repair removes abnormal or chemically modified bases from DNA, whereas ________ excision repair removes larger lesions like thymine dimers
Base, nucleotide
In an interrupted mating experiment, it is seen that after 10 min AziR gene is in the recipient cell, after 15 mins the recipient is lac+, and after 20 mins the recipient is Leu+, but the recipient is never his+. Where in the genome is the origin of transfer?
Between His+ and AziR
The MSY (male specific region of the Y)
Contains the sex determining region
Linkage _____ as the distance between two genes _____
Decreases, Increases
There is a mutant of the lac repressor gene called I^s. The operon can never be induced. What do you think the I^s protein is doing?
It can't bind to lactose
Eukaryotic DNA sequences that can move from one position to another are known as
Jumping Chromosomes
Which of the following substances is the inducer for the lac operon?
Lactose
The term normally applied when two genes fail to assort independently is _______.
Linkage
Bacteriophages engage in two interactive cycles with bacteria. What are these cycles?
Lytic and Lysogenic cycles
Match SRY with one of the following:
Male
The dominant allele for Huntington disease shows complete penetrance. This means:
A person carrying the disease-associated genotype always develops Huntington
dosage compensation
Mechanism in which X chromosome inactivation equalizes gene expression between males and females.
A human individual with 45 chromosomes has a _____.
Monosomy
Which term would be applied to a regulatory condition that occurs when protein is associated with a particular section of DNA and greatly reduces transcription?
Negative control
When chromosomes fail to separate during meiosis, thereby producing an egg with two X chromosomes or an egg with no X chromosome at all, this event is referred to as
Nondisjunction
Which of the following categories of mutations is not possible to pass to offspring?
Somatic
Which of the following is the part of the Y chromosome that is critical for normal male development?
SRY
Calico cats are an example of
Lyon Hypothesis
Which of the following is true about conjugation in bacteria:
All of the above
Familiar down syndrome is caused by
Robertsonian translocation of chromosome 21 on chromosome 14
Bacteriophage lambda can form a prophage. What is a prophage?
the phage genome when it is integrated into the host genome
Individuals with a genetic conditions indicated by XXX
will have two bar bodies
There is 30% recombination frequency between two genes. The distance between them in cM is:
30
Turner syndrome in humans is caused by which chromosomal condition?
45, XO
The condition known as cri-du-chat syndrome in humans has a genetic constitution designated as _________.
46, 5p-
missense mutation
A base-pair substitution that results in a codon that codes for a different amino acid.
silent mutation
A mutation that changes a single nucleotide, but does not change the amino acid created.
Which of the following is more likely to be sterile?
A triploid plant
How does the mismatch repair system distinguish between the parental DNA strand and the newly synthesized strand containing the mismatched base?
Adenine in the parental strand of the helix is methylated
Which of the following can create a point mutation?
Alkyating agent Tautomeric shift Base analog Deamination
Which of the following is true about intercalating agents?
All of the above
Which of the following statements about Down syndrome is false?
All of the above are false
Which of the following is true about the NER repair mechanism
All of the above are true
Which of the following is true about the mismatch repair system?
All of the above are true
Which of the following enzyme(s) is involved in base excision repair?
DNA glycosylase and AP endonuclease
Why is the Y chromosome able to pair with the X chromosome during meiosis?
The X and Y chromosomes share small segments that allow them to act like homologues during meiosis
The Lyon Hypothesis states that
The X chromosome is inactivated early during development in females
Which of these statements is/are true of inversions?
all of the above
Alkylating agents
donate an alkyl group to nucleotides alter base-pairing affinity may result in point mutations were used in chemiotherapy
In humans, the Y chromosome carries ________ genes than the X chromosome.
fewer
Which of the following substances is the inducer for the lac operon
lactose
Transformation is a form of recombination in bacteria that involves
uptake of free DNA
Autotriploids
-A failure of all chromosomes to segregate during meiotic divisions can produce a diploid gamete, which then gets fertilized by a haploid gamete, a zygote with three sets of chromosomes is produced -Two sperm can fertilize an ovum -Crossing diploids with tetraploids
A HFR bacteria mates with an F- bacteria. What will be the types of bacteria after conjugation is complete?
A HFR and a F-
In the BER system if the base to be corrected is a U
A Uracil-DNA-glycosylase excises the incorrect base and the endonuclease recognizes the lesion and nicks the strand. DNA polymerase and ligase then fill the gap
Base analogs are chemicals that have dimensions and shapes that allow them to wedge between DNA base pairs
False
Dosage compensation balances the dose of X chromosome gene expression in females and males by silencing the Y chromosome
False
In C. elegans, sex determination results from the presence of one X in the males and two in females
False
Secondary sexual differentiation involves only the gonads where gametes are produced
False
The Ames test uses a number of different strains of Drosophila selected for their ability to reveal the presence of specific types of mutations
False
Transduction is a form of recombination in bacteria that involves contact between the bacteria involved
False
UV radiation create purine dimers that distort the DNA conformation
False
In humans an individual who is genotyped as XO is a
Female
Predict the phenotype of the male and female domestic fowl with genotype hh (for plumage pattern).
Female hen feathered, and male cock feathered
Which of the following matings would most likely produce an F- cell with a new genetic makeup after conjugation
Hfr donor and F- recipient
Mendel did not observe linkage due to
Independent assortment
The process of transformation
Involves the uptake of free DNA by bacteria
Due to which of the following mechanisms, mismatch repair system is able to distinguish newly synthesized DNA strand from older one?
Old strands are methylated and new ones are not
Which term refers to a contiguous set of genes that is under coordinate control?
Operon
You cross a P+P+/V+V+ male drosophila to a P-P-/V-V- and obtain the F1 P+P-/V+V-. Now you cross the F1 male with double recessive a p-p-/v-v- female. What will the phenotypes in F2?
P+V+ and p-v- and also p+v- and p-v+
The percentage of individuals with a given genotype who exhibit the phenotype associated with that genotype is called:
Penetrance
Which of the following DNA repair mechanisms is often used by bacteria (but not by eukaryotes) to repair thymine dimers?
Photoreactivation repair
Which of the following DNA repair mechanisms is often used by bacteria to repair thymine dimers?
Photoreactivation repair
What is the difference between primary and secondary sex ratio?
Primary sex ratio are the females and males that were conceived while secondary sex ratios are the females and males that were born
In the lactose operon, what happens when a repressor is bound to the operator?
RNA polymerase is prevented from transcribing the structural genes in the operon
What happens when a repressor is bound to the operator?
RNA polymerase is prevented from transcribing the structural genes in the operons
In the nematode C. elegans
There are only males and hermaphrodites
What happens in the lac operon when both lactose and glucose are present in the environment?
Transcription of the lac operon will be limited because of catabolite repression
Which process relies on phage as a vehicle of DNA transport
Transduction
Base-pair substitution involving the replacement of a purine with a pyramidine and vice versa are called:
Transversions
Which of the following would be most likely to be sterile?
Triploid organisms
A nonsense mutation may result into an abnormal shortening of a polypeptide
True
Chlamydomonas haploid gametes are of two mating types mt- and mt+
True
Eukaryotic DNA sequences that can move from one position to another are known as transposons
True
Primary sexual differentiation involves only the gonads where gametes are produced
True
Repeats of three nucleotide pairs (such as CGG) can expand, or increase in copy number, from one generation to the next and cause human diseases such as fragile X syndrome and Huntington disease.
True
Replication slippage is common in repeat sequences and is responsible of Fragile-X and Huntington disease
True
The presence of the pseudoautosomal regions in the Y chromosome is critical to segregation of the X and Y chromosomes during male gametogenesis
True
How many bar bodies will an XXXY individual have in their cell?
Two
Gene duplication car arise through which of these processes?
Unequal crossing over during meiosis
Under the system of genetic control of the tryptophan operon, ______
When there is no tryptophan in the medium, transcription of the trp operon occurs at high levels
Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from ________.
Xeroderma pigmentosum
The condition known as cri-du-chat syndrome in humans has a genetic constitution that results from _______
a deletion on chromosome 5
Non-sense mutation
a mutation in which a sense codon that corresponds to one of the twenty amino acids specified by the genetic code is changed to a chain-terminating codon.
Which of the following can cause a frame shift mutation?
all of the above
Which of the following is true about Chlamydomonas reproduction:
all of the above are true
Polyploids created by interbreeding between two species are known as
allopolyploids
Lyon hypothesis
the name of the hypothesis that one of the two X chromosomes in mammals is inactivated
The transfer of a gene from a bacteria cell to another by a bacteriophage is known as
transduction
When a segment from one chromosome is detached and reattached to a non-homologous chromosome this is known as:
translocation
The condition known as down syndrome in humans has a genetic constitution that results from ______
trisomy of chromosome 21
Chemical mutations that shift one proton in a nitrogenous base are known as tautomeric shifts
true
