Final Exam Genetics All Exam Questions
All of the cells in the figure are from the same species. What is the number of chromosomes in this cell when at G2? 6 pairs of chromosomes (3 red, 3 blue)
6
What is the difference between a genetic map and a physical map?
A genetic map gives the relative distance between genes based on recombination, and a physical map gives distance based upon DNA sequence.
Chargaff
A=T, C=G
Which of the following is not evidence for telomere length being a molecular clock.
The length of telomeres in extinct hominids is shorter than in modern man.
To activate the transcription of permease (and the whole lac operon) lactose needs to be present in the cell. How can lactose get in the cell when the permease gene is not activated?
The repressed lac operon is never completely repressed.
How do the sugars of RNA and DNA differ?
The sugar of RNA has a hydroxyl group that is not found in the sugar of DNA
Hershey & Chase
Use of 32P and 35S to confirm that DNA is transforming agent
What evidence indicated that eukaryotic genes are not collinear with their proteins?
When DNA was hybridized to the mRNA transcribed from it, regions of DNA that did not correspond to RNA looped out.
Waxy endosperm (wx), shrunken endosperm (sh), and yellow seedlings (v) are encoded by three recessive genes in corn that are linked on chromosome 5. A corn plant homozygous for all three recessive alleles is crossed with a plant homozygous for all the dominant alleles. The resulting F1 are then crossed with a plant homozygous for the recessive alleles in a three-point testcross. The progeny of the testcross are: Wx Sh v 125 Wx Sh V 3,200 wx Sh v 1,500 wx sh V 105 wx Sh V 320 Wx sh V 1,400 wx sh v 3,020 Wx sh v 330 Total 10,000 Determine the order of these genes on the chromosome.
Wx-V-Sh
F transfer begins by nicking at the ______ site, located on the F plasmid.
oriT
Polydactylism is an example of....
penetrance and expressivity
The National DNA Index System (NDIS) examines 13 ______________ loci to generate a DNA fingerprint. Which of the following words best fills in the blank?
polymorphic
What type of chromosome mutations increase the amount of genetic material of just one chromosome?
polysomic
F+
present as a separate circular DNA
f'
present as a separate circular DNA, but contains some bacterial DNA
HFr
present, integrated into chromosome
5'--> 3' exonuclease activity
primer removal
The P value obtained from a Chi-square test represents the:
probability that the observed data would arise by chance if the hypothesis was correct
Which of the following is a trait, given in class, of model organisms?
produce lots of offspring
A deletion can give rise to which of the following?
pseudodominance
Which of the following is the best definition of a gene (as given in class)?
region of DNA responsible for encoding RNA
What is the first step in performing "reverse" genetics?
sequence DNA
You identify a mutant whose chromosomes shorten after each round of replication. A mutation in which gene would most likely explain this observation?
telomerase
A diploid organism is exposed to X-rays and a mutant with an altered phenotype is produce. What type of experiment would you do to determine if that altered phenotype is due to a single mutation?
testcross the mutant and see if the offspring follow a 3:1 phenotypic ratio
The antiparallel nature of DNA refers to:
the opposite direction of the two strands of nucleotides
Which of the following is NOT true?
the rate of recombination between any two genes can vary between 0-1.0
What are the type(s) of genetic variation that can be a consequence of meiosis, as discussed in class? Give all answers that are correct.
-recombination between homologous chromosomes -random assortment of chromosomes into gametes
As indicated in class, Gregor Mendel was successful because he (give all answers that are correct):
-used a good model system. -used math to analyze results and form an hypothesis. -chose traits that were easy to study.
What percentage of the genome would be the same (assuming no crossing over) between a man and his grandson?
0-50
Waxy endosperm (wx), shrunken endosperm (sh), and yellow seedlings (v) are encoded by three recessive genes in corn that are linked on chromosome 5. A corn plant homozygous for all three recessive alleles is crossed with a plant homozygous for all the dominant alleles. The resulting F1 are then crossed with a plant homozygous for the recessive alleles in a three-point testcross. The progeny of the testcross are: Wx Sh v 125 Wx Sh V 3,200 wx Sh v 1,500 wx sh V 105 wx Sh V 320 Wx sh V 1,400 wx sh v 3,020 Wx sh v 330 Total 10,000 Determine the interference among these genes.
0.165
What is the probability of rolling two six-sided dice and obtaining the following numbers? --> two of the same number
1/6
In a monohybrid cross, the genotypic ratio of the F2 should be
1:2:1
The following F2 progeny from a monohybrid cross are observed: 60 purple, 40 orange. You thought homozygous purple is a lethal genotype, and so decide to test that hypothesis by performing a Chi-square analysis. What is the Chi-square value calculated when and what conclusion should be drawn?
2.02; homozygous purple may be a lethal genotype
What fraction of live-birth offspring will be phenotypically normal from one normal parent and the other a 14-21 translocation carrier?
2/3
Species I has 2n = 8 chromosomes and species II has 2n = 14 chromosomes. What would the expected chromosome numbers be in individuals with autotetraploidy in species II?
44
One nucleotide strand of a DNA molecule has the base sequence 5'-ATTGCTACGC-3' Which of the following sequences is the complementary DNA strand?
5'-GCGTAGCAAT-3'
Alkaptonuria is a metabolic disorder in which affected persons produce black urine. Alkaptonuria results from an allele (a) that is recessive to the allele for normal metabolism (A). Sally has normal metabolism, but her brother has alkaptonuria. Sally's father has alkaptonuria, and her mother has normal metabolism. If Sally marries a man with alkaptonuria, what is the probability that their first child will have alkaptonuria?
50
f III-2 and III-7 were to mate, what is the probability (as a percentage) that one of their children would have the condition? .
50
A man with genotype IBIA Hh mates a woman with blood type IOIO hh. Which phenotype would be expected in the offspring?
A or B or O
Primers are synthesized where on the lagging strand?
At the beginning of every Okazaki fragment
Bill and Betty have had two children with Down syndrome. Neither Bill nor Betty have Down syndrome. Bill's brother has Down syndrome and his sister (who does not have Down syndrome) has two children with Down syndrome. On the basis of these observations, indicate which of the following statements is most likely correct.
Bill's sister has 45 chromosomes
Low levels of glucose lead to all of the following, EXCEPT that:
CAP-cAMP loses its affinity to DNA
Researchers have proposed the early life on Earth used RNA as its source of genetic information and that DNA eventually replaced RNA as the source of genetic information. What aspects of DNA structure might make it better suited than RNA to be the genetic material?
DNA is more chemically stable because it lacks a 2' OH group
3′ --> 5′ exonuclease activity
DNA proofreading
Which of the following statements is NOT correct about the process of transcription?
During transcription the RNA molecule is synthesized in the 3′ to 5′ direction.
Which of the following is a characteristic of epistasis
F2 ratio in a dihybrid cross is not 9:3:3:1
"Evolution is _______________________ change over time."
Genetic
Place the following components in the order in which they are first used in the course of replication: DNA gyrase Helicase Initiator proteins Single-strand-binding protein
Initiator proteins, Helicase, Single-strand-binding protein, DNA gyrase
The advantage to DNA in bacterial cells being negatively supercoiled is:
It takes less energy to form single-stranded DNA
Joe has classic hemophilia, an X-linked recessive disease. Based upon what was covered in class, from whom could Joe have inherited the gene for this disease A. his father's mother B. his father's father C.his mother's mother D.his mother's father E. more than one of the other answers are correct
More than one answer is correct
DNA ligation
Phosphodiester bond linkage at DNA nicks
Which of the following is not a possible mechanism, as discussed in class, to explain epigenetics
RNA splicing
Which of the following is NOT one of the steps described in class for the initiation of transcription?
RNAP binds transcription activator
What is responsible for sex determination in humans?
SRYgene
Which of the following are NOT implications of all organisms having similar genetic systems?
That interspecies matings can produce fertile offspring.
In the California poppy, an allele for yellow flowers (C) is dominant over an allele for white flowers (c). At an independently assorting locus, an allele for entire petals (F) is dominant over an allele for fringed petals (f). A plant that is homozygous for yellow and entire petals is crossed with a plant that is white and fringed. A resulting F1 plant is then crossed with a plant that is white and fringed, and the following progeny are produced: 54 yellow and entire, 58 yellow and fringed, 53 white and entire, and 10 white and fringed. Use a Chi-square test to compared the observed with expected offspring, give the Chi-square value along with the conclusion you would draw.
X2 = 35, cc ff plants may be less viable than other genotypes
Which genotype is Klinefelter syndrome?
XXY
The process that allows different mRNAs to be produced from a single pre-mRNA is
alternative splicing
The definition of a supercoil, as given in class, is
an excess or deficiency of turns in the primary helix of double-stranded DNA
In a positive inducible operon, the regulator protein is synthesized as...
an inactive activator
Discontinuous replication is a result of which property of DNA?
antiparallel nucleotide strands
J.A. Moore investigated the inheritance of spotting patterns in leopard frogs. The pipiens phenotype has the normal spots that give leopard frogs their name. In contrast, the burnsi phenotype lacks spots on its back. Moore carried out the following crosses, producing the progeny indicated. Parent phenotypes /Progeny phenotypes burnsi x burnsi/ 39 burnsi, 6 pipiens burnsi x pipiens/ 23 burnsi, 33 pipiens burnsi x pipiens/ 196 burnsi, 210 pipiens On the basis of these results, what is the most likely mode of inheritance of the burnsi phenotype?
burnsi is dominant to pipiens
genetic map distance can be expressed as
cM or m.u.
Genetic material can be located in which of the following organelle(s) of eukaryotic cells?
chloroplast
What DNA strand has the same sequence (replacing T with U) as the transcribed RNA?
coding strand
The number of bacterial cells is enumerated by counting ________ and the number of viruses by counting _______.
colonies; plaques
Red-green color blindness is X-linked recessive. A woman with normal color vision has a father who is color blind. The woman has a child with a man with normal color vision. Which phenotype would NOT be expected?
color-blind female
direct cell to cell transfer of DNA
conjugation
Palomino horses have a golden yellow coat, chestnut horses have a brown coat, and cremello horses have a coat that is almost white. A series of crosses produce the results given below. Which answer best described the genotype of these horses and the type of genetic control that affects horse coat color? Palomino x palomino --> 2 palomino: 1 chestnut : 1 cremello Chestnut x chestnut --> all chestnut Cremello x cremello --> all cremello Palomino x chestnut --> 1 palomino: 1 chestnut Palomino x cremello --> 1 palomino: 1 cremello Chestnut x cremello --> all palomino
cremello and chestnut are homozygous, palomino is heterozygous; incomplete dominance
for two genes, the frequency of formation of recombinant gametes equals the frequency of______
crossing over
What would be the most likely effect of a base change mutation at the -10 location in an E. coli gene?
decreased transcription
Which of the following is a purpose in performing a complementation test.
determine if two mutations are in the same gene
genes on _________ chromosomes cannot be ________ mapped (relative to each other)
different, genetically
Jacob and Monod are credited with which of the following
elucidating lac operon genetics
That a difference in methylation produces different coat colors in mice is an example of.....
epigenetics
Which phrase best describes the relationship between genotype and phenotype?
genotype represents what phenotypes are possible
The experiments Griffith performed with Streptococcus bacteria involved infecting mice with virulent and/or avirulent forms of the bacteria and observing if the mice died. In the key experiment that demonstrated a strain was being transformed, he mixed________ (choose type of cells) and saw _________ (choose result).
heat killed smooth + live rough --> death
In the diagram below, what is the genotype of individual III-8? .
homozygous recessive
A reciprocal cross is used to determine... (give all answers that are correct)
if a trait is sex-linked
Observing a 9:3:3:1 ratio in the F2 of a dihybrid cross was used to support the principle of.
independent assortment
Which of the following is not a function of a replicon, as given in class?
initiate cell division
Which of the following is not a requirement, given in class, for what must be true for any genetic material?
is chemically stable
A promoter
is the binding site for RNA polymerase
What is the term for a display of a set of chromosomes
karyotype
When mutants of the lac operon are isolated they separate into two classes: Lac+ and Lac-. Which of the following mutations would NOT result in a mutant that fits into the Lac- category (as discussed in class)?
lacOC
Which genotype of the lac operon gives rise to the indicated phenotype? Lactose absent Lactose present b-galactosidase permease b-galactosidase permease - - + -
lacY-
During which process(es) does the number of chromosomes per cell decrease by half?
meiosis I
Which of the following is an example, given in class, of a technological advancement that has affected the field of genetics?
microscope
Which of the following was not given in class as being a characteristic of eukaryotic gene regulation?
most gene under negative control
Bob has XXY chromosomes and is color blind. His mother and father have normal color vision, but his maternal grandfather is color blind. Assume that Bob's chromosomes abnormality arose from nondisjunction in meiosis. In which parent and in which meiotic division did nondisjunction take place?
mother, meiosis II
A cell in G1 of interphase has 8 chromosomes. How many chromosome sets (n), chromatids (Ch), and DNA per cell (C) will be found when this original cell enters G2 of interphase?
n = 2; Ch = 16; C = 4
Consider the partial diploid strain of E coli: lacI+ O+ lacZ+ lacY-/lacI- Oc lacZ- lacY+. Under what conditions will this strain make b-galactosidase?
only when lactose is present
"r" is
the ratio of non-parentals to total offspring in a cross
Which of the following is the correct designation for a bacterial gene followed by the correct designation for that gene's encoded protein?
thr Thr
eight genotypes are created when performing a ______
three-point cross
a cell that has taken up bacterial DNA delivered by a phage
transductant
virus-mediated transfer of DNA
transduction
process of a cell taking up external DNA
transformation
Catabolite repression is....
when genes involved in metabolism of sugars other than glucose are repressed in the presence of glucose
