Exam 4
Color blindness is an X-linked recessive trait. A color-blind man has a daughter with normal color vision. What is the genotype of the daughter
XCXc
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents
XCXc and XCY
If B represents the allele for black eyes (dominant) and b represents the allele for orange eyes (recessive), what would be the genotypic ratio of a cross between a heterozygous black-eyed MendAlien and an orange-eyed MendAlien
0 homozygous black (BB): 1 heterozygote (black) (Bb): 1 homozygous orange (bb)
If B represents the allele for black eyes (dominant) and b represents the allele for orange eyes (recessive), what would be the phenotypic ratio of a cross between a heterozygous black-eyed MendAlien and an orange-eyed MendAlien
1 black : 1 orange
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an X-linked dominant. An unaffected woman mates with a male with hypophosphatemia. What is the expected phenotypic ratio of their offspring?
1 daughter with hypophosphatemia : 1 normal son
Suppose that having three nostrils is a Y-linked character. A woman with two nostrils mates with a man with three nostrils. What is the expected phenotypic ratio of their offspring?
1 daughter with two nostrils : 1 son with three nostrils
Color blindness is an X-linked recessive trait. A color-blind woman mates with a male with normal color vision. What is the expected phenotypic ratio of their offspring?
1 normal vision daughter : 1 color-blind son
Color blindness is an X-linked recessive trait. A color-blind man has a daughter with normal color vision. She mates with a color-blind male. What is the expected phenotypic ratio of their offspring?
1 normal vision female : 1 color-blind female : 1 normal male : 1 color-blind male
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an X-linked dominant. A woman without hypophosphatemia and a man with hypophosphatemia have a daughter. The daughter mates with a male without hypophosphatemia. What is the expected phenotypic ratio of their offspring?
1 unaffected female : 1 female with hypophosphatemia : 1 unaffected male : 1 male with hypophosphatemia
Huntington's disease is a dominant condition with late age of onset in humans. If one parent has the disease, what is the probability that his or her child will have the disease?
1/2
Color blindness is an X-linked recessive trait. A color-blind man has a daughter with normal color vision. She mates with a male who has normal color vision. What is the expected phenotypic ratio of their offspring?
2 normal vision females : 1 normal vision male : 1 color-blind male
A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes?
46
What is a karyotype
A display of every pair of homologous chromosomes within a cell, organized according to size and shape
Which of these is a testcross
A? X aa
A color-blind woman mates with a male with normal color vision. Which of these results would indicate that color blindness is caused by an X-linked recessive allele
All of the sons, and none of the daughters, are color-blind.
Color blindness is an X-linked recessive trait. A woman who is homozygous for normal color vision mates with a color-blind male. What is the expected phenotypic ratio of their offspring?
All the offspring have normal color vision.
How does the sexual life cycle increase the genetic variation in a species?
By allowing independent assortment of chromosomes
How could the botanist best determine whether the genotype of the green-pod plant is homozygous or heterozygous?
Cross the green-pod plant with a yellow-pod plant.
New combinations of linked genes are due to which of the following
Crossing over
This is the step in the cell cycle when the cytoplasm divides in two.
Cytokinesis
Which of the following is true of a species that has a chromosome number of 2n = 16
Each cell has 8 homologous pairs
Which of these phases encompasses all of the stages of mitosis?
First sliver during the mitotic-- look at picture
Cells that are in a nondividing state are in which phase?
G0
This is the portion of the cell cycle just after division, but before DNA synthesis. During this time the cell grows by producing proteins and organelles.
G1 Phase
This third sub-phase of interphase is a period of metabolic activity and growth. During this phase the cell makes final preparations for division.
G2 Phase
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
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their sons would be color-blind and of normal height
Half
Color blindness is an X-linked recessive trait. Under what conditions can an unaffected male have a color-blind daughter?
He can't.
Order of cell cycle
I Peel Mangos And Tomatoes
A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible genotype for the mother
IAi
Typically, this phase accounts for 90% of the cell cycle. It is a time of high metabolic activity. The cell grows by producing proteins and organelles, and chromosomes are replicated.
Interphase
Cell Cycle Order (not phrase)
Interphase Prophase Metaphase Anaphase Telephase
A gene's location along a chromosome is known as which of the following
Locus
_________ is based on gametes getting only one copy of each allele of each gene
Mendel's law of segregation
That each gamete contains a single allele of the eye color gene is an illustration of _____
Mendel's law of segregation only
This is when division of the nucleus occurs. The that have been replicated are distributed to two daughter nuclei.
Mitosis
Cell division occurs during this short phase, which generally involves two discrete processes: the contents of the nucleus (mainly the duplicated chromosomes) are evenly distributed to two daughter nuclei, and the cytoplasm divides in two.
Mitotic Phase
A couple has a child with Down syndrome when the mother is 39 years old at the time of delivery. Which is the most probable cause?
One member of the couple underwent nondisjuntion in gamete production
A female wild type head top mates with a flat head top and produces all wild type head tops. The result of the following cross indicates that the genotype of the female parent is _______.
RR
A pedigree analysis for a given disorder's occurrence in a family shows that, although both parents of an affected child are normal, each of the parents has had affected relatives with the same condition. The disorder is then which of the following
Recessive
DNA synthesis (or replication) occurs during this phase. At the beginning of the phase, each chromosome is single. At the end, after DNA replication, each chromosome consists of two sister chromatids.
S-Phase
A Barr body is normally found in the nucleus of which kind of human cell?
Somatic cells of a female only
What is a genome?
The complete complement of an organism's genes
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
Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?
TtRr - tall and pink
What is the chromosomal system for determining sex in mammals?
X-Y
The frequency of Down syndrome in the human population is most closely correlated with which of the following
age of the mother
Centromeres divide and sister chromatids become full-fledged chromosomes during ______.
anaphase
During _______ centromeres come apart, and sister chromatids become full-fledged chromosomes, which migrate to opposite poles of the cell.
anaphase
Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?
anaphase
During _______, homologous chromosomes separate by moving with the spindle microtubules toward the poles
anaphase I
During _______, sister chromatids separate and move toward the poles
anaphase II
A female wild type head top mates with a flat head top and produces all wild type head tops. The result of the following cross indicates that genotypically the offspring _____.
are all Rr
The centromere is a region in which
chromatids remain attached to one another until anaphase.
Genes are located on chromosomes; the behavior of chromosomes during meiosis accounts for inheritance patterns
chromosome theory of inheritance
Chiasmata are what we see under a microscope that let us know which of the following has occured
crossing over
Pairing of homologous chromosomes is followed by ____________, the exchange of genetic material between nonsister chromatids of homologous chromosomes.
crossing over
_________________ involves the formation of a cleavage furrow.
cytokinesis in animal cells
__________________ involves the formation of a cell plate.
cytokinesis in plant cells
During which phases of mitosis are chromosomes composed of two chromatids?
from G2 of interphase through metaphase
During _____ the cell grows and replicates both its organelles and its chromosomes
interphase
Nucleoli are present during _____.
interphase
During gamete formation, the alleles for one gene separate independently of the alleles for all other unlinked genes
law of independent assortment
During gamete formation, the two alleles for each gene separate so that each gamete receives only one allele
law of segregation
Suppose that the botanist carried out the test cross described in Parts A and B and determined that the original green-pod plant was heterozygous (Gg). Which of Mendel's findings does her test cross illustrate?
law of segregation
Genes that are located on the same chromosome tend to be inherited together
linkage
Males are more often affected by sex-linked traits than females because
males are hemizygous for the X chromosome.
Differences between meiosis I and meiosis II
meiosis I --pairing of homologous chromosomes during prophase and their separation during anaphase. meiosis II --sister chromatids
During which part of meiosis (meiosis I or meiosis II) do the two alleles of a gene separate? During which phase does the separation occur?
meiosis I, anaphase
During ________ chromosomes align along the metaphase plate.
metaphase
In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis?
metaphase
Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment - happen when?
metaphase
During ______, pairs of homologous chromosomes align in the center of the cell
metaphase I
During _______, individual chromosomes (each composed of sister chromatids) align in the center of the cell.
metaphase II
The somatic cells derived from a single-celled zygote divide by which process
mitosis
During _____ both the contents of the nucleus and the cytoplasm are divided.
mitotic phase
The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because
one phenotype was completely dominant over another.
Spindle fibers attach to kinetochores during _______.
prometaphase
The events of ___________ include the attachment of spindle fibers to kinetochores.
prometaphase
Chromosomes become visible during _____.
prophase
Chromosomes first become visible during which phase of mitosis?
prophase
Events of _________ include the condensation of chromatin and the dispersal of nucleoli.
prophase
Which term describes centrioles beginning to move apart in animals cells
prophase
During _______, chiasmata form and crossing-over occurs
prophase I
During _______, a spindle apparatus forms and individual chromosomes (each composed of sister chromatids) begin to move toward the center of the cell
prophase II
True-breeding
punnett square - 1&4
Black-eyed X Black-eyed alien have a ratio of 247Black-eyed and a ratio of 86Orange-eyed offspring. The result of the following indicates the orange eyes are _______ black eyes
recessive to
______________ are composed of material derived from both parents.
recombinant chromosomes
Which of the following does not occur during mitosis?
replication of the DNA
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 x roan
A female wild type head top mates with a flat head top and produces all wild type head tops. The result of the following indicates that the genotype of the male parent is _____
rr
DNA is replicated at this time of the cell cycle:
s-phase
Cytokinesis often, but not always, accompanies _____.
telophase
During _________ both nuclear envelopes and nucleoli re-form.
telophase
During ________, the separated chromosomes cluster at the poles of the spindle and cytokinesis occurs, forming two daughter cells, each with a haploid set of replicated chromosomes
telophase I
During _______, the seperated chromotids elongate and (usually) cytokinesis occurs, forming four genetically distinct haploid daughter cells
telophase II
__________ is used to determine whether an individual expressing the dominant phenotype is homozygous dominant or heterozygous.
testcross
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests
that the parents were both heterozygous.
What is the reason that linked genes are inherited together
they are located close together on the same chromosome
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.
During prophase a homologous pair of chromosomes consists of _____.
two chromosomes and four chromatids
In animals, meiosis results in gametes, and fertilization results in
zygotes