Exam #2 Flashcards
What phase do Spindle microtubules attach to kinetochores?
Prophase
what phase does Cytokinesis generally begins?
Telophase
what phase do Chromatin condenses
Prophase
What phase do Chromosomes decondense?
Telophase
What phase do Sister chromatids separate at their centromeres?
Anaphase
What phase do Nuclear envelope fragments?
Prophase
What phase do Mitotic spindle forms?
Prophase
What phase do Chromosomes align at the cell’s midplane?
Metaphase
What phase do Homologous chromosomes undergo synapsis?
Prophase I
What phase do Sister chromatids separate and chromosomes move to opposite poles?
Anaphase II
What phase do Tetrads line up at the cell equator?
Metaphase I
What phase do Nuclear envelope forms around single-stranded chromosomes?
telophase II
What phase do Homologous chromosomes separate and move to opposite poles?
Anaphase I
What phase does Crossing-over occurs?
Prophase I
Nucleosomes are best described as?
eukaryotic DNA associated with histone proteins
When is a cell in metaphase?
The chromosomes are aligned at the midplane of the cell
The M phase of the cell cycle involves two main processes:
mitosis and cytokinesis
Chromosomes are duplicated during the ____ of the cell cycle?
S phase
To prevent disastrous consequences, the eukaryotic cell cycle is controlled by
a series of cell cycle checkpoints
What evolutionary advantage is provided by sexual reproduction?
Increased genetic diversity
What would happen if meiosis did not occur in sexually reproducing organisms?
The chromosome number would double in each generation
Homologous chromosomes undergo synapsis during
Prophase I
During prophase I of meiosis, homologous chromosomes lie side by side. This phenomenon is known as
Tetrad formation
An animal with a diploid number of 36 chromosomes will have ____ chromosomes in its gametes and ____ chromosomes in its somatic cells.
18;36
Scientists use the term ____________ to refer to the genetic makeup for that organism
genotype
The physical appearance of an organism for a given trait is known as
Phenotype
____ are alternative forms of a gene that govern the same feature, such as eye color, and occupy corresponding positions on homologous chromosomes.
Alleles
Mendel’s principle of segregation states that
alleles separate from each other before forming gametes
A pear plant with the genotype Aa can produce gametes containing
either A or a
The physical location of a gene on a chromosome is called
Its locus
Which of the following represents the possible genotype(s) resulting from a cross between one homozygous (BB) individual and one heterozygous (Bb) individual?
BB and Bb
Mating an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype is an example of a(n)
Test cross
A mating between individuals with different alleles at two loci is known as?
Dihybrid cross
The cells of female mammals, including humans, contain two __________.
X chromosomes
Which of the following refers to the expression of an intermediate phenotype in heterozygous individuals?
Incomplete dominance
Blood types A, B, AB, and O are controlled by how many alleles representing a single locus?
Three
The ability of a single gene to have multiple effects is known as _____.
pleiotropy
Which describes the interaction between genes such that the presence of certain alleles in one locus affects the expression of certain alleles in the other locus?
Epistasis
An organism with the genotype of AaXx can produce gametes containing ____ if the two genes are unlinked.
AX, Ax, aX, or ax
The offspring of two heterozygous gray-bodied, normal-winged flies should be 50% gray-bodied/normal wings (BbRr) and 50% black-bodied/vestigial wings (bbrr) because these alleles are linked. Suppose a small number, say 15%, of the offspring are instead black-bodied with normal wings. This is most likely the result of
crossing-over
The probability that two genes will be separated by crossing-over is related to
the distance between the two genes on the chromosome
What are the possible phenotypes of the children if the mother has Type O blood and the father has type AB blood? (Use the Punnett square to verify your answer.)
A,B
Breeding a yellow dog with a brown dog produced puppies with both yellow and brown hairs intermixed. This is an example of
codominance
A gene that controls seed coat color in peas also determines the susceptibility of these peas to a particular disease. This situation is referred to as
pleiotropy
Karyotyping is useful for determining:
the number of chromosomes in an individual
The normal human karyotype contains ____ total chromosomes, consisting of ____ autosomes and ____ sex chromosomes.
46; 44; 2
Autosomal monosomy is not seen in live births because:
its effects are so lethal as to cause spontaneous abortion early in pregnancy
Persons having an XO karyotype are sterile females. They have ____ syndrome
Turner
Down syndrome is an example of a ____ condition.
trisomic
Translocation occurs when:
part of a chromosome breaks off and attaches to a nonhomologous chromosome
In a chromosomal inversion, a segment of a chromosome is:
reversed
Cri du chat syndrome arises from:
deletion of part of chromosome 5
Aneuploidies describe:
a condition in which an extra chromosome is present or one is absent
Which of the following must be true for a female to have hemophilia?
Her mother is a carrier and her father has the disease
What are the predicted phenotypes of the children from a union of a woman who is heterozygous for hemophilia and a man who is normal? (Use the Punnett square to verify your answer.)
25 % hemophilia: 75% normal
Which gene is in the middle if B & C are 10 map units apart?
How many map units apart are A & B
6 map units
Genes A & B have a recombination rate of 6%, and A & C have a recombination rate of 4%.
How many map units apart are A & C?
4 map units
Which gene is in the middle if B & C are 10 map units apart?
Which gene is in the middle if B & C are 10 map units apart?
A
Which gene is in the middle if B & C are 10 map units apart?
Which is in the middle if B and C are 2 map units apart?
C
Aneuploidy results from nondisjunction - abnormal meiotic division where homologous chromosomes or sister chromatids fail to separate. This may happen in which phase/phases of Meiosis?
Both Anaphase I and Anaphase II
For recessive X-linked trait such as Hemophilia to be expressed: female needs two copies of allele while male needs only one copy of allele
True
What is Trisomy Down Syndrome?
Three copies of chromosomes 21
What is Translocation Down Syndrome?
Part of chromosomes breaks off and joins to chromosome 14
What is Cri du chat Syndrome?
Deletion of chromosome 5 short arm
What is Klinefelter Syndrome?
One extra X chromosomes
What is Turner syndrome?
One less X chromosomes
What if gametes were produced by mitosis? How would this affect chromosome number in
the offspring?
If gametes were produced by mitosis, they would have the same chromosome number as the parent cell. This would result in offspring with double the chromosome number, potentially causing abnormalities or inviability. Meiosis, on the other hand, ensures gametes have half the chromosome number to maintain stability across generations.
We know the fusion of gametes (fertilization) introduces genetic variation.
How does the production of gametes introduce genetic variation?
The production of gametes introduces genetic variation through processes like crossing over and independent assortment during meiosis, which shuffle genetic material. This results in unique combinations of genes in each gamete.
Allele Vs Gene
A gene is a segment of DNA that codes for a specific trait, while an allele is a variation of that gene. Different alleles can produce different versions of a trait.
