Ch. 10, 11, 12 Flashcards
Meiosis usually produces how many daughter cells?
Four haploid
At which stage of meiosis are sister chromatids seperated from each other?
Anaphase II
The part of meiosis that is most similar to mitosis is..
Meiosis II
If a muscle cell of a typical organism has 32 chromosomes, how many chromosomes will be in a gamete of that same organism?
16
What is the genetic content of the two daughter cells in prophase II of meiosis?
two haploid cells with two copies of each gene
How do telophase I and telophase II differ during meiosis in animal cells?
The chromosomes are usually still condensed during telophase I but recondense after telophase II
Crossing-over in meiosis occurs during..
prophase I
When does crossing over occur in mitosis?
crossing over does not occur in mitosis
What distinguishes prophase I of meiosis from prophase of mitosis?
In prophase I of meiosis, homologous chromosomes pair up, while it does not occur in mitosis
When does DNA synthesis occur in meiosis and mitosis?
In S part of interphase
When do the homologous chromosomes line up in meiosis?
Metaphase II
Meiosis is a type of cell division that produces…
gametes
During which phase do chromosome first become visible?
prophase
What structure is responsible for moving the chromosomes during mitosis?
spindle fibers
Cytokinesis begins in which phase?
telophase
The process of mitosis ensures that…
A spindle forms during which phase?
prophase
What can be determined from a karyotype?
the sex of the individual and the number of chromosomes present
Compared to the X chromosome, the Y chromosome is…
smaller
What are some external events that could cause a cell to divide?
death of other cells, horomones
What happens when a cell gets too big?
It divides
What is a gene that codes for a positive cell-cycle regulator called?
proto-oncogene
What is the main prerequisite for clearance at the G2 checkpoint?
accurate and complete DNA replication has occured
What are changes to the order of nucleotides in a segment of DNA that codes for a protein?
mutations
At which of the cell-cycle checkpoints do external forces have the greatest influence?
G2
Identical copies of chromatin held together by cohesin at the centromere are called?
sister chromatids
The first level of DNA organization in a eukaryotic cell is maintained by which molecule?
histones
Attachment of the mitotic spindle fibers to the kinetochores is a characteristic of which stage of mitosis?
prometaphase
The chromosomes become visible under a light microscope during which stage of mitosis?
prophase
If the M checkpoint is not cleared, what stage of mitosis will be blocked?
anaphase
Is this characteristic of mitosis, meiosis, or both? One round of DNA duplication
both
If Huntington’s disease is dominant and always deadly, why do people still have it?
Because it doesn’t show up until after people have passed it on
When two genes are on the same chromosome, which of Mendel’s laws will be violated
The law of independent assortment
The law of independent assortment
All of these are true
Human eye color depends on a pathway of genes. Brown eyes mask green eyes which mask blue eyes. What pattern is this?
Epistasis
When DNA is tightly packed, the chromosomes are called…
chromatids
When proto-oncogenes mutate, what do they become?
oncogenes
A male who is color-blind marries a heterozygous woman. What percent of their male children will be color-blind?
50%
All cells must go through this stage.
G1
At this checkpoint, the cell checks if there are enough building blocks to duplicate the DNA and if the DNA is intact.
G1
A recessive trait will be observed in individuals that are ________ for that trait.
homozygous
The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one quarter of their offspring will have AB blood type (IAIB) in which both antigens are expressed equally. Therefore, ABO blood groups are an example of:
multiple alleles and codominance
In a mating between two individuals that are heterozygous for a recessive lethal allele that is expressed in utero, what genotypic ratio (homozygous dominant:heterozygous:homozygous recessive) would you expect to observe in the offspring?
1:2:0
If the allele encoding polydactyly (six fingers) is dominant why do most people have five fingers?
Genetic elements suppress the polydactyl gene.
The forked line and probability methods make use of what probability rule?
product rule
How many different offspring genotypes are expected in a trihybrid cross between parents heterozygous for all three traits when the traits behave in a dominant and recessive pattern? How many phenotypes?
27 genotypes; 8 phenotypes
Assuming no gene linkage, in a dihybrid cross of AABB x aabb with AaBb F1 heterozygotes, what is the ratio of the F1 gametes (AB, aB, Ab, ab) that will give rise to the F2 offspring?
1:1:1:1
epistasis
antagonistic interaction between genes such that one gene masks or interferes with the expression of another
hemizygous
presence of only one allele for a characteristic, as in X-linkage; hemizygosity makes descriptions of dominance and recessiveness irrelevant
law of dominance
in a heterozygote, one trait will conceal the presence of another trait for the same characteristic
law of independent assortment
genes do not influence each other with regard to sorting of alleles into gametes; every possible combination of alleles is equally likely to occur
law of segregation
paired unit factors (i.e., genes) segregate equally into gametes such that offspring have an equal likelihood of inheriting any combination of factors
product rule
probability of two independent events occurring simultaneously can be calculated by multiplying the individual probabilities of each event occurring alone
sum rule
probability of the occurrence of at least one of two mutually exclusive events is the sum of their individual probabilities
test cross
cross between a dominant expressing individual with an unknown genotype and a homozygous recessive individual; the offspring phenotypes indicate whether the unknown parent is heterozygous or homozygous for the dominant trait
blending theory of inheritance
hypothetical inheritance pattern in which parental traits are blended together in the offspring to produce an intermediate physical appearance
discontinuous variation
inheritance pattern in which traits are distinct and are transmitted independently of one another
Human papillomavirus can cause cervical cancer. The virus encodes E6, a protein that binds p53. Based on this fact and what you know about p53, what effect do you think E6 binding has on p53 activity?
E6 binding marks p53 for degradation
