Ch. 10, 11, 12 Flashcards by Max Richards

Meiosis usually produces how many daughter cells?

Four haploid

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At which stage of meiosis are sister chromatids seperated from each other?

Anaphase II

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The part of meiosis that is most similar to mitosis is..

Meiosis II

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If a muscle cell of a typical organism has 32 chromosomes, how many chromosomes will be in a gamete of that same organism?

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What is the genetic content of the two daughter cells in prophase II of meiosis?

two haploid cells with two copies of each gene

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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

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Crossing-over in meiosis occurs during..

prophase I

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When does crossing over occur in mitosis?

crossing over does not occur in mitosis

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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

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When does DNA synthesis occur in meiosis and mitosis?

In S part of interphase

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When do the homologous chromosomes line up in meiosis?

Metaphase II

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Meiosis is a type of cell division that produces…

gametes

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During which phase do chromosome first become visible?

prophase

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What structure is responsible for moving the chromosomes during mitosis?

spindle fibers

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Cytokinesis begins in which phase?

telophase

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The process of mitosis ensures that…

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A spindle forms during which phase?

prophase

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What can be determined from a karyotype?

the sex of the individual and the number of chromosomes present

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Compared to the X chromosome, the Y chromosome is…

smaller

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What are some external events that could cause a cell to divide?

death of other cells, horomones

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What happens when a cell gets too big?

It divides

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What is a gene that codes for a positive cell-cycle regulator called?

proto-oncogene

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What is the main prerequisite for clearance at the G2 checkpoint?

accurate and complete DNA replication has occured

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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?

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

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.

At this checkpoint, the cell checks if there are enough building blocks to duplicate the DNA and if the DNA is intact.

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