BIOL 2170 Ch 11

A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely:

S phase

Synapsis is best described as:

the pairing of homologous chromosomes in prophase I

What is the function of histone proteins?

to package DNA in eukaryotic chromosomes

true or false: A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous.

true

true or false: An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.

true

true or false: The alignment of chromosomes at metaphase of meiosis II is most similar to the alignment of chromosomes during metaphase of mitosis.

true

true or false: There are no discernible phenotypic effects for an individual with the genotype XYY.

true

The protein p53 is an example of:

tumor suppressor

Proteins whose normal activities inhibit the cell cycle are:

tumor suppressors

Why don't plant cells use a contractile ring to divide their daughter cells?

a contractile ring can't "pinch" a cell wall

What type of protein is being activated by the G1 /S cyclin-CDK complex to promote the expression of histone genes?

a transcription factor

What protein forms the contractile ring during cytokinesis in animal cells?

actin

The development of cancer requires both the _____ of an oncogene and the _____ of a tumor suppressor.

activation: inhibition

During what step in meiosis do homologous chromosomes separate?

anaphase I

The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule?

away from the centrosome and toward the kinetochore

The process of cell division in a prokaryotic cell is called:

binary fission

The division of the cell's cytoplasm in a eukaryotic cell is known as:

cytokinesis

Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell.

cytokinesis does not occur

A zygote is:

diploid

During meiosis I:

diploid cells become haploid

true or false: Nondisjunction can only occur in the sex chromosomes and not the autosomes.

false

A phragmoplast functions to:

form a new cell wall

A human cell with a total of 23 chromosomes is:

haploid

If a human has the genotype XXXY, they would:

have 2 inactivated X chromosomes and be male.

First-division nondisjunction occurs when:

homologous pairs fail to separate during anaphase I.

What is the role of the protein FtsZ in prokaryotes?

it forms a ring at the site of constriction

Homologous chromosomes separate from each other in:

meiosis I

The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex?

microtubules

The division of genetic material in a eukaryotic cell is called:

mitosis

Nondisjunction results when:

pairs of chromosomes fail to separate during anaphase.

A woman has her genome sequenced and finds that she carries a mutation in p53. Will she develop cancer?

possibly, this mutation is likely to predispose her to developing certain types of cancer

In which phase of mitosis do chromosomes condense?

prophase

A gene associated with promoting normal cell division is called:

proto-oncogene

Genes that participate in cell growth and division, but do not cause cancer, are:

proto-oncogenes

Reproduction by mitotic cell division:

results in two daughter cells that are genetically identical.

Second-division nondisjunction occurs when:

sister chromatids fail to separate during anaphase II

Mitotic cell division is considered asexual because:

the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical

How would the loss of p53 activity affect a cell?

-The G1/S checkpoint would not be functional. -DNA damage could accumulate. -CDK activity would not be appropriately regulated.

What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?

-The sister chromatids would not separate. -The chromosome would not line up properly at metaphase. -One of the daughter cells would have an extra copy of that chromosome.

Cell division is regulated by:

-growth factor signals. -signals that indicate a sufficient size of the cell. -signals that indicate that DNA has been replicated. -signals about the nutritional status of the cell.

The second meiotic division resembles mitosis because:

-sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells. -the daughter cells have the same number of chromosomes as the parent cell. -spindle microtubules attach from opposite directions to the centromere of -each sister chromatid pair. chromosomes decondense during telophase II.

A cell that is not actively dividing is in what phase of the cell cycle?

G0

Meiosis _____ is sometimes called reductional division because _____.

I: the number of chromosomes is reduced by half

At the start of mitosis, how many sister chromatids are present in a human cell?

46

At which stage of the cell cycle could you see sister chromatids with a microscope?

M

Crossing over occurs during which step in meiosis?

Prophase I

Replication of DNA in a eukaryote occurs during which phase of the cell cycle?

S phase