Biology Ch. 8

A human somatic cell contains ________ chromosomes

46

Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell?

92

a human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. There are...

92 chromatids

A cell replicates its entire chromosomal DNA only...

before it is about to divide

asexual and sexual reproduction differ in that sexual reproduction...

can produce great variation among the offspring

meiosis differs from mitosis in that _______ only occurs in meiosis

crossing over

chromatids are...

identical copies of each other if they are part of the same chromosome

during binary fission , one copy of the duplicating chromosome moves to the opposite end of the cell. What does this achieve?

it ensures that each daughter cell receives one copy of the chromosome

DNA replication occurs in...

the S phase of interphase

One event occurring during prophase is _____.

the beginning of the formation of the mitotic spindle

crossing over is...

the exchange of homologous portions of nonsister chromatids

Individual chromosomes are usually observed with a light microscope during mitosis , even though cells spend more time in interphase. This is because....

they have uncoiled to form long thin strands

Benign tumors differ from malignant tumors in that the cells of a benign tumor...

remain confined to their original site

immune system cells enter a resting phase after undergoing mitosis. When activated-for example, by an infection- they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct sequence of events?

G1, S, G2, M

A fragment of chromosome 21 reattaches to chromosome 21 but in the reverse direction. What is the name given to this change?

Inversion

During cell division, what role do centrosomes play?

They organize the microtubules.

Asexual reproduction...

produces offspring genetically identical to the parent

The term binary fission is best applied to...

prokaryotes

At which point do centrosomes begin to move apart to the opposite poles of the cell in a dividing human liver cell?

prophase

in the telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in...

prophase

Which of the following shows mitosis in the correct chronological order?

prophase, prometaphas, metaphase, anaphase, telophase