Chapter 10 - Cell Division and Mitosis

The separation of duplicated chromosomes into two new nuclei is known as ____.

Mitosis

A somatic cell divides to form two genetically identical daughter cells during mitosis. Prior to mitosis, what must occur?

The cell must replicate its DNA.

At the conclusion of mitosis, each daughter cell has ____.

DNA identical to the parent cell.

If a diploid cell with 40 chromosomes undergoes meiosis, each daughter nucleus will have ____ chromosomes.

20

Loosely packed regions of DNA associated with histones are called ____.

Euchromatin

The tight packing of chromatin into visible chromosomes during nuclear division is due to links between which proteins?

H1 histone proteins

What is the role of nonhistone proteins in the nucleus?

To provide additional chromosomal structure.

A plant cell with three sets of chromosomes is ____.

Triploid

How many unique chromosomes does an organism with 4n = 32 have?

8

The first eukaryotic genome to be sequenced was that of ____.

Saccharomyces cerevisiae

At the conclusion of S phase, a diploid cell with 40 chromosomes will have ____ chromosomes and ____ sister chromatids.

40 chromosomes and 80 sister chromatids

If a cell has 36 chromosomes at the beginning of G1, how many will it have at the end of G2?

36

When chromatin condenses early in mitosis, what process becomes easier?

Orderly distribution of DNA into the two new nuclei.

Compared to the parent cell, each daughter cell from normal mitotic division contains ____ chromosomes and is genetically ____.

The same number; identical.

Where is the centromere found?

At the central region of a chromosome where spindle microtubules attach.

If a cell contains 84 sister chromatids at metaphase of mitosis, how many chromosomes will be present in each nucleus in late telophase?

42

The cells produced by mitotic divisions are considered to be ____ the original cell.

Clones of

Replication of DNA occurs during ____.

S phase

Once human nerve cells become mature, they normally exit the cell cycle and remain in ____.

G₀ phase

Generally, which phase of the cell cycle varies the most in length?

G₁ phase

Chromatin condenses into chromosomes and the mitotic spindle begins to form during ____.

Prophase

Chromosomes decondense into chromatin at which point in the cell cycle?

At the end of telophase

Chromosomes are condensed during which stage(s) of the cell cycle?

Throughout mitosis until late telophase

Which sequence of the cell cycle is correct?

Interphase → Prophase → Prometaphase → Metaphase → Anaphase → Telophase

During which phase(s) of mitosis are chromosomes composed of two sister chromatids?

Prophase, prometaphase, and metaphase

Identify the stage of mitosis shown in panel A.

Interphase

Identify the stage of mitosis shown in panel B.

Anaphase

Identify the stage of mitosis shown in panel C.

Prophase

Identify the stage of mitosis shown in panel D.

Telophase

Identify the stage of mitosis shown in panel E.

Metaphase

Karyotype analyses are performed on cells in which phase of mitosis?

Metaphase

Colchicine inhibits microtubule formation. Mitotic cells exposed to colchicine will be arrested at ____.

Metaphase

During which stage do microtubules disassemble, pulling chromatids to the ends of the spindle?

Anaphase

After four mitotic divisions of a zygote, how many cells will the embryo contain?

16

Cytokinesis typically begins during which stage of mitosis?

Telophase

In animal cells, cytokinesis occurs by the formation of a ____.

Cleavage furrow

In plant cells, cytokinesis occurs by the formation of a ____.

Cell plate

What is the main purpose of mitosis?

To divide the nucleus so that each daughter cell receives an identical set of chromosomes.

What happens during metaphase?

Chromosomes align at the metaphase plate.

What happens during anaphase?

Sister chromatids separate and move toward opposite poles.

What occurs during telophase?

Chromosomes decondense, new nuclear envelopes form, and the nucleolus reappears.

What happens during prometaphase?

The nuclear envelope disintegrates and spindle fibers attach to kinetochores.

Why are mitotic checkpoints important?

They ensure chromosomes are properly aligned and attached before division proceeds.

What is the spindle apparatus composed of?

Microtubules and associated proteins.

What is the role of motor proteins in mitosis?

They move chromosomes along microtubules and elongate the spindle.

At the end of mitosis and cytokinesis, each daughter cell has how much DNA compared to the parent cell?

The same amount.

The cell cycle is regulated primarily by which molecules?

Cyclins and cyclin-dependent kinases (Cdks).

What is the G₁/S checkpoint responsible for?

Ensuring the cell is ready for DNA replication.

What does the G₂/M checkpoint ensure?

That DNA replication has occurred correctly before mitosis begins.

What does the spindle checkpoint verify?

That all chromosomes are properly attached to spindle fibers before anaphase.

What happens if a cell fails a checkpoint?

It either pauses for repair or enters apoptosis (programmed cell death).

What is binary fission?

The process by which prokaryotic cells divide.

How does binary fission differ from mitosis?

It occurs in prokaryotes without the formation of a mitotic spindle.

Why is mitosis essential for multicellular organisms?

It allows growth, repair, and maintenance of tissues.