study guide ch 09 cell cycle

Name three reasons why cells divide

Cells divide for growth, for repair and maintenance of tissues, and for reproduction.

How is the genome organized in prokaryotes?

In prokaryotes, the genome is usually a single circular chromosome located in the nucleoid region, and the cell may also contain small extra pieces of DNA called plasmids.

How is the genome organized in eukaryotes?

In eukaryotes, the genome consists of multiple linear chromosomes that are located inside the nucleus and are wrapped around proteins called histones.

How do bacterial cells divide?

Bacterial cells divide by a process called binary fission, in which the DNA replicates and the cell splits into two identical cells.

What happens to bacterial chromosomes during division?

During bacterial cell division, the single chromosome replicates and the two copies move to opposite sides of the cell.

How is bacterial division different from eukaryotic division

Bacterial division is simpler and faster and does not involve a nucleus or mitosis, while eukaryotic cells divide using mitosis and a spindle apparatus.

What is a chromosome?

A chromosome is a structure made of DNA that carries genetic information.

What is chromatin?

Chromatin is the loose, uncoiled form of DNA found in the nucleus during interphase.

What is a chromatid?

A chromatid is one of the two identical halves of a duplicated chromosome.

What is a centromere?

A centromere is the region of a chromosome where the sister chromatids are attached.

What are somatic cells?

Somatic cells are body cells that contain two sets of chromosomes, also known as diploid cells.

What are gametes?

Gametes are sex cells, such as sperm and egg cells, that contain only one set of chromosomes and are haploid.

What is a kinetochore?

A kinetochore is a protein structure located at the centromere where spindle fibers attach during cell division.

What is the spindle?

The spindle is a structure made of microtubules that helps move chromosomes during cell division.

What is a centrosome?

A centrosome is a region in the cell that organizes the spindle fibers.

What is the metaphase plate?

The metaphase plate is the imaginary line in the middle of the cell where chromosomes line up during metaphase.

What are the stages of the cell cycle in order?

The stages of the cell cycle are interphase (G1, S, and G2), followed by mitosis, and then cytokinesis.

What happens during G1 phase?

During G1 phase, the cell grows and carries out its normal functions.

What happens during S phase?

During S phase, the cell replicates its DNA so that each chromosome consists of two sister chromatids.

What happens during G2 phase?

During G2 phase, the cell continues to grow and prepares for division.

What happens during prophase?

During prophase, the chromosomes condense, the spindle begins to form, and the nuclear envelope starts to break down.

What happens during prometaphase?

During prometaphase, the nuclear envelope breaks down completely and spindle fibers attach to the kinetochores of the chromosomes.

What happens during metaphase?

During metaphase, the chromosomes line up along the metaphase plate in the center of the cell.

What happens during anaphase?

During anaphase, the sister chromatids separate and are pulled to opposite sides of the cell.

What happens during telophase?

During telophase, two new nuclei form and the chromosomes begin to uncoil back into chromatin.

If a cell has 8 chromosomes, what will anaphase look like?

During anaphase, the sister chromatids separate so there are 16 chromosomes total, and 8 chromosomes move to each side of the cell.

How many chromosomes are in a human somatic cell?

A human somatic cell contains 46 chromosomes.

How many chromatids are present after DNA replication in a human cell?

After DNA replication, a human cell contains 92 chromatids because each chromosome consists of two sister chromatids.

How does cytokinesis occur in animal cells?

In animal cells, cytokinesis occurs when a cleavage furrow forms and pinches the cell into two daughter cells.

How does cytokinesis occur in plant cells?

In plant cells, cytokinesis occurs when a cell plate forms and develops into a new cell wall between the two daughter cells.

What regulates the cell cycle?

The cell cycle is regulated by signaling proteins and checkpoints that ensure each stage is completed correctly.

What are growth factors?

Growth factors are proteins that stimulate cells to grow and divide.

What are checkpoints?

Checkpoints are control points in the cell cycle that determine whether the cell is ready to proceed to the next stage.

What happens to cell cycle control in cancer cells?

In cancer cells, cell cycle control is lost because checkpoints fail, causing cells to divide uncontrollably.