Chapter 8

What is the term used to describe duplicated chromosomes?

sister chromatids

what structure, that helps chromosomes move, forms during prophase?

spindle

During which phase of mitosis does the nuclear envelope reform and the nucleolus reappear?

telophase

What is cytokensis?

Differs for animal and plant cells, the cell plate in plant cell forms which the plasma membrane and cell wall develops

What do animals need to complete cytokinesis?

A cleavage furrow superate the cytoplasm until there are two independent daughter cells

What is cytokinesis?

A division of the cytoplasm

Distinguish between a sister chromatid and a chromosome.

Before cell division the chromosomes are duplicated to produce two sister chromatids, each of which are held together at a centromere. Each chromatid is identical to the other.

What is uncontrolled cell division known as?

Cancer

What is metastasis?

Cause of cancer to spread throughout the body

What structure gives rise to new plant cell walls?

Cell plate

Explain the significance of checkpoints in the cell cycle.

Checkpoints regulate the cell cycle by ensuring that each step is completed correctly before the next step begins.

What holds chromosomes together?

Chromatin

What is prophase?

Chromosomes are condensing, each consistent of two sister chromatids held together at a centromere

What occurs during the S stage of interphase?

Chromosomes are duplicated

How is DNA packaged?

DNA and its associated proteins are packaged into chromosomes to make cell division easier and allow for the distribution of DNA to the daughter cells

Compare and contrast what is occurring during each phase of interphase: G1, S, and G2.

During interphase the cell is performing its normal functions. In the G1phase organelles are duplicated. During S phase DNA is duplicated, and in G2 growth occurs and proteins are synthesized that are needed for cell division.

When does nuclear division occur?

During mitosis

list the four stages of the cell cycle

G1, S, G2, M

What happens in interphase?

G1. growth occurs as organelles double S. synthesis-DNA replication occurs as chromosomes duplicate G2. Growth occurs as cell prepares to divide

What is apoptosis? What is it used for?

Helps keep number of cells at appropriate level and prevents an abnormal cell from forming a tumor

Predict what might happen to an organism if apoptosis were not regulated.

If apoptosis were not regulated the balance between controlled cell death and the cell cycle would be disrupted. Normal cell levels would be altered.

What do plants need to complete cytokinesis?

In plant cells, a cell plate forms from which the plasma membrane and cell walls develop.

What are kinases and cyclins?

Internal signals that promote either DNA replication or mitosis

In which phase of the cell cycle do cells spend most of their time?

Interphase

What is the name for the period of time when a cell is a performing its usual functions and replicating DNA?

Interphase

What is the order of mitosis?

Prophase, Metaphase, Anaphase, Telophase

Contrast the activity of proto-oncogenes with that of tumor suppressor genes.

Proto-oncogenes code for proteins that promote the cell cycle and inhibit apoptosis. Tumor suppressor genes code for proteins that inhibit the cell cycle and promote apoptosis. Mutations in these genes can lead to unregulated cell growth.

Explain why cellular reproduction is necessary for life?

Single-celled organisms divide in order to reproduce. Multicellular organisms must undergo cellular reproduction in order to develop from a single cell. Mature organisms need to replenish worn-out cells and repair injuries.

Summarize how chromosomal influences, such as telomeres and translocations, may cause cancer.

Teleomere shortening regulates cell division by limiting the number of times a cell can divide. Without it cells continue to divide indefinitely. Rearrangement of segments of chromosomes results in translocations which can disrupt genes that regulate the cell cycle. This can lead to cancer.

What are the ends of chromosomes called?

Telomeres

Explain the importance of the cell cycle.

The cell cycle is an orderly set of steps with checkpoints that is followed when cells duplicate. It ensures accuracy of the process.

Explain why cytokinesis is different in plants and animals

The cleavage furrow formed in animal cells between the two daughter nuclei contracts until the two daughter cells separate. In plants the rigid cell wall does not permit cytokinesis by furrowing. Instead the cell builds a new plasma membrane and cell wall between the two daughter cells.

What is angiogenesis?

The development of blood vessels that supply oxygen and nutrients to a tumor, allowing It to enlarge

If asters are observed in cells undergoing mitosis, are the cells animal or plant cells?

animal

why is it necessary for chromosomes to duplicate before mitosis?

because mitosis produces two daughter cells with an exact copy of each chromosome, the parent cell must duplicate the chromosomes before division in order to provide each daughter cell a copy.

list several parts of body where you would expect to find actively dividing cells and several parts where you would find mostly resting cells.

cells in your skin and intestinal linings would be dividing actively. cells in your brain or liver would not be dividing very actively

When are organelles divided up between daughter cells?

cytokinesis

why is it important for sister chromatids to be attached to each other during the beginning phase of mitosis?

each daughter cell must receive only one copy of each chromosome. being attached allows chromatids to stay organizes before being divided between daughter cells

Why do organisms perform mitosis?

growth and repair, to create cells with the same number of chromosomes

When do chromosomes align at the equator of the spindle?

metaphase

What is metaphase?

the chromosomes are aligned at the spindle equator in the middle between the spindle poles\

What is anaphase?

the sister chromatids separate and become daughter chromosomes. each pole receives a set of daughter chromosomes

What is telophase?

the spindle disappears as a new nuclear envelope form around the daughter chromosomes.

What happens to sister chromatids during anaphase of mitosis?

they move to opposite poles