5. The Mitotic Cell Cycle Flashcards

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1
Q

State the components that make up a chromosome.

A

DNA
Histone proteins
Sister chromatids
Centromere
Telomeres

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2
Q

What is the significance of mitosis in respect to growth?

A

Growth is achieved by an increase in the number of cells in an organism. Mitosis helps to increase cell numbers, thus causing growth.

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3
Q

What is the importance of mitosis in respect to replacing cells?

A

Cell are constantly dying and need to be replaced by identical cells

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4
Q

What is a stem cell?

A

a relatively unspecialised cell that retains the ability to divide an unlimited number of times, and which has the potential to become a specialised cell (such as a blood cell or muscle cell)

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5
Q

What is a telomere?

A

A repetitive sequence of DNA at the end of a chromosome that protect genes from the chromosome shortening that happens at each cell division.

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6
Q

Define mitosis.

A

The division of a nucleus into two so that the two daughter cells have exactly the same number and type of chromosomes as the parent cell

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7
Q

Name the stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

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8
Q

What happens during the prophase?

A
  1. Chromosome condense become visible.
  2. Centrioles move to opposite poles of cell
  3. Nucleus disappears
  4. Phase ends with the breakdown of the nuclear membrane.
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9
Q

Outline the process of metaphase.

A
  1. Spindle fibers connect centrioles to chromosomes
  2. Chromosomes align along equator of cell and attaches to a spindle fiber by its centroomere.
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10
Q

Outline the process of anaphase?

A
  1. Centromeres split allowing chromatids to separate
  2. Chromatids move towards poles pulled by kinesin.
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11
Q

Outline the process of telophase

A
  1. Spindle fibers disperse
  2. Nuclear membranes form around each set of chromatids
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12
Q

Define a chromatid.

A

One of two identical parts of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.

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13
Q

What are the three phases of a cell cycle?

A

Interphase- G1, G2 and S phase
Mitosis
Cytokinesis

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14
Q

Describe what happens during G1 phase.

A

During G1, cells make the RNA, enzymes and other proteins needed for growth.

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15
Q

Describe what happens during G2

A

During G2, the cell continues to grow and the new DNA that was made during the S phase is checked. Any errors are usually repaired.

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16
Q

Define asexual reproduction

A

The production of new individuals of a species by a single parent organism

17
Q

What is the main function of telomeres?

A

To ensure that the ends of the molecule are included in the replication and not left out when DNA is replicated
*to prevent the loss of genes during cell division and to allow continued replication of a cell.

18
Q

What is potency?

A

The power of a stem cell to produce different types of cell

19
Q

Define the word cancers

A

A group of diseases that result from a breakdown in the usual control mechanisms that regulate cell division; certain cells divide uncontrollably and form tumors, from which cells may break away and form secondary tumors in other areas of the body (metastasis)

20
Q

What is a mutation?

A

A random change in the base sequence of DNA or in the structure of chromosomes

21
Q

What is a carcinogen?

A

A substance or environmental factor that can cause cancer

22
Q

Difference between malignant and benign tumors

A

Benign are tumors that do not spread from their site of origin and are not cancerous.
Malignant tumors spread though the body, invading and destroying other tissues.

23
Q

What are totipotent cells

A

Stem cells that can produce any type of cell

24
Q

What are histones and what do they do?

A

Organize and condense the DNA tightly so it fits in the nucleus.

25
Q

Why are stem cells important?

A

-required to replace old cells
-produce new specialized cells when necessary

26
Q

Totipotent cells

A

These stem cells can divide and produce any type of body cell.

27
Q

Pluripotent stem cell

A

These stem cells are found in embryos and can become almost any type of cell.
Can be used to regrow damaged cells in humans

28
Q

Multipoint stem cells

A

Adult stem cells that are mature and can divide to form a limited number of different cell types

29
Q

Describe the role of spindle fibers during mitosis

A

Attaches to the centromeres
Arranges the chromosomes on the equator
Pulls chromosomes apart to the poles