Cell Division (1.6) Flashcards

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1
Q

What are the two types of cell division?

A

Mitosis: The division of the nucleus into two genetically identical daughter nuclei. Occurs in all cells.Miosis: Cell division for the production of gametes (sex cells). Occurs in the ovaries and testes.

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2
Q

The Cell Cycle

A

The series of events that take place in a cell leading to its division and replication. Includes mitosis and cell growth.

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3
Q

What stage precedes mitosis?

A

Interphase - DNA is present as uncondensed chromatin in a nucleus. Centrosomes and other organelles are duplicated.

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4
Q

First stage of mitosis

A

Prophase - DNA supercoils and condenses into chromosomes. Chromosomes are made up of genetically identical sister chromatids joined at a centromere. The nuclear membrane breaks down and dissolves.

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5
Q

Second stage of Mitosis

A

Metaphase - Microtubule spindle fibres from the centrosomes connect to the centromere of each chromosome causing the chromosomes to align along the centre of the cell.

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6
Q

Third stage of Mitosis

A

Anaphase - The chromosomes segregate, pulling the chromatids apart. Move to opposite poles of the cell.

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7
Q

Last stage of Mitosis

A

Telophase - Spindle fibres dissolve. Chromosomes decondense, nuclear membranes reform. Cytokinesis occurs, splitting the cell into two nuclei.

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8
Q

Stage after Mitosis

A

Cytokinesis - Division of the cytoplasm. The cell splits in two.

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9
Q

Cytokinesis differences in plant and animal cells

A

Animal cells don’t have a cell wall so in cytokinesis a cleavage furrow is formed instead of a cell plate.

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10
Q

Mitotic Index

A

Mitotic Index = number of cells in mitosis/total number of cells x 100

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11
Q

Stages of the Cell Cycle

A

G1 - Period of cell growth. Interphase begins. S - Period where the DNA is replicated (Interphase)G2 - Period after DNA has been replicated. (End of Interphase). Mitosis - Prophase, Metaphase, Anaphase, Telophase. Nuclear division.Cytokinesis - Cytoplasm divides, forming two separate cells.

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12
Q

What are Cyclins?

A

Cyclins are chemicals that signal the beginning and end of different stages in the cell cycle. They do this by undergoing periods of chemical synthesis and by activating cyclin-dependent kinases (CDKs) which control cell processes by phosphorylation.

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13
Q

Metastatic cancer

A

Where cancerous cells spread into other surrounding tissues and travel to other parts of the body, producing new tumours.

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14
Q

What is a tumour?

A

A tumour is a group of cells that has formed as a result of uncontrolled cell division and growth.

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15
Q

Oncogenes

A

Oncogenes code for proteins that promote cell growth and the cell cycle. When oncogenes mutate they become cancer causing as they accelerate cell division.

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16
Q

Tumour suppressor genes

A

Tumour suppressor genes code for proteins that promote cell apoptosis and repress the cell cycle. Their normal function prevents cancer so they are sometimes referred to as anti-oncogenes. If both copies in the cell fail to work, cancer may occur.