MItosis Flashcards

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1
Q

Define mitosis

A
  • type of nuclear division
  • production of 2 daughter nuclei, genetically identical to parent
  • same no. of chromosomes as parent nucleus
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2
Q

Chromosomes

A
  • rod-like structure
  • visible in nucleus during cell division
  • contains 1 DNA molecule that is highly coiled and condensed arnd histones
  • carries genes
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3
Q

Homologous chromosomes

A
  • exist pairs, one paternal, one maternal
  • same gene loci, centromere position, length
  • diff alleles
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4
Q

Gene

A
  • segment of DNA in a chromosome
  • where specific genetic (hereditary) info is stored
  • controls production of specific polypeptide/specific protein
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5
Q

Alleles

A
  • diff forms of same gene
  • occupy same relative positions on a pair homologous chromosome
  • letters used to represent alleles
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6
Q

The cell cycle

A
  • sequence of events frm when cell is formed till its division in to 2 daughter cells
  • 3 stages
  • interphase( resting stage), mitosis (nuclear division), cytokinesis (division of cytoplasm)
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7
Q

Interphase

A
  • resting/non-dividing stage
  • cells absorb nutrients
  • build up protoplasm
  • synthesis new organelles
  • replicate DNA
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8
Q

What happens in interphase

A
  • chromosomes appear as chromatin threads
  • chromatin threads replicate
  • centrioles replicate and divide (animal cells)
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9
Q

Why must DNA replication and mitosis be precisely controlled

A
  • ensures all daughter cells are genetically stable
  • error during replication, new DNA formed diff frm original
  • known as gene mutation and is passed to daughter cell
  • gene mutation lead to uncontrolled division of cells (cancer), may be fatal
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10
Q

Stages of mitosis (PMAT)

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
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11
Q

Early prophase

A
  • in animal cell, asters (short microtubules that grow out from centrioles) form arnd centrioles
  • 2 pairs of centrioles move apart to opp poles of cell
  • nucleolus disappears
  • chromatin condense, coil and shorten to become chromosomes
  • each chromosome, 2 sis chromatids attached to centromere (x-shaped)
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12
Q

DNA replication

A
  • chromatin threads replicate to produce 2 identical chromatin threads
  • chromatin threads coil and shorten to form chromosomes
  • each chromosome have 2 genetically identical DNA molecules (sis chromatids)
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13
Q

Late prophase

A
  • nuclear envelope breaks down

- spindle forms with spindle fibres, extending from one pole of cell to the other

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14
Q

Metaphase

A
  • line up singly along equator of spindle
  • spindle fibre attached to centromere
  • spindle fibres help to align chromosomes
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15
Q

Anaphase

A
  • each centromere divides
  • spindle fibres shorten pull sis chromatids to opp poles of the cell
  • once sis chromatids are separated, known as sis chromosomes
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16
Q

Telophase

A
  • spindle fibres disintegrates
  • nuclear envelope form arnd each set of chromosomes
  • a nucleolus forms inside each nucleus
  • chromosomes uncoil and lengthen into thread-like structures (chromatin)
17
Q

Cytokinesis

A
  • division of cytoplasm

- animal cells: furrows form, deepen and eventually divide cell into 2

18
Q

Mitosis in plants

A
  • centrioles absent
  • cleavage of cytoplasm dont occur,
  • cell plate form between 2 daughter nuclei (by fusion of fluid filled vesicles)
19
Q

Mitosis in animals

A
  • centrioles present

- cleavage of cytoplasm occur during cytokinesis (formation of furrows)

20
Q

Why is mitosis important?

A
  • growth
  • repair of worn-out parts of tissue, wound healing, replacement of dead cells
  • asexual reproduction in plants ie. development of shoots and roots in storage organs