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CELS 191 > Mitosis and meiosis > Flashcards

Mitosis and meiosis Flashcards

1
Q

Impact of application of genetics to society (6)

A
  • Agriculture (crop improvement)
  • Medicine (can scan genetic info to know about disorder than may come later in life)
  • Law (stopping immigrants from coming in)
  • Sociology
  • Philosophy
  • Ecology
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2
Q

Organisms and genetic information storing (acellular, prokaryotic, eukaryotic)

A

Acellular (viruses) - ds or ss DNA or RNA
Prokaryotic (bacteria) - circular, single copy, naked ds DNA
Eukaryotic (animal, plants, fungi, protists) - linear, many copies of histone-bound DNA (not naked)
Sexual cycle - resulting in mixing of DNA from 2 parents in each generation

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3
Q

Human DNA (storage and number of chromosomes)

A

Stored in chromosomes

23 pairs - 22 pairs of autosomes and a pair of sex chromosomes

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4
Q

What does X,X code for

A

female

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5
Q

What does X,Y code for

A

male

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6
Q

What does multicellular organisms depend on cell division for (3)

A

Development form a fertilised cell
Growth to adult
Repair

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7
Q

Define cell cycle and its 2 major phases

A

Cell cycle is the lifetime of the cell, depends on the type of cell
Interphase and mitotic phase

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8
Q

Describe interphase and explain the 3 different phases within it

A

Interphase occurs in between different mitotic stages - it prepares cell for division. Most of the time, the cells are in some part of the interphase

  1. G1 - all the organelles and cytoplasmic components replicates. Cell grows in size. synthesis mRNA and proteins
  2. S phase - DNA replication/synthesis occurs. By the end of S phase, each chromosome has been duplicated, containing 2 chromatids. Amount of DNA has been doubled
  3. G2 - all the enzymes required in cell division are produced
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9
Q

Phases of mitosis

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase (and cytokinesis)
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10
Q

At G2 stage of interphase, what does the cell contain

A 
Duplicated chromatin
Centromeres (with centriole pairs)
Nucleolus
Nuclear envelope
Plasma membrane
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11
Q

What phase does the chromosome become visible

A

prophase

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12
Q

First phase of mitosis (4)

A

Prophase

  • Nuclear envelope breaks down
  • chromosomes start to condense
  • Nuclear membrane starts to break down
  • Aster form around centrosome and aster-covered centrosomes migrate towards opposites of the nucleus in preparation for mitotic spindle formation
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13
Q

Second phase of mitosis (3)

A

Prometaphase

  • The point where spindle fibres grow out of centrioles to the equator of the cell
  • Asters are on complete opposite sides of the cell but are connected by microtubules
  • begin pushing chromosomes to centre of cell
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14
Q

Third phase of mitosis

A

Metaphase

- Alignment of chromosomes on the metaphase plate (equator of cell - imaginary) due to growth of spindle fibre

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15
Q

Fourth phase of mitosis

A

Anaphase

  • Kinetochore microtubules connected to the chromosomes shortens and pulls the sister chromatids apart
  • Non-kinetochore microtubules lengthen at the same time causing centrosomes to be further apart and splitting the centromeres
  • One pole gets one identical copy of each sister chromatid and now called chromosomes
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16
Q

Fifth/last phase of mitosis + cytokinesis

A 
Telophase
- Re-formation of nuclear membrane
- Chromosomes de-condense
- spindle fibres break 
- nucleus forming
- cleavage furrow begins to form in the centre of the cell made from constricting belt of actin filament surrounding the inside of the cell circumference 
- cytoplasm begins to separate
Cytokinesis
Separation into 2 cells
17
Q

Checkpoints

A

During the cell cycle, certain checkpoints are encountered to make sure the process is occurring accurately

18
Q

3 checkpoints

A

G1/S checkpoint - primary checkpoint at which the cell continues or stops. External signals and growth factors can influence the cell cycle and affect the progress at or before this critical checkpoint
G2/M checkpoint - allows cells that have successfully completed all 3 phases of interphase to begin mitosis
Spindle checkpoint - ensuring that all chromosomes have attached to the spindle in preparation in anaphase
Once all checkpoints in interphase are cleared, mitosis can occur

19
Q

What are the factors in cell cycle regulation that ensues only certain cells divide at certain times

A

Growth factors, the size of cell and the nutritional state of the cell

20
Q

Cell division rate

A 
Skin cells = high cell division rate due to wear and tear
Other cells (Eg. adult neurons and muscle cells) = low cell division rate
21
Q

Importance of mitosis accuracy and consistency of checkpoints during interphase

A

Ensures that most cells in an eukaryotic organism can produce identical copies of themselves

22
Q

how do single-celled organisms reproduce

A

by binary fission

23
Q

Mitosis vs. meiosis (number of replication and products)

A

Mitosis undergoes 1 replication to form 2 identical daughter cells
Meiosis undergoes 2 replications to produce 4 different cells with half the number of chromosomes

24
Q

What phase occurs before meiosis I

A

Interphase (same as mitosis)

- duplication of chromosomes to produce 4 sets of chromosomes

25
Q

Meiosis I - purpose

A

separates homologous chromosomes

26
Q

Prophase I of Meiosis I (3) - difference to mitosis (3)

A

Chromosomes condense and become visible
Nuclear membrane breaks down/disintegrate
Centromeres moving apart from each other forming spindles
Difference to mitosis
- homologous pairs of chromosomes come together and crossing-over occurs
- Formation of chiasmata where crossing-over occurs between non-sister chromatids
- crossing over occurs away from centromere towards the end of chromosomes

27
Q

Metaphase I of meiosis (2)- difference to mitosis (1)

A
  • Homologous pairs and chiasmata line up on the metaphase plate
  • Pairs of homologous chromosomes attach to kinetochore microtubules through centromeres
    Difference to mitosis
  • Homologous pairs align on metaphase plate in meiosis whereas individual chromosomes line up in mitosis
28
Q

Anaphase I of meiosis (1) - difference to mitosis (1)

A
  • kinetochore microtubules shorten to pull each homologous pair to each pole
    difference to mitosis
  • In meiosis, the sister chromatids remain attached resulting in homologous paris being pulled to each pole, whereas in mitosis, the sister chromatids are being pulled to each pole
29
Q

Telophase I & cytokinesis (4) - difference to mitosis (1)

A

The following does not go to completion
- Reformation of nuclear envelope
- Chromosomes de-condense
- Spindle fibres break
Cleavage furrow formation and cell divides to form 2 cells
Difference to mitosis
- In meiosis, the daughter cells produced here will have 1 copy of the each of the homologues chromosomes and are NOT IDENTICAL. In mitosis, the daughter cells produced are IDENTICAL

30
Q

Meiosis II - purpose

A

separate sister chromatids (Same as mitosis)

31
Q

Prophase II

A

2 centrosomes connected by spindle in each of the daughter cells

32
Q

Metaphase II

A

Sister chromatids connected by kinetochore microtubules and align at metaphase plate

33
Q

Anaphase II

A

Spindle fibres pull apart the sister chromatids

  • kinetochore microtubules shorten and drag the sister chromatids via the centromere
  • Non-kinetochore microtubules lengthen
34
Q

Telophase II & cytokinesis

A
  • cleavage furrow forms

- produces 4 haploid daughter cells with 1 copy of each of the chromosomes needed

35
Q

Importance of variation/sex (3)

A

Changing environments
Spatially variable environments
Reducing sibling-sibling competition for better use of resources

CELS 191 (8 decks)

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