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Bioleg > 1.6 The Cell Cycle And Cell Division > Flashcards

1.6 The Cell Cycle And Cell Division Flashcards

1
Q

What is the two type of chromosome numbers ?

A

Haploid and diploid

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2
Q

What is a haploid number ?

A

One complete set of chromosomes (n)

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3
Q

What is a diploid number

A

Two complete sets of chromosome (2n)

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4
Q

What are the three phases in the cell cycle ?

A

Interphase
Mitosis
Cytokinesis

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5
Q

What happens in the interphase

A
  1. Organelle replication
  2. DNA replicates - quantity doubles
  3. Proteins and enzymes synthesised
  4. Cell increases inside - atp synthesis
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6
Q

What is the 4(6) stages of mitosis

A

(Interphase)
Prophase
Metaphase
Anaphase
Telophase
(Cytokinesis)

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7
Q

What happens in the prophase ?

A
  1. Chromosomes condense ( pairs of chromatids)
  2. Centrioles move (animal cells)
  3. Microtubules form
  4. Spindle fibres extended from pole to pole
  5. Nuclear envelopes disintegrates + nucleolus disappears
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8
Q

What happens in the metaphase

A
  1. Chromosomes attach to spindle fibres at centromere
    2.align on equator
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9
Q

What happens in anaphase

A
  1. Rapid stage
  2. Centromeres separate
  3. Spindle fibres shorten
  4. Separated chromatids are pulled to poles, centromeres first
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10
Q

What happens in telophase

A
  1. Final stage
  2. Chromatids reach poles (referred to as chromosomes)
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11
Q

Reverse of phrophase changes ?

A
  1. Chromosomes uncoil and lengthen
  2. Spindle fibres break down
  3. Nuclear envelopes reforms
  4. Nucleolus reappears
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12
Q

What happens in cytokinesis during mitosis

A
  1. Division of the cytoplasm
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13
Q

What is the change in shape in animal cells after mitosis

A

Cell becomes more round after mitosis

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14
Q

Are centrioles present in animal and plant cells ?

A

Present in animal not in plant

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15
Q

What is the difference in cytokinesis phase between animal and plant cells

A

In animal cells, cleavage furrow develops from the outside inwards

In plant cells, cell plate develops from the center outwards

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16
Q

What are the three significance of mitosis

A
  1. Chromosome number (remains the same) 2x daughter cells genetically identical to parent greater genetic ability
  2. Growth and repair
  3. Asexual reproduction
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17
Q

What is proto-oncogenes

A

A gene that does not cause cancer (can become an oncogene if altered by mutation or virus)

18
Q

What is oncogenes

A

A gene with a potential to cause cancer

19
Q

Terminology for labelling a homologous pair

A

Chromosome
Chromatid
Centromere
Homologous pair

20
Q

What happens in meiosis

A
  1. Chromosomes duplicate
  2. Homologous chromosomes separate
  3. Sister chromosomes separate
21
Q

What is the 5 phases of meiosis 1

A

Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Cytokinesis

22
Q

What is a haploid

A

Containing a single set of chromosomes

23
Q

What is a gamete

24
Q

What is a zygote

A

The result of the fusion of a sperm and an egg

25
Q

Where does Meiosis take place

A

Takes place in reproductive organs

26
Q

What happens in meiosis 1

A

Homologous pairs separate. Each daughter cells has half the initial number of chromosomes but each chromosome compromises two chromatids

27
Q

What happens in meiosis 2

A

Chromatids separate. Each daughter cells genetically identical has half the initial number of chromosomes, each with only one chromatid

28
Q

What happens in meiosis - prophase 1

A
  1. Chromosomes condense - visible as two chromatids
  2. Centrioles separate (animals) - move to poles
  3. Polymerisation of microtubules and spindle forms
  4. Homologous chromosomes associate in pairs - bivalent
  5. Crossing over
29
Q

What happens in meiosis - metaphase 1

A
  1. Pairs of homologous chromosomes arrange themselves either side of equator
  2. Independent assortment
30
Q

What is independent assortment

A

Either of a pair of homologous chromosomes moves to either pole at anaphase 1 of meiosis, independently of the chromosomes of other homologous pairs

31
Q

What happens in meiosis - anaphase 1

A
  1. Spindle fibres shorten
  2. Homologous chromosomes separate
  3. One pulled to each pole
  4. At each pole random mixture of maternal and paternal chromosomes
32
Q

What happens in meiosis - telophase 1

A
  • some species - nuclear envelope reforms,
    female mammals
    nuclear envelope reforms, long time between meiosis 1 and meiosis 2
  • many species - chromosomes stay condensed,
    Male mammals
    Meiosis 2 follows meiosis 1 rapidly ( no telophase 1 or interphase )
33
Q

What happens during cytokinesis in meiosis 1

A

Division of cytoplasm
= 2 haploid cells

34
Q

What are the 4 stages of meiosis 2

A

Prophase 2
Metaphase 2
Anaphase 2
Telophase 2

35
Q

What happens in meiosis - prophase 2

A
  1. Centrioles separate
  2. Organise new spindle at right angles to old spindle
36
Q

What happens during meiosis - metaphase 2

A
  1. Chromosomes line up on equator
  2. Each chromosomes attached to spindle fibre by its centromere
  3. Independent assortment - chromatids of chromosomes face either pole
37
Q

What happens in meiosis - anaphase 2

A
  1. Centromeres divide
  2. Spindle fibres shorten
  3. Chromatids pulled to opposite poles
38
Q

What happens in meiosis - telophase 2

A
  1. Chromatids lengthen
  2. Spindle disintegrates
  3. Nuclear envelope reforms
  4. Nucleoli re-form
39
Q

What happens in cytokinesis during meiosis 2

A

Produced 4 haploid daughter cells

40
Q

What is the significance of meiosis

A
  1. Keeps chromosome number constant from one generation to next
  2. Generates genetic variation in gametes - crossing over and independent assertion
  3. Variation - important for survival or species

Bioleg (8 decks)

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