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Biology A level > Mitosis and Meiosis tonight > Flashcards

Mitosis and Meiosis tonight Flashcards

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1
Q

mitosis vs meiosis key points

A

mitosis vs meiosis
1 division vs 2 division
daughter cells genetically identical vs genetically different
2 cells produced vs 4 cells produced
diploid to diploid/ haploid to haploid vs diploid to haploid
Same number of chromosomes vs half the number of chromosomes
meiosis only - separation of homologous chromosomes
crossing over
indenpendent segregation

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2
Q

meiosis def

A

produces daughter cells that are genetically different from each other

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3
Q

independent assortment/ segregation

A

alleles of 2 to more diff gene get sorted into gametes independently of one another

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4
Q

compare and contrast mitosis and meisois (6marks)

A

both - PMAT (phrophase, metaphase, anaphase, telophase)
- contraction of spindle fibres seperates chromatids or chromsomes
- chromosomes line up at equator of cell and there is movement towards poles
- process ends with cytokinesis/ new cell is produced
- DNA must be copied during interphase

Mitosis
- genetically identical daughter cells
- individual chromosomes line up at equatoe in metaphase
- no idependent segregation
- no bivalents and crossing over
- diploid cells produced
- 2 daughter cells

Meiosis
- genetically different daughter cells
- homologous pairs line up at equator in metaphase 1
- independent segregation of homologous chromosomes
- Bivalents form- crossing over occurs
- Haploid cells produced
- 4 daughter cells

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5
Q

Describe and explain the arrangement of genetic material in prophase:

A

1- Chromosomes visible
2- still condensing
3- chromosomes arranged randomly/ not lined up
4- Because no spindles

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6
Q

Meiosis key words (6marker)

A

A
2- divisions - meiosis 1, meios 2

DNA Replication in late interphase

Seperation of homologous chromosoemes - 1st division

Seperation of sister chromatids - 2nd division

produce 4 haploid cells

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7
Q

cell cycle

A

the process of interphase, mitosis and cytokinesis

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8
Q

Prophase

A

The chromosomes thicken and condense, becoming visible. The nuclear envelope breaks down

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9
Q

Metaphase

A

The chromosomes align in the centre of the cell. Spindle fibres begin to attach to each sister chromatid

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10
Q

Anaphase

A

The sister chromatids are pulled apart to opposite poles of the cell. The centromeres divide in two and move to opposite poles of the cell, pulled by microtubules

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11
Q

Telophase

A

The start of the cell division where the spindle fibres disintergrate and the nucleolus reforms

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12
Q

Cytokinesis

A

The process by which the cell splits into two at the end of mitosis, forming a new nuclear envelope and plasma membrane
(dividing cytoplasm follows nuclear division)

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13
Q

Chromatid

A

Half a chromosome

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14
Q

Homologous Chromosomes

A

Identical chromosome

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15
Q

Centromere

A

The central region of a chromosome that holds the two chromatids together

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16
Q

Mitosis

A

The process that produces two daughter cells and have the same number of chromosomes as the parent cell

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17
Q

binary fusion

A

The process of cell division in prokaryotic cell

18
Q

First Stage of Binary Fission

A

The circular DNA replicates, both copies attach to the cell membrane. The plasmid also replicates

19
Q

Second Stage of Binary Fission

A

The cell membrane grows between the replicated DNA and begins to pinch inwards which splits the cytoplasm in two. The new cell wall forms, forming the complete daughter cells (identical)
each with single copy of circular DNA and variable copies of plasmids

20
Q

The Importance of Mitosis

A

Used for growth, repair and reproduction

21
Q

Outline prophase

A

Chromosomes become more visible, thicken.
2. Centrioles move to opposite ends of the cell (poles).
3. Spindle fibres develop from each of the centrioles (spindle apparatus).

22
Q

Outline Interphase

A

Precedes Mitosis

  1. Cell is not dividing.
  2. Considerable cellular activity - replication of DNA, two copies on centromere.
23
Q

Outline Metaphase

A

centrosomes reach opposite poles
1. Chromosomes seen to be made up of two chromatids.
2. Microtubules attach to centromere - chromosomes pulled to the cell equator where they line up.
spindle fibres extend from centrosomes

24
Q

Outline Anaphase

A
  1. Centromeres divide, separating each pair of sister chromatids.
  2. Chromatids pulled to their respective poles as spindles contract, centromeres first - v-shaped. (now called chromosomes)
25
Q

Outline Telophase

A
  1. Chromosomes reach their respective poles and then uncoil, become long and thin again - chromosomes again.
  2. Spindle fibres disintegrate; nuclear envelope and nucleolus reform.
  3. Cytoplasm divides in cytokinesis.
26
Q

Outline the process of Binary Fission

A

How prokaryotic cells divide:

  1. Circular DNA molecule replicates, and both copies attach to the cell membrane.
  2. Plasmids also replicate.
  3. Cell membrane begins to grow between the two DNA molecules and begins to pinch inwards - dividing cytoplasm in two.
  4. New cell wall forms between the DNA molecules, dividing the original cell into two identical daughter cells - each with a copy of the circular DNA and a variable number of copies of the plasmids.
27
Q

Outline how viruses replicate
Acellular, non-living, so do not undergo cell division.

A
  1. Attach to host cell with the attachment proteins on their surface.
  2. Inject nucleic acid into host cell.
  3. Viral nucleic acid then hijacks the cell’s machinery and codes for metabolic processes to produce viral components - nucleic acid, enzymes, structural proteins, which are then assembled into new viruses.
28
Q

Crossing over

A

between homologous pairs
- chromatid break during mitosis and reform to the chromatid of its homologous chromosome so that its alleles are exchanged

29
Q

what creates genetic variation in daughter cells

A

crossing over in late prophase 1 and independent segregation of chromatids in anaphase 11

30
Q

what is independent segregation

A

segregation of chromosomes
- alleles of 2 or more diff genes get sorted into gametes independent of one another
- homologous chromosomes line up in random orientation

31
Q

meisois stages

A

x2 stages

32
Q

meiosis reproduction

A

sexual

33
Q

mitosis produces

A

produces genetically identical parent cells
- same number of chromosomes as parent cells

34
Q

cell division in prokaryotic cells …

A

binary fusion

35
Q

cell division in eukaryotic cells..

A

mitosis and meiosis

36
Q

cytokenesis key points

A

forms two genetically identical daughter cells
animal:
contractile ring and cleavage furrow
plant:
cell plate formed

37
Q

cell cycle x3 stages

A

interphase
nuclear divison
cytokinesis

38
Q

cancer cells

A

uncontrolled cell division
- damage to the genes that regulate mitosis and cell cycle

39
Q

eukaryotic cells process

A

cell cycle

40
Q

mitosis is a

A

controlled process

41
Q

interphase processes

A

no division occurs
x3 stages
DNA replication

42
Q

x3 stages of interphase

A

g1 phase: cell growth, signal received for cell to divide
s phase: synthesis of DNA
g2 phase- further cell growth, error checking of newly synthesised DNA

Biology A level (23 decks)

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