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Biology > Chapter 9 SAC > Flashcards

Chapter 9 SAC Flashcards

1
Q

homologous pairs

A

chromosomes that are derived from each parent

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2
Q

homologous pairs of chromosomes are organized according to

A
  • size of autosome
  • position of the centromere
  • the sex chromoosme
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3
Q

Autosomes

A

chromosomes other than sex chromosomes (44 in humans,22 pairs)

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4
Q

Somatic cells

A

diploid body cells where sex chromosomes are found

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5
Q

Mitosis

A

nuclear Division of cells in eukaryotes for growth + repair

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6
Q

Prophase

A
  • chromosomes are already duplicated
  • centrioles move to opposite pole of cell
  • chromosomes become more visible
  • nuclear membrane disintegreates
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7
Q

Metaphase

A
  • spindle fibres attach to chromosomes

- chromosome lines up along the equator

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8
Q

Anaphase

A

chromatids are pulled apart by spindle fibres, forming 2 sets of chromosomes

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9
Q

Telophase

A

nuclear membrane forms around the new sets of chromosomes

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10
Q

cytokinesis

A

division of cytoplasm that follows mitosis

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11
Q

Inputs of Mitosis

A

1 diploid cell - 2 sets of chromosomes

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12
Q

Output of mitosis

A

2 diploid daughter cells - genetically identical to parent

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13
Q

Process overview of mitosis

A
  • DNA replicates + chromatids separate = nuclear division
  • Cytokineses = cytoplasmsic division
  • Only 1 nuclear division
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14
Q

Why is the root tip often used in mitosis?

A

as it is still growing, therefore still cell division

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15
Q

Advantages of Asexual reproduction

A
  • if the conditions are suitable + stable in a not changing environment,, the organism can produce many genetically identical offspring
  • doesn’t need a mate
  • well suited to environment
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16
Q

Disadvantages of Sexual reproduction

A

if the environmental condition changes, then the whole species will be come extinct, as all genetically identical

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17
Q

3 main parts of the Cell Cycle

A
  1. Interphase = G1,2,G2
  2. Mitosis = nuclear division
  3. Cytokinesis = cytoplsmic division
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18
Q

Gap 1?

A
  • cell growth
  • cell is functioning
  • producing proteins which some will be enzymes of DNA replication
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19
Q

Synthesis

A

DNA replication occurs here in readiness for mitosis

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20
Q

Gap 2

A
  • continued cell growth

- producing proteins necessary for mitosis

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21
Q

What happens when there is a problem after DNA replication?

A

the check point G2 would detect the problem, then the DNA maybe repaired or undergo apoptosis of the cell

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22
Q

What happens when check points don’t function properly?

A

the faulty cell may continue to divide which leads to cancers

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23
Q

Apoptosis

A

programmed cell death for the benefit of the whole organism, as it saves energy and resources

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24
Q

Meiosis

A 
call reproduction (division) for the production of gametes needed for sexual reproduction
- can also be called reduction division, as the no. of chromosomes in the daughter cells is half of the chromosomes in the original parent diploid cell
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25
Q

Sexual reproduction

A

requires cell division celled meiosis and it only occurs in specialized diploid cells found in gonads (testes and ovaries)

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26
Q

Why is it important or the gametes to be haploid in meiosis

A

so that the diploid chromosome number can be restored at fertilization
eg. 23 chromosomes in each gamete, therefore, 46 chromosomes in zygote resulting human

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27
Q

Meiosis 1

A

lining up of homologous pairs and crossing over occurs in prophase 1

28
Q

Crossing over

A

In prophase 1, homologous pairs can exchange genetic material resulting in a genetical variety in gamete

29
Q

Synapsis

A

pairing of homologous chromosomes

30
Q

Chiasma

A

point of exchange of genetic material between homologous pairs

31
Q

Independent assortment of chromosomes

A

homologous pairs separate, 2 cells produce

  • the separation of one homologous has no influence on the separation of another homologous pair, resulting in the mixing of m +p chromosomes
    ie. more genetic variety in gamete
32
Q

Independent assortment of homologous pairs of chromosomes

A

occurs in meiosis 1

33
Q

Independent assortment of homologous pairs of chromatids

A

occurs in meiosis 2 when the chromatids are separating

34
Q

Meiosis 2

A

chromatids separate, 2 cells produced from each cell from meiosis 1, total of 4 haploid daughter cells that are genetically different from each other and parent cells.

35
Q

Purpose of Mitosis

A

to make daughter cells identical to the parent cells for growth and repair

36
Q

Purpose of Meiosis

A

to produce sex cell (gametes)

37
Q

Where does mitosis take place?

A

in all cells apart from gametes

38
Q

Where does meiosis take place?

A

in the ovaries and testes

39
Q

How many cells does mitosis produce?

A

2 daughter cells

40
Q

how many cells does meiosis produce?

A

4 gametes

41
Q

What happens to the number of chromosomes in mitosis?

A

same number as parent cell

42
Q

What happens to the number of chromosomes in meiosis ?

A

half as many as in parent cell

43
Q

How do parent and daughter cells differ genetically in mitosis?

A

not at all, identical to parent

44
Q

How do parent and daughter cells differ genetically in meiosis?

A

contain a mixture of chromosomes from 2 parent gametes

45
Q

Is there a variation between daughter cells in mitosis?

A

no, they’re clones

46
Q

Is there a variation between daughter cells in meiosis

A

yes, genetically different from each other because chromosomes get shuffled up during division

47
Q

Aneupoidy

A

results in one chromosome too many or few

- caused by non-disjunction of chromatids or chromosomes during meiosis

48
Q

Nondisjunction

A

when a pair of chromosomes fail to dis-join so that 2 copies of a chromosome are present in the gamete , instead of usually one

49
Q

Trisomy

A

union of a gamete with 2 copies of one chromosome, with a normal gamete leads to 3 copies of the chromosome
- down syndrome, 47 XX, XY 21

50
Q

Monosomy

A

union of gamete without one chromosome with a normal gamete leads to only 1 copy of the chromosome. Zygote usually dies unless missing chromosome is sex chromosome
ie. 45 XO

51
Q

Mitosis daughter cell

A

identical as they’re diploid and somatic

52
Q

meiosis daughter cell

A

genetically different as genetic recombination of chromosomes occur

53
Q

Why are the daughter cells different?

A

as in meiosis

  1. Crossing over
    - Where there is exchange of genetic material (alleles) between non-sister chromatids of homologous pairs, therefore, different alleles (PROPHASE I)
  2. Independent assortment of chromosomes
    - Where the separation of one homologous pair has no influence over another, therefore, mixing maternal and paternal chromosomes (ANAPHASE I)
54
Q

Chromosome

A

threadlike structure made up of DNA and protein, only visible during cell division

55
Q

Haploid

A

cells with one set of chromosomes (n)

eg. eggs sperm and gametes.
- these cells are produced by gametes
- in humans the haploid number is 23

56
Q

Diploid

A

cells with two sets of chromosomes (2n)

  • one set derived from each parent
  • includes all somatic cell- skin, muscle, wbc
  • in humans diploid number is 46
57
Q

Gametes

A

eggs, sperm

haploid cells which fuse during fertilization

58
Q

Genome

A

all of the genes in a cell which every cell has the same of

59
Q

Chromatid

A

copy of a duplicated chromosome, joined to the other copy by the centromere. Required for both cell division and is produced in the S phase of the cell cycle

60
Q

Somatic cells

A

Diploid body cells

aka all bosy cells except gametes

61
Q

Alleles

A

different variations of genes

62
Q

Chromatin

A

chromosomes when not in mitosis or meiosis
ie when NOT dividing
- made up of protein and DNA

63
Q

homologous pairs of chromosomes

A

2 chromosomes with the same genes but different alleles

64
Q

sex chromosomes

A

chromosome in the genome that is involved in the determination of sex

65
Q

genes

A

the basic unit of heredity

66
Q

centromere

A

where chromatids are held and the point of attachment for spindle fibers

67
Q

autosomes

A

non-sex chromosomes

Biology (21 decks)

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