MITOSIS, MEIOSIS, MENDEL, HARDY WEINBERG Flashcards

1
Q

mitosis

A

formation of 2 daughter cells

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2
Q

interphase; how do chromosomes look

A

they are diffuse/uncondensed so not visible as individual entities

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3
Q

interphase

A
  • RNA and protein synthesis
  • DNA synthesis
  • cell growth
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4
Q

prophase- chromosomes look?

A
  • replicated chromosomes visible as 2 sister chromatids joined at centromere
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5
Q

prophase

A

nuclear membrane breaks down, centrioles move to opposite poles, spindle forms between centrioles

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6
Q

metaphase

A
  • replicated chromosomes attach to spindle by their kinetochores
  • line up at equator
  • condensed and visible
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7
Q

anaphase

A

centromeres divide, chromosomes (sister chromatids) pulled apart to 2 poles by contracting spindle fibres

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8
Q

telophase

A

nuclear membrane reforms, chromosomes de-condense, daughter cells back to interphase

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9
Q

why are chromosomes condensed?

A

allows cell to avoid getting knotted DNA (also have topoisomerase to untangle DNA)

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10
Q

are somatic cells haploid or diploid? how do they propagate?

A

haploid, mitosis

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11
Q

are germ cells haploid or diploid? how do they propagate?

A

diploid or haploid, by mitosis or meiosis

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12
Q

meiosis

A

reduction in chromosome number from diploid to haploid. 2 consecutive cell divisions.

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13
Q

prophase 1: leptotene

A

chromosomes become visible as thin threads within nucleus

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14
Q

prophase 1: zygotene

A

homologous pairs of chromosomes become closely associated along their lengths by process called synapsis to form bivalents

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15
Q

prophase 1: pachytene

A

synapsis is complete and bivalents are held together throughout length by synaponemal complex. Homo chromosomes cross over

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16
Q

prophase 1: diplotene

A

homo chromosomes appear to repel each other and remain held only at chiasmata and centromere

17
Q

metaphase 1

A

bivalent chromosomes (sister chromatids joined at centromere) attach to spindles, line up at equator, independent assortment

18
Q

anaphase 1

A

chromosomes (sister chromatids) pulled to opposite poles by contracting spindles

19
Q

telophase 1

A

each daughter cell has half number chromosomes, but each chromosomes is pair of chromatids. nuclear membrane reforms, chromosomes decondense and daughter cells return to interphase.

20
Q

prophase 2

A

nuclear membrane breaks down, chromatids condense, centrioles to app end poles

21
Q

metaphase 2

A

sister chromatids attach to spindles by kinetochores, equatorial metaphase plate rotated to 90 degrees vs meiosis 1

22
Q

anaphase 2

A

sister chromatids (now called sister chromosomes) pulled apart

23
Q

telophase 2

A

nuclear membrane reforms, chromosomes decondense, 2 haploid cells formed with 23 chromosomes.

24
Q

mendels 0 law

A

inheritance is by particles not fluids

25
mendel 1st law
law of segregation of characteristics: of a pair of characteristics, only one can be represented in a gamete.
26
Mendel's second law
independent assortment for 2 characteristics, genes ar inherited independently / all combinations of gametes equally probable. exception is linked genes
27
what is sex linkage?
- males are hemizygous (one X chromosome) so recessive alleles will show as phenotype - males more likely to develop a lethal disease if gene for it is on X chromosome as they only have one
28
X-linked recessive disorders?
- red green colour blindness - haemophilia A and B - duchanne muscular dystrophy
29
what is the hardy Weinberg equilibrium equations?
p + q = 1 p2 + 2pq + q2 = 1
30
conditions for hardy Weinberg?
- infinite population size - random mating - no selection either in favour of or against specific genotype - no introduction of new alleles by mutation - no net migration into or out population
31
why do we use hardy Weinberg?
- test if assumption is false | - estimate frequency of carrier of recessive alleles