MITOSIS, MEIOSIS, MENDEL, HARDY WEINBERG

Question 1

mitosis

Answer 1

formation of 2 daughter cells

Question 2

interphase; how do chromosomes look

Answer 2

they are diffuse/uncondensed so not visible as individual entities

Question 3

interphase

Answer 3

• RNA and protein synthesis
• DNA synthesis
• cell growth

Question 4

prophase- chromosomes look?

Answer 4

• replicated chromosomes visible as 2 sister chromatids joined at centromere

Question 5

prophase

Answer 5

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

Question 6

metaphase

Answer 6

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

Question 7

anaphase

Answer 7

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

Question 8

telophase

Answer 8

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

Question 9

why are chromosomes condensed?

Answer 9

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

Question 10

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

Answer 10

haploid, mitosis

Question 11

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

Answer 11

diploid or haploid, by mitosis or meiosis

Question 12

meiosis

Answer 12

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

Question 13

prophase 1: leptotene

Answer 13

chromosomes become visible as thin threads within nucleus

Question 14

prophase 1: zygotene

Answer 14

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

Question 15

prophase 1: pachytene

Answer 15

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

Question 16

prophase 1: diplotene

Answer 16

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

Question 17

metaphase 1

Answer 17

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

Question 18

anaphase 1

Answer 18

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

Question 19

telophase 1

Answer 19

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.

Question 20

prophase 2

Answer 20

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

Question 21

metaphase 2

Answer 21

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

Question 22

anaphase 2

Answer 22

sister chromatids (now called sister chromosomes) pulled apart

Question 23

telophase 2

Answer 23

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

Question 24

mendels 0 law

Answer 24

inheritance is by particles not fluids

Question 25

mendel 1st law

Answer 25

law of segregation of characteristics: of a pair of characteristics, only one can be represented in a gamete.

Question 26

Mendel’s second law

Answer 26

independent assortment

for 2 characteristics, genes ar inherited independently / all combinations of gametes equally probable.

exception is linked genes

Question 27

what is sex linkage?

Answer 27

• 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

Question 28

X-linked recessive disorders?

Answer 28

• red green colour blindness
• haemophilia A and B
• duchanne muscular dystrophy

Question 29

what is the hardy Weinberg equilibrium equations?

Answer 29

p + q = 1

p2 + 2pq + q2 = 1

Question 30

conditions for hardy Weinberg?

Answer 30

• 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

Question 31

why do we use hardy Weinberg?

Answer 31

• test if assumption is false

- estimate frequency of carrier of recessive alleles