patterns and principles of heredity

Question 1

in meiosis a diploid cell produces

Answer 1

4 haploid gametes

Question 2

the 4 haploid gametes will be..

Answer 2

genetically different

Question 3

Meiosis 1

Answer 3

reductive division- chromosome number is reduced

Question 4

Meiosis 2

Answer 4

separation of sister chromatids

Question 5

Meiosis 1- detail

Answer 5

• division of homologous pairs of chromosomes
• as in mitosis, meiosis is preceded by phase (cells have replicated their DNA)
• Prophase 1- chromosomes condense and homologous pairs form synaptonemal complexes–> cross over occurs
• Metaphase 1- each pair of homologues line up at the equator- centromere doesn’t divide- orientation is random to one another

Question 6

orientation is random to one another

Answer 6

independent assortment/segregation

Question 7

synaptonemal complexes

Answer 7

The synaptonemal complex is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids) during meiosis and is thought to mediate chromosome pairing, synapsis, and recombination.

Question 8

meiosis 2- detail

Answer 8

division of sister chromatids

• Metaphase 2- individual chromosomes line up
• anapase 2- centromeres split and chromatids separate to opp poles
• Telophase 2- each daughter cell contains one chromosome of each type

Question 9

Gene

Answer 9

specific sequence of DNA which codes for a protein/proteins (alternative splicing)

Question 10

allele

Answer 10

an alterative form of a gene

Question 11

genotype

Answer 11

alleles at locus

Question 12

phenotype

Answer 12

observable characteristics

Question 13

homozygote

Answer 13

identical (YY) alleles at a locus

Question 14

particulate theory is associated with

Answer 14

gregor mendel

Question 15

what is the particulate theory (5)

Answer 15

1) characters are distinct and hereditary determinants (genes) are particulate in nature
2) each adult has two gene for each character- diff forms of the genes are called alleles
3) members of the gene pair and segregate equally into gametes
4) fusion of the gametes at fertilisation restores the pair of genes and is RANDOM
5) different genes assort independently in gametes

Question 16

fusion of gametes and therefor the restoration of the pair of genes is..

Answer 16

RANDOM

Question 17

meiosis results in the formation of two types of gametes..

Answer 17

in equal numbers

Question 18

fertilisation..

Answer 18

restores the two copies of the gene to the offspring

Question 19

if both parents are heterozygous

Answer 19

3 different genotypes and 2 phenotypes

Question 20

independent assortment

Answer 20

When homologous chromosomes, one from each parent, pair up along the equator during metaphase 1 of meiosis, the particular arrangement is determined by chance.

• increases variation within populations

Question 21

when does independent assortment occur

Answer 21

metaphase 1

Question 22

what occurs in metaphase 1

Answer 22

independent assortment

Question 23

probability applied to hybrid crosses
-two alleles possible (from each parent) and each gamete can only carry one allele, therefore what is the probability of either gamete is..

Answer 23

1/2

Question 24

therefore if two heterozygous parents are crossed

Answer 24

genotypic ratio is 1:2:1

phenotypic ratio is 3:1

Question 25

therefore if two heterozygous parents are crossed: probability of (YY)

Answer 25

p(Y gamete) from parent 1 and p(Gamete) from parent 2=

1/2 x 1/2 =1/4

Question 26

therefore if two heterozygous parents are crossed: probability of (Yy)

Answer 26

p(Y gamete) parent 1 and p(y gamete) from parent 2 =

(1/2 x 1/2) + (1/2 x 1/2) = 1/4 + 1/4 = 1/2

Question 27

in dihybrid crosses one must

Answer 27

consider each trait independently

Question 28

if two traits are independent normal ratio is

Answer 28

9: 3:3:1

- ration is a random combination of two independent 3:1 ratios