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Flashcards in patterns and principles of heredity Deck (28):
1

in meiosis a diploid cell produces

4 haploid gametes

2

the 4 haploid gametes will be..

genetically different

3

Meiosis 1

reductive division- chromosome number is reduced

4

Meiosis 2

separation of sister chromatids

5

Meiosis 1- detail

-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

6

orientation is random to one another

independent assortment/segregation

7

synaptonemal complexes

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.

8

meiosis 2- detail

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

9

Gene

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

10

allele

an alterative form of a gene

11

genotype

alleles at locus

12

phenotype

observable characteristics

13

homozygote

identical (YY) alleles at a locus

14

particulate theory is associated with

gregor mendel

15

what is the particulate theory (5)

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

16

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

RANDOM

17

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

in equal numbers

18

fertilisation..

restores the two copies of the gene to the offspring

19

if both parents are heterozygous

3 different genotypes and 2 phenotypes

20

independent assortment

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

21

when does independent assortment occur

metaphase 1

22

what occurs in metaphase 1

independent assortment

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..

1/2

24

therefore if two heterozygous parents are crossed

genotypic ratio is 1:2:1
phenotypic ratio is 3:1

25

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

p(Y gamete) from parent 1 and p(Gamete) from parent 2=
1/2 x 1/2 =1/4

26

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

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

27

in dihybrid crosses one must

consider each trait independently

28

if two traits are independent normal ratio is

9:3:3:1
-ration is a random combination of two independent 3:1 ratios