HYS - CH12.3 - Analytical Approaches In Genetics

Question 1

Monohybrid

Answer 1

One trait is being studied

Parent or P is the crossed generation
Offspring are F or filial generation
Uses subscripts for generations

Question 2

Monohybrid cross creates what genotypes and what phenotypes

Answer 2

100% Pp genotype and P phenotype

Question 3

Crossing two heterozygotes for a trait with complete dominance results in what genotype and what phenotype ratio?

Answer 3

Genotype
1:2:1
PP, Pp, pp

Phenotype
3:1

Question 4

Test cross (back crosses determines parent genotype based on phenotype of offspring)

Answer 4

Determines the unknown genotype
Organism with unknown genotype is crossed with an organism known to be homozygous recessive

If 100 percent are dominant, unknown is likely homozygous dominant

If 1:1 or split of dominant to recessive phenotypes then the unknown is likely heterozygous

Question 5

Dihybrid cross with complete dominance

What if we cross 2 plants which are heterozygous for 2 traits?

Answer 5

Inheritance of two different genes
Remember inheritance of one gene is independent from inheritance of another gene (unlinked genes)

If we use P and p for purple
And T and t for height

Crossing 2 plants which are heterozygous for 2 traits
Phenotypic ratio 9:3:3:1
9 tall and purple, 3 tall and white, 3 dwarf and purple, 1 dwarf and white

3:1 phenotypic ratio exists for each trait (12 tall 4 dwarf and 12 purple 4 white

Question 6

Sex linked crosses
What do we use for a disease carrying allele on X chromosome?

Answer 6

Females have 2 X chromosome and can be heterozygous (carrier) or homozygous for a condition

Males are hemizygous for X linked conditions as they have 1 X chromosome

Xh for disease carrying allele

Question 7

What are the genotyping and phenotypic ratios of crossing carrier female of X related disorder and normal male

Answer 7

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Question 8

What are the genotypes for cross between carrier female and hemophiliac male?

Answer 8

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Question 9

What is a Chiasma and gene separation? What is recombination frequency?

Answer 9

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Question 10

What is a genetic map, map unit, centimorgan?

Answer 10

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Question 11

Allele frequency

Answer 11

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Question 12

Hardy Weinberg principle assumptions

Answer 12

X

Question 13

What is hardy Weinberg equation and what does it stand for?

Answer 13

Fill in

Question 14

If a plant pop has pea plant frequency of T allele as 0.8 what is the frequency of the short allele, heterozygous dominant, homozygous recessive, and dominant phenotype (homozygous and heterozygous dominant genotypes)?

Answer 14

Fill in

Question 15

why type of zygosity is in the figure?

Answer 15

hemizygous

Question 16

zygosity

Answer 16

degree of similarity of DNA between homologous chromosomes at a gene locus

Question 17

Loci A, B, C are on the same chromosome. What could represent a chromosome of cell with genotype AABbcc?

Answer 17

since genotype is AABbcc

AA shows dominant A
Bb shows recessive b and dominant B
cc shows 2 recessive c

two combinations can be
ABc or
Abc

depends on if B is recessive or dominant

Question 18

which blood types show codominance

Answer 18

when both AB are present
AB- and AB+

Question 19

which events happen in mitosis and meiosis?

Answer 19

DNA replication (interphase in meiosis)
spindle formation
chromosmal segregation

Question 20

what events occur in meiosis and not mitosis?

Answer 20

synapsis (when homologous chromosomes pair up in prophase I meiosis),

recombination (crossing over in prophase I meiosis) and

reduction division only occur in meiosis bc in the second division it takes 1 female inherited daughter cel (2n) and 1 male inherited daughter cell (2n) and reduces chromsomes in half of each making 4 daughter cell, 2 hapliod with female sister chromatid and 2 hapliod with male sister chromatid

Question 21

polyalleism

Answer 21

presence of multiple alleles at a gene locus

Question 22

Answer 22

shows aaBBCc

Question 23

which sister chromatids exhange genetic material?

Answer 23

the NON sister chromatids (across female and male) in meiosis

Question 24

centriole vs centromere

Answer 24

centromere holds sister chromatic together

centriole is a protein structure tha forms poles and pulls sister chromatid

Question 25

which is an example of codominance and which is an example of imcomplete dominance

-dominant BB for black
-recessive bb for white

1. offspring with grey (Bb)
2. offpsring with spots of black and white (Bb)

Answer 25

incomplete dominance - intermediate phenotype of heterozygous offspring

• offpsring with grey hair (Bb)

complete dominance - both alleles are dominant

• offpsring with black and white hair (Bb)