7.1 Inheritance

Question 1

define genotype

Answer 1

the genetic constitution of an organisms

Question 2

define phenotype

Answer 2

the expression of an organisms genetic constitution combined with its interaction with the environment

Question 3

define an allele

Answer 3

different forms of a particular gene found at the same locus on a chromosome, a single gene could have many alleles

Question 4

how many alleles per gene do diploid organisms carry

Answer 4

2

Question 5

define dominant allele

Answer 5

an allele whose characteristics will always appear in the phenotype whether one or two are present

Question 6

define recessive allele

Answer 6

an allele whose characteristic only appears in the phenotype if no dominant allele is present meaning two must be present

Question 7

what is a codominant allele

Answer 7

two equally dominant alleles that both contribute/are expressed to the phenotype either by showing a blend of both characteristics or the characteristics appearing together

Question 8

define homozygous

Answer 8

pair of homologous chromosomes carrying two identical alleles for a single gene

Question 9

define heterozygous

Answer 9

pair of homologous chromosomes carrying two different alleles for a single gene

Question 10

define monohybrid inheritance

Answer 10

genetic inheritance cross of one phenotypic characteristic is determined by one gene

Question 11

define dihybrid inheritance

Answer 11

where two phenotypic characteristics are determined by two different genes present on two different chromosomes at the same time

Question 12

define sex linkage

Answer 12

when an allele is located on one of the sex chromosomes meaning its expression depends on the sex of the individual

Question 13

why are males mo0re likely to express a recessive sex-linked allele

Answer 13

most sex linked alleles are located on the X chromosomes

therefore males only get one copy of the allele so will express this characteristic even if its recessive

since females get two alleles this will be less likely

Question 14

which parent do males inherit sex-linked characteristic from

Answer 14

their mother since Y chromosomes can only come from the father

therefore if the mother is heterozygous for sex linked alleles

she is the carrier and may pass on the trait

Question 15

what is autosomal linkage

Answer 15

when two or more genes are located on the same (non-sex) chromosome
so only one homologous pair is needed for all four alleles to be present

Question 16

what is epistasis

Answer 16

when one gene modifies or masks the expression of a different gene at a different locus

Question 17

name the two types of epistasis

Answer 17

recessive
dominant

Question 18

what is recessive epistasis

Answer 18

where two homozygous recessive alleles mask expression of another allele

Question 19

what is dominant epistasis

Answer 19

where one dominant allele masks expression of multiple other alleles

Question 20

two things that can effect punnet square outcomes

Answer 20

crossing of meiosis :resulting in new combinations of alleles in gamete

autosomal linkage: where alleles for each gene are linked on the same chromosome so must be inherited together

Question 21

what is chi-squared

Answer 21

a stats test to find out whether the difference between observed and expected data is due to chance or real effect

Question 22

4 criteria for chi-squared

Answer 22

• data is discrete
• large sample size
• only raw count data NOT %
• no data values = 0