inheritance

Question 1

what is a gene

Answer 1

section of DNA that codes for a polypeptide

Question 2

whats an allele

Answer 2

a version of a gene

Question 3

whats genotype

Answer 3

the genetic makeup of an organism

Question 4

whats phenotype

Answer 4

the expression of a characteristic due to environment and genes

Question 5

whats homozygous

Answer 5

when the alleles of a particular gene are identical e.g both recessive or one h one g

Question 6

whats heterozygous

Answer 6

when the alleles of a particular gene are different e.g dominant and recessive

Question 7

whats haploid and diploid

Answer 7

haploid has half the number of chromosomes in a cell than a normal body cell. has 23 chromosomes not in homologous pairs

diploid full number of chromosomes 23 pairs of homologous chromosomes

Question 8

when are dominant and recessive alleles shown in the phenotype

Answer 8

dominant always shown in phenotype

recessive only shown when in phenotype when there are no dominant alleles. in crosses use same letter

Question 9

what does multiple alleles mean

Answer 9

term used to describe a gene with more than 2 possible alleles
e.g blood group

Question 10

whats co dominance

Answer 10

when both alleles are expressed in the phenotype because both alleles are dominant e.g roan hair = red and white together so would be RW

Question 11

whats sex linked

Answer 11

any gene found on the x or y chromosomes. males xy females xx

Question 12

what is the common pattern for sex linked conditions

Answer 12

are caused by a mutation of a gene on the x chromosome the mutation usually leads to a non functional protein being made. males only have one x chromosome y is shorter so only need to have1 allele that codes for the non functional protein

Question 13

why can we use drosophila in experiments

Answer 13

lay lots of eggs
short life cycle
small space needed
not endangered

Question 14

what are the offspring ratios

Answer 14

monohybrid = 3:1 for the f2 generation Gg Gg
dihybrid = 9:3:3:1
autosomal linkage= 3:1

Question 15

whats monohybrid inheritance and how to know its a question on it

Answer 15

inheritance of a single gene

one gene
dominant and recessive in 3:1 ratio with heterozygous parents
only this used in hardy Weinberg
evidence of recessive condition in offspring

Question 16

what’s dihybrid inheritance and how to identify question

Answer 16

how two different genes on different chromosomes are inherited

two genes not on same chromosome
independent characteristics one doesn’t control the expression of the other
9:3:3:1

Question 17

what’s sex linkage and how to identify question

Answer 17

when any gene is found on x or y chromosomes males have xy females have xx

x and y present
sometimes combned with multiple alleles and co dominance
evidence of recessive sex linked, parents have dominant condition but parents have recessive

Question 18

whats multiple alleles and co dominance and how to identify q

Answer 18

co dom= both alleles equally dominant leads to expression of both in the phenotype

multiple = where there are more than two alleles of which only two may be present at the loci of an individuals homologous chromosomes

question = phenotype combo of two alleles
denoted with capital letters for each allele
three or more phenotypes present
codominance cant be used for hardy Weinberg multiple alleles can but only two at once

Question 19

what is epistasis and how to identify question

Answer 19

when the allele of one gene affects or masks the expression of another in the phenotype

two genes
not on same chromosome
one controls the expression of the other
not 9:3:3:1

Question 20

whats autosomal linkage and how to identify the question

Answer 20

when 2 genes inherited at the same time on same chromosome
the combo of inheritance only altered by crossing over always draw 2x2 grid for AL
A with B and a with b

q = two genes on same chromosome
few offspring with phenotype from heterozygous gametes which only occurs from crossing over
many offspring with phenotype from homozygous gametes

Question 21

whats an autosome

Answer 21

all 22 chromosomes other than x and y

Question 22

what does hardy Weinberg predict and the equation

Answer 22

frequency of alleles will stay constant over 1 generation to the next

p2+2pq+q2=1 p+q=1

Question 23

what are the assumptions for hardy weinberg

Answer 23

random mating
no mutations
large populations
population genetically isolated
no migration

Question 24

what is the evidence from a pedigree chart that proves its a recessive gene that causes a condition

Answer 24

2 parents don’t have condition but child does

parents must be carriers/both parents have condition so all children must do too

Question 25

evidence from pedigree chart that proves its a dominant gene that causes condition

Answer 25

parents have a condition but child doesn’t

parents have heterozygous alleles condition caused by dominant one child have homozygous recessive

Question 26

evidence from pedigree chart that proves its sex linked condition

Answer 26

if father has dominant condition daughters will always be dominant
daughters can only have recessive condition if their father is recessive and mother both x recessive