monogenic inheritance

Question 1

what is monogenic inheritance

Answer 1

the inheritance of a single gene

Question 2

outline the 6 stages of performing a genetic cross

Answer 2

1. state the phenotype of both parents
2. state the genotype of both parents (assign letter code to represent the alleles being studied)
3. state the gametes of each parent (commonly circled)
4. use a Punnett square to show the results of the random fusion of gametes during fertilisation
5. state the proportion of each genotype which are produced among the offspring (can be a percentage, ratio or “x out of y offspring”
6. state the corresponding type for each of the possible genotypes

Question 3

what is a true/pure bred individual

Answer 3

an organism that contains homozygous alleles for a particular gene

Question 4

what is codominance

Answer 4

when two different alleles occur for a gene and are equally dominant

Question 5

what is incomplete dominance?

Answer 5

both alleles are expressed but the phenotype is mixed so only displayed as one

Question 6

describe codominant notation

Answer 6

• gene represented as a large letter
• allele shown as superscirpt capital letter
• eg. if allele for red coat = CR genotype is CR CR
• allele for white coat = CW genotype is CW CW
• red and white coat = CR CW

Question 7

what does monogenic inheritance show?

Answer 7

the likelihood of different alleles of that gene being inherited by offspring

Question 8

what are multiple alleles

Answer 8

• occurs when there are more than 2 alleles
• however, homologous chromosomes only contain 2 alleles

Question 9

what is sex linkage

Answer 9

traits inherited by one biological sex

Question 10

state 3 examples of sex linked traits

Answer 10

• red green colourblindness
• haemophilia
• coat colorations

Question 11

biological sex is determined by a pair of chromosomes called….

Answer 11

X and Y

Question 12

at some point in human evolution, the top part of the Y chromosome broke off and was lost. this means it is …. than the X chromosome and is missing some….

Answer 12

shorter
genes

Question 13

the part present on both X and Y chromosomes is called the ….

Answer 13

homologous region

Question 14

the part missing from the Y chromosomes but present on X is called the ….

Answer 14

non-homologous region

Question 15

where is gene loci for sex linked traits found?

Answer 15

on the X chromosome

Question 16

how many alleles do males carry for sex linked traits

Answer 16

one X chromosome

Question 17

how many alleles do females carry for sex linked traits and what does this mean?

Answer 17

two X chromosomes

Question 18

what type of alleles code for sex linked traits

Answer 18

recessive X alleles