17 inherited change

Question 1

what is a genotype

Answer 1

the genetic constitution of an organism, describes all the alleles that an organism has

Question 2

what is a phenotype

Answer 2

the expression of the genes and it’s interaction with the environment

Question 3

what is a gene

Answer 3

section of DNA on a chromosome coding for one or more polypeptides

Question 4

what is a locus

Answer 4

the position of a gene on a DNA molecule

Question 5

what is an allele

Answer 5

one of a number of alternative forms of a gene

Question 6

what is monohybrid inheritance

Answer 6

the inheritance of a single gene

Question 7

what does pure-breeding mean?

Answer 7

pure breeding produces offspring with the same phenotype as the parents, parents have to be homozygous

Question 8

what is the theoretical ratio when the f1 generation are crossed with one another?

Answer 8

3(dominant) : 1(recessive)

Question 9

what is the dominant allele?

Answer 9

an allele that is always expressed in the phenotype

Question 10

what is the recessive allele?

Answer 10

an allele that is only expressed in the phenotype if it is homozygous

Question 11

what is dihybrid inheritance?

Answer 11

the inheritance of two different genes on different chromosomes simultaneously
(RRGG, RRGg, RRgg, rrGG etc)

Question 12

what is the theoretical ratio for a dihybrid cross?

Answer 12

9:3:3:1

Question 13

what is codominance?

Answer 13

when both alleles are equally dominant, both expressed in the phenotype

Question 14

what is multiple alleles?

Answer 14

more than two alleles for a single gene (only two can be present at any one time)

Question 15

example of multiple alleles

Answer 15

blood groups could be group A, B or O

Question 16

what is sex-linkage?

Answer 16

occurs when genes are on the X chromosomes

Question 17

what chromosomes do males and females have

Answer 17

male = XY
female = XX

Question 18

what is autosomal linkage?

Answer 18

occurs when two genes are on the same chromosome

Question 19

what is the chi-squared test used for in genetics?

Answer 19

to see if the difference between the observed value and the expected value is significant or nor

Question 20

why does autosomal linkage reduce variation?

Answer 20

pairs of alleles are inherited together

Question 21

why do some males suffer from sex-linked diseases?

Answer 21

their Y chromosomes is missing some genes that are carried on their X chromosome, so some recessive alleles on the X chromosome are expressed alone, giving the disease phenotype

Question 22

what is homozygous?

Answer 22

a pair of homologous chromosomes carrying the same alleles for a single gene

Question 23

what is heterozygous?

Answer 23

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

Question 24

what is epistasis?

Answer 24

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