3.7.1 Inheritance

Question 1

What is the genotype?

Answer 1

All the alleles that an organism has

Question 2

What is the phenotype?

Answer 2

The observable or biochemical characteristics of an organism

Question 3

What is a gene?

Answer 3

A length of DNA which is a sequence of nucleotide bases

Question 4

What is an allele?

Answer 4

One of the different forms of a gene

Question 5

What is the locus?

Answer 5

The position of a gene on a particular DNA molecule

Question 6

What are homologous chromosomes?

Answer 6

Chromosomes in pairs with the same gene loci

Question 7

What are homozygous alleles?

Answer 7

When both alleles are the same

Question 8

What are heterozygous alleles?

Answer 8

When the alleles are different

Question 9

What is a dominant allele?

Answer 9

One that is expressed

Question 10

What is a recessive allele?

Answer 10

One that is not expressed

Question 11

What is it called when a homozygous organism has two dominant alleles?

Answer 11

Homozygous dominant

Question 12

What is it called when a homozygous organism has two recessive alleles?

Answer 12

Homozygous recessive

Question 13

Define codominant alleles

Answer 13

When both alleles contribute to the phenotype. This can either be a blend of features or when both features are represented

Question 14

What is it called when an organism is said to have multiple alleles?

Answer 14

When a gene has more than two allelic forms

Question 15

What is a Punnett square?

Answer 15

A cross diagram used to show the genes of genetic offspring

Question 16

What are pure breeding strains?

Answer 16

When alleles are the same

Question 17

What is the generation called if it is a cross between two pure breeding parents?

Answer 17

First filial or F1 generation

Question 18

What is the generation called when an F1 generation is crossed with another F1 generation?

Answer 18

Second filial or F2 generation

Question 19

What is dihybrid inheritance?

Answer 19

How two characteristics, determined by two different genes located on different chromosomes, are inherited

Question 20

How many chromosomes do humans have?

Answer 20

23 pairs

Question 21

Define sex-linked

Answer 21

When a gene is carried on the X or Y sex chromosome

Question 22

Which sex chromosome is longer?

Answer 22

X
So most of the X chromosome don’t have an equivalent homologous portion
Those non-homologous chromosomes have no pairing so will always be expressed

Question 23

What is an X-linked genetic disorder?

Answer 23

A disorder caused by a defective gene on the X chromosome

Question 24

How is a sex linked allele represented?

Answer 24

X or Y to the power of (letter respresenting the allele)

Question 25

Why do males always inherit an X-linked genetic disorder from their mothers?

Answer 25

They have to get their Y chromosome from their father so the X chromosome must be from the mother

Question 26

What are the sex chromosomes for males and females?

Answer 26

XX for females | XY for males

Question 27

What is a carrier?

Answer 27

A person who has an allele of a disease without displaying the physical symptoms

Question 28

What is a pedigree chart?

Answer 28

A chart which shows the inheritance of sex-linked characters in a family A male is represented as a square A male is represented by a circle Shading indicates the presence of a character in the phenotype

Question 29

What are autosomes?

Answer 29

The chromosomes which aren't sex chromosomes

Question 30

Define linked genes

Answer 30

When two genes occur on the same chromosome

Question 31

What forms a linkage group?

Answer 31

All the genes on a single chromosome

Question 32

What is the name of the situation where two or more genes are carried on the same autosome?

Answer 32

Autosomal linkage

Question 33

Draw a diagram of non-linked genes

Answer 33

See card

Question 34

Draw a diagram of linked genes?

Answer 34

See card

Question 35

Does independent selection affect autosomal linkage?

Answer 35

No

Question 36

How do you complete the chi squared test?

Answer 36

Columns: category, observed number (O) , expected number (E) , O - E, (O - E)2, (O - E)2 / E X2 = Sum of: (O - E)2 / E

Question 37

How do you evaluate the value calculated in the chi squared test?

Answer 37

If your calculated value is less than the degree of freedom, accept the null hypothesis that there is a significant difference between your observed and expected results If the value is larger than the degree of freedom, there is epistasis or linkage of the alleles

Question 38

What is epistasis?

Answer 38

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

Question 39

How do you use the word epistatic?

Answer 39

If one gene locus prevents the expression of a second gene, the first locus is epistatic to the second and the second is hypostatic to the first