Inheritance

Question 1

Gene

Answer 1

The factor that determines an inherited characteristic.

Located in chromosomes

Question 2

Allele

Answer 2

An alternative form of a gene that arise by mutation and are found at the same place of a chromosome.

Question 3

Dominant

Answer 3

An allele that masks the effect of another allele

Question 4

Recessive

Answer 4

An allele that is masked by the alternative, dominant allele.

Question 5

Homozygous

Answer 5

The situations where an individual has the same alleles for a particular characteristic, also called pure-bred.

Can be recessive or dominant

Question 6

Heterozygous

Answer 6

The situation where an individual possess different alleles for a particular characteristic, also called hybrid.

Is dominant

Question 7

Phenotype

Answer 7

The physical appearance of an individual as determined by the expression of the alleles for that characteristic

Question 8

Geneotype

Answer 8

The genetic make-up of an individual as determined by the alleles for the characteristic being considered.

Question 9

First filial generaion

Answer 9

The offspring on the first set of parents

Question 10

Punnet squares

Answer 10

Can be used to model a cross, and therefore, to calculate the probability of genotypes and phenotypes of offspring.

Question 11

Pedigree

Answer 11

Model that is used to investigate the patterns of inheritance of traits over generations of a family.

Question 12

Types of chromosomes

Answer 12

1. Sex-chromosomes, Chromosomes responsible for determination of gender, found on the x chromosome, known as x-linked.

2.Autosomes, Chromosomes not responsible for determining gender. known as autosomal.

Question 13

Autosomal inheritance

Answer 13

When a trait is passed down from an autosome. (1-22).

Can be dominant or recessive.

Question 14

X linked

Answer 14

When a trait is passed down from a sex linked chromosome. (23)

can be recessive and dominant

Question 15

Disorders

Answer 15

Autosomal dominant - Huntingtons, dwarfism

Autosomal recessive - cystic fibrosis, pheylketoniria

X - lined dominant - NONE

X - linked recessive - haemophilia, red and green colour blindness.

Question 16

Huntingtons disease

Answer 16

Brain disorder causing movement, mood and intellect fading away.

Affected people always going to be Hh

Autosomal dominant

Question 17

Phenylketonuria

Answer 17

• A metabolic disorder as the gene codes for an enzyme that metabolises phenylalanine.

Autosomal recessive

Question 18

Cystic fibrosis

Answer 18

A disorder making secretions (thick and sticky).

Autosomal recessive.

Question 19

Complete dominance

Answer 19

Alleles can be either dominant or recessive in nature.

Question 20

Co - dominance

Answer 20

Situation where-by two or more alleles in a gene will be represented in the organisms phenotype.

Question 21

Multiple alleles

Answer 21

When two or more alleles are present on a gene.

Example blood groups.

Question 22

Hints for genotype

Answer 22

1. If individual is homozygous recessive ‘aa’ the both parents must have at least one recessive allele.
2. If both parents are homozygous recessive than offsprings will be homozygous recessive.

Question 23

Mendels two principles

Answer 23

1. Various heredity characteristics were controlled by factors ( genes) that occurred in pairs.
2. During the formation of the gametes (in humans, egg and sperm), the pairs of factors separate. Each gamete receives only one set of factors, or genes, with the other set going to another gamete. Gametes unite at fertilisation, allowing different combinations of genes to come together.

Question 24

Hemizygous

Answer 24

When an individual has only one copy of a gene instead of the usual two.

Males are hemizygous for genes on the X chromosome because they have only one X (XY), while females have two (XX).