DNA 1 Gentics and Inheritance

Question 1

Structural Units of DNA and RNA

Answer 1

nucleotides

Question 2

Nuclei contain ? chromosomes and ? pairs and are made up of ? *** and 2 *** chromosomes

Answer 2

Nuclei contain 46 chromosomes and 23 Pairs and are made up of 44 autosomes and 2 sex chromosomes

Question 3

What do Autosomes responsible for?

Answer 3

The expressions of traits

Question 4

What do the XX sex chromosomes produce?

Answer 4

Female

Question 5

What do the XY sex chromosomes produce?

Answer 5

Male

Question 6

what is a Karyotype?

Answer 6

number and size of chromosomes in a cell. (all somatic cells of a living organism have the same karyotype)
Downs syndrome exception 3 21 chromosomes.

Question 7

define alleles

Answer 7

pair of chromosomes (1 from each parent) found on same loci (location) that give a specific trait. Is the code for a specific trait (either same or different trait)

Question 8

define homozygous

Answer 8

2 alleles of the same trait

Question 9

Define Heterozygous

Answer 9

2 Alleles of different traits (dominant/recessive)

Question 10

Define Dominant/recessive inheritance

Answer 10

When a certain trait is produced by a certain Alleles, either dominant or recessive.

Question 11

give examples of expressions of phenotype due to dominant inheritance (DD Dd)

Answer 11

Dimples, Freckles, Skin Pigment, ability to roll tounge into u shape, Normal Arches, unattached earlobes

Question 12

give examples of expressions of phenotype due to recessive inheritance

Answer 12

Albinism, absence of freckles, inability to roll tounge into a u shape, flat feet, absence of dimples, attached earlobes

Question 13

Define sex linked inheritance

Answer 13

Inherited traits are determined by the sex

chromosomes. if trait is recessive, it is not masked in males. (XY)

Question 14

Examples of sex linked inherited disease

Answer 14

colour blindness, haemophilia

Question 15

Define multiple allele inheritance

Answer 15

Some genes exhibit more than 2 alleles forms eg.blood groups. lA lB, (dominant) i, (is recessive)

Question 16

What is the genotype of blood group A and what is its phenotype?

Answer 16

The genotype is lA lA and is group A

Question 17

What is the genotype of blood group B and what is its phenotype?

Answer 17

The genotype is lB lB and is group B

Question 18

What is the genotype of blood group O and what is its phenotype?

Answer 18

The genotype is ii ii and is group O

Question 19

What is the genotype of blood group AB and what is its phenotype?

Answer 19

The Genotype is lA lB and is group AB

Question 20

Define incomplete dominance

Answer 20

Both alleles expressed in heterozygous to produce different phenotype to either homozyous, (intermediate). eg inheritance of hair texture.

Question 21

Define polygenic inheritance

Answer 21

Some traits require several alleles eg skin colour,

eye colour. Skin colour based on 3 gene pairs, each with 2 alleles.

Question 22

name a simple autosomal recessive disease

Answer 22

Cystic fibrosis

Question 23

name a simple autosomal Dominant disease

Answer 23

Huntington’s disease

Question 24

name a co-dominance disease

Answer 24

Sickle Cell anemia

Question 25

name an x-linked recessive disease

Answer 25

Haemophilia

Question 26

Name a disease that is a result of abnormal chromosomal activity

Answer 26

downs syndrome (Trisomy 21 )

Question 27

Define Gene

Answer 27

Code of genetic information. Smallest unit

Question 28

Define Chromosomes

Answer 28

The structures that carry genetic information, formed within the nucleus of a cell by the super coiling of DNA