What is ‘Genetics’?

Genetics is the study of heredity and variations.

What is this?

DNA molecule

Z

DNA

is found

Inside the nuclei of cells

A DNA moleculeconsists of 2 polynucleotide chains. The

chains run in opposite directions and twist to form a

Double helix

A DNA molecule contains bases

which are

G, C, A, T

In DNA molecule, base G

Pair with

C

Protein synthesis is in the

Cytoplasm

In nucleus, genetic codes are copied to

RNA

DNA control the characteristics of an organism by

Forming different protein

What is sex chromosomes of individual 3 and 4?

3: XX 4: XY

The allele for normal body pigmentation is dominant (D) and the allele for albino is recessive (d).

State the genotype of individuals 1, 6, 10, 11

1: Dd 6: Dd 10: dd 11: DD/Dd

The allele for normal body pigmentation is dominant (D) and the allele for albino is recessive (d).

Explain by means of a genetic diagram, the expected phenotypic ratio of the offspring when individual 7 is

married to individual 10.

P: dd x dd:

Complete by yourself

The proteins formed may be

(a)used to formed structures of the body,

(b)Enzyme which speed up metabolic reactions,

and

(c)Hormone which regulate physiological

processes.

The base sequence of a DNA molecule can form the

Genetic code

How many pairs of chromosome are there in one body cell?

23

The 23rd pair of chromosomes determine the sex of an

individual and are called the

Sex chromosome

Sex chromosome in female are

XX

Sex chromosome in male are

XY

Female produce only

X-bearing egg

A fertilized egg will develop into a girl if the egg is fertilized by

An X-bearing sperm

A fertilized egg will develop into a boy if the egg is fertilized by

An Y-bearing sperm

Chromosomes are made up of

Protein and DNA

A gene can exist in two or more alternative forms called

Allele

An organism genotype contains two identical alleles is called

Homozygote

An organism genotype contains two different alleles is called

Heterozygote

What is abnormal with this set of chromosomes?

There are 3 chromosomes in chromosome 13

Is this person a male or female? Why?

Female because there is no Y chromosome

What is abnormal with this set of chromosomes?

There are 3 sex chromosomes

The genotype of Blood group O is

ii

The genotype of Blood group AB is

IAIB

What are the four blood groups in human?

A, B, AB and O

Tongue rolling is a dominant character in human. The dominant allele for

tongue rolling is T and the recessive allele for non-rolling is t.

What is the genotype of a non-roller?

tt

Tongue rolling is a dominant character in human. The dominant allele for

tongue rolling is T and the recessive allele for non-rolling is t.

What are the possible genotypes of a roller?

TT/ Tt

A DNA molecule is known to contain 10% adenine (A), what is percentage of thymine (T)? (Hints: A

pairs with T and C pairs with G on the two polynucleotide chain of a DNA molecule.)

10%

A DNA molecule is known to contain 10% adenine (A), what is percentage of cytosine (C)? (Hints: A

pairs with T and C pairs with G on the two polynucleotide chain of a DNA molecule.)

40%

A DNA molecule is known to contain 30% adenine (A), what is the ratio of thymine (T) to cytosine (C) in the same molecule? (Hints: A pairs with T and C pairs with G on the two polynucleotide chain of a

DNA molecule.)

3:2

State the genotype of the individuals 1, 2 and 11, 13.

1: ii 2: IAi 11: IAIA/IAi 13: IAi

Z

What is the chance of individual 3 and 4 having a boy with blood group O?

12.5%

Z

What is the chance of individual 1 and 2 having a baby with blood group A?

50%

Z

Allele which can express in heterozygous condition

Is called

Dominant

Allele which can express in homozygous condition only

Is called

Recessive