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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