Mendelian and Non-Mendelian Modes of Inheritances

Question 1

Every trait is controlled by genes (single or multiple), and each gene has different alternative forms called ،،،،،.

Answer 1

Alleles

Question 2

،،،،،،،،: Physical appearance of a trait/individual resulting from a
genotype (e.g. red, white).

Answer 2

Phenotype

Question 3

………..allele is one which can express its effect in heterozygous form and mask the effect of the other allele.
•…………..: which needs only one mutant allele to express its
effects on protein function.

Answer 3

@Dominant (trait & allele): dominant

Dominant trait

Question 4

…………..: Trait which needs both mutant alleles to express its effect ، expresses its effect in homozygous form.

Answer 4

@ Recessive (trait or allele):

Question 5

،،،،،،،،،،،،،،: Single allele for a gene locus on male X chromosome.
،،،،،،،،،،،: Same alleles for a particular gene locus (e.g AA, CC).
،،،،،،: Different alleles for a particular gene locus (e.g Aa,
Gg).

Answer 5

@@Hemizygous
@Homozygous
Heterozygous

Question 6

Mendel’s Laws:

Answer 6

Law of Dominance.
2. Law of Segregations.
3. Law of Independent Assortment.

Question 7

In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation.
Offspring that are hybrid for a trait will have only the dominant trait in the phenotype.
Which is the law ?

Answer 7

Mendel’s Law of Dominance:

Question 8

• The two copies of a gene segregate (separate) from each other during transmission from parent to offspring.
@Therfore, only one copy of each gene is found in a gamete
At ferilization, two gametes combine randomly, potentially producing different allelic combination.
Which is the law ?

Answer 8

Mendel’s law of Segregation

Question 9

Two hypotheses to explain how different genes assort during
gamete formation:

Answer 9

(a) The linked hypothesis
, the two genes always stay with each other.
(b) In contrast, the independent association hypothesis proposes that
the two different genes rand
segregate into haploid cells.

Question 10

relatively few genes are located only on the Y chromosome.
These few genes are called …………….

Answer 10

holandric genes.

Question 11

An example of a holandric gene is the

Answer 11

Sry gene

Question 12

Neither allele is dominant and heterozygous individuals have an intermediate phenotype.

Answer 12

Incomplete Dominance; Four-O’clock
Flowers

Question 13

Two equally dominant alleles are expressed at the same time.
Heterozygous phenotype will have both phenotypes visible

Answer 13

Codominance: Shorthorn Cattle
@They are called “roan”.