Genetic and inheritance

Question 1

how did Mendel’s experiment give rise to our modern knowledge of genetics?

Answer 1

Mendel’s experiment using peas gave us 1knowledge of the unit of inheritance called a gene
2 showed traits are controlled by two factors that did not blend / one factor
expressed while the other was masked
3 allowed us to understand dominant and recessive traits
factors was random
4 experiments were well done can be reproduced for further use results are
trusted and still applicable today

Question 2

What are monohybrid crosses

Answer 2

A hybrid is an individual that results from a cross between parents that are genetically different. A monohybrid cross involves a single pair of contrasting characteristics

Question 3

what is an allele

Answer 3

alternative forms of a gene found on corresponding positions of homologous chromosomes

Question 4

Co-dominance

Answer 4

different alleles of a hybrid are equally dominant over each other

Question 5

complete dominance

Answer 5

: only one characteristic is expressed in the phenotype of a hybrid

Question 6

Dominant gene

Answer 6

a gene that expresses itself in the phenotype of an individual and masks the effect of the recessive gene

Question 7

filial gen

Answer 7

the first generation after mating, namely F1

Question 8

gene

Answer 8

a segment of a chromosome containing a unit of genetic information. Two or more genes may be responsible for each characteristic of an individual.

Question 9

genotype

Answer 9

the genetic make-up of an individual as reflected in the chromosomes

Question 10

phenotype

Answer 10

physical (external) appearance of an individual as determined by the individual’s genetic make up

Question 11

dihybrid cross

Answer 11

a cross involving two characteristics at a time

Question 12

hetreozygous

Answer 12

an individual having two contrasting genes (alleles e.g. Bb, Rr, Yy) in the corresponding position of homologous chromosomes.

Question 13

homozygous

Answer 13

an individual having two of the same genes (BB, rr) for a particular characteristic so that both the alleles are expressed in the phenotype. A homozygous individual is referred to as pure breed for that characteristic.

Question 14

human genome

Answer 14

all the genes that are present in the DNA of a human.

Question 15

recessive gene

Answer 15

a gene that does not express itself in the phenotype, i.e. its effect is masked/hidden.

Question 16

Explain sex-linked inherited disorders

Answer 16

The Y chromosome is very small and carries almost no genes, while the X chromosome is much larger and carries many genes. two disorders that are caused by the recessive genes found on the x chromosome are Hemophilia and red-green color blindness
Since men only have one x chromosome they will have the disorder if the recessive gene on their X chromosome. A woman may have the recessive gene on one of her X chromosomes while the other X is normal. This would make her a carrier of the disorder and she will not express the disorder in her phenotype.
A woman needs to have the recessive gene on both her X chromosome in order to express the disorder in her phenotype. making them rare in women