4b Inheritance

Question 1

Allele

Answer 1

One or more alternative versions of a gene, the order mid bases in each allele is slightly different - they code for different versions of the same characteristic. Represented using letters B b bb BB

Question 2

Genotype

Answer 2

The genetic constitution if an organism - the alleles an organism has is BB Bb or bob for eye colour

Question 3

Phenotype

Answer 3

The expression of genetic constitution and it’s interaction with the environment

Question 4

Dominant allele

Answer 4

An allele who’s characteristics appear in the phenotype even when there’s only one copy. Dominant alleles are shown by capital letters.

Question 5

Recessive allele

Answer 5

An allele who’s characteristics only appear in the phenotype if two copies are present. Recessive alleles are shown by lower case letters.

Question 6

Co-dominant alleles

Answer 6

Allele that are both expressed in the phenotype. Neither one is recessive - e.g. The allele for haemoglobin

Question 7

Locus

Answer 7

The fixed position if a gene on a chromosome. Alleles of a gene are found at the same locus on each chromosome in a pair.

Question 8

Homozygote

Answer 8

An organism that carried two copies of the same allele - e.g. BB or bb

Question 9

Heterozygote

Answer 9

An organism that carries two different alleles - e.g. Bb

Question 10

Species

Answer 10

A group if similar organisms that can reproduce to give fertile offspring

Question 11

A population

Answer 11

Is a group if organisms of the SAME species living in a particular area

Question 12

A gene pool

Answer 12

Is the complete range if alleles present in a population

Question 13

Hardy-Weinberg Equation.,,

Answer 13

P + Q = 1

Question 14

What does the Hardy-Weinberg principle predict?

Answer 14

That the allele frequencies in a population won’t change from one generation to the next.

Question 15

Certain conditions needed for the Hardy-Weinberg principle to be true?

Answer 15

It has to be a large population with no immigration, emigration, mutations or natural selection.

There also needs to be random mating - all possible genotype a can breed with all others!

Question 16

Equation to predict genotype frequency (hardy Weinberg)

Answer 16

p2 + 2pq +q2 = 1

Question 17

Gene

Answer 17

A sequence of bases in a DNA molecule that codes for a protein (polypeptide) which results in a characteristic e.g. The gene for eye colour

Question 18

Change made to the phenotype due to environmental factors is called a??

Answer 18

A modification and it is not part of the genotype - not inherited

Question 19

Change made to the genotype (by gametes) is called?

Answer 19

Called a genetic mutation that can be inherited by offspring

Question 20

A sex cell is called a….

Answer 20

Gamete!

Question 21

A characteristic is said to be sex-linked when…. ?

Answer 21

…when the allele that codes for it is located on the sex chromosome!

Question 22

Compare Y and X chromosomes ?

Answer 22

Y chromosomes are smaller and carry fewer genes!

Question 23

Males are more likely to show recessive phenotype a for genes that are sex-linked???

Answer 23

As males only have one X chromosome they often have one allele for sec linked genes. So they express the characteristic for this allele even if it’s recessive.