Topic 3- Genetics

Question 1

Definition of sexual reproduction

Answer 1

Fertilisation of a female sex cell by a male sex cell

Question 2

Definition of asexual reproduction

Answer 2

Producing clones

(offspring that are genetically identical to the parent)

Question 3

Zygote

Answer 3

• A fertilised egg cell

* A single cell made by the fertilisation of two gametes

Question 4

Gamete

Answer 4

A sex cell produced by meiosis

Eg. Sperm, egg, pollen

Question 5

Meiosis

Answer 5

Nuclear division that reduces the number of chromosomes by half

Question 6

Chromosome

Answer 6

One molecule of DNA

For example in humans they’re in pairs, one from the mother and one from the father

Question 7

DNA

Deoxyribonucleic acid

Answer 7

The genetic molecule

Question 8

Haploid

Answer 8

• One set of a species chromosomes

Eg. Humans written as n=23

Question 9

Diploid

Answer 9

The chromosomes come in pairs

Eg. Humans written as 2n=46

Question 10

Genes

Answer 10

A section of DNA that makes a chromosome, that codes the instructions to make a protein

Question 11

Proteins

Answer 11

Polymers of amino acids

Often an enzyme

Question 12

Nucleotides

Answer 12

Basic building block of DNA

Made up of sugar,phosphate and nitrogenous base

Question 13

Chromatin

Answer 13

Uncoiled chromosomes

Question 14

Alleles

Answer 14

Different versions of a single gene

Eg. The gene for human eye colour has 2 alleles (brown and blue)

Question 15

Parental phenotype

Answer 15

Characteristic of the parent

Eg. Purple flower for a pea plant

Question 16

Parental genotype

Answer 16

Which alleles for the gene of the phenotype does the parent have

Eg. A parent pea plant with purple flowers may have a genotype of Rr

Question 17

How are dominant genotypes symbolised?

Answer 17

As a capital letter

Eg. Rr the capital R is the dominant genotype

Question 18

How are recessive genotypes symbolised?

Answer 18

With a lower case letter

Eg. Rr, the lower case R is the recessive genotype

Question 19

Homozygous

Answer 19

Has the same alleles

Eg. RR

Question 20

Heterozygote

Answer 20

Has different alleles

Eg.Rr

Question 21

Pure breeding

Answer 21

Means an individual has the same alleles for a gene

It is homozygous and has no genetic variation

Question 22

How many sex chromosomes does a human have?

Answer 22

1 pair of chromosomes are the sex chromosomes

Question 23

How many autosomes does a human have?

Answer 23

22 pairs are ordinary chromosomes called autosomes

Question 24

What are the different blood groups

Answer 24

A, B, AB or O

Question 25

Sex linked genetic disorder

Answer 25

Where the position of the gene that causes the disorder is on the sex chromosomes and is on the sex chromosomes region of the X chromosome that is absent on the y

Question 26

Example of a co dominant blood group

Answer 26

AB

Question 27

Harmful mutations

Answer 27

A change in the base sequence that stops the gene from being able to code for a functional protein (usaully an enzyme)

Question 28

A whole chromosome mutation

Answer 28

A section of chromosome is lost or is added to another chromosome Eg. X and Y chromosome

Question 29

Muation

Answer 29

A mutation is a change in the sequence of a gene

Question 30

Where do mutations come from?

Answer 30

1) during the replication of DNA 2) UV damage, x-ray damage, gamma ray damage 3) mutagenic chemicals

Question 31

3 types of muation

Answer 31

* neutral mutation (have no affect on phenotype) * harmful mutations * a whole chromosome mutation

Question 32

Stages of meiosis

Answer 32

1. DNA is duplicated DIVISION 1 -chromosomes line up in the centre of the cell -the pairs are pulled apart so each new cell only has one copy of each chromosome -each cell has a mixture of the mother’s and father’s chromosomes DIVISION 2 -chromosomes line up in the centre again -chromatids are pulled apart