Dna

Front 1

What are introns

Back 1

Section of non coding DNA

Front 2

During which part of cell cycle is mutations likely to occur

Back 2

DNA synthesis

Front 3

What is an allele

Back 3

Different variation of a gene

Front 4

Describe appearance of chromosome

Back 4

Two chromatids joined by centrosome

Front 5

Name and explain parts of cell cycle

Back 5

Interphase: normal cell activity

First growth- proteins are synthesised

DNA synthesise - DNA is replicated

Second growth- organelles grow and divide

Front 6

Explain crossing over

Back 6

Homologous Chromatids cross over
Chromatids break off and then attach to homologous chromosome
This exchanges alleles

Front 7

Name stages of cell division

Back 7

Prophase
Metaphase
Anaphase
Telophase

Front 8

Describe what happens at each stage

Back 8

Prophase- nuclear envelope disintegrates and chromosomes become visible and dense

Metaphase- chromosomes line up down centre and spindle fibres form

Anaphase- spindle fibres attach to centrosome and pull chromatids to polls of cell

Telephase- chromatids become indistinct and nuclear envelope reforms

Front 9

What is importance of reducing chromosome number in meiosis

Back 9

When fertilisation occurs the two gametes combine to to form original number

Front 10

Name 3 differences between meiosis and mitosis

Back 10

Mitosis-
1. Genetically identical
2. 1 cell division
3. No crossing over

Meiosis
1. Genetically different
2. 2 cell divisions
3. Crossing over

Front 11

Give two processes other than crossing over, which result In genetic variation

Back 11

Mutations

Independent segregation

Front 12

Name number of chromosomes in diploid cell in humans

Back 12

46

Front 13

Name number in hapoid

Back 13

23

Front 14

Describe meiosis 1

Back 14

Homologous chromosomes line up and cross over.
Separate and divide

Front 15

Describe meiosis 2

Back 15

Normal mitosis