Biology - 2 Cell division - 2.1 Cell Division

Cell division

the formation of two genetically identical daughter cells

Where are the chromosomes?

in the nucleus

What are chromosomes?

long, thin strings of genes that contain instructions for making new cells

What are genes?

Genes are sections of DNA that control a single genetic trait.

How many chromosomes are in the nucleus of a body cell?

46 chromosomes

How are chromosomes arranged in cells?

23 pairs - one from mother and one from father

How many chromosomes do gametes have?

23 chromosomes

Cell cycle

series of events that cells go through as they grow and divide

Mitosis

asexual reproduction by splitting the nucleus

How long is the cell cycle?

24 hours to several years

When is the cell cycle rapid?

as a baby develops and throughout childhood

When does the cell cycle slow?

after puberty

What areas continue rapid cell division in adults? [4]

the hair follicles, the skin, the blood, the lining of the digestive system

Cell cycle: stage 1 [4]

• longest stage

• cells grow bigger and increase mass

• replicate DNA to form two copies of each chromosome

• replicate organelles

Cell cycle: stage 2 [3]

• mitosis

• one set of chromosomes is pulled to each side

• nucleus divides

Cell cycle: stage 3 [1]

• cytoplasm and cell membranes divide to form daughter cells

Diploid

46 chromosomes

Interphase [3]

• cell grows

• cell replicates chromosomes

• organelles replicated

Prophase [3]

• chromosomes condense

• nuclear membrane dissolves

• spindle fibres form

Metaphase [2]

• nucleus dissolves

• chromosomes align in centre

Anaphase [1]

• chromosomes moved to opposite poles of cell

Telophase [3]

• just before cells split

• nuclear membranes reform

• spindle fibres dissolve

Cell cycle order

• interphase

• prophase

• metaphase

• anaphase

• telophase