Biology - Cell Divison

Define cell continuity

When cells develop from other existing cells

State the composition of a chromosome

DNA and protein

State the location of chromosomes in a cell

Nucleus

Define the term haploid cell and name an example

Has one set of chromosomes (e.g. sperm and eggs)

Define the term diploid cell and name an example

Has two sets of chromosomes (e.g. skin cells)

Define the term homologous pair

Two chromosomes with similar genes

List the two stages of the cell cycle and which one is shorter

Interphase and mitosis, mitosis is shorter

Define mitosis

When one nucleus divides into two identical nuclei

Function of mitosis in a single celled organism

asexual reproduction

Function of mitosis in a multi cellular organism

Growth and repair of cells

List the four stages of mitosis in order

Prophase, Metaphase, Anaphase, Telophase

prophase

chromosomes are double stranded. spindle fibres start to move to the poles stage 1. 30m

metaphase

chromosomes line up in the equator. spindle fibres attach to the chromosome. membrane of nucleus is broken down. 30m stage 2,

Define centromere

The point at which chromosomes are attached together in a double stranded structure

anaphase

stage 3. spindle fibres contract chromosomes pulled apart chromosomes move towards the poles. about 10m

telophase

stage 4, chromosomes change back into chromatin. membrane of the nucleus is reformed. takes about 30m.

Name the feature that allows animal cells to split in two

Cleavage furrow

Name the feature that allows plant cells to split in two

Cell plate

Define cancer

when a cell loses the ability to control the rate of mitosis. This forms a mass of cells called a tumour

Define carcinogen

Cancer causing agent

Define oncogene

Cancer causing genes

Distinguish between a benign and malignant tumor

A benign tumour does not invade other cells and stops dividing after some time, a malignant tumour invaded other cells and is an uncontrolled division of tumours

Define meiosis

Where a nucleus divides into four new nuclei that are not identical and contain only half the number of chromosomes as the parent nucleus

State two functions of meiosis

Allows sexual reproduction/ allows for greater variation within a species

Where does meiosis occur in males

Testes

Where does meiosis occur in females

Ovaries

chromatin

Long thin threads of DNA which is found in the nucleus of cells that are not dividing.

gene

section of dna that contains the structure for the formation of a protein.