AQA GCSE cell divivsion

what is cell division

the division of a cell into two daughter cells with the same genetic material.

what are advantages of being multicellular

• allows organism to be larger

• allows for cell differentiation and specialise

• allows organism to be more complex.

what are the levels of oraganisation

organelle, cell, tissue, organ, organ system, organsim

what is an oragnelle

a part of cell with a particular role eg. ribosomes

what is a cell

building block of life eg. palasade

what is a tissue

A group of cells that act together to perform a specific function. eg. stem

what is an organ

A group of different tissues that work together to perform a certain function. eg. leaf

what is an organ system

A group of organs working together to perform a particular function eg. digestive system

what is an organism

A living thing eg. cats

what are chromosomes

Chromosomes are long, thin strings of genetic material made of DNA and proteins.

where are chromosmes stored

in the nucleus

what does DNA carry

carries the controls what your cells are made of

What is a chromotid?

half of a duplicated chromosome

what is base pairs

T = A

C = G

what is a homologous

Two genes that code for the same type of characteristic. but not always the same version

how many pairs do human cells have

23

why do cells need to divide

growth of a multicellular organism

replacment of worn out cells

repair to damaged tissues

what is the cell cycle

what is the interphase

period of the cell cycle between cell divisions

how to work out the length of time in phase

length of time in phase

( observed cells at that stage /observed cells)

* total lenght of time of cell cycle

What is mitosis?

Cell division that generates new cells for growth and repair. The division of one cell into two genetically identical daughter cells

describe the steps of mitosis

Prophase: chromosomes shorten and thicken, asters appear, and spindle fibers form. (Prometaphase): describes late prophase, marked by sister chromatids attaching via kinetochores. Metaphase: chromatids align at the cell's equator. Anaphase: chromatids separate and pull apart; errors may cause unequal genetic distribution. Telophase: chromatids reach opposite ends, and two nuclei form.

(Prometaphase): popular term to describe the events of late prophase. Marked by attachment of sister chromatids to specific fibers by a proteinaceous hook (kinetochore).

Metaphase: Chromatids align along the equatorial plane

Anaphase: Chromatids are separated and pulled apart. Errors during anaphase could result in an unequal distribution of genetic material.

Telophase: Chromatids move to opposite ends of the cell and two new nuclei are formed.

what are stem cells

unspecialized cells from which differentiated cells develop

what are stem cells early cells of

an embryo

uses of stem cells

- replacing faulty blood cells

- making insulin producing cells

- making nerve cells

What is theraputic cloning?

Producing an embryo with the same DNA as a patient, so that stem cells can be used for medical treatment. The stem cells will not rejected by the patient's body.

ethical concerns with uses of stem cells

destroying embroys

could have been a being

what is a plant stem cell

A cell that can differentiate into any type of plant cell throughout the whole life of the plant. it can be used to produce clones of plants quickly and economically. Found in the meristems in plants/

Uses of plant stem cells

• Rare species can be cloned to protect from extinction.

• Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.