Mitosis Flashcards
What does the nucleus contain
Your genetic material in the form of chromosomes
What are chromosomes
Coiled up lengths of DNA molecules
What do genes do
They control the development of different characteristics
What do chromosomes carry
Large number of genes
How many copies of chromosomes do bodies cells have
They have two copies of each chromosome - one from the father and one from the mother
How many pairs of chromosomes do humans have
23 pairs
How many chromosomes do humans have
46
What is mitosis
The stage of the cell cycle when it divides
1st stage of cell cycle - growth and repair
At the start of interphase the new cells, formed by mitosis and cytokinesis grow
Then the DNA and organelles, such as mitochondria, are replicated ready for cell division
A cell is interphase for the majority of its lifespan
2nd stage of cell cycle - mitosis
4) At the start of mitosis chromosomes condense making them visible under a microscope
5) the chromosomes line up in pairs at the centre of the cell and the cell fibres pull them apart. The two arms of each chromosome go to the opposite ends of of the cell
- membranes form around each of the sets of chromosomes, these become nuclei of the two cell, the nucleus then divides
What is differentiation
The process when a cell changes to become specialised for its job
What are stem cells
Undifferentiated cells that can develop into one or more types of specialised cell
What can stem cells do
They can differentiate into different types of cells depending what instructions they are given and can divide to produce lots more undifferentiated cells
Where are embryonic stem cells found
Early human embryos
Where are adult stem cells found
Bone marrow
Difference between embryonic stem cells and adult stem cells
Adult stem cells can only turn into certain types of cells whilst embryonic stem n turn into any kind of cell
What can stem cells from embryonic and bone marrow do
- they can be grown in a lab to reduce clones and differentiate into specialised cells to use in medicine or research
How are adult stem cells used to cure disease
The stem cell is transferred from the bone marrow of a healthy person to replace the fatty blood cells in a sick patient
How can embryonic stem cells be used in medicine
- they can replace fatty cells in sick people
- they can be used to make insulin producing cells for people with diabetes
- they can be used to make nerve cells for people paralysed by spinal injuries
How does therapeutic cloning works
An embryo is made to have the same genetic information as the patient so the stem cells produced from it would also contain the same genes and would be rejected by the patients immune system and once inside the patient the stem cells can then differentiate to replace cells which have stopped working correctly
Risks of stem cells in medicine
- stem cells grown in labs may be contaminated with a virus which could be passed onto a patient, making them sicker
Why are some people against stem cell research
- as they feel that human embryos should not be used for experiments since each one is a potential human life
- they feel that scientists should concentrate more in finding and developing other sources of stem cells so people could be helped without having to use embryos
Why are some people for stem cell research
- they argue that embryos used in research are usually unwanted ones from fertility clinics so if they weren’t used for research they would be destroyed
- they think curing patients who are suffering is more important than the rights of embryos
Where are stem cells found in plants
Meristem
What are the stem cells in plants used for in agriculture
- to produce clones of the whole plant quickly and cheaply
- to grow more plants of rare species to prevent them being wiped out
- to grow crops of identical plants that have desired features for farmers
How are embryos formed
1)sperm cell joins with the ovum through fertilisation
2) the fertilised ovum goes under mitosis and forms a ball of cells called an embryo
Bone marrow transplant - how to treat leukaemia
1) the patient existing bone marrow is destroyed using radiation
2) the patient then receives a transplant of bone marrow from a donor
3)the stem cells in the bone marrow divide and form a new bone marrow and can also differentiate to form blood cells
Disadvantages of bone marrow transplant
- donor has to be compatible with the patient or the white blood cells produces by the donated bone marrow could attack the patient’s body
- risk that viruses can be passed from the donor to the patient
What medical conditions do therapeutic cloning help with
- diabetes
- paralysis
How long can plant cells differentiate for
Throughout the plants life
What is leukaemia
Cancer in the bone marrow
what happens in cytokenesis - stage 3
8) the cytoplasm and the cell membrane divides and this produce two daughter cells which are genetically identical and their DNA is also identical to the parent cell
