Topic 2: Cell Division and Stem Cells Flashcards
A* LFG
What is a chromosome?
The structure made of DNA that codes for all the characteristics of an organism.
Where is a chromosome found?
Found in pairs in the nucleus of the cell.
What does a chromosome do?
Carry genetic information in a molecule called DNA.
What is DNA?
Carries information about how an organism looks and functions.
Is everyone’s DNA different?
Everyone’s is different but identical twins who share the same DNA.
How many chromosomes do human’s have?
46 (23 pairs)
What is a gene?
A short length of DNA.
What is an allele?
Alleles are different versions of the same gene.
(for example:
gene= eye colour
allele=blue eye colour)
What do genes code for?
They code for a specific protein.
What is mitosis?
A type of cell division that creates cells with identical genetic information.
When does mitosis occur?
When an organism grows, needs to replace worn-out cells or needs to repair damaged tissue.
How many cells does mitosis produce?
2 (daughter) cells.
How many divisions occur in mitosis?
1
What is the process of mitosis?
The cell begins its divide
DNA replicates to form two copies of each chromosome
The nuclear membrane breaks down and the chromosomes line up across the centre of the cells
One set of chromosomes is pulled to each end of the cell and the nucleus divides
The cytoplasm and cell membranes divide to form two identical cells.
What happens when a cell becomes cancerous?
It begins to grow and divide uncontrollably.
What is cancer?
A disease caused by normal cells changing so that they grow and divide in an uncontrollable way.
What is a group of cancerous cells that causes a lump called?
A tumour.
What causes cancer?
Carcinogens
Mutations
Genetic factors
Lifestyle factors
What is a carcinogen?
A chemical or other agent that causes cancer.
What do carcinogens do?
Damage DNA which can cause mutations to occur (a random change in the structure of a gene, chromosome or number of chromosome).
What lifestyle factors increase risk of cancer?
HPV
Cigarettes
Alcohol intake
Ultraviolet radiation
Poor diet
Exposure to smoke
What is meiosis?
A type of cell division that produces gametes.
What is a gamete?
A sex cell (sperm/egg)
What is a zygote?
A fertilised egg cell.
How is a zygote created?
The fusion of a male and female gamete.
How many chromosome does a gamete have?
23 (half).
What is an embryo?
An organism in the early stages of development.
What are the gametes in an animal?
Sperm and eggs.
What are the gametes in flowering plants?
pollen and eggs.
How many gametes are formed in meiosis?
4.
How many cell divisions occur in meiosis?
2.
Are all gametes genetically the same?
No, they are different.
How are mitosis and meiosis different in the production of cells?
Mitosis produces genetically identical daughter cells. Meiosis produces genetically varied daughter cells.
How are mitosis and meiosis different in the amount of chromosomes produced?
Mitosis’s daughter cells have a full set of chromosomes. Meiosis’s daughter cells have half a set of chromosomes.
What is the difference in amount of cells produced in mitosis and meiosis?
Mitosis produces 2 daughter cells. Meiosis produces 4 daughter cells.
What is the difference in why mitosis and meiosis produce cells?
Mitosis occurs for growth, to replace worn-out cells and to repair damaged cells. Meiosis occurs for the formation of gametes in sexual reproduction.
What is a stem cell?
Cells that have not undergone differentiation.
Where are stem cells found?
In foetuses, embryos and some adult tissues.
What is differentiation?
When an unspecialised cell becomes a more specialised cell type.
What is a specialised cell?
A cell that has become more differentiated to carry out a particular function.
What is an example of a specialised cell?
Nerve cells, blood cells, and reproductive cells
you can say any
What is an embryonic stem cell?
A type of cell that is removed from the embryo.
What is an adult stem cell?
A type of stem cell that remains in the body.
Where can adult stem cells be found?
Examples: brain, eyes, blood, heart, bone marrow.
What can adult stem cells only differentiate into?
Related cell types only.
What are some medical conditions and diseases that stem cells could help treat?
Type 1 diabetes
Multiple sclerosis - can lead to paralysis
Spinal cord or brain injury - can lead to paralysis
What is the differences between embryonic and adult stem cells?
Embryonic: wider range of cell types to differentiate to + difficult to obtain
Adult: narrower range of cell types
What are the clinical issues of using stem cells in medicine?
No guarantee how successful the therapies will be
Difficult to find suitable stem cell donors
Difficult to obtain+store embryonic cells
May transfer cancerous cells if mutated
What are some ethical issues of using stem cells in medicine?
Is it right to make embryos for therapy + destroy them in this process
Embryos viewed as a developing person - some people believe it is playing god to use these embryos
What is a social issue with stem cell use?
Patients may be exploited if treatments don’t work
