Topic 2A Cell division and stem cells Flashcards
Where is our genetic material stored?
In the nucleus as chromosomes.
What are chromosomes?
Chromosomes are long lengths of a molecule called DNA.
What is the cell cycle?
When the body cells in multicellular organisms divide to produce new cells.
What is mitosis?
When a cell reproduces itself by splitting in two to form two genetically identical offspring.
What two processes take place at the same time?
Mitosis and Cytokinesis.
What happens during the cell cycle?
Interphase.
What are the 4 stages of mitosis?
Prophase, Metaphase, Anaphase and Telophase.
Explain what interphase is
Where the cell grows, the amount of subcellular structures increase and the DNA is copied.
Explain prophase
Chromosome becomes dense, membrane around the nucleus breaks down and chromosomes lie in the nucleus.
Explain metaphase
Chromosomes line up at the centre of the cell.
Explain anaphase
Cell fibres pull chromosomes apart. Two arms of chromosomes go to opposite ends of the cell.
Explain telophase
Nucleus now divides as as membrane forms around each set of chromosomes.
What are the uses of mitosis?
By multicellular organisms to grow.
By multicellular organisms to replace cells that have been damaged.
By some organisms to reproduce by asexual reproduction.
How to calculate the the number of cells?
number of cells=2^n
(n is the number of divisions in mitosis)
What processes do plants and animals grow and develop by?
Cell division and cell differentiation.
Plants also grow by cell elongation.
Explain cell differentiation
When a cell changes to become specialised for its job.
Explain cell elongation
Where a plant cell expands making the cell bigger and so making the plant grow.
What’s growth in animals?
Cell division used to grow when animal is young then for repair as an adult.
What’s growth in plants?
Plants height mainly due to cell elongation and cell division on the roots and shoots.
How does change in genes affect the body?
A change in gene will make the cell divide uncontrollably so growth doesn’t stop and can result in tumours. This invades and destroys surrounding tissue causing cancer.
What is a percentile chart?
A chart which measures a baby’s growth and development to create a pattern and problems can be spotted.
What are stem cells?
Undifferentiated cells. Adult cells are used to cure disease.
Where are stem cells found?
Stem cells are found in early human embryos that have the ability to divide and produce any cell.
What may embryotic stem cells help with?
It may be possible to use embryonic stem cells to replace faulty cells in sick people.
