Topic 2a: Mitosis & Stem Cells - PAPER ONE Flashcards
What does mitosis produce?
2 genetically identical diploid daughter cells, each with identical sets of chromosomes in the nucleus to the parent cell
Describe the process of interphase, mitosis and cytokinesis
IPMAT
Interphase: Cell grows to increase subcellular structures, DNA in cell duplicates so that there’s one copy for each cell
Mitosis:
Prophase - Chromosomes condense; membrane around the nucleus breaks down; chromosomes lie free in the cytoplasm
Metaphase - Chromosomes line up at the centre of the cell; spindle fibres attach to chromosomes at the centromere
Anaphase - Spindle fibres pull chromosomes apart to the edge of the cell
Telophase - Nuclear membranes form around each set of chromosome to become the nuclei of the two cells, separating them from one another
Cytokinesis - Before telophase ends, cytoplasm and cell membrane divide to form two separate diploid cells with identical chromosomes
What is mitosis?
A stage of the cell cycle when the cell divides
Why is mitosis important?
(3 functions)
Growth - More cells for growing organism
Repair - Replacing cells that have been damaged
Asexual reproduction - Produced genetically identical offspring
What is cancer?
A result of a change in cells (e.g. a mutation) that lead to uncontrollable cell division BY MITOSIS. This can result in a mass of abnormal cells called a tumour which destroys surrounding tissue.
What are the different ways in which plants and animals grow?
Cell differentiation: a cell changes to become specialised for its job
Cell division: by mitosis - animals’ cells divide at a fast rate when young, but when you get old most cell division is for repair
Cell elongation: In plants (grow continuously) - makes a plant’s cells expand
What are stem cells?
Undifferentiated cells (cells that haven’t become specialised)
where are embryonic and adult stem cells found? What is their function?
Embryonic stem cells:
- Found in early human embryos
- Have the potential to divide and produce any kind of cell
- So, stem cells are important for growth and development of organisms
Normal stem cells:
- Adults have stem cells but only found in places like bone marrow
- Not as versatile as embryonic stem cells (can’t produce any cell type)
- Used to replace damaged cells
Explain the importance of specialised cells
Allow multicellular organisms to work more efficiently
Describe the function of stem cells in plants
- Found in the meristem (tissue in areas of a plant that are growing - tips of roots and shoots)
- Meristems produce unspecialised cells that can divide and form any cell type
- These cells can divide and differentiate for as long as the plant lives
- Unspecialised cells form specialised tissues like xylem and phloem
What are the risks of using stem cells in medicine?
- Stem cells divide very quickly. So, if scientists can’t control the rate at which the transplanted cells divide inside the patient, a TUMOUR may develop
- If donor stem cells are infected with a virus, the virus could be passed on to the recipient making them sicker
- The patient’s body may recognise the cells as foreign and trigger an immune response to reject the,. The patient can take drugs to suppress this response, but this makes them susceptible to diseases
What are the benefits of using stem cells in medicine?
- Adult stem cells have been used to cure diseases e.g. bone marrow transplants
- Scientists extract stem cells from early human embryos and grow them to differentiate into specialised cells. So, they could create specialised cells to replace those damaged by a disease
What part of a plant root does cell division occur?
Meristem
