Cells and control (2) Flashcards
Define mitosis.
Mitosis is a type of cell division involving a mother cell splitting into two identical daughter cells for growth and repair.
Describe the stages of mitosis.
Interphase - the mother cell duplicates its DNA forming an exact duplicate of each chromatid.
Prophase - the chromosomes condense and the membrane of the nucleus starts to break down into spindle fibres.
Metaphase - the chromosomes line up in the middle of the cell.
Anaphase - chromosomes are pulled to either side of the cell on spindle fibres.
Telophase - membranes form around each set of chromosomes.
Cytokinesis - cytoplasm and cell membrane divide splitting the cell into two identical cells.
Define growth.
A permanent increase in size or mass.
What is cell differentiation?
The process in which a cell becomes specialised.
What is cancer and how does it affect people?
Cancer is uncontrolled cell division. It forms a tumor which invades and destroys surrounding tissue.
What is the difference between embryonic and adult stem cells?
Embryonic:
Found in embryos and can differentiate into any cell.
Adult:
Found in bone marrow and can only differentiate into damaged cells like skin and red blood cells.
How do stem cells in plants work?
Found in meristem in roots and shoots and can divide and form any kind of cell for as long as the plant lives.
How can stem cells be used in medicine?
- Treat sickle cell anemia with bone marrow transplant.
- Use embryonic stem cells to replace damaged cells in the future.
Risks of using stem cells in medicine.
- Tumours can develop as stem cells divide rapidly.
- Disease transmission as viruses can live inside cells.
- Cells can be rejected by the person’s immune system making them vulnerable to diseases.
How does the brain work?
Cerebral cortex is split into two hemispheres and manages language, intelligence and memory. The right side communicates with the left side of the body and vice versa. Cerebellum is responsible for muscle coordination and balance. Medulla oblongata controls unconscious like heart rate and breathing.
What’s the difference between a CT scan and PET scan?
CT scan:
Produces images of structures of the brain.
PET scan:
Use radioactive chemicals to show active areas of the brain. Shows structure and function of the brain.
How does the eye focus on things?
Distant objects:
Ciliary muscle relaxes which allows the suspensory ligaments to pull tight making the lens less round so the light is refracted less.
Near objects:
Ciliary muscle contracts which allows the suspensory ligaments to slacken and make the lens more round to refract light more.
Long sightedness and short sightedness.
Long sightedness:
Cannot focus on near objects because lens doesn’t refract light enough or eyeball is too short so light focuses behind retina. Can be fixed with converging lens.
Short sightedness:
Cannot focus on far objects because lens refracts light too much or eyeball is too long so light focuses before retina. Can be fixed with diverging lens.
