Cells and Control - Flashcards
What is the cell cycle?
A cycle that most cells go through in order to replicate.
What are the 3 main stages of the cell cycle?
- Growth and replication of organelles (interphase)
- DNA replication (interphase)
- Mitosis
What happens during the prophase?
- the nuclear envelope begins to break down
- spindle fibres appear
- chromosomes become visible (they condense)
What happens during the metaphase?
- chromosomes line up at the equator of the cell
- spindle fibres attach themselves to these chromosomes at the equator
What happens during the anaphase?
- chromosomes break at the equator of the cell
- sister chromatids move to opposite ends with the spindle fibres still attached.
What happens during the telophase?
- nuclei membranes forms around the two chromosomes
- spindle fibres break down
- cytoplasm begins dividing
What happens during cytokinesis?
- cell surface membrane forms to separate two genetically identical cells
- (in plant cells) the cell wall begins to form.
What is growth?
a permeant increase in mass, size and length.
Why is it beneficial to have lots of cells?
So that these cells can be used for a specialised function.
What is differentiation?
The process of which stem cells become specialised cells.
Describe one feature of a fat cell.
It has fat droplets.
What are the advantages of using the meristem in plants?
- to produce rare plants
- to produce exotic plants
- for food production
What disadvantages does using stem cell treatment bring?
- it may be unethical for some people
- it can carry viruses
- if the cell is defected, it will pass on this defect
- if the cell division is uncontrollable - it could cause tumours which may be cancerous.
- unknown effects on the body
- it could be rejected from the patient’s body
- cells could differentiate into the wrong type of cell
What are the two parts of the nervous system and what do they consist of?
CNS (Central Nervous System) - The brain and the spinal chord
PNS - (Peripheral Nervous System) - All other nerves
What do ears sense?
Sound and position of head.
What does the tongue sense?
Chemicals in food.
What does the nose sense?
Chemicals in the air.
What do the eyes sense?
Light.
What does the skin sense?
temperature, touch, pressure and pain.
In what order is the Nervous System triggered?
stimulus –> receptor cells –> sensory neuron –> relay neuron –> motor neuron –> effector –> response.
Name two different types of effectors.
Muscles and glands.
Why is the myelin sheath useful?
It insulates the impulses which allow them to jump along the cell which speeds up the transmission.
How does a CT scan work?
It uses X-Rays. The affected part of the brain will absorb more X-Rays than the non-affected areas.
How does a PET scan work?
The patient ingests or is injected with a radioactive tracer like glucose. The machinery detects the gamma rays the radioactive tracer produces. The affected area of the brain will have a larger amount of ongoing chemical reactions than the non-affected areas.
