Topic B2 Flashcards
Cell cycle
A series of stages in which cells divide to produce new cells
What is a cell in when it is not dividing?
Interphase
What does a cell do before it is dividing?
-copy some of its subcellular structures
-Make a copy of its DNA
Mitosis
Stage of a cell cycle when the cell divides
Prophase
1st stage
Membrane around nucleus breaks down
Metaphase
2nd stage
Chromosomes lineup at the centre of the cell
Anaphase
3rd stage
Chromosomes split in half
-Each half pulled to opposite ends of the cell
Telephase
4th stage
Membranes form around chromosomes
Cytokinesis
5th stage
Cytoplasm and cell membranes divide into 2 daughter cells
What does mitosis allow?
Organisms to grow or replace cells that have been damaged
Where is mitosis sometimes used?
Asexual reproduction
Plants and animals methods of growth
-Cell differentiation (when a cell changes to become specialised for its job)
-Cell division
-Cell elongation
What are percentile charts used for?
-Monitor a child’s growth (Mass length and head size)
What does the 50th percentile mean?
The size 50% of babies will have reached at certain age
When my doctors be concerned over a percentile chart?
If a baby size is below the 0.4th percentile or changed by more than 2 percentile lines over time
Stem cells
Undifferentiated cells that can divide to produce lots more stem cells and can differentiate into many other types of cell
Adult animal stem cells can become..
Many kind of cell
Human embryo stem cells can become..
Any kind of human cell
Plant meristem stem cells can become..
Any kind of plant cell
Where can stem cells be grown?
In a lab
What can be done with specialised cells?
-Transferred into people
-Used in medicine
Benefits of stem cells
Could replace cells that could have been damaged e.g. new heart muscle cells could treat heart disease
Risks of stem cells
-Tumours
-Disease
-Rejection by immune system
Neurones
Cells that carry information as electrical impulses in the nervous system
What does the nervous system allow?
Humans can react to their surroundings and coordinate their behaviour
What does the CNS consist of
Brain and spinal cord
Order of nervous system
- Stimulus
- Sensory receptor
- Sensory neurone
- CNS
- Motor neurone
6. Effector (muscles or glands) - Response
Sensory neurone
Carries impulses from receptor cells to the CNS
Motor neurone
Carries impulses from the CNS to effector cells
Relay neurone
sensory neurones>motor neurones
What does the myelin sheath do?
Speeds up the electrical impulse
Synapse
The connection between 2 neurones 
What happens in a synapse?
An electrical impulse is transferred across it by neurotransmitters moving across the gap
Reflexes
Rapid, automatic responses that don’t involve the conscious part of the brain. They can reduce the chance of injury.
Reflex arc
The passage of information reflex, from receptor to effector 
The five steps in a reflex arc
1.Simulation of receptor
2.Impulses travel along sensory neurone>relay neurone>motor neurone
5.Effector responds
