Cells And Control Flashcards
What is mitosis?
cell division, producing 2 genetically identical diploid body cells
What does haploid mean?
Only contains 23 chromosomes
Eg sperm and egg
What does diploid mean?
46 chromosomes
Eg animals
What is the cell cycle?
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
What happens in interphase?
New subcellular structures are made and dna replicates
What happens in prophase?
Nucleus breaks down and spindle fibres begin to form
What happens in metaphase?
Spindle fibres attach to the chromosome which then line up in the equator of the cell
What happens in anaphase?
Spindle fibres shorten pulling the chromosomes to the poles of the cell
What happens in telophase?
Two new nuclei form
What happens in cytokinesis?
Cytoplasm splits to form two new cells
How can mitosis cause cancer?
When cell division becomes out of control and form lumps of cells called tumours
What is cell differentiation?
Stem cells are able to change to become specialised cells
What is cell elongation?
Plant cell expands making the cell bigger
What happens in animal growth?
Cell division
No elongation
Stop growing when adults
What happens in plant growth?
Cell division
Elongation in shoot and root tips
Don’t stop growing
What are growth percentile charts used for?
To assess a child’s development over time
What are stem cells?
Undifferentiated
Can divide to make more cells or can differentiate into specialised cells
Where are plant stem cells found?
Meristem
What can embryonic stem cells do?
Become almost any type of cell in the body so the embryo can become a full person
Where are adult stem cells found?
Only in certain places in differentiated tissues
Adult stem cells can only become…
A small range of cell types
How are stem cells used in medicine?
Doctors can make stem cells differentiate into the type of cell that is damaged in the ill person and inject them where they are needed
Also used to test new drugs
Why can’t adult stem cells be used to treat every disease?
Difficult to remove
Why would taking adult stem cells from the ill person be beneficial?
They are less likely to be rejected by the body’s immune system
Why are embryonic stem cells easy to extract?
An embryo is just a ball of cells and can become almost any cell type
Why would embryonic stem cells be rejected by the ill person’s immune system?
Because it doesn’t come from the ill persons body
What is an ethical objection of using an embryonic stem cell?
Catholics believe life begins at fertilisation so it would be seen as murder
What is the cns?
Central nervous system
Brain and spinal chord
What is the peripheral nervous system?
The rest of the body, made up of lots on nerve cells called neurones
What is a stimulus?
Change in environment
What do neurones do?
Carry electrical signals called impulses to the cns which coordinates the response and sends impulses to effectors which bring about the response
What is sending impulses called?
Neurotransmission
What is the order of neurotransmission?
Stimulus Receptor Sensory neurone Relay neurone Motor neurone Effector Response
What does the myelin sheath do?
Insulates and speeds up transmission
What is a reflex arc and why is it needed?
When we need to react fast, the impulse only goes to your spinal chord, not your brain which makes it faster
What is a synapse?
Gaps between neurones
What do synapses do?
Convert electrical energy into chemical energy
What do neurotransmitters do?
Diffuse across the synapse
