B2 CELLS AND CONTROL Flashcards
What is the cell cycle
The life of a cell comprising interphase and mitosis
What is interphase
Preparation for mitosis in which extra cell parts are made and DNA chromosomes are replicated
What is mitosis
When one cell divides into two genetically identical daughter cells.
What is PMATC
Stages Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
What is prophase
The membrane of the nucleus breaks down and spindle fibres start to form
What is metaphase
Spindle fibres fully form and chromosomes line up across the middle of the cell
What is anaphase
Chromosomes copies separate and move to each end of the cell
What is telophase
A new membrane forms around each set of chromosomes to for two nuclei
What is cytokinesis
The two new cells fully separate
What is cancer
When mitosis happens out of control forming large lumps of cells called Tumours
Growth
Increase in size due to increased numbers of cells
Percentile
A measure of the growth of a child that compares them to other children of the same age
90th percentile
A child is taller than 90% of children of the same age
50th percentile
Average for height/mass for the age
Percentile graphs
Graphs showing how height/mass change with age with different lines for each percentile
Cell differentiation
When a cell divides by mitosis to produce two different types of cell
Specialised cell
A cell special features designed for a specific job
Importance of differentiation in animals
To produce all the different types of cell the body needs such as red blood cells fat cells nerve cells and muscle cells
Plant growth
Cell division creates more cells elongation makes these cells get bigger
Meristems
Areas just behind the tips of roots and shoots where cell division and differentiation happens
Importance of differentiation in plants
To produce all the different types of cell a plant needs such as root hair cells and xylem cells
Calculating percentage changes
% change = (final value - starting value ) / starting value x 100
Stem cell
A cell that can differentiate when it divides, to produce two different cells
Embryonic stem cell
A stem that can become any kind of cell
Found in developing embryos
Adult stem cell
A stem cell that can only become w few types of cell
Found in animals after birth
Stems cells in medicine
It’s is hoped they can be used to replace damaged cells in diseases like type 1 diabetes or leukaemia, or to grow new organs for transplant
Problems with stem cells
They may potentially cause cancer stem cells can only be used in the person they have come from
Nervous system
All the nerves in your body working together to gather information make decisions and control responses
Central nervous system
The brain and spinal cord - makes decisions
Peripheral nervous system
All your other nerves gathers information from your sense and carries messages from the CNS to your muscles
Neurone
A nerve cell
Impulse
Electrical message carries by a neutron
Cell body
The central part of a nerve cell containing its nucleus
Dendron and axon
The long parts of a nerve cell carrying out impulses towards the cell body and away form it
Myelin sheath
A fatty layer around the axon and dendron that insulates it to prevent the impulse from escaping and speeds the impulse up
Neurotransmission
The travelling of an impulse along a neuron and into another
dendrites
branches at the beginning of a dendron that connect to receptor cells or another neuron
axon terminals
branches at the end of an axon that connect to a muscle or another neuron
synapse
small gap between two neurons where the axon terminals of one meet the dendrites of another
neurontransmitter
chemicals released by axon terminals that diffuse across the synapse to trigger a new impulse the dendrite of another neuron
sensory neuron
nerve cell that carries impulses from sense organs to the CNS has a long dendron and a long axon
relay neuron
nerve cell in the CNS that makes decisions. dendrites join onto cell body short axon
motor neuron
nerve cell that carries impulses from the CNS to muscles dendrites join onto cell body long axon
stimulus
a piece of information detected by the nervous system
receptor
cells that detect a stimulus
response
the action that the produces the response , often a muscle
effector
the body part that produces the response , often a muscle
voluntary movement
a stimulus is detected by a receptor , causing an impulse to be carried by a sensory neuron to the brain. replay neurons in the brain decide what to do and send another impulse down a motor neuron to the effector to cause a response
reflexes
automatic responses that happen very quickly without conscious thought to keep the body safe
reflex arc
movement is caused in the same way as for voluntary movement except the spinal cord makes the decision without needing the brain to think
