Topic 2: Cells & Control Flashcards
What is a cell cycle?
A series of stages where cells divide to produce new cells
When a cell isn’t dividing, it’s in interphase. What three things does the cell do before dividing?
- Grows in size
- Increases amount of sub cellular structures
- Duplicates DNA
What is mitosis?
The stage of the cell cycle when the cell divides.
What are the 5 phases of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What is prophase?
When chromosomes condense from DNA
The membrane around nucleus breaks down
What is metaphase?
Chromosomes line up across the equator of the cell
Spindle fibres attach to the centromere on the chromosome
What is anaphase?
Spindle fibres contract & pull apart the chromosome to the opposite sides of the cell
What is telophase?
Nuclear membrane forms around the two sets of chromosomes
What is cytokinesis?
2 genetically identical diploid cells daughter are produced
How to remember stages of mitosis?
Pee MAT Cat
What does mitosis do?
Allows organisms to grow or replace cells that have been damaged
What are the three methods of growth?
- Cell differentiation - when a cell changes to become specialised for its job
- Cell division - mitosis
- Cell elongation (plants only)
What is a percentile chart?
They’re used to monitor a child’s growth
Used to see if there should be a cause for concern for the baby
E.g. 50th percentile = the size that 50% of children will reach at a certain age
What are stem cells?
Undifferentiated cells that divide to produce lots more stem cells, these can differentiate into many other types of cells
Can be grown in a lab and made to differentiate
What can stem cells from adult animals become?
A limited amount of cells
What can stem cells from a human embryo become?
Any kind of human cell
There are moral and ethical arguments against the use of these
What can stem cells from plant meristem become?
Any kind of plant cell
What are some potential benefits of the uses of stem cells in becoming differentiated for medicine?
Could replace cells that have been damaged by disease or injury
E.g. cardiac muscle cells treat heart disease
What are some potential risks of the uses of stem cells in becoming differentiated for medicine?
Tumour development
Disease transmission (if the donor stem cells are infected with a virus)
Rejection by patients immune system
What are the 3 parts of the brain?
- Cerebrum
- Cerebellum
- Medulla oblongata
What is the role of the cerebrum?
Controls: movement, intelligence, memory, language & vision
2 parts of the cerebrum (hemispheres) - right hemisphere controls movement of the left side of the body & left hemisphere controls movement of the right side of the body
What is the role of the cerebellum?
Controls: muscle coordination & balance
What is the role of the medulla oblongata?
Controls: unconscious activities
What is the CNS?
Consists of the brain and spinal cord
CNS = centralised nervous system
Why is treating and investigating the CNS and brain difficult?
Complex and delicate
CNS nervous tissues cannot be repaired
Operating on the brain or spinal cord risks permanent damage
Tumours can grow in parts of the brain that are hard to access
What are neurones?
Cells that carry information as electrical impulses in the nervous system. The nervous system means that humans can react to their surroundings and coordinate their behaviour.
What’s a neurotransmitter?
Chemical messenger
E.g. dopamine
How does the reflex arc work?
Stimulus
Receptor
Sensory neurone
Synapse
Relay neurone
Synapse
Motor neuron
Effector
Release
How to remember the process of the reflex arc?
Smelly - Stimulus
Rectum - Receptor
Smelly - Sensory neurone
Smelly - Synapse
Rectum - Relay neurone
Smelly - Synapse
Men - Motor neurone
Eat - Effector
Rectum - Release
What is a synapse?
The connection between two neurones
A nerve signal is transferred across a synapse by the diffusion of neurotransmitters
What are effectors?
Effectors can be muscles (which respond to nervous impulses by contracting) or glands (which secrete hormones)
What are the 3 types of neurones?
- Sensory neurone
- Motor neurone
- Relay neurone
What does a sensory neurone do? What is its structure?
Converts a stimulus into an electrical impulse and transmits the impulse from receptor cells to the relay neurone in the spinal cord by neurotransmission
Structure: receptor cells detect electrical impulse, dendrite, cell body, axon where the impulse is transmitted/passes through
What does a motor neurone do? What is its structure?
Transmits electrical impulses from the relay neurones to effector cells to generate a response
Structure: cell body, dendrites, myelin sheath which insulates the axon and speeds up the impulses, axon which passes the impulse, effector cells
What does a relay neurone do? What is its structure?
Carries impulses from the sensory neurones to the motor neurones
Structure: cell body where the impulse is detected, dendrites, axon where the impulse passes through
What is the role of the myelin sheath?
Insulates the axon
Speeds up electrical impulses
What is a reflex?
Rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain, they can reduce the chance of injury
What is a reflex arc?
The passage of information in a reflex, from receptor to effector
What are the steps of the reflex arc?
- Stimulation of receptor
- Impulses travel along sensory neurone
- Impulses passed along relay neurone in CNS
- Impulses travel along motor neurone
- Effector responds, e.g. muscle contracts
How do painkillers work?
Painkillers act on neurones in the spinal cord
They block the release of neurotransmitters
If the neurotransmitter isn’t released, no impulse can be generated in the next neurone
What are the stages of neurotransmission?
- Electrical impulses reaches axon terminal
- Vesicles are triggered to release neurotransmitters
- Neurotransmitters diffuse across the synapse
- Electrical impulse is generated at the dentrite
- The electrical impulse travels down the next neurone
What is the structure of the eye? (Outside —> inside)
- Cornea
- Pupil
- Iris
- Lens
- Retina
- Optic nerve
What is the role of the cornea?
Refracts light into the eye
What is the role of the iris?
Contains muscles controlling pupil size
What is the role of the lens?
Focuses light onto the retina
What is the role of the retina?
Contains receptor cells that are sensitive to light intensity (rods) and colours (cones)
What is the role of the optic nerve?
Carries impulses from receptor cells to the brain
How does the eye focus to look at near objects?
Lens becomes thicker
Light refracted more
How does the eye focus to look at distant objects?
Lens becomes thinner
Light refracted less
What are the four common defects of the eye?
- Long sightedness
- Short sightedness
- Colour blindness
- Cataracts
What is longsightedness and how can it be fixed?
When lens doesn’t bend light enough or eyeball is too short so image of near objects is brought into focus’s behind the retina
Fixed using convex lens
What is shortsightedness and how can it be fixed?
When lens bends light too much or eyeball is too long so images of distant objects are brought into focus in front of retina
Fixed using concave lens
What is colour blindness?
When some cones (eye receptors that allow colour to be seen) don’t work properly and so colours are hard to tell apart
What are cataracts and how can they be fixed?
They’re cloudy patches on the lens and therefore cause blurred vision
Fixed by replacing lens with an artificial one
What is the function of the reflex arc? Why?
To protect the body against dangers and threats - creates an involuntary response to a stimulus
What are the 3 scanning techniques?
- CT scans
- PET scans
- MRI scans
What is an awake craniotomy?
When peoples brains are operated on whilst they are awake - to ensure no other parts of the brain have been harmed
What is PET scanning?
When a radioactive tracer is swallowed, these tracers collect in areas of increased blood flow (where there are clots and tumours)
Advantages of PET scans?
Structure and function of the brain can be studied
Helps understand diseases like Parkinson’s
What is a CT scan?
When a 3D image of the brain is produced using X-rays
Advantages of CT scans?
Physical features of the brain are shown
Allows any visualisation of any tissue
Disadvantages of CT scans?
Don’t directly show function of the brain structures
Not recommended for pregnant patients or children - x ray radiation is given at a higher level than normal x rays
What are all 6 stages of the cell cycle?
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
