B2 Cells and control

Mitosis

Body cells making copies of themselves for growth and repair by splitting to form two genetically identical offspring

Order of cell cycle

• interphase

• prophase

• metaphase

• anaphase

• telophase

• cytokinesis

Interphase

Growth and cloning

Prophase

membrane breaks down

Metaphase

Chromosomes go middle

Anaphase

Segregation in cell

Telophase

New membrane forms

Cytokinesis

Cell pinches and divides

Meiosis

a form of cell division which produces four non-identical haploid sex cells or gametes

How is cancer caused

mutations in cells that lead to uncontrolled cell division

how does growth occur in animals through cell division and differentiation

• Growth and cell division = mitosis

• mitosis increases the number of cells allowing tissues and organs to grow

how does growth occur in animals through differentiation

• differentiation is when cells become specialised for specific functions

growth in plants

• cell division - occurs in meristems found at tips of roots

• cell elongation - when cell grows longer

• differentiation - allows specialised type of cells

embryonic stem cells

• cells found in early stage embryos

• they can develop into any cell in the body

• made to differnetiate

stem cells

• include both embryonic stem cells and adult stem cells

• adult stem cells are found in tissues like bone marrow and skin

• can develop into a limited range of cell types

• made to replace damaged or dead cells and contribute to tissue repair and regeneration

meristems in plants

• regions in plants where rapid cell division occurs

• found in tips of roots

benefits of stem cells in medicine

• regenerative medicine

• treatment of blood disorders

• personalised medicine

• drug testing and development

risks of stem cells in medicine

• tumors

• immune rejection

• ethical concerns

• unknown long-term effects

cerebral hemisphere

• structure - largest part of the brain divided into left and right

• function - higher brain functions and sensory information

cerebellum

• structure - located back of the brain below the cerebral hemisphere

• function - muscle movement, balance, coordination, posture, smooth/preciseness

medula oblongata

• structure - at the base of the brain connecting the brain to the spinal cord

• function - subconscious movement and reflex actions

why is it hard to access brain tissue in the skull

• skull protects brain

• brain surgery is invasive and risky

how CT scanning helps investigate brain functions?

• CT scanning uses X-rays to create detailed images of the brains structure

• non invasive

how PET scanning helps investigate brain functions?

• PET scanning uses radioactive tracer injected into the body to measure brain activity

• Non invasive

limitations of treating brain damage

• complexity of the brain

• surgical risk

• limited regeneration

limitations of treating spinal injuries

• limited ability to regenerate

• complex

limitations of treating brain tumours

• invasive treatment

• its in the brain

sensory receptors

detect stimuli and convert them into electrical impulses

sensory neurones

transmit electrical impulses from sensory receptors to the central nervous system

relay neurones

connect sensory neurones to motor neurones and process information within the CNS

motor neurones

carry electrical impulses causing movement or secretion

synapse

• gap between two neurones

• neurotransmitters help pass impulse across the gap

axon, dendron and myelin sheath

• axon carries impulses away from neurone

• dendron - carries impulse towards the neurone

• myelin sheath - insulates the axon and speeds up impulses

neurotransmitters

• chemicals that transmit signals across synapses

• carry impulses between neurones

reflex arc

1. stimulus: detects something

2. sensory neurone: sends impulse from sensory receptor to CNS

3. relay neurone: processes the information and sends the impulse within the CNS

4. motor neurone: carries the impulse from the CNS to the muscle

5. response: muscle acts

cornea

bends light to help focus retina

lens

focuses light precisely onto the retina for a clear image

iris

controls the size of the pupil and amount of light entering the eye

rod cells

detect dim light and night vision

cone cells

detect colour and help with day vision

common eye defects

cataracts - cloudy eyes

long sightedness - can’t see close

short sighted - can’t see far

colour blindness - can’t see all colour (no cure)

fix for cataracts

surgical remove the cloudy lens and replace with an artificial one

fix for long sightedness

convex lenses to focus light onto the retina

fix for short sightedness

concave lenses to move the focus back onto the retina