B2 - Cells and Control

What is mitosis

allows for DNA to divide, and cells to grow

creates genetically identical daughter cells

interphase

cell increases sub cellular structure

cell duplicates dna

prophase

chrmosomes condense and nucleus breaks down

metaphase

chromosomes line up in centre of cell

anaphase

chromosomes are pulled apart

telophase

membranes form around each of the chromosomes

cytokinesis

cytoplasm and cell membrane divide into two seperate cells

how and why do animal cells grow

animal growth occurs by mitosis either for growth or repair

how and why do plant cells grow

cell elongation (cells expand), however some mitosis in tips of roots and shoots - in meristem tissue

cancer cells

mutation occurs within genes, cells divide unctrollably causing a tumor. if thi sinvades surrounding tissue, it is called cancer

where are stem cells found

human embryos, bone marrow, meristem tissue

how are stem cells used in medicine

can be used to regrow destroyed cells, can cure anaemia with bone marrow transplants

risks associated with stem cells

ethical concerns, disease transmission as cells could contain viruses. tumor development as stem cells divide very quickly, rejection

cerebrum

largest bit. controls movement, memory, language, vision an dintelligence

cerebellum

controls muscle coordination

medulla oblongata

at top of spinal chord controls unconscious activites

PET scans

uses radioactive chemicals to show active areas. very detailed

CT scans

use xrays, show main structures but not uses.

what is color blindness caused by

red/green cones not working properly

long sightedness

unable to focus on close objects. lens doesnt bend light enough. light is focused behind retina. convex lens fixes

short sightedness

lens is bending light too much. light is focused in front of retina. concave lens

Reflex arc

stimulus stimulates pain receptors

impulses travel across sensory neurone

passed along a relay neurone

passed along a motor neurone

when impulses reach muscles, it contracts

response to stimulus

info converted into electical impulse

sensory neurones carry info to brain

travels by relay neurones, and sends info by motor neurone to an effector

what are synapses

connect neurones

transmitted by chemicals (neurotransmitters)

synapses slow reaction time