cell structure

paper 1

cell membrane

controls what can and cant enter the cell

cytoplasm

where chemical reactions happen, surrounds sub cellular structures

DNA

the genetic material that controls the activities of the cell

ribosomes

the site of protein synthesis

specialised cell

a cell that has a particular structure, that undergoes a process called differentiation

eukaryotic cells

animal and plants cells, between 10 and 100 um

animal cells

nucleus, cell membrane, ribosomes, mitochondria, cytoplasm

plant cells

cell membrane, cell wall, ribosomes, vacuole, mitochondria, cytoplasm, nucleus, chloroplast

nerve cell function

conducts impulses

nerve cells have extensions of the cytoplasm forming dendrites and axons

allows the neurone to communicate with other nerve cells, muscles and glands

nerve cells have an axon

which is covered with a fatty sheath, speeding up nerve impulses

nerve cells have a cell body

where most cellular structures are located and protein sythehesis ocurs

muscle cell function

has contraction for movement

muscle cells have layers of protein filaments

these slide over each other causing muscle contractions

muscle cells have a high density of mitochondria

provides sufficient energy via respiration for muscle contractions

sperm cell function

function is to reproduce, passing on fathers genes

sperm cells head contains a nucleus

contains half the normal number of chromosomes

sperm cells acrosome contains digestive enzymes

these break down the outer layer of an egg cell so they can fuse

sperm cell mid-piece has lots of mitochondria

this releases energy to move the cell

prokaryotic cells

cell membrane, circular loop of dna, plasmid, ribosomes, cytoplasm, cell wall

root hair cell function

absorbs water and mineral ions from the soil

root hair cell has root hair

to increase the surface area so the rate of water uptake by osmosis is greater

root hair cells have thinner walls

so that water can pass through easily, shorter diffusion distance

root hair cell has permanent vacuole

this contains cell sap which is more concentrated than soil water, maintaining water potential gradient

xylem cell function

transport tissue for water and dissolved ions

xylem have no top and bottom walls

forming hollow tubes through which water is drawn upwards towards the leaves by transpiration

phloem cell function

transports dissolved sugars and amino acids

phloem cell have few subcellular structures

this aids the flow of materialsd

1mm to 1000um

mm to um

1um to 1000nm

um to nm

cell wall

made of cellulose and gives the cell extra support

chloropasts

contains green chlorophyll pigment to absorb light energy and the enzymes needed for photosynthesis

vacuole

contains cell sap a solution of sugars and salts dissolved in water

used for storage of certain materials

specialised cell

a cell that has a structure that aids its specific function

image size = actual size x magnifacation

image size calculation