Topic 1-Cell Biology Flashcards
prokaryotes
single celled, small organism
eukaryotes
complex organisms
nucleus
contains genetic material that controls the activities of the cell
cytoplasm
gel-like substance where most of the chemical reactions happen.
cell membrane
holds the cell together and controls what goes in and out
mitochondria
where most of the reactions for aerobic respiration takes place
ribosomes
where proteins are made in the cell
cell wall
(PLANT ONLY) supports and strengthens the cell
permanent vacuole
(PLANT ONLY) contains cell sap which is a weak solution of sugar and salts
chloroplasts
(PLANT ONLY) where photosynthesis occurs. contains a green substance called chlorophyll which absorbs the light needed for photosynthesis.
examples of eukaryotes
plants and animals
examples of prokaryotes
bacteria
plasmids
(BACTERIA ONLY) small ring of DNA
strand of DNA
(BACTERIA ONLY) where genetic information is stored instead of a nucleus
light microscopes
use light and lenses to form an image of a specimen and magnify it. they let us see cells and large subcellular structures (eg nuclei)
electron microscopes
use electrons to magnify an image. they let us see very small things like the internal structure of mitochondria.
magnification equation
magnification=image size/actual size
which lens do you use first?
lowest powered objective lens (lowest magnification)
cell differentiation
the process where a cell changes to become specialised for its job.
sperm cells
specialised for reproduction. long tail and streamlined head to help it swim to the egg and lots of mitochondria to provide enough energy.
nerve cells
specialised for rapid signalling. very long to cover more distance and have branched connections to form a network throughout the body.
muscle cells
specialised for contraction. long so they have space to contract and have lots of mitochondria for energy.
root hair cells
specialised to absorb water and minerals. large surface area so the plant can absorb more.
phloem and xylem cells
specialised for transporting substances. cells are long and joined end to end . xylem cells are hollow and phloem have very few subcellular structures.
