function of cell membranes Flashcards
what is a cell membrane
the structures that spearate the contents of the cell from their environment. they also separate the different areas within cells (organelles) from eachother and the cytosol. some organelles are divided further by internal membranes
what is compartmentalisation
the formation of separate membrane bound areas in a cell
why is compartmentalisation essential
metabolism includes many different and often imcompatible reactions. containing reactions in separate parts of the cell allows the specific conditions required for cellular reactions such as chemical gradients to be maintained and protects vital cell components.
which organelles in an animal cell contain a membrane
rough endoplasmic reticulum
nucleus
nucleolus
golgi apparatus
golgi vesicle
vacuole
peroxisome
smooth endoplasmic reticulum
lysosome
mitochondria
what is the basic function of a cell membrane
they cover the surface of every cell and most organelles
why do cells need a membrane
- communication with external environment
- compartmentalise individual cell processes
- isolating organelles from the rest of the cytoplasm allowing cellular processes to occur separately
- site of chemical reactions
- contain enzyme controlled processes
- controls entry and exit of substances
- allows cells to change shape
- transport and packaging within a cell
how do cell membranes help with cell communication
the membrane contains receptors for some chemical signals and so is a site for cell communication or signalling. hormones and drugs may bind to membrane bound receptors which may be the site for chemical reactions.
how do membranes help with transport into the cell
at the surface of cells, the membrane regulates transport material into and out of the cell. the membrane has antigens so that the organism’s immune system can recognise the cell as being ‘self’ and not attack it.
what do internal membranes do
the membranes around many organelles present in eukaryotic cells separate the organelle contents from the cell cytoplasm so that each organelle is a discrete entity and able to perform its function
give examples of organelles with membranes
mitochondria, chloroplasts
and embedded enzymes
describe the membrane in mitochondria
have folded inner membranes called cristae
may contain enzymes involved in specific metabolic pathways
the folds give a large surface area for some of the reactions of aerobic respiration and localise some of the enzymes needed for respiration to occur
describe the membrane in chloroplasrs
inner membranes of chloroplasts are called thylakoid membranes which house chlorophyll
it is on these membranes that some of the reactions of photosynthesis occur
describe the membranes on embedded enzymes
there are some digestive enzymes on the plasma membranes of epithelial cells that line the small intestine and these enzymes catalayse some of the final stages in the breakdown of certain types of sugars
