3.2.1 Cell Structure Flashcards
what are the distinguishing features of eukaryotic cells?
- cytoplasm containing membrane-bound organelles
- so DNA enclosed in a nucleus
animal cell organelles (8)
cell-surface membrane
mitochondrion
nucleus
ribosomes
rough endoplasmic reticulum
smooth endoplasmic reticulum
golgi apparatus + vesicles
lysosome
plant cell organelles (11)
cell-surface membrane
mitochondrion
nucleus
ribosomes
rough endoplasmic reticulum
smooth endoplasmic reticulum
golgi apparatus + vesicles
lysosome
chloroplast
cell wall
cell vacuole
describe the structure of the cell-surface membrane
- hydrophilic phosphate heads - attracted to water
- hydrophobic fatty acid tails - repelled from water
- made of phospholipids in a phospholipid bilayer
describe the function of the cell-surface membrane
- selectively permeable - enables control of passage of substances in/out of cell
- molecules/receptors/antigens on surface - allow cells recognition/signalling
describe the structure of the nucleus
- nuclear envelope, has a double membrane and nuclear pores
- nucleoplasm
- nucleolus (dense region)
- protein/histone-bound, linear DNA - chromatin = condensed, chromosome = highly condensed
describe the function of the nucleus
- holds/stores genetic information which codes for polypeptides (proteins)
- site of DNA replication
- site of transcription (part of protein synthesis) producing mRNA
- nucleolus makes ribosomes/rRNA
describe the structure of a ribosome
- made of ribosomal RNA nad a protein (2 subunits - large and small)
- not a membrane-bound organelle
function of a ribosome
- site of protein synthesis (translation
structure of rough endoplasmic reticulum
- contains network of membranes,enclosing a fluid-filled space - cisternae
- surface of cisternae is covered with ribosomes
- attatched to outer nucleus membrane
structure of smooth endoplasmic reticulum
- contains network of membranes,enclosing a fluid-filled space - cisternae
- attatched to outer nucleus membrane
function of rough endoplasmic reticulum
- ribosomes on surface synthesise proteins
- proteins processed/folded/transported inside rER
- proteins packaged into vesicles for transport e.g. to golgi apparatus
function of smooth endoplasmic reticulum
- synthesises and processes lipids e.g. cholesterol and steroid hormones
structure of golgi apparatus + golgi vesicles
- flattened membrane sacs
- golgi vesicle - small membrane sac
function of golgi apparatus + vesicles
golgi apparatus:
- modifies protein e.g. adds carbohydrates to produce glycoproteins
- modifies lipids e.g. adds carbohydrates to make glycolipids
- packages proteins/lipids into golgi vesicles
- produces lysosomes
golgi vesicles:
- transports proteins/lipids to their required destination e.g. moves to and fuses with cell-surface membrane
structure of lysosomes
- membrane
- hydrolytic enzymes
function of lysosomes
- release hydrolytic enxymes (lysozymes)
- to break down/hydrolyse pathogens or worn-out cell components
structure of mitochondria
- outer membrane
- cristae - inner membrane fold
- matrix - containing small (70S) ribosomes + circular DNA
function of mitochondria
- site of aerobic respiration
- to produce ATP for energy release e.g. for protein synthesis, vesicle movement, active transport
describe the structure of chloroplasts in plants and algae
- double membrane
- stroma including: thylakoid membrane, small/70s ribosomes, circular DNA, starch granules/lipid droplets
- lamella - thylakoid linking grata
- grana - stacks of thylakoid
function of chloroplasts in plants and algae
- absorbs light energy for photosynthesis
- to produce organic substances e.g. carbohydrates/lipids
structure of cell wall in plants, algae and fungi
- composed mainly of cellulose in plants/algae
- composed of chitin (nitrogen-containing polysaccharide) in fungi
function of cell wall in plants, algae and fungi
- provides mechanical strength to cell
- so prevents cell changing shape of bursting under pressure due to osmosis
structure of cell vacuole in plants
- tonoplast membrane
- cell sap
