2.1.1 structure of eukaryotic cells Flashcards
what are the distinguishing features of eukaryotic cells
- cytoplasm containing membrane bound organelles
- DNA enclosed in a nucleus
what is the general structure of eukaryotic cells
- cell surface membrane
- mitochondria
- nucleus
- ribosomes
- rough endoplasmic reticulum
- smooth endoplasmic reticulum
- golgi apparatus
- lysosomes
- chloroplasts ( in plants and algae )
- cell wall ( in plants, algae and fungi )
- cell vacuole ( in plants )
describe the structure of cell surface membrane
- hydrophilic phosphate heads which point towards water
- hydrophobic fatty acid tails which point away water
describe the function of the cell surface membrane
- selectively permeable enabling the control of passage of substances in and out of the cell
- has receptors of the surface allowing cell recognition and signalling
describe the structure of the nucleus
- nuclear envelope which has a double membrane and nuclear pores
- nucleoplasm
- nucleolus ( dense region )
- histone bound, linear DNA with chromatins meaning condensed and chromosomes meaning highly condensed
describe the function of the nucleus
- holds and stores genetic information which codes for polypeptides
- site of DNA replication
- site of transcription producing mRNA
- nucleolus makes ribosomes/rRNA
describe the structure of a ribosome
- made of ribosomal RNA and protein
- not a membrane bound organelle
describe the function of a ribosome
site of protein synthesis ( translation )
describe the structure of rough endoplasmic reticulum and smooth endoplasmic reticulum
a system of membranes, RER has ribosomes attached
describe the function of the rER
- ribosomes on the surface synthesise proteins
- proteins are processed and transported inside the rER
- proteins are packaged into vesicles for transport eg. to golgi apparatus
describe the function of the sER
synthesises and processes lipids such as cholesterol and steroid hormones
describe the structure of the golgi apparatus
flattened membrane sacs
describe the structure of the golgi vesicle
small membrane sac
describe the function of the golgi apparatus
- modifies proteins eg. adds carbohydrates to produce glycoproteins
- modifies lipids eg. adds carbohydrates to produce glycolipids
- packages proteins and lipids into golgi vesicles
- produces lysosomes
describe the function of the golgi vesicles
transports proteins and lipids to their required destination by moving yo and fusing with cell surface membrane
describe the structure of lysosomes
- membrane
- hydrolytic enzymes
describe the function of lysosomes
releases hydrolytic enzymes ( lysozymes ) to break down and hydrolyse pathogens or worn out cell components
describe the structure of the mitochondria
- outer membrane
- cristae ( inner membrane fold )
- matrix containing small 70s ribosomes and circular DNA
describe the function of mitochondria
site of aerobic respiration to produce ATP for energy release eg. for protein synthesis
describe the structure of chloroplasts in plants and algae
- double membrane
- stroma containing thylakoid membrane, small 70s ribosomes, circular DNA and starch granules
- lamella ( thylakoid lining grana )
- grana ( stacks of thylakoid )
describe the function of chloroplasts in plants and algae
absorbs light energy for photosynthesis to produce organic substances eg. carbohydrates
describe the structure of the cell wall in plants, algae and fungi
- composed mainly of cellulose ( a polysaccharide ) in plants and algae
- composed of chitin ( a nitrogen containing polysaccharide ) in fungi
describe the function of the cell wall in plants, algae and fungi
provides mechanical strength to the cell preventing it from changing shape or bursting under pressure due to osmosis
describe the structure of the cell vacuole in plants
- tonoplast membrane
- cell sap
describe the function of the cell vacuole in plants
- maintains turgor pressure in cell to stop plant wilting
- contains cell sap which stores sugars, amino acids, pigments and any waste chemicals
describe how eukaryotic cells are organised in complex multicellular organisms
in complex multicellular organisms, eukaryotic cells become specialised for specific functions
what is tissue
group of specialised cells with a similar structure working together to perform a specific function often with the same origin
what is an organ
aggregations of tissues performing specific functions
what is an organ system
groups of organs working together to perform specific functions
