2.1 Cell Structure Flashcards
what are the distinguishing features of eukaryotic cells
-cytoplasm containing membrane-bound organelles
-so DNA enclosed in a nucleus
which cells have similar structures to plant cells
-algal cells
-fungal cells
describe the structure of the cell surface membrane
-hydrophilic phosphate heads that are attracted to water
-hydrophobic fatty acid tails that repel water
-which both make up a phospholipid
-phospholipid bilayer
-proteins
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 cell recognition / signalling
describe the structure of the nucleus
-nuclear envelope
with double membrane
has 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 and protein (two subunits)
-not a membrane-bound organelle
describe the function of a ribosome
-site of protein synthesis (translation)
describe the structure of rER and sER
-ribosomes
-systems of membranes
describe the function of rER
-ribosomes on surface synthesise proteins
-proteins processed / folded / transported inside rER
-proteins packaged into vesicles for transport eg. to golgi apparatus
describe the function of sER
-synthesises and processes lipids
-eg. cholesterol and steroid hormones
describe the structure of golgi apparatus and vesicles
golgi apparatus = flattened membrane sacs
golgi vesicle = small membrane sac
describe the function of the golgi apparatus
-modifies protein, eg. adds carbohydrates to produce glycoproteins
-modifies lipids, eg. adds carbohydrates to make glycolipids
-packages proteins / lipids into golgi vesicles
-produces lysosomes (a type of golgi vesicle)
describe the function of golgi vesicles
-transports proteins / lipids to their required destination
-eg. moves to and fuses with cell-surface membrane
describe the structure of lysosomes
-membrane
-hydrolytic enzymes
describe the function of lysosomes
-release hydrolytic enzymes (lysozymes)
-to break down / hydrolyse pathogens or worn-out cell components
describe the structure of mitochondria
-outer membrane
-cristae -inner membrane fold
-matrix containing 70s ribosomes and circular dna
describe the function of mitochondria
-site of aerobic respiration
-to produce ATP for energy release
-eg. for protein synthesis / vesicle movement / active transport
describe the structure of chloroplasts in plants and algae
-double membrane
-stroma containing
●thylakoid membrane
●70s ribosomes
●circular dna
●starch granules/lipid droplets
-lamella - thylakoid linking 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 / lipids
describe the structure of the cell wall in plants, algae and fungi
-composed mainly of cellulose (a polysaccharide) in plants / 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 cell
-so prevents cell 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 (stopping plant wilting)
-contains cell sap → stores sugars, amino acids, pigments and any waste chemicals
describe how eukaryotic cells are organised in complex multicellular organisms
-specialised for specific functions
-tissue
-organ
-organ system
define tissue
-group of specialised cells with a similar structure working together to perform a specific function, often with the same origin
define organ
-aggregations of tissues performing specific functions
define organ system
-group of organs working together to perform specific functions
suggest how you can apply your knowledge of cell features / organelles to
explain adaptations of eukaryotic cells
-general answer format:
-[Named cell] has many [named organelle, eg. ribosomes]
-to [link organelle function to cell function eg. increase rate of protein synthesis, making many antibodies]
what are the distinguishing features of prokaryotic cells
-cytoplasm lacking membrane-bound organelles
-so genetic material not enclosed in a nucleus
examples of prokaryotic cells
-bacteria
-archaea
describe the general structure of prokaryotic cells
-cell surface membrane
-cell wall (containing murein)
-cytoplasm
-70s ribosomes
-circular DNA (free in cytoplasm and not associated with proteins)
and sometimes
-capsule
-plasmids
-flagella
compare and contrast the structure of eukaryotic and prokaryotic cells
eukaryotic cell
-has membrane-bound organelles
-has a nucleus containing DNA
-DNA is long & linear & associated with histone proteins
-larger (80S) ribosomes (in cytoplasm)
-cell wall only in plants, algae and fungi containing cellulose or chitin
-plasmids / capsule never present (sometimes flagella)
-larger overall size
prokaryotic cell
-no membrane-bound organelles
-no nucleus DNA is is free in cytoplasm
-DNA is short & circular
& not associated with proteins
-smaller 70s ribosomes
-cell wall in all prokaryotic cells containing murein, a glycoprotein
-plasmids, flagella and a capsule sometimes present
-much smaller overall size
explain why viruses are described as acellular and non-living
-acellular - not made of cells, no cell membrane / cytoplasm / organelles
-non-living - have no metabolism, cannot independently move / respire / replicate / excrete
describe the general structure of a virus particle
- nucleic acids (RNA or DNA) surrounded by a capsid
(protein coat) - attachment proteins allow attachment to specific host cells
- no cytoplasm, ribosomes, cell wall, cell-surface membrane etc
- some also surrounded by a lipid envelope eg. HIV
