structure of eukaryotic cells Flashcards
what are the distinguishing features of eukaryotic cells
cytoplasm containing membrane bound organelles
so DNA enclosed in a nucleus
describe the general structure of eukaryotic cells
cell-surface membrane
mitochondria
nucleus
ribosomes
rough endoplasmic reticulum
smooth ER
golgi apparatus
lysosome
plant only
chloroplast - plants and algae
cell wall - plants algae and fungi
cell vacuole - plants
describe the structure of the cell surface membrane
phospholipid bilayer
phospholipid
- hydrophilic phosphate heads
- hydrophobic fatty acid tails
proteins
describe the function of the cell surface membrane
selectively permeable - enables control of passage of substances in or out of cell
receptors on surface - allow cell recognition
describe the structure of the nucleus
nuclear envelope
- double membrane
- has nuclear pores
nucleoplasm
nucleolus
histone bound linear DNA
- chromatin = condensed
- chromosome = highly condensed
describe the function of the nucleus
- stored generic information which codes for polypeptides
- side of DNA replication
- site of transcription producing mRNA
- nucleolus makes ribosomes
describe the structure of a ribosome
made of RNA and protein
not a membrane bound organelle
describe the function of a ribosome
site of protein synthesis
describe the structure of rough and smooth endoplasmic reticulum
rough
- ribosomes
- system of membranes
describe the function of rER and sER
rough
- ribosomes on surface synthesise proteins
- proteins processed and transported inside
- proteins packed into vesicles for transport
smooth
- synthesises and processes lipids
Describe the structure of Golgi apparatus and Golgi vesicles
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)
golgi vesicles
● Transports proteins / lipids to their required destination
● Eg. moves to and fuses with cell-surface membrane
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
matrix
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
thylakoid membrane
strach granules
lamella
grana
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 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
