Topic 2 Flashcards
Cell membrane structure
Phospholipid bilayer with embedded intrinsic & extrinsic proteins
Cell membrane function
Selectively permeable barrier controls passage of substances in and out the cell
barrier between internal and external cell environments
Nucleus Structure
Nuclear pores, nucleolus, DNA and nuclear envelope
Nuclear envelope is inner and outer membrane and nuclear pores
Nucleus Function(4)
Site of transcription & pre- mRNA splicing - mRNA production
site of DNA replication
nucleolus makes ribosomes
nuclear pore allows movement of substances to/from cytoplasm
Mitochondria Structure
Double membrane with inner membrane folded into cristae
70S ribosomes in matrix
small circular DNA
enzymes in matrix
Mitochondria Function
Site of aerobic respiration
produces ATP
Chloroplast structure
Thylakoid membranes stacked to form grana, linked by lamellae
stroma contains enzymes
contains starch granules, small circular DNA and 70S ribosomes
Chloroplast function
Chlorophyll absorbs light for photosynthesis to produce organic molecules (glucose)
Organisms containing chloroplasts
Plants
Algae
Golgi apparatus stucture
Fluid-filled, membrane-bound sacs (horseshoe shaped)
vesicles at edge
Golgi apparatus function
Modifies proteins received from RER
packages them into vesicles to transport to cell membrane for exocytosis
makes lysosomes
Lysosome structure
Type of Golgi vesicle containing digestive enzymes
Lysosome function
Contains digestive enzymes
e.g lysozymes to hydrolyse pathogens/cell waste products
Rough endoplasmic reticulum function(3)
Site of protein synthesis
folds polypeptides to secondary & tertiary structures
packaging into vesicles to transport to Golgi
Smooth endoplasmic reticulum function
Synthesises and processes lipids
Cell wall function
Provides structural strength, rigidity and support to cell
helps resist osmotic pressures
Ribosome structure
Small and large subunit
made of protein and rRNA
free floating in cytoplasm & bound to RER
70S in prokaryotes, mitochondria and chloroplasts
80S in eukaryotes
Ribosome function
Site of translation in protein synthesis
Rough endoplasmic reticulum structure
System of membranes with bound ribosomes
continuous with nucleus
Smooth endoplasmic reticulum structure
System of membranes with no bound ribosomes
Cell wall structure
In plant, fungal and bacterial cells
plants - made of microfibrils of cellulose
fungi - made of chitin
bacteria - murein
Cell vacuole structure
Fluid-filled
surrounded by a single membrane called a tonoplast
Contrast prokaryotic & eukaryotic cells(5)
Prokaryotic cells are smaller
prokaryotes have no membrane bound organelles
prokaryotes have smaller 70S ribosomes
prokaryotes have no nucleus - circular DNA not associated with histones
prokaryotic cell wall made of murein instead of cellulose/chitin
Occasional features of prokaryotes
Plasmids - loops of DNA
capsule surrounding cell wall - helps agglutination + adds protection
flagella for movement