cell structure Flashcards
what are the components of the nucleus
nucleolus - produces ribosomes and composed of RNA and proteins
nuclear envelope - double membrane where DNA is contained
nucleoplasm - contains chromatin
RER - produce, process & stores lipids, carbs and steroids
describe the structure of mitochondria
has a double membrane
inner membrane (cristae) folded
cristae contain enzymes for aero. resp.
fluid inside the cristae is matrix
contains mitochondrial DNA (mt)DNA
allows mitochondria to produce their own enzymes and reproduce
describe the function and structure of vesicles
membraneous sacs that store and transport substances around the cell
single membrane with a fluid inside
describe the structure and function of lysosomes
specialised vesicles that contain hydrolytic enzymes
break down waste material
also break down pathogens ingested by phagocytic cells
also play a role in apoptosis
describe the cytoskeleton
network of fibres necessary for the shape and stability of a cell
organelles held in place by the cytoskeleton and controls cell movement and within cells
describe the three components of the cytoskeleton
microfilaments - contractile fibres formed from actin. responsible for cell mvt. and cell contraction
microtubules – globular tubulin proteins polymerise to form tubes that form scaffold-like structure
act as tracks for movement of organelles
intermediate fibres - give mechanical strength to cells & maintain their integrity
describe the function of centrioles
component of the cytoskeleton in eukaryotes (not flowering plants and fungi)
composed of microtubules
two associated centrioles form centrosome
describe flagella
whip-like extensions protruding from cells
enable cell motility
sometimes used as sensory organelle detect chemical change in the cell environment
describe cillia
hair-like
can be mobile or stationary
stationary cilia have important role in sensory organs
mobile cilia beat in rhythmic manner creating a current and causing fluids/objects adjacent to cell to move
describe the 9+2 arrangement of a cillium
two central microtubules
surrounded by 9 pairs of microtubules arranged like a wheel
describe the structure and function of golgi apparatus
formed of cisternae
modifies proteins and packages them into:
secretory vesicles – to leave cell
lysosomes – stay in cell
how are proteins produced
proteins synthesised on ribosomes bound to RER
pass into cisternae and packaged into secretory vesicles
move toward golgi apparatus
proteins are structurally modified before leaving via vesicles from its trans face
secretory vesicles carry proteins and fuse with c.surface membrane releasing the components out the cell by exocytosis
describe the structure and function of the cell wall
made of cellulose
freely permeable
defence mechanism protecting the contents of the cell against invading pathogens
vacuole
membrane lined sacs in cytoplasm containing cell sap
important in maintenance of turgor so that the contents of the cell push against the cell wall and maintain a rigid framework for the cell
surrounded by tonoplast membrane
selectively permeable
chloroplast
responsible for photosynthesis
double membrane structure
fluid enclosed called stroma
has thylakoids stacked together forming granum
grana are joined by membranes (lamellae)
grana contain chlorophyll pigments
contain DNA and ribosomes
internal membranes provide large SA for enzymes in photosynthesis
