ch1 cellular structure and function Flashcards
cell structure and function
mitochondria
- site of aerobic cellular respiration
- provides energy to the cell in the form of ATP
Chloroplasts
-found in plants and protist cells
- responsible for photosynthesis
- double membrane
- sacks of membrane called grana
endoplasmic reticulum
- transports materials around inside the cell.
1. rough endoplasmic reticulum- studded with ribosomes, tends to modify and transport proteins made by them.
2. smooth endoplasmic reticulum- lacks ribosomes but do sometimes transport proteins. involved in synthesis and transport of lipids.
ribosomes
- found in prokaryotes and eukaryotes
- made of RNA dont have a membrane
- responsible for constructing proteins from amino acids
golgi apparatus
- flattened sacks of membrane, called cristernae.
- responsible for final modification of proteins.
- package materials to be secreted into vesicles
vacuole
- sacks of membrane used to store materials inside cells
- in animals- small, many, temporary.
- in plants- large, permanent, one of them. used to store water then push the cytoplasm hard up against the membrane
lysosomes
contain digestive enzymes to break down and recycle old organelles brought into the cell
plastids
- organelles responsible for containing coloured pigment.
- includes chloroplasts (green, photosynthesis), chromoplasts (gives flower colour) , leucoplasts (white, starch storage, protein, fat)
cytoskeleton
- structure of fibres made of microtubules and microfilaments.
-microtubules made of protein called tubulin, forms flagella that allows some cells to move - microfilaments made of actin, stretchy, allows muscles to contract
cell wall
-provide support and stop cells expanding too much.
-fungal cell walls- chitin
- bacterial cell walls- murein
- plant cell walls- cellulose
Surface area and volume
- limit on how large cells can be
- too large- exchange of materials becomes too slow for life
- size is limited by rate of diffusion
- volume increases faster than surface area
compartmentalization
- organelles in cells form compartments
- different processes which require different conditions can all take place at the same time in the cell.
crossing the membrane
substances cross membrane by
- diffusion
- facilitation
- active transport
- endo/exocytosis
the plasma membrane
- described by the fluid mosaic model
- is a phospholipid bilayer with embedded proteins and cholesterol.
- phospholipids- phosphate head (hydrophilic head attracted to water)
and fatty acid tail (hydrophobic tail repelled by water)
-hydrophilic=lipophobic
-hydrophobic=lopholic
equilibrium
- equal particles in both places.
- diffusion no longer occurs but molecules still move in both directions
passive transport
easy
active transport
tough
simple diffusion
small uncharged or lipid soluble molecules pass straight through the lipid bilayer
diffusion
movement of molecules from an area of high concentration to an area of low concentration
osmosis
when the substance diffusing is water.
-net movement of water from a dilute solution to a concentrated solution across a semi permeable membrane.
facilitated diffusion
- a passive process
- moves molecules down concentration gradients
- carrier molecules or protein channels
- glucose enters cells through facilitated diffusion using carrier protein,
active transport
- energy requiring
- moves substances against the concentration gradient
- uses protein channels and carrier proteins
- results in the movement of large and charged atoms, ions and molecules.
water and lipid soluble
-water soluble= polar, hydrophilic, lipophobic
-lipid soluble= non-polar, hydrophobic, lipophilic
Bulk transport
involves the movement of substances through the formation of vesicles
- requires energy
- out of cell=exocytosis
- into the cell=endocytosis
