Cell biology Flashcards
what are the two types of prokaryotes
Bacteria and archaea
what are the benefits of organisms being multi cellular
longer lifespan, better adaptation, fewer predators
what 2 components is cytoplasm composed of?
cytosol and organelles
what is cytosol and what is it the site for?
intercellular fluid that contains dissolved ions, glucose, amino acids, ATP, lipids and water.
And its the site for enzyme reactions
what is the cytoskeleton?
dynamic structure which is constantly reorganised as the cell changes shape (e.g. during the segregation of chromosomes)
what is the cytoskeleton responsible for
large scale movements, such as contraction of muscles
what are the 4 stages of the movement of actin
protrusion, adhesion, deadhesion, movement
what are intermediate filaments specialised for
bearing tension
what are microtubules constructed of
globular proteins, tubulin
what are the 3 components of the cytoskeleton
actin monomer, intermediate filament, microtubule
why do actin monomers cover the outer layers of the cytoskeleton
as they’re highly responsible for movements and contractions of muscles
what disorders are associated with cytoskeleton defects
skin conditions, neuropathies (alzheimers)
what does less cilia cause people to become more susceptible to?
infection
what are the structures of the nucleus
nucleolus, chromatin, nuclear membrane, nuclear pore
what is the endoplasmic reticulum
a network of membranes in the form of flattened sacs and tubules extending from the nuclear envelope
what is the rough ER the site for
protein synthesis
what is the smooth ER the site for
synthesis of fatty acids and steroids - in the liver it helps release glucose from glucose - 6 - phosphate and detoxify drugs such as alcohol
what do ribosomes consist of
A large subunit made of 60S eukaryotes and small subunit 40S eukaryotes - each is rich in ribosomal RNA and contains over 50 protiens
what are the 3 areas of the Golgi and where are they located?
Cis- faces the ER, Medial- between the cis and trans, Trans - faces the plasma membrane
what are the 3 different types of endosomes
early, late, recycling
what are endosomes
a collection of intracellular sorting organelles in eukaryotic cells
what is the function of endosomes
sorting proteins to their final location
what is mitochondria the site of
aerobic respiration
what is autophagy
the digestion of substances entering the cell or worn out cells
what is autophagy required for
renewal and control of growth & tissue remodelling
what is Tay-Sachs disease
an inherited condition that affects children, caused by the absence of lysosomal enzyme Hex A - causes seizures and blindness
what is a peroxisome
derived from the ER, contains oxidases and are involved in amino acid and fatty acid metabolism
what disorder is linked to dysfunctional mitochondria
Parkinson’s
how does cholesterol help the membrane maintain fluidity
reduces fluidity at modern temperature, reduces solidification at low temperatures
why is transport across membranes important
to regulate the concentrations from outside o the inside of the cell
which area of a phospholipid is hydrophobic and which is hydrophilic
the head is hydrophilic and the tails are hydrophobic
can lipid bilayers be asymetrical
yes
what helps maintain membrane fluidity
cholesterol
why does the body need a fluid membrane
to allow movement,
what is passive transport
molecules moving down a concentration gradient, doesn’t require energy
what molecules move via facilitated diffusion
large uncharged molecules, ions
what does the level of symmetry between the lipid bilayers say about the health of a cell
the more symmetrical the unhealthier/dying a cell is
what molecules can move via simple diffusion
hydrophobic and small, uncharged molecules
what is osmosis
the movement of water down a water potential gradient through a partially permeable membrane through aquaporins in the lipid bilayer
what are the cell shapes that change with the concentration of water
hypertonic, isotonic, hypotonic
what is active transport
movement against a concentration gradient, requires energy
what are the two types of passive transport
diffusion and facilitated diffusion
what does it mean when a cell is hypertonic
the cells have shrivelled due to water leaving the cell
what does it mean when a cell is isotonic
when the water level is balanced outside and inside the cell, so shape remains the same
what does it mean when a cell is hypotonic
when cells lyse/ burst as too much water enters the cell
what 2 types of proteins are used in facilitated diffusion
carrier and channel
what molecules do channel proteins transport
small and highly selective molecules
what molecules do carrier proteins transport
large and highly selective molecules
what are the 3 types of gated ion channels
volage gated, ligand gated, mechanically gated
what are the 2 main types of membrane proteins
integral and peripheral
what are the 3 types of integral proteins and what are their uses
a-helix (receptors), helical bundle (enzymes and transporters) and b-barrel (channel proteins)
what are the 3 types of facilitated diffusion carriers
uniport, symport and antiport
the glucose transporter (GLUT) is an example of what type of diffusion
facilitated diffusion
what is cystic fibrosis caused by
defective chloride ion transport causing a build up in sodium inside the cells causing an increase in osmosis
what are first 1-3 stages of the insulin dependant glucose uptake system
1- insulin binds to an insulin receptor
2- phosphorylation of insulin receptor substrate1 (IRS-1)
3 - IRS-1 activates PI 3-kinase
what are he stages 4-6 in the insulin dependant glucose uptake system after PI 3-kinase has been activated
4- activated PI 3-kinase activates GLUT4
5 - GLUT4 facilitates uptake of glucose into the cell
6 - glucose is converted to energy in the mitochondria
what is primary active transport
the moving of ions by the hydrolysis of ATP
