Cells Flashcards
Endogenous origin of eukaryotic compartments
Invagination of plasma membrane - then RER and nucleus formed
Exogenous origin of eukaryotic compartments
cell encases another cell, this forms mitochondria
Eukaryote origin - Archezoa hypothesis
phase 1 - invagination of membrane leads to first set of organelles
phase 2 - phagocytosis - one group of bacteria ingested which then forms mitochondria
Meanings of exogenous and endogenous origins
endogenous = nucleus and RER formed exogenous = mitochondria and plastids formed
function of plasma membrane
encloses cell content and separates it from the external environment
allows different concentrations of substances to be maintained
function of lipid bilayer
communication w environment and diff cells
barrier functions to pass molecules in and out
cell growth, movement, division
membrane fluidity
transporter/ enzyme activity regulated by fluidity
membrane can be adjusted to environment
lipid composition and temperature influence fluidity
function of transporter proteins
move nutrients/ions across membranes
function of linker proteins
join membranes to macromolecules
function of receptors
transduce signals from environment
function of membrane enzymes
catalyse reactions at membrane surfaces
ampiphilic meaning
both hydrophobic and hydrophilic regions present
glycosylated meaning and function
glycoproteins and glycolipids form a cell coat called the glycocalyx which prevents cell damage
4 glycocalyx functions
protection, adhesion, recognition, storage
3 types of active transport used to transport molecules across membrane
coupled, ATP driven, light/redox
3 types of intracellular transport and meaning
Gated - through nuclear pores
transmembrane - across membranes
vesicular - via vesicles
proteins made by ribosomes and sorted by signals
- nuclear localisation signal
- mitochondrial signal sequence
- vesicles travel from RER to other compartments
sorting proteins to RER
- protein synthesis in cytosol
- proteins contain N terminal signal sequence
- signal sequence binds receptor on RER
- ribosome associates with RER
- polypeptide synthesis completed on RER
- protein translocates into RER membrane during synthesis
- signal peptide cleaved
protein glycosylated
N = asparagine O = serine, threonine
3 different vesicular transport pathways
secretory, endocytic, retrieval
Autophagy
Induction: organelles free
Closure: Autophagosome formed containing organelles
Autophagosome fuses with lysosome
lysosome digests what it contains
