compartmentalization

nuclear membrane (envelope)

• protects it from cellular reactions that occur in the cytoplasm • allows gene transcription and translation to be kept seperate • rna can be edited in the nucleus before it does to the ribosome. this is an advantage for eukaryotic cells as variants of a protein can be produced from a single gene due to gene splicing. prokaryotes cant do ts

structure that is specialised for a specific function within a cell

• allows the correct conc of metabolites to be present for specific metabolic processes and the appropriate enzymes to be present (prokaryotes are so small because they are non-compart..) • helps to maintain different conditions in different parts of the cell (pH, solute concentration) • storing damaging substances (the hydrolytic enzymes are active only in the lysosome’s acidic interior)

• recognition of foreign particle • ingestion of foreign partcile in a phagocytic vauole (temp) • fusion of the vacuole with lysosome, creating phagolysosome • destruction

• outer membrane • inner membrane • intermembrane space • matrix

• seperates mitochondria from rest of the cell • contains transport proteins, which move pyruvate into the mitochondria

• all proteins for etc and chemiosmosis are present here. • atp synthase present here • folds in inner membrane (cristae) = increased sa

• high conc of enzymes for link reaction and krebs cycle here

• small, so a high conc of h+ can rapidly be established • if it were big itll take lot of time to create electrochemical gradient for proton pump.

• chlorphyll - absorbs light, exists in the grana • thylakoid membranes of the grana provide large sa, so maximum light absorption • thylakoid membrane = very small so electrochemical gradient easily formed here • stroma has apt enzymes and optimum pH for calcin cycle. • compartmentalization within chloroplasts allows seperation of LDR from LIR

• many pores = high sa • has large pores (created by integral proteins) • the pores allow mRNA do leave the nucleus • the pores allow ribosomal subunits to leave the nucleus • a double membrane is easier to break down during mitosis • inner membrane of the double envelope is lined with the nuclear lamina, a network of intermediate filaments that provides structure to the nucleus • The outer membrane is continuous with the rer, allowing for efficient protein synthesis post-export.

• free ribosomes produce proteins used within the cell • ribosomes on rer produce proteins for secretion • Multiple ribosomes attach to a single mRNA molecule to form a structure called a polysome (or polyribosome) to maximize efficiency, allowing the cell to rapidly produce many copies of a specific protein from one transcript. This method saves time and energy, reducing the need to continuously transcribe new mRNA. • in lumen of rer, modification and folding of newly synthesized proteins occurs

• network of flattened membranous sacs called cisternae (wifi lookin w vesicles emerging out) • processes protein (sulfation, glycosylation, phosphorylation) • packages them into vesciles for secretion via exocytosis

• receptor mediated endocytosis • specialised protein causes membrane to invaginate (clathrin) • polymerises into a lattice network to form a clathrin coated pit • invaginated membrane breaks off and fuses to form a vesicle receptor mediated endocytosis also used by viruses to enter cell