3 – Nature of Cytoplasm Flashcards
What is cytoplasm?
Material in which organelles are embedded
What is cytoplasm like?
Salty water – for an ion
Jelly / petroleum jelly (vaseline) – for protein
Glass – for large organelle, can’t more because it’s too corwded
It depends on who you ask
-Which species of molecules
(Ribosome, Ion)
Cytoplasm is crowded, what does it have
Ions/water (~0.1nm)
Sugar/amino acids/small molecules (~1nm)
Proteins/DNA/RNA (10-100nm)
Organelles (1um)
Cytoplasm is crowded, How crowded?
As crowded as protein crystal
-20-60% protein by weight
Red blood cells
35% protein by weight
-basically no space in between the hemoglobins
Dilute solution: ~0.1% protein by weight
Cytoplasm is a rough-and-tumble place
-Proteins collide each other – Brownian motion
-Smashed by thermal energy
-Amino acid side chains are distorted
Cytoplasm is a rough-and-tumble place, Structure of individual proteins is distorted by
collisions
-Amino acid side chains are distorted
Cytoplasm is viscous, think about ratio between … relative to its ….
-Inertia: resistance of an object to any change in its state of motion
-Viscosity: a measure of a fluid’s resistance to flow
Honey/heavy oil texture
Reynolds number
Re=inertial/viscous
Cells/organelles/proteins are in … Reynold’s number environment
-LOW
Inertia is negligible in cytoplasm
-Bacteria: inertia<viscosity
Comes to a stop immediately when stops swimming
-Human swimming: inertia>viscosity
Can glide some distance when stop swimming in water
Cytoplasm is elastic, waht is elasticity
-Elasticity: tendency of an object to return to its original shape after deformation
Cytoplasm = … material
viscoelastic
Cytoplasm is a meshwork
Cytoplasm contains long protein polymers –> meshwork (cage)
Meshwork: effective pore size –> determine what molecules move & what gets trapped
Cytoplasm is an active material
far from equilibrium
-constant energy churn that drives the motion of molecules & particles inside it
Carbon starvation of bacteria turn their cytoplasm to..
glass
what freezes cytoplasm of E. coli
Rapid ATP depletion
Diffusion is …, not thermal
active
-active metabolic processes in the cell make the cytoplasm more fluid-like
-increases overall protein movement, preventing them from being confined to a very restricted region
Without active processes, movement is …
minimal, and the cytoplasm behaves more like glass.
Fluidity of cytoplasm changes with
stress/age
