Flashcards in Cellular Organisation - Velta Deck (81):
What does HOMER stand for?
Homeostasis, organisation, metabolism, evolution and reproduction
What are the 6 structural levels of organisation?
5. Organ system
What does the Mitochondrion do?
Cellular respiration to produce ATP
Function of plasma membrane?
Protect the some from EC materials. Has a selectively permeable membrane
Forming cytoskeleton and moving organelles, vesicles etc inside cell
Pull chromatids apart during division and organise microtubules
Support and allow flexibility/rigidity, structure in the cytoskeleton
Smooth ER function?
Makes products like hormones and lipids (which make the cellular membrane)
Secretory vesicle function?
Transports material to the cell surface from the Golgi apparatus, such as hormones
Breakdown of long chain fatty acids
Maintains the right pH, as well as being filled with molecules and water to support cell
Provides structure for organelles to move in
Golgi apparatus function?
To process and bundle macromolecules which are then transported to ECF through vesicles. Also makes lysosomes
Packaging DNA to fit into nucleus
Makes ribsosomal subunits from proteins and rRNA
Contains cells genetic information
Rough ER function?
Production and transportation of proteins
Synthesis of proteins
Intermediate filament function?
Mechanical support for cell membrane
Increase surface area for cellular diffusion
Nuclear envelope function?
Is the membrane that surrounds the nucleus. Encases the genetic material
Sorting and delivery of material from ECF, And Golgi apparatus
List the 3 Tenents of cell theory
1. All living organisms are made up of 1 or more cells
2. All living cells arose from pre exisiting cells through division
3. Cell is the fundamental structure and function in living things
Why are cells so small? (SA:V)
Raw materials and waste enter through cell membrane. For volume, there is specifically SA. As size increase, ratio decreases, thus decrease in efficiency
Structure of cell membrane allows it to....
1. Asymmetric distribution of ions (Chemical gradient)
2. Separation of charge/ions (electrical gradient) = resting membrane potential
What are Phospholipids?
Amphipatic monomers (hydrophobic and hydrophilic parts)
Forms the lipid bilayer instantly
Formation of hydrophobic core
Draw a cell with its organelles
Draw a Phospholipid
Draw a glycolipid
What are fatty acids?
Building blocks of lipids
Polar head (-COOH) and non polar tail
As chain length increases, solubility decreases
What is the fluid mosaic model?
Describes the structures (phospholipids, cholesterol and protein) in the cell membrane
Draw the fluid mosaic model?
Role of phospholipids in the FMM
Joined non covalently
Fatty acid tails are either saturated or non saturated (kink in tail)
Form the lipid bilayer
Role of cholesterol in FMM?
Attached between fatty acid tails
Stabilises membrane by preventing membrane from going from a liquid to a solid (inhibiting phase transition)
Name the 2 types of proteins in the FMM?
Integral: transmembrane protein and spans across the membrane
Peripheral: associated with membrane but not transmembrane
Name the 3 membrane proteins not used for membrane transport
1. Anchoring: attach to membrane and stabilize
2. Recognition: detected by immune system
3. Receptor: binds to ligand (EC molecules)
Role of Carbs in FMM?
Attach to either lipids (glycolipids) or proteins (glycoproteins)
Difference between Prokaryotes and Eukaryotes?
Prokaryotes have no nucleus and limited membrane bound organelles unlike eukaryotes which have both
Prokaryotes are bacteria and archaea
What is compartmentalisation?
Unique to Eukaryotes
Increase the complexity
Name 2 reasons why compartmentalisation is beneficial?
1. Efficient: different compartments do different functions
2. Protective: provides specific environments for specific functions
What is the endomembrane system?
Set of membranes which form a single functional unit = COMPARTMENTS
Connected either directly or through exchange of materials by vesicle transport
What does the endomembrane system include?
Nuclear envelope, ER, golgi, lysosomes, endosomes, vesicles and membrane
What are lysosomes?
Derived from golgi
Cells digestive system
Contains enzymes active at pH of 5 (acid hydrolases)
What is Tay Sachs?
Where there is not enough lysosomal enzyme produced, thus resulting in the build up of a type of lipid, leading to the destruction of brain and spinal cells
List the 3 functions of lysosomes?
1. Lysosomes fuse with membrane of another organelle, thus activating lysosomal enzyme = digestion. Nutrients are absorbed or waste is ejected from cell when vesicles fuses with membrane
2. Lysosomes fuses with vesicle containing outside material, function 1 occurs
3. Lysosomes may break down following cell death/injury, lysosomal enzymes active and attach cytoplasm (autolysis)
Describe the double membrane in the mitochondria
The inner membrane is folded (cristae) to increase SA
This membrane is highly impermeable and established proton motive force
What is endosymbiosis?
The believe that mitochondria evolved from FAHB (free living, aerobic, heterotrophic bacteria)
Caused by mutations (inherited or acquired) and either in mitochondria DNA or genes in nuclear genome that in mitochondria
Describe the cytoskeleton
Non membrane organelle
Contains ordered array of protein elements - internal scaffold
Provides cell with key functions - MOSS
What is simple diffusion?
As the cell membrane is semi permeable, lipids, lipophilic and soluble gases pass through unrestricted
What is facilitated diffusion?
Water, hydrophilic and ions diffuse through channels, whilst larger molecules which can't travel through channels, are transported by protein carriers
Name the 4 factors affecting diffusion
1. Magnitude of gradient
4. Diffusion coefficient
What is a diffusion coefficient? List the 3 factors which affect it
Measure of membrane permeability.
1. lipid solubility of gradient
2. MW of solute
3. Molecule is lipophilic or lipophobic
Is diffusion passive or active?
passive - requires no energy, as there is the presence of a gradient
Name the 2 types of diffusion
Simple: chemical or pressure gradient (oxygen, carbon dioxide)
Facilitated: requires a protein carrier, but still requires gradient
What is osmosis?
Diffusion of water across membrane
moves from an area of low solute to high solute
What is osmotic pressure?
force with which water moves due to differing solute concentrations
What is hydrostatic pressure?
pressure exerted at equilibrium, due to force of gravity
What are aquaporins?
integral membrane proteins that form pores in membrane
Allows more water to permeate cell, in the case of kidney cells, which require increased water permeability
What is tonicity?
measure of the effect that a solute has on a cell, when the cell is bathed in the solution
Name the 3 types of tonicity
Isotonic: solute concentration is equal, thus no movement of water
hypertonic: more solute outside the cell, thus water travels out of the cell, resulting in crenation (cell shrinks)
hypotonic: more solute in cell, thus water travels into the cell, resulting in hemolysis (cell expands)
Time of diffusion
t=x^2/2D x = distance, D = diffusion coefficient
thus distances must be small (relating to SA:V)
What is Bulkflow?
Net movement of water AND solutes together, due to passive pressure gradient.
In capillaries, which 3 mechanisms allow for exchange of material?
2. Bulk Flow
Faciliated vs Simple diffusion (Kinetics)
As the solute concentration increases, the rate of transport decreases, as protein carriers become saturated.
Doesnt happen in simple diffusion
Are carrier proteins slow? Why/why not?
They are, as they undergo multiple changes whilst transport solutes
Name the 2 types of protein channels
1. Gated channels (ligand, mechanical or voltage)
2. Gated channels (leaky)
What do carrier proteins do?
Allow large and polar molecules to pass - eg. glucose
Name the 3 types of carrier proteins
1. Uniporter - one solute in one direction
2. Symporter - 2 solutes in 1 direction
3. Antiporter - 2 solutes in 2 different directions
What is a GLUT?
Facilitated glucose transporter
14 types, all with different functions due to different locations in body
Name 3 types of GLUT
1. GLUT 1 = uniporter
2. GLUT 2 = bidirectional (glucose flows in 2 directions)
founds in renal tubule cells, liver, pancreas
3. GLUT 4 = adipose tissue and muscle cells
What is active transport?
transport which requires the use of ATP to allow for transport, as solute travels from area of low to high (pressure, electrochemical, etc)
1 or 2 active transport
Requires a carrier protein
What is the Na/K APTase pump?
Transports Na and K AGAINST there respective gradients, with the help of ATP and antiporter carrier protein
Carrier pumps 3 Na out of cell and 2 K in cell, using 1 ATP
What is another name for the Na/K ATPase pump? Why?
Electrogenic pump - maintains the cells electrical gradient (membrane potential)
How does the ATPase pump work?
There is a high conc. of Na outside the cell, and high conc. of K inside the cell, thus Na diffuses into cell slowly, and K leaks out through channels. Homeostasis. Na/K APTase pump pumps 3 Na out and 2 K into cell, to replace this.
osmotic equilibrium is achieved, but chemical equilibrium is not, as it allows the cell to do work
How does the membrane potential gain a slightly negative charge?
the ATPase pump causes asymmetric distribution of charge, thus deficit of anions in cell, but increase in cations. K is more freely permeable, due to ungated channels, whilst Na is less permeable due to decreased leak channels, so K will follow it's gradient to the outside of the cell
What is solute co-transport
2 active transport
doesn't require direct use of ATP
1 solute goes down the gradient (Na) whilst the other goes up its gradient (glucose)
ATP is invested to pump Na out of cell using ATPase pump
What is membrane polarity?
Property that produces unequal physical effects
allows cells to carry out function
is a function of localisation of specific proteins to specific areas, thus leading to directional movement of molecules across epithelial sheet
What is apical membrane in epithelial cells?
membrane of the cell which faces the lumen
What is basolateral membrane in EC? What does it do?
membrane of the cell which faces away from the lumen
Takes up metabolic waste into cell for disposal into lumen as well as
recycling of substrates, rescued from lumen