BIO130 2nd Half Flashcards
Week 7
Structures unique to animal cells and what they do for the cell
Membrane stuff
Extracellular matrix
>large network of proteins and other molecules that surround, support, and give structure to cells and tissue in the body.
>specialized material outside the cell (release materials into space)
>special composition in animal cell
-Lysosomes
>membrane enclosed organelles contain an array of enzymes capable of breaking down stuff (degradation).
-Animal cells do not contain: cell wall, vacuole, or chloroplast
Week 7
Components of Eukaryotic cells and what they include (How the cell is broken up, broadly)
Membrane stuff
-Cytoplasm
>contents of cell outside nucleus, includes ribosomes and cytoskeleton
-Cytosol
>aqueous part of cytoplasm, does not include membrane bound organelles
-Lumen
>inside organelles, between nucleus membrane
Week 7
Membrane structure - Bilayers
Membrane stuff
-Bilayer
>fluid mosaic model of membrane due to mobility of lipids
Lipid bilayer
>1 membrane, 2 layers/leaflets, forms with the heads out and the tails inward , packed tightly.
-Phospholipid molecule
>hydrophilic head and 2 hydrophobic tails
Week 7
Lipids (used to form bilayers)
Membrane stuff
-Phospholipids
>must have a glycerol group (Phosphoglyceride), there are many phosphoglycerides
>composed of a group, phosphate, glycerol, and hydrocarbon tail
>kink: unsaturated, cis double bond (Tail)
>this bilayer forms balls that are energetically favorable called liposomes
-Sterols
>sub group of stereroids with a hydroxyl group
-Glycolipid
>lipid with carbohydrate attached covalently
Week 7
Ways in which a membrane may move and effects on fluidity
Membrane stuff
-Membrane can be deformed without damage
>diffuse laterally (back/forward)
>rotate
>flex (wiggle)
>flip flop, 1 leaflet to another (RARE)
-Temperature effects
>lower temp less fluid
-Composition:Saturation effects
>more fluid with cis double bonds (kink means can’t pack as tight, must remain fluid)
-Composition:Tail length effects
>more fluid with shorter tails
-Composition:Lipid effects
>less fluid with cholesterol (stabilizer)
Week 7
How do plant and animal cells reduce fluidity of the membrane
Membrane stuff
-Stiffens membrane and makes it less permeable for polar molecules
-Animal
>cholesterol
>1:1 ratio cholesterol:phospholipids
-Plants
>sterols
Week 7
Explain the flip flop movement of lipids
Membrane stuff
-Flip flop is a rare movement of lipids between leaflets
-Enzyme in the ER membrane preforms the flip
>scramblase catalyzes
>flipase moves
-Why does this happen
>phospholipids synthesized in systolic leaflets of endoplasmic reticulum, they need to be mixed in
Week 7
Explain the difference between scramblase and flipase
Membrane stuff
-Scramblase
>no ATP required
>non specific and bi directional
>mixed properly
-Flipase
>need ATP
>specific and mono directional
>in the golgi (asymmetric)
Week 7
Model Eukaryote
Membrane stuff
Saccharomyces cerevisiae
>has a cell wall
Week 7
What causes the flip flop of lipids catalyzed by flipase
Membrane stuff
-Glycolipids and glycoprotein
>formed by adding sugar group on luminal face of golgi
>something on the membrane facing the noncytosolic side of the cell
>to get it into the cell and to a subunit the membrane needs to stay intact the way it is, therefore it will form a vacuole with the glyco.. inside of it
Week 7
Describe integral membrane proteins
Membrane stuff
-Proteins insert in some way into the membrane
>transmembrane
>monolayer associated
>lipid linked
-Proteins are directly attached to lipid bilayer
>inserted in bilayer
>attached to lipid insterted in bilayer
-Extraction
>detergents
>lipid bilayer destroyed
Week 7
Describe peripheral membrane protiens
Membrane stuff
-Associated with membrane or integral membrane proteins non covalently
>protein attached
-Do not insert into membrane
>bound to other proteins and lipids
-Extraction
>gentle
>lipid bilayer intact
Week 7
Describe transmembrane proteins
-What is it
-Whats special about its structure
-Structure
-Orientation
Membrane stuff
-INTEGRAL
-Amphipathic
>has both hydrophobic and hydrophilic parts
>hydrophobic membrane spanning domains, AA side chain non polar (part that runs through the membrane)
>hydrophilic domains, AA side chain polar (outside the membrane)
-Membrane spanning domains
>single alpha helix (20 hydrophobic AA)
>multiple alpha helix
>betta barrel
-Each transmembrane protein has a specific orientation essential for function
>transporters and channels
>anchors
>receptors
>enzymes
Week 7
List ways that transmembrane proteins can be identified
Membrane stuff
-X ray crystallography
>determines 3D structure
-Hydrophobicity plots
>identify single alpha helicies
>positive value indicates free energy is required for transfer to water, value assigned is the amlount of energy needed
>peaks in hydropathy index indicate positions of hydrophobic segments
Week 7
Describe monolayer associated proteins
Membrane stuff
-Proteins anchored on cytosolic face by amphipathic alpha helicies
>connected into the bilayer but does not rub through to the non cytosolic side
>hydrophobic segment is in the bilayer the rest is in the cytosol
Week 7
Describe lipid linked membrane proteins
Membrane stuff
-GPI anchor
>glycosylphosphatidylinostiol
>synthesized in ER lumen
>ends up on non cytosolic face
-Another lipid anchor
>cytosolic enzymes add anchor
>directs protein to cytosolic face
Week 7
Describe the different ways to extract a membrance protein and the differences in methods
Membrane stuff
-Detergent
>INTEGRAL
>TritonX100
>amphiphilic
>form spheres (micelles)
>disinigrate the lipid bilayer by inserting in between the bilayer breaking it apart (lysed)
>micelles can extract lipids from the bilayer, cause insymmetry, and it will break
>can grab onto proteins
>protein might not be in the right direction
-FRAP
>Floursecence recovery after photobleaching
>lateral diffusion within the leaflet (no flip flop)
>protein fused to GFP outside the cell, photobleach with laser, labelled proteins diffuse, neighboring unbleached proteins migrate in to replace bleached patch
Week 8
Permeability
-What is permeability
-How can we move difficult objects through
-What can get through the lipid bilayer
Membrane stuff
-Permeable
>movement via simple diffusion through lipid bilayers
>always towards a lower concentration (down the gradient)
>more hydrophobic or non polar, faster diffusion rate
-Impermeable
>require membrane proteins for transport
-Lipid bilayer, no assistance
>small non polar molecules
>small uncharged polar molecules
-Lipid bilayer, assistance or not at all
>larger uncharged polar molecules
>ions
Week 8
Describe transmembrane transport proteins
Membrane stuff
-Includes channels and transporters
>create protein lined path across cell membrane to transport polar and charged molecules
>each transport protein is selective
-Channel
>selective based on size and charge
>brief interactions as solute passes through, kept open, no conformational change
-Transporter
>selective based on binding site
>binding of solute, opens and closed, conformational change
Week 8
Describe the 2 different types of transport
Membrane stuff
-Passive
>with the concentration gradient
>does not directly require energy
-Active
>against the concentration gradient
>directly requires energy
Week 8
Explain the electrochemical gradient
Membrane stuff
-Made up of the concentration gradient and membrane potential
>want to move positive to negative space
>concentration gradient alone has no membrane potential
Week 8
Describe channel proteins and different types
Membrane stuff
-Hydrophilic pore across membrane
>selective
>passive transport
-Ion channels
>non gated, always open
>gated, some type of signal to open
>mechanically gated, mechanical stress
>ligand gated extracellular, ligand
>ligand gated intracellular, ligand
>voltage gated, change in voltage across membrane
Week 8
Describe transporter proteins and different types
Membrane stuff
-Binds a specific solute
-Conformational change
-Passive, Uniport
>one solute
>down gradient
>direction of transport reversible
>GLUT uniporter
-Active, Gradient driven pump
>against gradient, needs energy
>symport, 2 solutes want to go same direction, conc opp
>Na+ glucose symporter
>antiport, 2 solutes want to go opp direction, conc same
>Na+H+ exchanger
>free energy from 1st moving down the gradient can be used to move the second against the gradient, something is always moving with its gradient
-Active, ATP driven pump
>moves against gradient with the energy from ATP hydrolysis
>p pump, phosphorylated during pumping cycle to move ions
>sodium potassium pump 3Na 2K
>ABC, 2 atp to move small molecules
>v pump, used to pump H+ to acidify
>f type ATP synthase, opp v pump to create ATP
Week 8
Explain the transcellular transport of glucose by transporters
Membrane stuff
-Relies on
>GLUT Uniporter
>Na glucose symporter
>NaK pump
-Epithelial cells
>line surfaces, cavities, and organ
>many form villus
>have microvillus
>apical side (faces gut lumen), lateral (side), basal domain (extracellular facing)
>tight junctions, stop things from going between cells and keep apical and basal lateral proteins on the right side
>glucose must go through the cell
>sodium and glucose move inwards Na moves with the gradient the energy can then be used to move glucose
>sodium potassium pump keeps sodium low inside cell so that sodium wants to move inside the cell with the gradient
>GLUT uniporter releases glucose to the inside
