Second Exam Flashcards
What do lipids do in cells?
Used as secondary energy sources
Major component of membranes
Why are lipids used for energy?
High energy to weight ratio
Harder to metabolize
What are triglycerides?
Storage lipids like fats and oils that consist of a glycerol bound to three fatty acids
What are fatty acids?
Long hydrocarbon chain with a carboxylic head
What are the two forms of fatty acids?
Saturated and Unsaturated
What are ester bonds?
The bond between the hydroxyl of a glycerol and the carboxyl of a fatty acid
What form do saturated fatty acids take?
Solid
What form do unsaturated fatty acids take?
Oils, liquid
What are phospolipids?
Glycerol ester bonded to 2 fatty acids and a phosphate group which is bound to a variable hydrophilic molecule
What is the cystol?
Aqueous part of the cytoplasm of the cell
What is the lumen?
Extracellular space
How does hydrocarbon tail length effect fluidity?
The shorter the tail, the greater the fluidity
How does unsaturation effect fluidity?
Unsaturated means more fluidity
What do sterols in membranes do to fluidity?
Decrease it
How does temp effect fluidity?
Fluidity increases with temp
Where are new phospholipids made?
Cystolic side of smooth ER membrane
What are scramblase enzymes?
Randomly moves phospholipids to even out the membrane
What does flippase and floppase do?
Move specific phospholipids to different sides of the layer
What are the membrane proteins?
Transporters
Anchors
Enzymes
Channels
Receptors
What are integral proteins?
Tightly associated with membranes, some embedded, sometimes transmembrane, and commonly are alpha and beta folded
What are peripheral proteins?
Loosely associated with membrane, may be linked to other substances
What are glycolipids?
Lipid tails attached to a sugar head, the head is exposed to the cell exterior
What are proteoglycans?
Proteins attached to long chains of repeating sugars
What are glycoproteins?
Proteins attached to short, highly branched sugar chains
What is glycocalyix?
Sugar coating of plasma membrane, promotes biofilm formation
What is a cell cortex?
specialized layer of cytoplasmic proteins on the inner face of the cell membrane
What is spectrin?
Protein that lines the intracellular side of the plasma membrane
What can cell cortex abnormalities result in?
Anemia
What can move through semi-permeable cell membranes?
Small nonpolar molecules and some uncharged polar molecules
What can not move through semi-permeable cell membranes?
Charged molecules and ions
What is passive transport?
No energy, movement goes with the gradient
What is active transport?
Needs energy, goes against the gradient
What factors affect passive transport?
Chemical gradient
Membrane potential
Electrochemical gradient
What is the chemical gradient?
the difference in molecule concentrations across a cell membrane
What is membrane potential?
the electrical potential difference across the plasma membrane
What is the electrochemical gradient?
measure of the free energy available to carry out transporting the molecule across the membrane
What are ways a cell tries to reach equilibrium?
Simple diffusion
Osmosis
Facilitated diffusion
What is isotonic?
Equal concentrations
What is hypotonic?
high solute inside cell, high water outside cell
What is hypertonic?
high solute outside cell, high water inside cell
What is osmolysis?
rupture of a cell membrane due to excessive water intake
What is plasmolysis?
Shriveling of a cell due to loss of water
How to protozoans regulate equilibrium
They discharge contractile vacuoles of water
What is a uniporter?
Facilitates the diffusion of a single substance
What is a symporter?
proteins that simultaneously transport two molecules across a membrane in the same direction
What is a antiporter?
protein that transports two molecules at the same time in the opposite direction
What are the different Transport Ion Channel Gates?
Voltage Gated
Ligand Gated
Mechanically Gated
What is a voltage gated channel?
Channel stimulated by membrane potentials
What is a ligand gated channel?
Channel stimulated by ligand binding
What is a mechanically gated channel?
Channel stimulated by mechanical force or stress
What is resting membrane potential?
Voltage across a membrane when cell is at rest
What is action membrane potential?
Change in membrane voltage that opens ion channels and allows ions to flow across the membrane
What are the facilitated diffusion transports?
Carriers
Channels
What do carrier transports do?
bind the specific solute to be transported and undergo a series of conformational changes to transfer the bound solute across the membrane
What do channel transports do?
acts like a pore in the membrane that lets water molecules or small ions through quickly
What are examples of Primary Active Transport?
ATP driven pumps
Light driven pumps
Bulk Transport
What is Secondary Active Transport?
Uses energy from ion movement going with the gradient to power the transport of ions against the gradient
What are examples of bulk transport?
Endocytosis
- Phagocytosis
- Pinocytosis
Exocytosis
What is endocytosis?
Bringing substances into the cell using vesicles
What is phagocytosis?
“cell eating”
What is pinocytosis?
“cell drinking”
What is exocytosis?
Releasing substances using a vesicle
What is clathrin?
Proteins involved in shaping vesicles and engulfments
What are adaptins?
Molecules that secure the clathrin coat to the membrane and hold cargo receptors that bind to target molecules
What is dynamin?
Molecules that pinch off the cell membrane into a vesicle
What are lysosomes?
Vesicles full of digestive enzymes
What terminus are signal sequences found on?
N-terminus
How are improperly folded proteins disposed of?
They are retained in the ER by chaperone proteins and degraded
What do vesicles shed to allow for membrane interaction?
Clathrin coat
What are the transmembrane proteins?
SNAREs
Rab proteins
Tethering proteins
Where do condensing vesicles go?
They remain in the cell
Where do secretory vesicles go?
They are exocytosed
What are the secretory pathways?
Constitutive
Regulated
What is the constitutive secretory pathway?
Unregulated exocytosis
What is the regulated secretory pathway?
Holds vesicles at the cell membrane then releases them all at once, such as the release of insulin
What is a nuclear localization signal?
The mark on proteins that are selected for nucleus import
How is a nuclear localization signal recognized?
cytosolic nuclear transport receptors that are attached to nuclear pore fibrils
