Ch. 7 Review Flashcards
What holds the lipid bilayer together?
Hydrophobic interactions
Where are the hydrophobic and hydrophilic regions of a transmembrane protein?
Hydrophilic- sides facing extracellular matrix and cytosol, interior of protein
Hydrophobic- outside facing lipid bilayer
The membrane is _______
FLUID
Phospholipids move _____ not _______
Laterally, they don’t FLIP-FLOP
Why don’t phospholipids flip-flop?
The phospholipids would have to then invert themselves, this requires more energy then lateral movement and it’s rare
Do proteins in the membrane move?
Yes, only laterally for the same reasons as phospholipids
Fluidity is essential for cells, what are the two reasons?
- for permeability (slight!)
- so the membrane proteins can function (ex. ETC in mitochondria for fluidity)
Ex homeostasis
What factors influence fluidity?
- temperature- High temp more fluid, low temp less fluid
- type of fatty acids- saturated vs. unsaturated (more fluid)
At a high temp there are more _______ fatty acids, at a low temp there are more _______ fatty acids
saturated, unsaturated
Single celled life can ______ which types of fatty acids are present?
alter
Membranes are mosaics that ______
- contain a diverse set of proteins
- some are embedded, some are not
-integral vs peripheral proteins
Membranes also contain 4 things
- glycoproteins (oligosaccharide attached to amino acide side chain)
- glycolipids (oligosaccharide and lipid)
- oligosaccharides
- receptors
Proteins have a specific _______ which determines its _______
orientation, function
What are the 6 types of membrane proteins mentioned in lecture?
- transport
- enzymatic activity
- signal transduction
- cell to cell recognition
- intercellular signaling (cell junctions)
- attached to the cytoskeleton
What do cells need from the environment?
- nutrients for energy, vitality and growth
-sugars, amino acids, fatty acids
-Na+ K+, vitamins allow us to do biochemistry - Gases (ex. O2)
- Need to eliminate waste
Membrane proteins maintain what and accommodate for what?
Must maintain internal environment, membrane proteins accommodate for the diversity of needs and nutrients
What are the barriers to getting nutrients into the cell? What is the solution?
PROBLEM
1. nutrients are polar and charged, proteins need to help
- The cell membrane has a hydrophobic core
SOLUTION
Membranes are selectively permeable
What does selective permeability depend on?
- permeability of a pure phospholipid bilayer
- the presence of transport proteins
What can cross the bilayer? What can’t?
CAN
small, nonpolar molecules (ex. O2)
small, polar molecules are partially blocked but can cross (ex. H2O)
CAN’T
large, polar molecules are totally blocked (ex. glucose)
charged substances of ANY size are totally blocked (ex. Na+ or K+)
What are the two types of transport?
passive and active
Is energy involved in passive transport?
There is no NET energy, BUT there is POTENTIAL energy
Is energy involved in active transport?
YES, ATP is used
What are the two types of passive membrane transport?
- simple diffusion (small nonpolar substances)
- Facilitated diffusion
-channel and carrier proteins for polar and charged substances
Transport and channel proteins are _______
SPECIFIC
Define channel proteins
- integral membrane protein completely spanning the membrane
2.Contains a HYDROPHILIC CORE, that recognizes ONE type of solute
How do channel proteins recognize one specific solute?
based on specific shape, size, and polarity. The channel protein is used by individual atoms.
What is an example of a channel protein?
ion channels (Na+, K+, Ca++) aquaporins
What is osmosis? Why is it special?
Osmosis is the diffusion of water
water VIOLATES high to low
water diffuses from high to low concentration, the solutes remain constant
What are examples of osmoregulation?
protists- contractile vacuoles
bacteria- cell walls
plants- cell walls
animals- solute balancing
Plants prefer which osmoregulation state? Animals prefer which one?
plants- hypotonic
animals-isotonic
Carrier proteins change _______ to allow _______ solute to pass through
shape, ONE
Channel proteins are ______ and _______ change shape
static, DON’T
Carrier proteins can transport
monomers like amino acids or glucose
Why active transport?
- so solutes can move AGAINST the concentration gradient to concentrate things within the cell
- requires INPUT of ENERGY
- requires a CARRIER protein
What are the two types of active transport?
primary- used to concentrate ions via ion pumps, driven by ATP
secondary- involves movement of TWO substances, COTRANSPORT, driven by the ion gradient
What pump is essential for osmoregulation in animal cells?
Sodium potassium pump, which MAINTAINS the gradient
3 Na+ out, 2 K+ in
What is an example of a secondary active transport?
Na+ driven glucose transport protein
Glucose transport doesn’t need ATP BUT it needs Na+, Na+ comes from active transport of sodium potassium pump, glucose transport needs ATP SECONDARILY
Vesicles transport ______
transport macromolecules, particles, and small cells
What are the two types of vesicle transport
exocytosis- secretion, out of cell
endocytosis- phagocytosis, into cell
Phagocytosis is ________ while receptor-mediated endocytosis is ________
nonspecific, specific
