Exam 2(3) - Membrane, Membrane Transport, ECM Flashcards
What is true about membranes?
All life occurs in, on, or across membranes
What is the general structure and function of the Plasma membrane?`
Structure:
phospholipid bilayer w/ stuff embedded
- fluid mosaic model
Function:
- isolates cell
- structure
- sensitivity
- communication
- regulation
- chem rxns.
- defense
- compartmentalization
what is the ICF?
Intracellular matrix
what is the ECF?
Extracellular matrix
What is the phospholipid bilayer?
- external surface lined w/hydrophillic polar heads
- cytoplasmic surface lind w/ hydrophilic polar heads
- nonpolar, hydrophobic, fatty acid tails in between.
What are the general parts of the Fluid Mosaic Model?
- phospholipid bilayer
- protein molecules
- cholesterol
-carbohydrates
What is the glycocalyx? Structure?
Made from carbohydrates, they are carbohydrate chains that attach to lipids or proteins in the PLB
What are the two types of proteins in the fluid mosaic model?
-Peripheral Proteins
-Integral proteins
What is a peripheral protein?
- found on the inner membrane surface
What is an integral protein?
- partially or wholly embedded in the PLB
- transmembrane
- lipid - anchored
Why is cholesterol important?
It stabilizes the fluidity and flexibility of the semi-fluid membrane.
tail length to fluidity?
shorter tail = more fluidity
bond # to fluidity?
double bond ( more= more fluid cholesterol)
How does temperature relate to fluidity?
incr. temp –> decr. fluidity
decr. temp—> incr. fluidity
Psychrophilic
Organism in cold temp/ more unsat. fatty acids
Mesophilic
Live in med. temp./ balance between sat and unsat. fatty acids
Thermophilic
very hot temp/ more sat. fatty bonds
psychrophilic, mesophilic, and thermophilic overall function.
Adaptations to help organisms live in different environments.
How do phospholipids move?
-laterally
- rotational
What is the function of membrane proteins?
Exchange resources
Channel protein
- tubular, allow passage
ex. aquaporins
Carrier proteins
-combine w/ substance to be transported (specific)
cell recognition protein
- unique ID ( chemical) for cells
- help the body recognize foreign substances
What is the function of the glycocalyx?
-to help identify cells as our own
what is the ligand??
signaling molecule binds to the receptor
receptor proteins
-bind w/ messenger molecules
- causes cells to respond to a message
enzymatic protein
- carry out metabolic reactions directly
What are the different kinds of membrane transport?
- Passive
- Active
What are the different kinds of passive transport?
-diffusion
- osmosis
-facilitated diffusion
what is passive transport?
- the net movement of solute down a concentration gradient
- molecules move both ways along the gradient
- move form high to low concentrations
- dynamic equilibrium
what is a dynamic equilibrium?
- when the NET change stops
- solute concentration uniform
What are some of the things that affect passive diffusion?
- distance
- size of the gradient
- the size of molecules
- temperature
-electrical charge - physical manipulation
what is osmosis?
diffusion of water across a differently permeable membrane - focus on the solvent
How does the water move?
Net movement of water is toward low water ( high solute) concentration.
What is osmotic pressure?
pressure to stop the movement of water - develops due to osmosis
- colligative property
what is a colligative property?
doesn’t matter the type of particles only the number of particles.
Isotonic solution?
solute+ water concentrations equal on both sides of the membrane
hypotonic solution
the concentration of solute lower than an inside cell, cells in a hypotonic solution will swell –> lysis
hypertonic
concentration of solute higher than inside the cell; cells in a hypertonic solution will shrink –> crenation
tonicity
strength of a solution - the ability of a solution to change cell shape through movement of water
What is facilitated diffusion?
movement of small molecules that can’t get through membrane lipids
- combine with carrier proteins ( specific)
- follow concentration gradient (passive)
what is active transport?
- movement of small molecules against the concentration gradient
- combining with carrier proteins ( transporter)
- requires energy
primary active transport?
ATP being spent directly
- establish a concentration gradient
secondary active transport?
relies on the gradient established by primary active transport
( can only ever be by cotransport)
uniport?
one substance being moved
cotransport?
two substances are being moved
symport?
Type of cotransport
- same direction across the membrane
antiport?
Type of cotransport
- the two substances move in opposite directions
Why is the sodium-potassium ATPase Pump important?
- can be seen in all cells
- transmembrane potential
What is transmembrane potential?
transmembrane potential (Vm) represents the difference in electrical potential between the extracellular and intracellular compartments of the cell.
What is step one of the NA K pump?
- sodium is low inside the cell and high outside –> carrier protein picks up 3 Na molecules
Step 2 of Na K Pump?
- split an ATP molecule, the phosphate goes onto the carrier
Step 3 of Na K Pump?
- A change in shape causes the carrier to release the 3 Na outside the cell
Step 4 of Na K Pump?
- Takes up 2 K molecules
Step 5 of Na K pump?
- phosphate group is released, shape change releases the K into the cell
What are the steps of the sodium-potassium ATPase pump?
- sodium is low inside the cell and high outside –> carrier protein picks up 3 Na molecules
- split an ATP molecule, the phosphate goes onto the carrier
- A change in shape causes the carrier to release the 3 Na outside the cell
- Takes up 2 K molecules
- phosphate group is released, shape change releases the K into the cell
what are the functions of the Ion Electrochemical Gradients?
- Transport of ions/molecules
- Production of energy intermediate
- regulation of cytosolic pH
-osmotic regulation - nerve signaling
- muscle contraction
- bacterial swimming
what does the chemical part of the electrochemical gradient refer to?
the concentration of ions
what does the electrical part of the electrochemical gradient refer to?
negative inside membrane attracts positive charges, positive outside of the cell repels positive charges
what is an excitable membrane?
-voltage-gated ion channels
- can generate big electrical signals that get sent out and are used as action potential
- nervous and muscle tissue
What uses membrane-assisted transport?
hormones, digestive enzymes, neurotransmitters, mucus, cell wall components etc.
Exocytosis?
- the vesicles fuse with the plasma membrane
- secrete contents
- materials are targeted to vesicle
- the vesicles move to the proper location
- signals trigger the release of materials from vesicles
Endocytosis?
cells engulf substances into a pouch which becomes a vesicle.
Phagocytosis?
( only certain cells)
- large solid material into vesicle
“ cell eating”
Pinocytosis?
( all cells can do)
- liquid or small solid particles go into vesicle
“ cell drinking”
Receptor-Mediated Endocytosis?
( specific format of pinocytosis using a coated pit - clathrin)
- surrounds ligands bound to their receptors and then it pinches off into a coated vesicle.
What is the extracellular matrix?
- the space between cells
- retinal meshwork of polysachriches + proteins
What is the function of the ECM?
-structure/support
- organization
- strength
- communication
What kind of proteins are found in the ECM?
-Adhesive proteins ( Fibronectin,, laminin)
- Structural proteins ( Collagen, Elastin)
- Proteoglycans ( GAGs)
What do adhesive proteins do?
Help cell stick
What do structural proteins do?
Add support ( Fibrous nature), elasticity, build
What is the structure and function of GAGs?
Structure:
- long unbranched polysaccharides
- highly negative
Function :
- gives extracellular fluid gel-like consistency
How do GAGs work?
- bind water and cations ( Na+, K+, Ca+2)
- resist compression
- hyaluronic acid, chondroitin sulfate, keratin sulfate
Is the ECM one set consistency?
No, the ECM can develop different consistency depending on the tissue or cell we are talking about
What are the different membrane junctions of animal cells?
- desmosomes
- tight junctions
- gap junctions
What kind of junctions do plant cells have?
-plasmodesmata
What is the structure and function of desmosomes?
structure:
- disk-like plaques at the surface of the plasma membrane
-intercellular filaments between cells ( keratin)
function:
- anchoring/ adhesion junctions
- stick stuff together
- mechanically strong
Tight Junctions ( occluding)
Structure :
- round proteins ( occludin and claudin) create a ring-like network
- form weak strands between the membranes
Function:
- occluding junctions - block
- allows sets of cells to form an impermeable barrier ( watertight)
- stuff can go through but not between
what are some examples of tight junctions?
blood-brain barrier
sperm testis barrier
What is the structure and function of gap junctions?
structure:
- series of 6 connexon proteins form tubes/channels from one membrane to another - allow communication
Function:
- communication between cells
- send signals from cell to cell
- communication in unison
Why are plant cells different than animal cells when it comes to junctions?
They do not have a cell membrane but rather are bound by a fairly permeable cell WALL ( made of cellulose)
What is the middle lamella?
found in plants
- layer of pectin ( carbohydrate) acts like a sticky glue
What is the structure and function of plasmodesmata?
Structure:
- found between the cell walls of adjacent plant cells
- channels from one cell to another through the cell wall
- line by cytoplasm
function:
- plant version of gap junctions
- allow passage of material
What are tissues?
Group of cells with similar structure or function
What is an organ?
A group of 2 or more tissues that perform a specific function or set of functions.
What is the structure and function of Epithelial tissue?
Structure:
- cells joined together forming continuous sheets to cover or line body surfaces.
- joined by tight and adhesive junctions
Function :
- regenerative
- protective barrier
What is the structure and function of connective tissue?
Structure:
- vary quite a bit - bone, blood, ligaments, fat deposits, etc.
- always a combination of ground substance, fibers, and cells
Function:
- support the body or connect tissues
- transport - blood
- temperature - fat deposits
- functions vary
What is the structure and function of nervous tissue?
Structure:
- excitable membrane
-neurons
Function:
- receives, generates, and conducts electrical signals
What is the structure and function of muscle tissue?
structure:
- skeletal, cardiac, smooth
-excitable membrane
Function:
- generates force that facilitates movement
