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What are the components of the plasma membrane
Plasma Membrane = Lipid ( cholesterol, phospholipid, glycolipids ) + Protein ( ID, enzymes, receptors, channels, carriers, cytoskeleton )
Explain how the amphipathic nature
of the phospholipid molecules
results in the formation of the plasma membrane.
- each molecule consists of a hydrophilic (water-loving) portion and a hydrophobic
- (water-hating) portion. Due to the amphipathic nature and insolubility
- in water, phospholipids are ideal compounds for forming the biological
- The fatty acid part minimize interaction with the water because it is
- hydrophobic which is non polar. While the Hyrdophilic head (polar) is
- faced outward because it loves water.
Define selective permeability.
Allows some things to go in/out depending on phosphilipid properties.
Sideways motion of proteins/fats across plasma membrane.
Explain how the phospholipid bilayer affects the selective permeability and fluidity of the plasma membrance.
- For selective permeability, Small, uncharged and non-polar molecules can get across.Large polar molecules and ions can't get across.
- Reduced fluidity= making all fatty acids saturated .Increase Fluidity= fatty acids have to be unsaturated
Explain why the fluidity is an important property of the plasma membrane.
- - cell division ex. cytokinesis
- - medicine ex. artifical fertilization
Explain how plant cells cope with temperature changes in thier environment.
- They change the fat content of the plasma membranes.
- Increase fluidity= increase the amount of saturated fatty acids, reduces fluidity, make fat saturated ( hot summer )
- Decrease fluidity= ( membrane can freeze ) -> increases the amount of unsaturated fatty acids ( cold winter )
How does cholesterol act as a " temperate buffer " for the plasma membrane?
- 20% of plasma membrane.
- - it resist chanes in fluidity
- - it strengthens plasma membrane
- At warm temperatures, cholesterol restrains the movement of phospholipidsand reduces fluidity
- .• At cool temperatures, cholesterol maintains fluidity by preventing tight packing.
Explain why Glycolipids are an essential component of the plasma membrane.
- " nametags" of the cell, identiflies cells, cell identity markers
- ex. organ transplant ( liver, heart,lungs,lens of eye,skin) why is it rejected sometimes?
- Its because of the differences in glycolipid
Explain some of the important roles of proteins in the plasma membrane.
- Transport proteins: movement of specific substances into or out of cells-
- Enzymes, sometimes catalyzing one of a number of steps of a metabolic pathway-
- Receptors, which relay hormonal messages to the cell
- Cytoskeleton anchors
- Identity markers
What are the cause and consequences of diabetes mellitus?
- Cause: affects plasma protein, pancreas doesnt produce enough insulin, # of glucose carriers drops, blood sugar levels go up
- Cosequences: cells starve, can't get sugars in cell, high sugar levels in urine
Explain how the shape of red blood cells is maintained by plasma membrane proteins.
- The position of the proteins along the plasma membrane serves a purpose
- as they function in anchoring the cytoskeleton within the cell. The
- cytoskeleton gives the specific structural shape to the cells, which
- ranges from the simple disc shaped red blood cells to the complex
- structure of neurons.
What is tight junction? function?
- web like arrangement of membrane proteins that encircle the cell
- Function : prevents leakages of fluids btwn cells
what is plasmodesmata? function?
- " cytoplasmic " connections btwn plant cells.
- it allows communication btwn cells
What are Desmosomes? function?
- localized, protein linkages that are reinforced by intermediate fibers.
- it anchors and prevents cells from falling apart
what are gap junctions? function?
- are open protein channels btwn cells.
- They allow for cells to communicate.
- Important for food to be moved down to stomach
- ex. peristalisis
Difference btwn Passive and active process.
- Passive: High to low conc. requires no energy(ATP), concentration gradient
- Active: Low to high conc. Requires ATP, protein->pump, against conc. gradient
Difference btwn diffusion and faciliate diffusion.
- DIFFUSION:the process
- by which molecules spread from areas of high concentratiion, to areas
- of low concentration
:"needs help" needs an ion pump or a protein channel
Plasma membrane transport= Passive ( diffusion, facilitated diffusion, osmosis ) + Active ( primary, secondary, bulk )
- form of diffusion.
- passage of free water from low solute to high solute conc. across a selected permeable membrane.
Explain how solutes affect osmosis.
- inverse relationship
- The more solute, the more it reduces the # of free water molecules.
what is kwashiorkor?
- a form of malnutrition caused by inadequate protein intake
- - rejected ones, mother stopes breast feeding them
- - stops taking in milk, stops taking in protein(solute)
How does hypotonic, isotonic, and hypertonic solutions affect animal and plant cells?
- hypotonic: high solute conc around cell than inside cell ( free water comes out, inside cell will swivle )
- Isotonic: same solute conc. inside and outside cell ( animal cells do well )
- Hypertonic: lower solute conc. compared to within cell ( plant cells do well )
How would u expect prokaryotes to become affected in hypotonic, isotonic, and hypertonic solutions?
- Animal cell=
- Hypotonic: Lysis, bursts/destruction
- Isotonic: normal
- Hypertonic: Crenation
- Plant cell=
what are active processes?
- all use energy in form of ATP, use membrane protein, moving things against
- conc, gradient, low to high conc.
What is primary transport?
- also called direct active transport, directly uses energy to transport molecules across a membrane
- It expends ATP energy to move sodium ions out of the cell and replace them with potassium ions.
- outside= more positive , inside= more negative
- every 3NA+ pumped out for 2K+ pumped in
what is secondary transport?
- -use of ATP indirectly
- -cotransporter=moving H+ and sucrose at the same time b/c we are using hydrogen ion conc. difference
- -Exchangers move two or more molecules in opposite directions. ( Na and H )
Why is the action of the sodium-potassium ATPase pump essential for life?
- it is most inportant pump in body, its how electrical signals happens in brain and nerves
- - for nerve impulses
Explain how cyanide poisoning causes death.
- -cant find cyanide in blood, only through hair folicles
- -The cyanide shuts off the power generater of cell
- -pumps shut off (Na+ dont go out and K+ dont go in anymore )
- - charge difference dissapears and then heart muscles and brain stops
Define Bulk transport.
movements of large amount of substance in/out of cell all at once; using vesicles
Difference btwn endocytosis and exocytosis.
- endocytosis: , the cell engulfs some of its extracellular fluid (ECF) including material dissolved or suspended in it.
- exocytosis: is a cellular process where cells eject waste products or chemical
- transmitters (such as hormones) from the interior of the cell
Difference btwn Phagacytosis, Pinocytosis, and recptor-mediated endocytosis.
: selective Cell eats(ingulfs) large particles ex. backteria, food particle
: non-selective, no receptors, cell bringing in fluids with dissolved particles inwards
: selective, receptor involed, bulges inwards, brings in dissolved fluids and vitamins
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