Membrane and Transport Quest Pt. 1

review notes + labs!

plasma membrane structure

composed of phospholipid bilayer (tails face inward because they are hydrophobic)

extracellular fluid

fluid outside cell, watery

intracellular fluid

fluid inside cell/cytoplasm, watery

phospholipid structure

hydrophilic head, hydrophobic tails - one straight, one “kinked” (not tightly packed, allows nutrients in)

fluid mosaic model

describes the phospholipid bilayer because there are diverse pieces embedded in framework (mosaic) that drift about in the membrane (fluid)

selective permeability

regulation of amount and type of molecules can enter and exit the cell; maintains different internal environment than external

proteins (purpose)

provide structure/framework, channels for transport, enzyme activity, receptors

types of proteins

peripheral and integral proteins

peripheral proteins

lays on surface of the membrane inside/outside cell; important for cell signaling

integral proteins

aka transmembrane proteins; extends into one/both layers; help transport of materials (e.g. ions, water, large molecules) through the cell; help with cell communication

types of integral proteins

enzymes, receptor mediated proteins, transport proteins (channel and gated/carrier)

enzymes

speed up chemical reactions to make new products

receptor mediated proteins

acts like a lock; requires correct receptor to gain access into cell

types of transport proteins

channel and gated/carrier proteins

channel proteins

“pore” that provides tunnel pathway through membrane

gated/carrier proteins

changes shape to allow molecules through; sometimes requires energy to function

carbohydrates

helps with cell-recognition (acts like an ID-tag); always on the extracellular layer; attaches to proteins/lipids

carb + protein

glycoprotein

carb + lipid

glycolipid

cholesterol

helps strengthen cell membrane by stabilizing it; keeps membrane fluid by preventing fatty acid tails from sticking together

types of transport

passive and active transport

concentration gradient

“flow amount”; difference in area of high concentration from area of low concentration

passive transport

requires no energy; molecules move down concentration gradient

active transport

requires energy; molecules move up concentration gradient

diffusion

the movement of molecules from a high concen

types of passive transport

simple diffusion, facilitated diffusion, osmosis

simple diffusion

movement of small, non-polar molecules

dynamic equilibrium

after equilibrium reached, molecules continue to move across equally

facilitated diffusion

movement of materials across membrane with the help of proteins (channel, gated/carrier)

factors that influence rate of passive transport

1. temperature

   hotter - faster; colder - slower

2. size

   bigger - slower; smaller - faster

3. state of matter

   solid - slow; liquid - fast; gas - fastest

4. steepness of concentration gradient

   larger difference in concentration - faster

how to calculate percent diffusion

(volume diffused / total volume) * 100

what maximizes effectiveness in cell diffusion

maximize surface area and minimize volume

purpose of benedict’s

to see if glucose diffused

what solutions were tested

iodine, water, starch glucose

purpose of weighing bag

to see if water diffused