Physiology Lecture 1 (Cell Membranes and Molecules inside Membranes)

Aqueous

cell environments are largely ____________

Hydrophobic

biological membranes are ___________________ enabling compartmentalization

Bendable

membranes are ________________ in nature, enabling different morphology, and allows the detection fo mechanical stress

cell membrane

separates the internal and external environments of the cell, and enables cells to carry out essential processes unperturbed by the vagaries of their environment

4-5 nm

membranes are _______ thick

membrane proteins

these allow cells to interact with the environment

transport

membrane protein key functions that enbales exchange of small molecules across the membrane

signaling

membrane protein key function that allows cells to receive signlas from external cues to regulate cellular processes

adhesion

membrane protein key function that allows cells to stick to one another

neuron

type of cell that has a bendable membrane for the reason of electrical signal propogation

microvilli

type of cell that has a bendable membrane for the reason of nutrient absorption in epithelial cells

Lipids, proteins, and carbohydrates

membranes are composed of these three types of molecules

varying

biological membranes have ___________ ratios of proteins, lipids, and carbohydrates

myelin

type of membrane that is focused on being an insulator, therefore has a high percentage of lipids in its membrane

human erythrocyte

type of membrane that has equal amounts of proteins and lipids due to the need to carry a lot of oxygen and expell lots of CO2

mitochondrial inner membrane

membrane type that has a high percentage of proteins in the membrane in order to properly carry out cellular respiration

saturated

________________ fatty acids contain only single bonds

triglyceride

type of lipid that is a glycerol bonded to 3 fatty acids

condensation

glycerol bonds to a fatty acid through a __________________ reaction

unsaturated

___________________ fatty acids contain single and double bonds

phosphoglyceride

this type of lipid is a glycerol bonded to TWO fatty acids and a phosphate/alcohol complex

sphingolipid

this type of lipid contains a sphingosine bonded to ONE fatty acid and a phosphate/alcohol complex

glycolipid

this type of lipid contains a sphingosine bonded to ONE fatty acid and a carbohydrate

nonpolar, polar

in complex lipids, the fatty acids are ______________ and the phosphate groups/carbohydrates are _________

phosphoglyceride, sphingolipid

two common classes of phospholipids found in cellular membranes

cholesterol

most common type of steroid found in animal cells

steroids

another type of common lipid component of biological membranes besides phospholipids

choline

group that is on a phosphatidylcholine that allows it to become a zwitteron (not the phosphate)

negative, positive, zwitteron

in phosphatidylcholine, the phosphate group is _________, and the choline group is ____________, which balance each other out in order to have a perceived neutral charge. When one molecule has a positive and negative part in order to balance to neutral, it is called a _____________

repel, far apart

If the choline was not attached to phosphate in phosphatidylcholine, the negative charges in the phosphate group would _________ causing them to get ______________

attracted, close together

Because choline is attached to phosphate, the positive choline is _____________ to the negative phosphate on another molecule, causing them to be ________ _____________

phospholipid bilayer

the cell membrane is called this due to the two sets of phosphate heads, and fatty acid tails that comprise it

hydrophillic, hydrophobic

the phosphate head groups are ___________________ and the fatty acid tails are ___________________

fluid mosaic model

this model describes the membrane strucutre, as the lipids and proteins of the cell membrane are diffused laterally

fatty acid, cholesterol

the fluidity of a membrane is determined by the __________ _________ and ______________ content

saturated

if a membrane contains more _____________ fatty acids, they are more tightly packed and make the membrane less fluid

unsaturated

if a membrane contains more __________ fatty acids, there are imperfectly packed and are not as tight, causing the membrane to be more fluid

proteins, lipids

in syntaxin (shown in class) a bunch of ___________ can cluster and form interactions with __________ causing some change in fluidity due to the amount of complexes formed between these two molecules

alpha helices, beta sheets, random coils

secondary structures of proteins include these three types of structures

integral membrane proteins

types of membrane proteisn that completely span the lipid bilayer, and can even span the membrane multiple times

peripheral membrane proteins

types of membrane proteins that are bound to the surface of the membrane, but do not completely span it

amphipathic

having both a hydrophilic and hydrophobic part

nonpolar

membrane spanning alpha helicies generally have _____________ residues because they can interact properly with hydrophobic lipids

amphipathic

_____________ helices interact both with lipid bilayer and with other protein transmembrane segments due to its polar and nonpolar natures

ionic, weak

peripheral membrane proteins associate with the surface of the membrane via __________ or other _______ interactions, but can also bind to lipid head groups or other membrane proteins

post-translationally modified

some of the peripheral membrane proteins are _______-_______________ ___________________ to enable membrane tethering (ex Palmitoylation of Cys residues)

facilitating endocytosis and exocytosis, enzymes

besides transport, signal transduction, and adhesion, these two functions are also utilized by membrane proteins

carbohydrates

this type of molecule in a membrane are always found bound to a protein or lipid

stability or protection

carbohydrates provide ___________ when bound to a protein or lipid in the membrane

Lysosome

in this organelle, the carbohydrates attached to the membrane proteins allow the high pH of the inside not consume the membrane proteins when the organelle is consuming the "garbage" that it needs to clean up from the cell

viruses

some different types of organism binds to the carbohydrates to initiate infection

not

the composition of the plasma membrane is _____ uniform all around the cell

apical

the part of an epithelial cell that is involved in bringing in nutrients to the cell

basolateral

the part of an epithelial cell that is involved in transporting nutrients out of the cell for dstribution in the blood stream

lipid rafts

this is a type of microdomain that have a lot of sphingolipids and cholesterol

caveolae

a subset of lipid rafts that are very big, enriched in cholesterol and have distinct phospholipid and protein compositions

Caveolin

the abundant protein component of the caveolae