Bio lecture 8

fluid-mosaic

parts can move, made of many smaller pieces (each with different functions)

phospholipids

________ are the most numerous molecule in our membrane (foundation)

bilayer

lipids structure

outwards

hydrophilic heads face…

towards the middle

hydrophobic tails face…

flipflop

phospholipids flip to the other side, very rare event

lipid raft

proteins and lipids are stuck in place, positioning a receptor or cell junction

temperature, presence of cholesterol, length of fatty acid tails, presence of double bonds

factors influencing fluidity (speed of movement)

higher temperatures create faster movement

how does temperature affect fluidity

cholesterol

seen in animal membranes, acts as a buffer and helps regulate membrane speed

longer → slower, shorter → faster

how does the length of fatty acid tails affect fluidity?

more unsaturated= faster, saturates= slower

how does the presence of double bonds affect fluidity?

synthesis

making, smooth ER- builds phospholipids

transported

all phospholipids are built on the other surface of the smooth ER, Fillapse

Fillapse

to even up surfaces

rough ER

what produces proteins

proteins

enzymes, receptors, cell junctions, transport (channels/carriers)

integral membrane proteins

embedded, amphipathic

transmembrane proteins

travels across the membrane- channels and carriers, receptors, (some) cell junctions

lipid-anchored proteins

surface proteins with a fatty acid tail, stays on the membrane surface

peripheral proteins

surface proteins, helps in place by hydrogen bonds

peripheral has proteins on the surface and free ribosomes, integral proteins are embedded on the rough ER

what’s the difference between peripheral and integral proteins

cell junctions and certain receptors

examples of immobile proteins

mobile proteins

most proteins are free moving

positioned

free ribosome attaches to the rough ER, proteins is threaded through a channel, when finished the channel is removed and protein remains

transportation proteins

rough ER, golgi body (modified), transported to its final destination

glycoprotein

ID tags

glycosylation

adding a carb to another molecule

glycolipid

carb + lipids

glycoprotein

carb + protein

N-linkes

carb is attached to a nitrogen, throughout the cell

O-linked

carb is attached to oxygen, unique to the golgi body

fluid-mosaic model

a molecular model for the structure of biological membranes consisting of a fluid phospholipid bilayer in which suspended proteins are free to move in the plane of the bilayer

transmembrane domains

a proteins region rich in hydrophobic amino acids that spans the phospholipid bilayer

cell recognition

the specific binding of cells to one another mediated by membrane proteins or carbohydrates

cell adhesion

the binding of one cell to another, often mediated by noncovalent forces

homotypic

pertaining to adhesion of cells of the same type

heterotypic

pertaining to the binding of the same types of cells, due to the interaction of the same molecules on the cell surfaces

desmosomes

an adhering junction between animal cells

integrin

in animals, a transmembrane proteins that mediates the attachment of epithelial cells to the extracellular matrix

signal transduction pathway

the series of biochemical steps whereby a stimulus to a cell is translated into a response of the cell

autocrine

pertaining to chemical signal that binds to and affects the cell that makes it

juxtacrine

pertaining to a chemical signal that binds to and affects only cells adjacent to it and with which it is in direct contact

paracrine

pertaining to a chemical signal that binds to and affects nearby cells

hormones

a chemical signal produced in minute amounts at one site in a multicellular organism and transported to another site where it acts on target cells

crosstalk

interactions between different signal transduction pathways

receptor protein

a protein that can bind to a specific molecule or detect a specific stimulus, within the cell or in the cells external environment

receptor (sensor)

a cell that is responsive to a particular type of physical or chemical stimulation

ligand

any molecule that binds to a receptor site of another (usually larger) molecule

dissociation constant

an equilibrium constant measuring the tendency of 2 substances that are bound together to seperate into 2 smaller components.

agonists

a chemical substance that elicits a specific response in a cell or tissue

antagonists

a biochemical substance that blocks the normal action of another biochemical substance

protein kinases

an enzyme that catalyzes the addiction of a phosphate group from ATP to a target protein

G protein-coupled receptors

a class of receptors that change configuration upon ligand binding such that a G protein binding site is exposed on the cytoplasmic domain of the receptor, initiating a signal transduction pathway

G protein

a membrane proteins involved in signal transduction, characterized by binding GDP or GTP

effector protein

in cell signaling, a protein responsible for the cellular response to a signal transduction pathway

intracellular receptors

a receptor that binds its ligand inside the cell

B

which of the following is a transmembrane protein

G

which of the following would be a channel

A

which of the following is the phospholipid

B-Glycoprotein

which of the following functions as an ID tag?

A- cholesterol

which of the following controls the speed of the membrane and is produced by the smooth ER

smooth ER

which organelle assembled molecule A

D

which of the following is a glycolipid

tight junction

what prevents digestive enzymes from leaking between cells

amphipathic

what is the term applied to phospholipids to indicate that they have a hydrophobic and hydrophilic region

glycolipids

carbohydrates attached to the surface of a membrane lipid

amphipathic

are phospholipids hydrophobic or hydrophilic

C- glycoprotein

which of the following can form a gel-like or mucus layer

H

which of the following is a peripheral protein

amphipathic

molecule E is described as

B

which of the following is a glycolipid

Rough ER

which organelle assmebled molecule G

gap junction

what allows cells to pass messages back and forth

membrane proteins

cell signaling, aid in cell-to-cell attachment, enzymes, transporters

tight junctions

what are the junctions that exist between the intestinal cells to prevent acid and enzyme from escaping

anchoring, gap, and tight junctions

Animal cell juncitons

plasmodesmata, middle lamella

plant cell junctions

cell junction

attaches cells to others, create pores between cells, controls molecule movement between cells

anchoring junctions (desmosomes)

cell to cell (cytoskeleton, surface proteins, transmembrane proteins)

surface proteins

helps connect transmembrane protein to the cytoskeleton

transmembrane proteins

membrane proteins that span the cell membrane, maintain homeostasis, and detects signals

tight junction

prevents movement of molecules between cells, water tight structure and force molecules through the membrane

gap junction

pores that connect cells, allow molecules and signals to travel cell to cell

middle lamella

attaches a cell to its neighbor, plant version of an anchoring junction

pectin- acts like double sided tape

middle lamella structure

plasmodesmata

forms pores that connect cells, organelles can travel from cell to neighboring cell (plant version of gap junction)

pores, lined with plasma membrane

plasmodesmata structure

A

which of the following is cholesterol

E

which of the following is a phospholipid

F

which of the following is an enzyme

E

which of the following is cholestrol

cholestrol

controls speed of membrane

B

which of the following is a glycoprotein and has gel mucus

binding is reversible

receptors bind to their ligands noncovalently, according to chemistry’s law of mass action. this means that…

receptor

the major difference between a cell that responds to a signal and one that does not is the presence of a…

paracrine signal

the specific term for a signal that is made by a cell and that diffuses to and affects a nearby cell is a…

look smooth

if a cell membrane lacking integral proteins is prepared by freezing and then fracturing it so that the two leaflets of the membrane are peeled away from one another and examined by electron microscopy, the exposed interior of the membrane bilayer will…

integral protein with a transmembrane domain

ion channels are formed by a particular kind of membrane protein that allows the passage of a specific ion under certain conditions. this type of protein is most likely a…

uses a phospholipid bilayer to separate the inside and outside of the cell

how does the plasma membrane function as a boundary