Bio 1080 Chapter 7

Front 1

selective permeability

Back 1

allows some substances to cross plasma membrane more easily than others, regulating the cell's molecular traffic

Front 2

fluid mosaic model

Back 2

cellular membranes are fluid mosaics of lipids and proteins, phospholipids in the plasma membrane can move within the bilayer, most of the lipids and some proteins drift laterally

Front 3

phospholipids

Back 3

are arranged in a bilayer (fluid)

Front 4

proteins

Back 4

various proteins are inserted in the lipid bilayer (mosaic of proteins)

Front 5

as temperatures cool membranes become less _______

Back 5

fluid

Front 6

fluidity dependent on

Back 6

types of lips

Front 7

membranes rich in __________ are more fluid than those rich in __________

Back 7

unsaturated fatty acids, saturated fatty acids

Front 8

cholesterol

Back 8

influences (balances) fluidity, restraining movement of phopholipids at warm temps, maintaing fluidity at cool temps by preventing tight packing

Front 9

peripheral proteins

Back 9

bound to the membrane surface

Front 10

integral proteins

Back 10

penetrate the hydrophobic core, it's hydrophobic regions consisting of one or more stretches of nonpolar amino acids, often coiled into alpha helices

Front 11

transmembrane proteins

Back 11

integral proteins that span the membrane,

Front 12

6 major funtions of membrane proteins

Back 12

1. Transport 2. Enzymatic activity 3. Signal transduction 4. Cell-cell recognition 5. Intercellular joining 6. Attachment to the cytoskeleton and extracellular matrix (ECM)

Front 13

carbohydrates, on the extracellular surface of the plasma membrane are used in ____ ________

Back 13

cell recognition

Front 14

glycolipids

Back 14

membrane carbohydrates covalently boned to lipids

Front 15

glycoproteins

Back 15

carbs bound to proteins

Front 16

hydrophobic (nonpolar) molecules

Back 16

can dissolve in the lipid bylater and pass through the membrane rapidly (CO2, O2, N2)

Front 17

polar molecules

Back 17

such as sugars, do not cross the membrane easily (glucose, sucrose)

Front 18

diffusion

Back 18

movement of a substance from higher to lower concentration

Front 19

osmosis

Back 19

the diffusion of water across a selectively permeable membrane

Front 20

water diffuses acros a membrane from the region of _______ solute concentration to the region of _______ solute concentration until the solute concentration is equal on both sides

Back 20

lower, higher

Front 21

tonicity

Back 21

the ability of a surrounding solution to cause a cell to gain or lose water

Front 22

isotonic solution

Back 22

equal solute concentration on both sides of plasma membrane- no net water movement = movement in and out

Front 23

hypertonic solution

Back 23

solute concentration is greater than that inside the cell; cell loses water

Front 24

hypotonic solution

Back 24

solute concentration is less than that inside the cell; cell gains water

Front 25

osmoregulation

Back 25

adaptations to control solute concentrations and water balance, is necessary adaptation for life of hypotonic or hypertonic areas-ex. paramecium is hypertonic to it's pond water environment, has a contractile valuole to pump water out

Front 26

cell walls help maintain ______ balance

Back 26

water

Front 27

plasmolysis

Back 27

in a hypertonic environment, plant cells lose water; eventually, the membrane pulls away from the wall, usually a lethal effect

Front 28

transport proteins

Back 28

move hydrophilic substances across the membrain

Front 29

channel proteins

Back 29

have a polar interior allowing polar molecules to pass through- ex. aquaporins allow diffusion of water across membranes, ion channels that open or close in response to a stimulus (gated channels)

Front 30

carrier proteins

Back 30

bind to molecules and change shape to shuttle them across the membrane *specific for the substance it moves- requires a concentration difference across the membrane- ex. ions, some sugars and amino acids

Front 31

both channel and carrier proteins are forms of __________ _________

Back 31

facilitated diffusion (a type of PASSIVE transport)

Front 32

passive transport

Back 32

diffusion of a substance across a membrain with no energy investment, molecules move down a concentration gradient

Front 33

equilibrium

Back 33

as many molecules cross the membrane in one direction as in the other

Front 34

facilitated diffusion

Back 34

transport proteins speed the passive movement of molecules across the plasma membrane

Front 35

active transport

Back 35

requires engery- ATP is used directly or indirectly to fuel it, requires the use of highly selective carrier proteins

Front 36

active transport moves substances from ____ to ____ concentration

Back 36

low, high (against gradient)

Front 37

sodium-potassium (Na+ -- K+) pump

Back 37

active transport mechanism pumps 3 Na+ out of the cell and 2 K+ into the cell against their concentration gradient- affinity of the carrier protein of either Na+ or K+ changes so the ions can be carried across the membrane

Front 38

in the sodium-potassium pump, ______ is used to change the conformation of the carrier protein

Back 38

ATP

Front 39

coupled transport

Back 39

uses the energy released when a molecule moves by diffusion to supply energy to active transport of a different molecule

Front 40

glucose--Na+ transport protein captures the energy from Na+ diffusion to move glucose against a _________ _________- an example of ________ ________

Back 40

concentration gradient, coupled transport

Front 41

bulk transport

Back 41

accomplished by endocytosis and exocytosis

Front 42

endocytosis

Back 42

movement of substances into the cell, occurs when the plasma membrane envelops food particles and liquids

Front 43

exocytosis

Back 43

movement of substances out of the cell- used in plants to export cell wall material, used in animals to secrete hormones, neurotransmitters, digestive enzymes

Front 44

phagocytosis

Back 44

the cell takes in a particulate matter

Front 45

pinocytosis

Back 45

the cell takes in only fluid (including dissolved solutes)

Front 46

receptor-mediated endocytosis

Back 46

specific molecules are taken in after they bind to a receptor