Membrane and Metabolism

Question 1

Boundary that separates the living cell from its surroundings

Answer 1

Plasma membrane

Question 2

Fluid mosaic model

Answer 2

the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids

Question 3

How are membranes held together

Answer 3

Held together by weak hydrophobic interaction

Question 4

What does cholesterol do

Answer 4

restrains movement of phospholipids at warm temperatures and maintains fluidity at lower temperatures

Question 5

Peripheral proteins

Answer 5

bound to surface of the membrane

Question 6

Integral proteins

Answer 6

penetrate the hydrophobic core

Question 7

Transmembrane proteins

Answer 7

Integral proteins that span the entire membrane

Question 8

6 functions of membrane proteins

Answer 8

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton and extracellular matrix

Question 9

What does selective permeability mean

Answer 9

plasma membranes regulate the cells molecular traffic

Question 10

Transport proteins

Answer 10

allow passage of hydrophilic substances across the membrane

Question 11

Aquaporins

Answer 11

Facilitate the passage of water molecules

Question 12

Diffusion

Answer 12

the tendency for molecules to spread out evenly into the available space

Question 13

Passive Transport

Answer 13

diffusion of a substance across a membrane with NO ENERGY investment

Question 14

Osmosis

Answer 14

Diffusion of water across a selectively permeable membrane

Question 15

Tonicity

Answer 15

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

Question 16

Isotonic solution

Answer 16

Solute concentration is the same as inside the cell; no net water movement

Question 17

Hypertonic solution

Answer 17

Solute concentration is greater outside than inside the cell; cell loses water

Question 18

Hypotonic solution

Answer 18

Solute concentration is less outside than inside the cell; cell gains water

Question 19

Osmoregulation

Answer 19

the control of solute concentrations and water balance

Question 20

Facilitated diffusion

Answer 20

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

Question 21

gated channels

Answer 21

Open or close in response to a stimulus

Question 22

Active transport

Answer 22

requires energy to move substances against concentration gradients

Question 23

Membrane potential

Answer 23

voltage across a membrane

Question 24

Electrochemical gradient

Answer 24

Drives the diffusion of ions across a membrane with chemical force and an electrical force

Question 25

Electrogenic pump

Answer 25

A transport protein that generates voltage across a membrane

Question 26

Cotransport

Answer 26

Active transport of a solute indirectly drives transport of other substances

Question 27

Exocytosis

Answer 27

Transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell

Question 28

Endocytosis

Answer 28

Cell takes in macromolecules by forming vesicles from the plasma membrane

Question 29

Metabolism

Answer 29

totality of an organisms chemical reactions

Question 30

Catabolic pathways

Answer 30

Release energy by breaking down complex molecules into simpler compounds

Question 31

Anabolic pathways

Answer 31

Consume energy to build complex molecules from simpler ones

Question 32

Spontaneous process

Answer 32

Positive entropy and negative free energy

Question 33

Exergonic reaction

Answer 33

Proceeds with a net release of free energy and is spontaneous

Question 34

Endergonic reaction

Answer 34

Absorbs free energy from its surroundings and is nonspontaneous

Question 35

Catalyst

Answer 35

A chemical agent that speeds up a reaction without being consumed by the reaction

Question 36

Cofactors

Answer 36

Nonprotein enzyme helpers

Question 37

Competitive inhibitors

Answer 37

Bind to the active site of an enzyme, competing with the substrate

Question 38

Noncompetitive inhibitors

Answer 38

Bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective

Question 39

Allosteric regulation

Answer 39

May either inhibit or stimulate an enzyme’s activity

Question 40

Feedback inhibition

Answer 40

The end product of a metabolic pathway shuts down the pathway