Proteins, Transport Mechanism

Question 1

The sum total of all chemical reactions and physical workings occurring in a cell

Answer 1

Metabolism

Question 2

2 Types of Metabolism

Answer 2

Anabolism and Catabolism

Question 3

• biosynthesis
• building complex molecules from simple ones
• requires energy (ATP)

Answer 3

Anabolism

Question 4

• degradation
• breaking down complex to simple molecules
• generates energy (ATP)

Answer 4

Catabolism

Question 5

• For a reaction to occur, an energy barrier must be surmounted
• the minimum quantity of energy which the reacting species must possess in order to undergo a specified reaction

Answer 5

Activation Energy

Question 6

• Point when a reaction can easily run in either direction, to product or back to reactant
• Unstable at the highest energy level
• Substrate is bound most tightly to an enzyme in this state

Answer 6

Transition State

Question 7

Enzymes consisting of proteins alone

Answer 7

Simple enzymes

Question 8

Enzymes that contain protein (apoenzyme) and nonprotein (cofactors) molecules

Metallic Cofactors: iron, copper, magnesium

Answer 8

Conjugated Enzymes or holoenzymes

Question 9

Enzyme-Substrate Interaction

a model for enzyme-substrate interaction suggesting that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.

Answer 9

Lock and Key Model

Question 10

a model for enzyme–substrate interaction to describe that the substrate is capable of inducing the proper alignment of the active site of the enzyme, causing the latter to subsequently perform its catalytic function.

Answer 10

Induced Fit Model

Question 11

These are anabolic reactions to form covalent bonds between smaller substrate molecules, require ATP, release one molecule of water for each bond

Answer 11

Synthesis/condensation reactions

Question 12

These are catabolic reactions that break down substrates into small molecules, requires the input of water

Answer 12

Hydrolysis Reactions

Question 13

a type of chemical reaction that involves a transfer of electrons between two species.

Answer 13

Oxidation-Reduction Reaction

Question 14

They convert one type of amino acid to another by transferring an amino group

Answer 14

Aminotransferases (or transaminases)

Question 15

The transfer of phosphate groups, involved in energy transfer

Answer 15

Phosphorylation

Three types: Photophosphorylation, Substrate level phosphorylation, Oxidative phosphorylation

Question 16

Control of Enzyme Activity Categories

Answer 16

• Control of enzyme activity directly
• Control of enzyme activity by regulating enzyme synthesis

Question 17

Control of Enzyme Activity Directly

Occurs when a substance that resembles normal substrate competes with substrate for active site

Answer 17

Competitive Inhibition

Question 18

Control of Enzyme Activity Directly

Characterized by a substance binding to the cofactor and distorts the shape of the active site

Answer 18

Noncompetitive Inhibition

Question 19

Control of Enzyme Activity Directly

Control mechanism wherein the concentration of product at the end of a pathway blocks the action of a key enzyme

Answer 19

Feedback Inhibition

Question 20

Control of Enzyme Activity by Regulating Enzyme Synthesis

always present, always produced in equal amounts or at equal rates, regardless of amount of substrate; enzymes involved in glucose metabolism

Answer 20

Constitutive Enzymes

Question 21

Control of Enzyme Activity by Regulating Enzyme Synthesis

• not constantly present, produced only when substrate is present, prevents cell from wasting resources
• synthesis of these enzymes is induced by a metabolite

Answer 21

Induced Enzymes

Question 22

Control of Enzyme Activity by Regulating Enzyme Synthesis

• enzymes that are not produced when the end product of the pathway is present
• synthesis of these enzymes is suppressed by a metabolite

Answer 22

Repressible Enzymes

Question 23

enzymes transported extracellularly, where they break down large food molecules or harmful chemicals
* cellulase, amylase, penicillinase

Answer 23

Exoenzymes

Question 24

enzymes retained intracellularly and function within the cell

Answer 24

Endoenzymes

Question 25

* The ability of the cell membrane to differentiate between different types of molecules, only allowing some molecules through while blocking others * **"Small, nonpolar molecules get in. Ions and polar molecules don't get in"**

Answer 25

Selective Permeability

Question 26

* A thin, polar membrane made of two layers of lipid molecules * Acts as a barrier to the passage of molecules and ions into and out of the cell

Answer 26

Phospholipid Bilayer

Question 27

* Reduces membrane fluidity at moderate temperatures by reducing phospholipid movement * At low temperatures, it hinders solidification by disrupting the regular packing of phospholipids

Answer 27

Cholesterol

Question 28

# Membrane Proteins * These proteins penetrate the hydrophobic inside of lipid bilayer * most are transmembrane proteins

Answer 28

Integral Proteins

Question 29

# Membrane Proteins * Proteins that attach to the lipid bilayer * Appendages loosely bound to either surface * Easily separable from the bilayer

Answer 29

Peripheral Proteins

Question 30

Proteins that provide hydrophilic channels

Answer 30

Transport Proteins

Question 31

Differentiate Uniport, Symport, and Antiport

Answer 31

* Uniport: type of membrane transport that transports one substance in one direction * Symport: transports two substances in the same direction * Antiport: transports two substances in opposite directions

Question 32

Transport protein that acts like a pore in the membrane that lets water molecules or small ions through quickly

Answer 32

Channel Proteins

Question 33

* Transport protein that is specific for an ion, molecule, or group of substances * This type of protein carries the ion or molecules across the membrane by changing shape after the binding of the ion or molecule

Answer 33

Carrier Protein

Question 34

Proteins that functions by binding a specific ligand molecule

Answer 34

Receptor Proteins

Question 35

* Proteins that can freely move within the lipid bilayer because of its fluidity * May also be confined to certain areas of the bilayer

Answer 35

Membrane Proteins

Question 36

The diffusion of a substance across membrane with no energy investment

Answer 36

Passive Transport

Question 37

* Random movement of molecules but has a net direction toward regions of lower concentration to reach equilibrium * No work required: spontaneous because particles have KE and are in constant motion * Both the solute and solvent move

Answer 37

Diffusion

Question 38

Diffusion that does not require the assistance of membrane proteins * Substances simply pass through the phospholipids

Answer 38

Simple Diffusion

Question 39

Movement of molecules along the concentration gradient that requires the help of carriers * Substances pass through channels instead of directly through the phospholipids

Answer 39

Facilitated Diffusion

Question 40

Factors that affect the rate of diffusion

Answer 40

* Concentration Gradient * Temperature * Mass of Particles * Solvent Properties

Question 41

Movement of SOLVENT across a semipermeable membrane from high to low solvent concentration * Only the solvent moves

Answer 41

Osmosis

Question 42

Difference between Diffusion and Osmosis

Answer 42

Diffusion: movement of MOLECULES from high to low concentration (both solute and solvent move) Osmosis: movement of SOLVENT from high to low solvent concentration (only solvent moves)

Question 43

* Ability of a surrounding solution to cause a cell to gain or lose water * Depends on concentration of solutes that cannot cross membrane relative to the concentration of all solutes in the cell

Answer 43

Tonicity

Question 44

A higher concentrated solution is (?) to a lower concentrated solution

Answer 44

Hypertonic

Question 45

A lower concentrated solution is (?) to a higher concentrated solution

Answer 45

Hypotonic

Question 46

Two solutions with equal concentrations are (?)

Answer 46

Isotonic

Question 47

* Transport of ions or molecules that require energy and assistance of enzymes * Lower to higher concentration (against concentration gradient) * Allows cell to maintain concentration gradients * Similar to facilitated diffusion but requires energy

Answer 47

Active Transport

Question 48

A difference in charge across membrane

Answer 48

Membrane potential

Question 49

Cations move into the cell while anions move out

Answer 49

Electrical Gradient

Question 50

* Transport proteins that generate voltage across a membrane * Generation of voltage increases potential energy

Answer 50

Electrogenic Pumps

Question 51

The major electrogenic pump in animal cells

Answer 51

Na+/K+/ATPase pump

Question 52

The major electrogenic pump in plant cells

Answer 52

Proton pump

Question 53

A type of secondary transport across a biological membrane in which a transport protein couples the movement of an ion (usually Na+ or H+) down its electrochemical gradient to the movement of another ion or molecule against a concentration or electrochemical gradient

Answer 53

Cotransport

Question 54

a mode of transport of large quantities of materials and food particles across the membrane

Answer 54

Bulk Transport | Exo/Endocytosis

Question 55

Process in which a cell transports molecules out of the cell

Answer 55

Exocytosis

Question 56

Process in which substances are brought into the cell

Answer 56

Endocytosis ## Footnote Phago and Pinocytosis

Question 57

* is the process by which large particles, such as cells or relatively large particles, are taken in by a cell * "Cell-eating"

Answer 57

Phagocytosis

Question 58

* was named at a time when the assumption was that the cell was purposefully taking in extracellular fluid * "Cell-drinking"

Answer 58

Pinocytosis

Question 59

* a form of endocytosis in which receptor proteins on the cell surface are used to capture a specific target molecule * allows cells to take in specifically what it needs * specific ligands bind to specific membrane proteins

Answer 59

Receptor-Mediated Endocytosis