Bio 101 Exam #3

Lipids

Phospholipids and cholesterol

Proteins

Within Most membranes

Carbohydrate groups

Glycoproteins and glycolipids

Micelle

lipid molecules that arrange themselves in a spherical form in aqueous solutions

Phospholipids

a lipid consisting of a glycerol bound to two fatty acids and a phosphate group.

Most membrane bound proteins are

amphipathic and held together by weak bonds.

Proteins and lipids move ____________ within the membrane.

Laterally

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

Phospholipids can flip sides, _______________ can not

protein

membrane fluidity

The property by which most of the plasma membrane lipids and proteins easily rotate and move side ways in their own half of the lipid bilayer. This property allows the membrane to self seal if torn; proteins seldom flip-flop from one half of the bilayer to to the other.

Some proteins are immobilized others...

Drift around the bilayer

Membranes are buffered so they don't...

Fall apart

Membranes are buffered by

Cholesterol

peripheral protein

do not enter into the hydrophobic space within the cell membrane.

integral proteins

penetrate the hydrophobic interior of the lipid bilayer

Most transmembrane proteins are ______.

glycoproteins and or hydrophobic

The membrane is impermeable by__________________.

Large molecules and ions

difuision

Free non-energized movement of particles so they can expand fully into their environment.

concentration gradient

difference in the concentration of a substance from one location to another

In non energy diffusion particles move from _______ to ________ gradient.

Higher , Lower

Diffusion with multiple solutes

Occurs in the same manner

Osmosis

Diffusion of water through a selectively permeable membrane

passive diffusion

diffusion of a solute through a membrane without transport protein

channel proteins

provide corridors that allow a specific molecule or ion to cross the membrane

Aquaporins

water channel proteins

ion channels

a complex of protein molecules in a cell membrane that form a pore through which ions can pass, only open when stimuli occurs.

carrier proteins

bind to molecules and change shape to shuttle them across the membrane

net movement

Down the concentration gradient

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

electrochemical gradient

The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential.

proton pump

An active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process.

electrogenic pump

a transport protein that generates voltage across a membrane

Animals: Sodium potassium

Plants: Protons

cotransport

The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.

bulk transport

The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis

Exocytosis

Process by which a cell releases large amounts of material

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

Metabolism

the combination of chemical reactions through which an organism builds up or breaks down materials

metabolic pathways are

sequences of enzymatically catalyzed chemical reactions in a cell

catabolic pathways

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.

anabolic pathways

Metabolic pathways that consume energy to build complicated molecules from simpler ones.

catabolism and anabolism

2 types of metabolism

kinetic energy

energy of motion

potential energy

stored energy that results from the position or shape of an object

amphipathic

having both a hydrophilic region and a hydrophobic region

Sodium-Potassium pumps

active transport mechanisms that pump Na+ ions out of neurons and K+ ions in

Tonicity

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

Proton pumps are protein complexes that

pump protons from the interior of the cell to the exterior.

membrane potential

The voltage across a cell's plasma membrane.

Electrogenic pumps help

store energy that can be used for cellular work

Osmoregulation

regulation of solute concentrations and water balance by a cell or organism

proton-motive force

The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis.

turgid

(adj.) swollen, bloated, filled to excess; overdecorated or excessive in language

flaccid

(adj.) limp, not firm; lacking vigor or effectiveness

secondary active transport

Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport.

primary active transport

Active transport in which ATP is hydrolyzed, yielding the energy required to transport an ion or molecule against its concentration gradient.

Plasmolysis

This happens when a cell shrinks inside its cell wall while the cell wall remains intact.

Entropy

a measure of the disorder of a system

Substrate

reactant of an enzyme-catalyzed reaction

Catabolism

Metabolic pathways that break down molecules, releasing energy.

Anabolism

Metabolic pathways that construct molecules, requiring energy.

Cofactors

Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis

allosteric regulation

The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.

energetic coupling

In cellular metabolism, the mechanism by which energy released from an exergonic reaction (commonly, hydrolysis of ATP) is used to drive an endergonic reaction.

Inhibitors of protein synthesis

Tetracyclines

Aminoglycosides

Macrolides

Clindamycin

Chloramphenicol

phosphorylated intermediate

A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

activators and inhibitors

Enzymes

1. Makes binding easier

2. Makes binding harder

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

transition state

a high-energy intermediate state of the reactants during a chemical reaction that must be achieved for the reaction to proceed

cooperativity

A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits.

second law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

activation energy (Ea)

the initial energy needed to start a chemical reaction

feedback inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

electron carriers

proteins arranged in chains on the membrane to allow the transfer of electrons from one carrier to another.

pyruvate oxidation

Conversion of pyruvate to acetyl CoA and CO2 that occurs in the mitochondrial matrix in the presence of O2.

Adenosine Triphosphate (ATP)

energy-carrying biological molecule, which, when broken down, drives cellular activities

NAD+/NADH

an organic molecule that serves as an electron carrier by being oxidized (losing electrons) to NAD+ and reduced (gaining electrons) to NADH

Acetyl CoA

Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.

aerobic respiration

Respiration that requires oxygen

FAD/FADH2

Oxidized and reduced forms, respectively, of flavin adenine dinucleotide. A nonprotein electron carrier that functions in the citric acid cycle and oxidative phosphorylation.

citric acid cycle

Completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide.

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

electron transport chain

A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.

oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

redox reactions (oxidation-reduction reactions)

electron transfers, oxidation being the loss of electrons and reduction being the gain of electrons

substrate-level phosphorylation

The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.

Phosphofructokinase (PFK)

a key rate-limiting enzyme of the anaerobic glycolytic energy system

oxidation-reduction reaction

any chemical change in which one species is oxidized (loses electrons) and another species is reduced (gains electrons); also called redox reaction

Glycolysis

A metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and release energy for the body in the form of ATP

Fermentation

A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

reducing agent

The electron donor in a redox reaction.

Glucose

the form of sugar that circulates in the blood and provides the major source of energy for body tissues. When its level is low, we feel hunger.

lactic acid fermentation

the chemical breakdown of carbohydrates that produces lactic acid as the main end product

oxidizing agent

The electron acceptor in a redox reaction.

Pyruvate

Organic compound with a backbone of three carbon atoms. Two molecules form as end products of glycolysis

ethanol fermentation

a form of anaerobic respiration found in yeast and bacteria