Bio test 2

Bio test 2

metabolism

emergent property of life that arises from interactions between molecules within the cell

metabolic pathway

begins with specific molecule and ends with product

catabolic pathways

release energy by breaking down complex molecules into simpler compounds

anabolic pathways

Consume energy to build complex molecules from simpler ones

Bioenergetics

study of how organism manage their energy resources

Energy

Capacity to cause change, prerequisite for performing mechanical work

Kinetic Energy

associated with motion

Heat (thermal energy)

random movement of atoms or molecules

potential energy

energy that matter possesses because of its location or structure

chemical energy

potential energy available for release in a chemical reaction

thermodynamics

study of energy transformations

open system

energy and matter can be transfered btw system and surroundings-organisms open system

First law of thermodynamics

Energy of universe is constant, cannot be created or destroyed

principle of conservation of energy

Second law of thermodynamics

every energy transfer or transformation increases the entropy (disorder) of the universe

some energy unusable (heat) every time

Spontaneous Processes

occur without energy input, increase the entropy of the universe

Free energy change

whether or not a reaction occurs spontaneously

energy that can do work when temperature and pressure are uniform

measure of instability

delta G

delta G=Gfinal state - Ginitial state

delta G negative for spontaneous process

During a spontaneous change

free energy decreases and stability increases

unless prevented each system willl move towards greater staility

equalibrum

state of maximum stability

spontaneous and can perform work only when moving towards stability

change in free energy during a process

delta G= delta H -Tdelta S (change in entropy)

Exergonic Reaction

net release of free energy and spontaneous

endergonic reaction

absorbs free energy from surroundings and nonspontaneous

Chemical work in cell

coupling energy from ATP to drive endergonic reactions

transport work in cell

pumping ions and molecules across membranes against concentration gradient

mechanical work in cell

muscle contraction, vesicle, flagella and cilia movement

phosphorylation

transfering a phosphate group to some other molecule

recipient becomes phosphorlyated

catalyst

chemical agent that speeds up reaction without being consumed

enzyme

catalytic protein

activation energy barrier

initial energy needed to start a chemical reaction

Substrate

reactant an enzyme acts on

active site

region on enzyme where substrate binds

active site can lower barrier by

orienting substances correctly

straining substrate bonds

providing favorable microenviromnet

covalently bonding to substrate

effect of local conditions on enzyme activity

temperature,pH, and chemicals can affect and denature

Cofactors

nonprotein enzyme helpers

competitive inhibitors

bind to active site of enzyme and compete with substrate

noncompetitive inhbitors

bind to another part of enzyme, cause enzyme to change shape and make active site less effective

allosteric regulation

regulatory molecule binds to a protein at one site and affects function at another site

inhibit or stimulate enzyme activity

allosteric regulated enzymes

binding of activator stabilizes active form

inhibitor stabilizes inactive form

Cooperativity

form of allosteric regulation that amplifies enzyme activity

plasma membrane

separates cell from surroundings

selectively permeable

phospholipid bilayer

fluid structure, hydrophobic tails and hydrophilic heads

proteins within it

fluidity of membranes

switch from fluid to solid state as they cool

cholesterol and membranes

reduces fluidity at moderate temperatures (37°C)

hinders solidification at low temperatures (prevents tight packing)

peripheral proteins

bound to surface of membrane

integral proteins

penetrate hydrophobic core

hydrophobic regions contain non polar amino acids often coiled in alpha helices

transmembrane proteins

integral proteins that span the membrane

6 functions of membrane proteins

transport

enzymatic activity

signal transduction

cell-cell recognition

intercellular joining

attached to cytoskeleton and extracellular matrix

membrane carbohydrates in cell-cell recognition

covalently bonded to lipids or proteins

on external side of plasma membrane

cells recognize each other by binding to surface molecules, often carbohydrates

build of membranes

distinct inside and outside faces

determined when built by ER and Golgi apparatus

Selective permeability

hydrophobic molecules can cross easily

polar molecules cannot cross easily

transport proteins

allow passage of hydrophilic substances

specific for substance it moves

channel proteins

hydrophilic channel

certain molecules and ions can use as a tunnnel

aquaporins

channel proteins that facilitate passage of water

Carrier proteins

bind to molecules

change shape to shuttle across membrane

passive transport

diffusion of a substance across a membrane with no energy investment

diffusion

tendency for molecules to spread out easily over available space

dynamic equilibrium

same amount of molecules cross directions

concentration gradient

difference on concentration of a substance from one area to another

osmosis

diffusion of water across selectively permeable membrane

Tonicity

ability of a substance to cause a cell to gain or lose water

Isotonic solution

solution concentration is same as that inside cell

no net water movement

hypertonic

solution concentration is greater than inside cell

cell looses water

hypotonic

solution concentration less than inside cell

cell gains water

osmoregulation

control of water balence

cell walls

help maintain water balance

flaccid

isotonic cell wall and surrondings

turgid

hypotonic solution and swollen cell wall

plasmolysis

membrane pulling away from wall in hypertonic environment

facilitated diffusion

transport proteins speed passive movement of molecules across membrane

active transport

moves substances against concentration gradient

requires ATP

performed by specific proteins

Bulk transport across Plasma Membrane

requires energy

small molecules enter or leave through bilayer or transport proteins

large molecules cross via vesicles

Exocytosis

transport vesicles migrate to membrane, fuse with it, and release their contents

Endocytosis

takes in macromolecules by forming vesicles from plasma membrane

reversal of exocytosis

Glycolysis

breaks down gluclose into two molecules of pyruvate

net production of 2 ATP

occurs in cytoplasm

anerobic

oxidized

substance looses electrons

reduced

substance gains electrons

reducing agent

electron donor

oxidizing agent

electron acceptor

NADH

nicotinamide adenine dinucleotide

reduced form of NAD+

represents stored energy

step 1 glycolysis

glucose enters cell

phosphorylated by hexokinase

step 2 glycolysis

glucose-6-phosphate converted to fructose-6-phosphate

step 3 glycolysis

transfer of phosphate group from ATP

fructose 1, 6-biphosphate

2 ATP used

step 4 glycolysis

cleavage reaction

splits sugar into 2 3 carbon sugars

dihydroxyacetone phosphate

glyceraldehyde-3-phosphate

Step 5 glycolysis

isomerase catalyzes reversible conversion

step 6 glycolysis

sugar oxidized, electrons transferred to NAD+ to form NADH

1,3-Bisphosphoglycerate

step 7 glycolysis

produces 2 ATP

2 molecules 3-phosphoglycerate

step 8 glycolysis

enzyme relocated remaining phosphate group

2-phosphoglycerate

step 9 glycolysis

enzyme causes double bond to form in substrate

phosphoenolpyruvate

step 10 glycolysis

transferes phosphate group from PEP to ADP

forms 2 ATP

pyruvate

citric acid cycle

aerobic

mitochondrial matrix

generates 1 ATP, 3 NADH, and 1 FADH2 from pyruvate

8 steps

before citric acid cycle

pyruvate converted to acetyl CoA

carboxyl group removed

2 carbon fragment ozidized

coenzyme A attached to acetate

FADH2

redox cofactor

energy carrying molecule

step 1 CAC

acetycl CoA adds 2 carbon group to ozoacetate

produces citrate

step 2 CAC

citrate converted to isomer isocitrate

1 H2O removed 1 added

step 3 CAC

isocitrate oxidzed

reduced NAD+ to NADH

loss of 1 CO2

alpha-keto-glutarate

step 4 CAC

another co2 lost

resulting compound oxidized

reduces NAD+ to NADH

remaining molecule attatched to coenzyme A

succinyl CoA

step 5 CAC

coenzyme A displaced by phosphate group

phosphate transfered to GTP

GTP may be used to make ATP

succinate

step 6 CAC

FAD to FADH2

oxidizes succinate to fumerate