BMB211 Exam 2

reaction happens according to...

thermodynamics (what can't happen) & history (what did happen)

glycolysis

turns glucose to pyruvate, producing 2 ATP

gluconeogenesis

uses ATP to turn pyruvate to glucose

catalyst function

only increases reaction rate by lowering activation energy

exothermic reaction

reaction that releases heat

endothermic reaction

reaction that takes in heat

entropy

measure of chaoticness or randomness

in the universe, ____________ is always increasing

entropy

reactions are more likely to be spontaneous in which conditions?

more entropy & difference in free energy between reactants & products

value of delta G in spontaneous reaction

delta G < 0 (negative)

value of the equilibrium constant in a spontaneous reaction

K > 1 (positive)

K is positive if...

the products have more energy than reactants

how do we drive non-spontaneous processes?

combining them to spontaneous reactions

how to determine if a system is at equilibrium

if no spontaneous reactions occur

speed of reaction is determined by...

free energy changes in intermediates

what determines reaction speed?

activation energy (the hill)

enzyme

molecule that catalyse chemical reactions

could be a protein, RNA, and few are DNA

how do enzymes differ from other catalysts?

they are specific to the substrate they bind to & the reaction they catalyze

lock & key hypothesis

enzymes interact w/ substances according to how well they fit w/ each other (think puzzle piece)

compatibility of substrates & enzymes

spatial complementarity & complementarity of hydrogen bond donors & acceptors

how to name enzymes

substrate + ase

substrate + reaction + ase

transition state

a temporary condition during a chemical reaction in which the bonds in the reactants are breaking and the bonds in the products are forming

what determines reaction rate?

the transition state represents an energy barrier for the reaction

the higher the height, the slower the reaction

does the equilibrium constant change w/ concentrations?

no

if an enzyme speeds up some reaction in the forward direction, does it speed up the reaction in the reverse direction also?

yes

how should an enzyme lower the barrier between the reactants & products?

should make better interactions w/ the transition state than w/ the reactants or products

does an enzyme have to bind substrates or transition states well?

transition states

enzymes must bind products ____________ in order to release them

weakly

enzyme-substrate complex _______________ activation energy

increases

why should the binding energy of ES not be too high?

it will increase activation energy

inhibitor

blocks activity of enzyme or biological process

During the course of an enzymatic reaction, which is the correct order of appearance of the following? product, transition state, substrate,enzyme-substrate complex

substrate

enzyme-substrate complex

transition state

product

forward rate

rate at which reactants are converted into products

biological roles of carbohydrates

energy metabolism, components of DNA & RNA, structural roles

are sugars capable of hydrogen bonding

yes due to quantity of hydroxyl groups

hydrogen bond to water, each other, & proteins

typical structure of sugar

1 carbon has C=O

rest have C-OH

lots of hydroxyl groups

outcome of sugar having a lot of hydroxyl groups

very soluble in water

lots of hydrogen bonding

D & L forms

mirror images that differ in configuration at about one specific carbon atom

changing the ________________ of different substituents on each carbon atom gives a different structure

spatial positions

monosaccharides that are active in biology

glucose

fructose

ribose

deoxyribose

galactose

glyceraldehyde

derivatives of sugars

glucose

galactose

fructose

__________ contains deoxyribose

DNA

__________ contains ribose

RNA

deoxyribose

ribose

sugars are in equilibrium between...

open-chain & ring structures

epimer

differ in configuration at exactly one asymmetric carbon

enantiomer

differ in configuration at all asymmetric carbons, complete mirror images

anomers

differ in configuration at carbon-1

D- & L- forms

differ in configuration at carbon atom further from C=O

______________ isomers are intercovertible

anomer

which two sugars are not interconvertible?

glucose & galactose

pyruvate churns into the...

Krebs cycle

aerobic metabolism

glucose -> pyruvate, & CO2 + H2O

fermentation

pyruvate -> ethanol

anaerobic

in the muscles, pyruvate is converted to...

lactate

anaerobic

glycolysis starts w/ a ___________ sugar that goes on to form ___________ structures

6-carbon

2, 3-carbon

pyruvate has _____________ carbons

3

_______________ of ATP can release free energy

free hydrolysis

________________ also provides free energy to drive a non-spontaneous reaction

ATP hydrolysis

metabolic processes capture energy by...

breaking reaction into smaller steps & coupling them to other reactions that capture energy

goal of glucose metabolism

capturing energy in a useful form by producing ATP

oxidation-reduction reactions involve transfer of...

electrons from one substance to another

energy to drive oxidation-reduction reactions is useless if...

electrons have nowhere to go

does ADP or ATP come first in glycolysis?

2 ADP -> 2 ATP

does NAD or NADH come first in glycolysis?

2 NAD -> 2 NADH

cellular respiration produces about _______ molecules of ATP

38

_______ molecules of ATP must be invested to initiate cellular respiration

4

the first five steps of glycolysis ___________ energy

cost

the last five steps of glycolysis ___________ energy

recover

in the six-carbon stage of glycolysis, ATP is ________

used

in the three-carbon stage of glycolysis, ATP is _________

produced

metabolic pathways branch at ____________

pyruvate

anaerobic metabolism: pyruvate -> _____________

ethanol or lactate

fermentation

aerobic metabolism: pyruvate -> ______________

CO2

______________ metabolism derives maximum possible energy from pyruvate

aerobic

fermentation

pyruvate -> ethanol

anaerobic