BIO 191 exam 4

energy

the ability to do work

kinetic energy

the energy of motion (heat and light)

potential energy

stored energy from location or structure (chemical energy)

sun

the source of most cellular energy

1st law of thermodynamics

energy is neither created nor destroyed
it can be transferred or transformed

2nd law of thermodynamics

no transfer of energy is 100% efficient
some energy is lost as heat from random movement of atoms/ molec.
results in entropy

entropy

disorder

free energy (G)

energy of a system available to do work

delta G

change in free energy

delta H

change in enthalpye

enthalpy

energy/heat

chemical reaction set up

reactants > products

exergonic

delta G < 0
energy out
reactants have more energy than the products

is cellular respiration exer/endergonic

exergonic

endergonic

delta G > 0
energy in
products have more energy than the reactants

is photosynthesis exer/endergonic

endergonic

energy flows...

in one direction

nutrients...

cycle

metabolism

entire set of chemical reactions occurring within an organism

catabolic reaction

breaking down
ex catastrophic

anabolic reaction

building up
ex anabolic steroids

cells use ___ reactions to power ___ reactions through ___

endergonic
exergonic
ATP

ATP

adenosine triphosphate
high energy with unstable P-P bonds
stores potential energy in bonds

ADP

adenosine diphosphate
lower energy

enzymes

molecules (usually proteins) that act as biological catalysts
they increase rate of reaction but not changed by the reaction
lower the activation energy of a reaction
delta G is unchanged

enzymes lower...

activation energy EA

each enzyme is ____ for a ____

specific
substrate

active site

enzyme binding site (4-6 aa)

induced fit

slight change in active site causes increased strain/ exposure of substrate bonds
- enables reaction to proceed more efficiently

enzymes are involved in almost all ____

biochemical reactions

human enzymes work best from

35C to 40C
95F to 104F

optimal pH and temp of an enzyme vary...

by species and enzyme

factors that can denature an enzyme

high temperature
extreme salinity
pH

enzymes may require ____ or ____ to aid in their functioning

inorganic cofactors ex minerals
organic cofactors ex vitamins

competitive inhibition

binds to the active site blocking the substrate

allosteric inhibition

non competitive
binds to a different site and changes shape of the active site making the enzyme non functional

feedback inhibition

the products of the reaction inhibit the reaction
often reversible
as product concentration declines, inhibitors are removed

photosynthesis

capturing suns kinetic (light) energy as potential (chemical) energy

photosynthesis reaction

6CO2 + 6H2O > C6H12O6 + 6O2

is the photosynthesis reaction exer/endergonic

endergonic

cellular respiration

metabolic reactions to obtain energy from food

cellular respiration reaction

C6H12O6 + 6O2 > 6CO2 + 6H2O

is the cellular respiration reaction ender/exergonic

exergonic

reduction

gains electrons

oxidation

loses electrons

redox reactions must...

occur together

respiration reaction

C6H12O6 > 6CO2 (OXIDATION)

6O2 > 6H2O (REDUCTION)

cellular respiration

harvesting energy from food

cellular respiration %

34% glucose energy ATP
the rest goes to heat

active muscle cells use and regenerate _____ ATP per second

10 million

glycolysis

- glucose begins with 6 carbons
- splits into 2 pyruvate (pyruvic acid) molec still maintaining 6 carbons, 2 NADH, and 2 ATP
- 2 net ATP

where does glycolysis occur

cytosol
can occur in both eukaryotes and prokaryotes

pyruvate oxidation to acetyl CoA

2 pyruvate molec split to 2 aacetyl CoA, 2NAHD, 2CO2

where does pyruvate oxidation occur

the mitochondria matrix

citric acid (krebs) cycle

2 Acetyl CoA split into 6NADH, 2FADH2, 2ATP, 4CO2

where does krebs cycle occur

mitochondria matrix

how many mitochondria are there per cell

100s to 1000s

oxidative phosphorylation

electrons from NADH and FADH2 go to the electron transport chain

where does oxidative phosphorylation occur

the inner membrane of the mitochondria

how many mitochondria are generated by ATP synthase

28

glycolysis

split sugar (10 enzyme-controlled steps)
1 glucose > 2 pyruvate + 2NADH + 2ATP
ADP > ATP by substrate-level phosphorylation

citric acid cycle

redox reactions occur
substrate-level phosphorylation
2 Acetyl CoA > 2ATP + 6NADH + 2FADH +4CO2

oxidative phosphorylation

e- from NADH & FADH2 pass down ETC proteins in inner mitochondrial membrane
series of redox reactions occur
cristae
H+ is pumped into intermembrane space from matrix
O2 is final e- acceptor, reduced to H2O

what is cristae

folds in mitochondria membrane to increase surface area

chemiosmosis

H+ move down the concentration gradient through ATP synthase powering reduction of ADP

anaerobic respiration

uses terminal e- acceptors other than O2

a lower electronegativity results in....

less energy yield

fermentation process

net 2 ATP during glycolysis
enough for yeast and bacteria
need to oxi NADH to NAD+ for reuse in glycolysis
- accomplished through lactic acid or alcohol fermentation
- lactate from anaerobic muscle activity can be converted back to pyruvate in the liver

aerobically

with oxygen

anaerobically

without oxygen

strict anaerobe

poisoned by O2f

faculative anaerobe

uses O2 if available but can survive without O2f

fermentation

anaerobic but ATP only through glycolysis

photoautotrophs

sunlight provides energy
get carbon from inorganic sources
ex. plants, algae, photosynthetic bacteria

energy flows..

nutrients cycle

visible light range

380 nm to 750 nmw

wavelength

distance between crests of adj waves

short wavelength results in

higher energy/frequency

chloroplasts

site of photosynthesis
leaf pigments capture suns energy
leaves reflect and transmit green all other light is absorbed

photon

particle of light

pigment molecules

located in chloroplasts
ex. chlorophyll a/b
absorb light photons

absorption spectrum

plots wavelength absorption by pigment

action spectrum

plots rate of photosynthesis by wavelength

light reaction

captures light energy

calvin cycle

light independent reaction
produces glucose

chloroplasts- photosynthesis

CO2 enters through the stomatas

stomata

leaf openings

H2O enters through the __ of a plant

roots

thylakoids

membrane sacs containing chlorophyll molecules which capture light energy

stroma

fluid inside chloroplasts where sugars are made

light reaction- photosystems

in thylakoid membrane
light harvesting complex
various pigment molecules absorb photons which excite e-

light reaction- reaction center

2 chlorophyll a molec pass e- to a primary e- acceptor (stored potential energy)

light reaction- photosystem II

captured energy sends e- down the electron transport chain to photosystem I
ETC pumps H+ into the thylakoid space
ATP synthase splits H2O to replace lost e- and release O2

light reaction- photosystem I

receives e- from photosystem II and captures light photons
e- reduce NAHP+ to NADPH with the enzyme NADP+ reductase

the calvin cycle is a ...

light independent cycle

calvin cycle

produces sugar using CO2 and energy (ATP and NADPH)
occurs in stroma in chloroplasts

key points of calvin cycle

3 RuBP > +3CO2 (aided by rubisco enzyme) > 3GP > glucose and other organic compounds

85% of plants use ___ photosynthesis

C3

C3 plants

trees/ shrubs
close stomata when hot/ dry to conserve H2O

consequence of C3

leaf CO2 level decreases
rubisco joins O2 instead of CO2 to RuBP
product is broken down releasing CO2 (photorespiration)
no ATP is generated- loss of photosynthesis energy