APBIO u3 review

Chemical reactions proceed at the rates

required to support life because of the catalytic action of enzymes

the function of Catalysts (enzymes) is to

speed up chemical reactions

enzymes are made of

proteins that have a 3d tertiary structure specific to function

Active site interacts with

substrate(reactant).

the shapes of the active site and substrate

must fit

If there are charged r groups on amino acids within the active site

there must be compatible charges on the substrate

Enzymes

catalyze reactions most efficiently at optimum temps and pHs that are specific to that enzyme

denaturation

A change to an enzyme's structure

what limits catalyzation of chemical reactions?

denaturation

denaturation can be reversed when

environment returns to favorable conditions

Competitive inhibitors

compete with substrates for the active site of an enzyme

What do Competitive inhibitors do?

lowers the rate of enzyme catalysed chem. Reactions

How can Competitive inhibitors effect can be diluted?

by adding higher concentration of substrate

Noncompetative/allosteric inhibitors

do not bind to the active site, binding instead to the allosteric site.

what do noncompetitive inhibitors do?

change shape of enzyme, affecting function

cofactors/inorganic molecules and coenzymes/organic molecules

increase efficiency of enzyme catalyzed reactions

how do cofactors and coenzymes work?

by binding to the active site or substrate

Free energy

(G)

Endergonic reactions

have products with higher G than reactants

Endergonic reactions are

Energetically unfavorable

exergonic reactions

have products with lower G than reactants

exergonic reactions are

Energetically favorable

There is an input of energy required to

reach the transition state to begin reactions

Activation energy (Ea) is

the difference between the energy level of reactants and the transition state of the reaction

Enzymes speed up chemical reactions by

lowering activation energy of reactions

1st way to lower activation energy of reactions

Bringing substrates together in the orientation for a reaction to happen

2nd way to lower activation energy of reactions

Destabilizing chemical bonds in substrate by bending it

3rd way to lower activation energy of reactions

Forming temporary ionic or covalent bonds with substrate

Enzymes cannot

change an endergonic reaction into an exergonic reaction

1st law thermodynamics:

energy cannot be created or destroyed

2nd law thermodynamics:

with each energy transformation, the disorder/entropy of a system increases

Living organisms need constant input of energy to

power cellular processes and maintain order

Energy input must be

higher than required

Processes releasing energy can be coupled/paired with

processes requiring energy

Many endergonic chemical reactions that are required for life are powered by

coupling them with exergonic reactions

Autotrophs:

organisms that produce their own organic molecules from inorganic molecules

When autotrophs use light energy, they are

phototrophs and do photosynthesis

6CO2 + 6H2O yields

C6H12O6 + 6O2

in photosynthesis,

Hydrogens from H2O move to carbon dioxide

in photosynthesis,

Carbon is reduced/ gains e-

in photosynthesis,

H2O loses H, so O2 is oxidized as it loses e-

Photosynthesis (occurs in the chloroplast) can be broken down into 2 processes:

light-dependent reactions and light-independent reactions

Light-dependent reactions:

Use photons to split water, producing e- and H+ (e- is taken from H), which are used for ATP and NADPH

light dep. reactions occur

in the thylakoid (individual sacs that make up grana)

Light-independent reactions

(Calvin cycle)

calvin cycle Utilizes ATP and NADPH and CO2 to

make sugars

in the calvin cycle, ATP turned into

ADP + P

in the calvin cycle, NADPH turned into

NADP+

in the calvin cycle, ADP + P and NADP+ are

sent back to light-dependent reactions

the calvin cycle

Occurs in the stroma (liquid surrounding grana that fills the cytoplasm's outer membrane)

In photosynthetic prokaryotes, light-dep. Reactions occur on

infoldings of the plasma membrane and calving cycle occurs in the cytosol

in light dependent reactions, Photons drive the production of ATP:

photophosphorylation.

what is phosphorylation?

Light energy excites e- in chloroplast to higher energy levels. Energy is released. In the end, NADP+ accepts e- and form NADPH (reducing power)

Chlorophyll is a

light absorbing pigment capturing photon energy.

chlorophyl are are the primary

light absorbing pigments of photosynthesis

chlorophyll is Found in

photosystems I and II

Photosystems are composed of

proteins, chlorophyll, and accessory pigments

photosystems Absorb light energy

at different wavelengths

photosystems are Connected

by an e- transport chain

in light dependent reactions, Energy in photons used to

boost e- to higher energy level in PSII

in light dependent reactions, Final e- donor in e- transport chain passes the e- to

PSI

in light dependent reactions, As e- pass through carrier molecules in ETC,

energy released makes a proton gradient and H+ ions are actively transported across thylakoid

in light dependent reactions, E- in PSII come from

splitting of water molecules

Photolysis:

process driven by photons-

in Photolysis, E- is

separated from H molecule, producing e-, H+, and O2(g)

in Photolysis, H+ used to

form a gradient as e- pass through ETC

in Photolysis, Photon gradient powers the production of ATP by enzyme ATP synthase:

chemiosmosis

Photolysis is Used in

mitochondria as well

in Photolysis, E- from ETC (in PSI) is boosted by photon and passes through a series of carriers, where it is

transferred, along with an H+ to NADP+ by the enzyme NADP+ reductase

photolysis Produces a molecule of

NADPH, providing reducing power

in the kalvin cycle, Fixation of carbon

turns unusable form into usable form

in Fixation of carbon, Enzyme Rubisco adds 1 molecule of CO2 to the 5-carbon molecule EuBP,

producing a 6-carbon intermediate that is unstable, which then breaks down into two individual 3-Carbon molecules

in the kelvin cycle, Reduction: ATP and NADPH are used to

reduce the 3-Carbon molecules.

in reduction, Energy comes from

ATP and the NADPH provided H atoms (reducing power)

in reduction, 3-C molecule called glyceraldehyde-3-phosphate (G3P) is produced at the end, which can be used to make sugars

in the kelvin cycle: Regeneration of RuBP+:

the 5C RuBP must be regenerated for photosynthesis to continue.

For every 5 molecules of G3P (3C molecule):

15 C atoms present.

Using ATP in the regeneration fo RuBP+, the 5 G3P molecules

rearrange and form 3 molecules of RuBP (5 C molecule), also containing 15 C atoms

cellular respiration is

the opposite of photosynthesis

C6H12O6 + 6O2

yields 6CO2 + 6H2O + ATP

cellular respiration Includes the following cellular processes:

glycolysis, oxidation of pyruvate, krebs cycle, and oxidative phosphorylation

in cellular respiration, Molecules that contain C are

oxidized

in cellular respiration, e- carriers NAD+ and FAD+ are

reduced

Anaerobic (oxygen is not present or needed)

can perform glycolysis and fermentation

Aerobic organisms can perform

glycolysis, oxidation of pyruvate, krebs cycle, and oxidative phosphorylation, but not fermentation

aerobic organisms Extract

more energy from organic compounds than anaerobic

glycolosis

Occurs in the cytosol

All living organisms can perform (anaerobic and aerobic)

glycolosis

6C molecule glucose enters glycolysis,

along with 2 molecules of the e- carrier NAD+.

in glycolosis, the glucose molecule is

oxidized

in glycolosis, each NAD+ is

reduced to NADH

in glycolosis, 2 ATP molecules

needed and 4 produced

the net gain of glycolosis is

2 ATP molecules

in glycolosis, the 6C glucose molecule is

cleaved into two separate 3C pyruvate molecules

glycolosis Inputs: glucose (6C); 2 NAD+; 2 ATP

glycolosis Outputs: 2 pyruvate (3C); 2 NADH; 4 ATP

Oxidation of pyruvate

Occurs in the mitochondria

in Oxidation of pyruvate, 3C pyruvate

must be modified to enter mitochondria

in Oxidation of pyruvate, Oxidized e- carrier NAD+ is

reduced and becomes NADH

in Oxidation of pyruvate, one of the carbons in pyruvate is

released as CO2, leaving behind a 2C acetyl group