GB1- Chapter 9

Cellular Respiration and Fermentation

oxidizing

giving hydrogens and electrons

energy vs. chemical

energy enters environment as light and exits as heat. it is often transferred by electron carrier- NADH

essential chemical elements are recycled

NADH- nicotinamide-adenine dinucelotide

NAD+: coenzyme that acts as a donor and acceptor (electron carrier) of electrons within all eukaryotes

important in cellular respiration

FAD- Flavin adenine dinuleotide

redox reaction

FAD- oxidized form/ lost electrons

FADH2- reduced form/ gained electrons

electron carrier in cellular respiration especially in ETC

Fermentation

partial degradation of sugars without oxygen

Aerobic respiration- consumes organic molecules + oxygen/ produces ATP

Anaerobic respiration- consumes compounds/ produces ATP

cellular respiration

has both aerobic and anaerboic respiration, but commonly known as aerobic. Carbohydrates, fats, and proteins are all consumed as fuel, but glucose is mainly traced.

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy (ATP + heat)

oxygen is required to make ATP! without oxygen, death by affixation will occur due to no ATP production.

energy is released as hydrogens/ electrons are transferred to O atoms- less free energy- more stable

glucose oxidation moves electrons from higher energy state to lower energy state with O atoms. ATP is synthesized with the released energy.

• oxidation happens in a series of steps because too much free energy is harmful to living things - electron travels with a hydrogen atom (proton) hydrogen atoms are first passed to electron carriers instead of going directly to O2.

catabolic pathways

releases energy by breaking down complex molecules.

linked to work by ATP

• cells must constantly create a ATP supply from ADP and phosphate.

redox reactions

chemical reactions that transfer electrons between reactants

oxidation- loss of electrons

reduction- gaining electrons

reducing agent- the thing getting oxidized

oxidizing agent- the thing reducing

less electronegative atom- more stable

more electronegative atom- less stable

• electron loses potential energy when it becomes more electronegative

coenzyme

an organic molecule that helps enzymes function by binding to their active sites and participating in catalytic reactions.

• derived from vitamins

harvesting energy from glucose from cellular respiration

1. glysolysis- breaks down glucose into two pyruvate molecules

2. pyruvate oxidation and citric acid cycle- completes the breakdown of glucose into CO2

3. oxidative phosphorylation- ETC and chemiosis

what would happen if NADH transferred electrons directly to oxygen?

energy would be released in one explosive reaction

substrate-level phosphorylation

occurs when a enzyme transfers a phosphate group directly from a substrate to ADP

hexokinase

adds a phosphate to the 6th carbon

kinases

catalyzes the transfer of Y phosphate group of ATP onto a substrate

Adolases

break down sugars

isomerase

enzyme that catalyzes isomerization- transfer of molecule conformation

ex) cis and trans forms that affect protein conformation

adolases

break down sugars

complete glucose oxidation

eukaryotes if O2 is present, pyruvate enters mitchodonria to complete glucose oxidation

aerobic prokaryotes- complete glucose oxidation finishes in the cytosol

cytochromes

proteins with heme groups containing an iron atom

reasons why exact ATP number isn’t known

1. photophosphorylation and redox reactions aren’t coupled. The ratio of NADH and ATP aren’t whole numbers

2. ATP yield depends on whether the electron is passed to NAD or FAD

3. proton motive force is used to drive other forces too

alcohol fermentation

step 1: produces CO2 from reducing pyruvate

step 2: produces NAD and ethanol

latic acid fermentation

pyruvate is directly reduced by NADH, forming lactate and NAD+

lactic acid fermentation by fungi and bacteria produces cheese and yogurt

human muscle cells fermentation

red skeletal muscle- oxidizes glucose completely to CO2

white skeletal muscle- produces lactate even under aerobic conditions

obligrate anaerobes

only carries out fermentation/ anaerobic respiration and cannot survive in the presence of O2

facultative anaerobes

can survive by using either fermentation or cellular respiration.

pyruvate is a optional fork for them

ex) yeast and many bacteria

glycolysis can use

carbohydrates including starch, glycogen, and several disaccharides. fats are also digested for glycerol and fatty acids

deamination

proteins used for fuel must be digested into amino acids and their amino groups must be removed

nitrogenous waste

excreted as ammonia, urea, or other products

beta oxidation

fatty acids are broken down and yield acetyl CoA, NADH, FADH2- products of cellular respiration

• oxidixed gram of fat produces twice as much ATP as oxidized gram of carbohydrate