Chapter Nine: Respiration

These flashcards cover essential terms and concepts related to respiration, focusing on aerobic and anaerobic processes, metabolic pathways, and energy production.

Respiration

A catabolic pathway that breaks down organic molecules to produce ATP.

Catabolism

oxidative breakdown of organic molecules primarily food to obtain energy through metabolic processes.

Aerobic Respiration

The breakdown of food molecules to obtain energy in the presence of oxygen.

Fermentation

The process of breaking down food molecules in the absence of oxygen.

Catabolic pathways are most known for breaking down ______?

glucose (in addition to carbohydrates, fats, & proteins consumed as fuel)

Redox Reactions

chemical reactions that transfer & move of electrons between molecules, resulting in oxidation and reduction of substances.

oxidation

substrate loses electrons; oxidized

reduction

substance gains electrons; (amount of + charged is reduced)

During cellular respiration what is the fuel being oxidized and what element is being reduced?

glucose & O₂ (oxygen)

NAD⁺

an electron acceptor & coenzyme during metabolic reactions, becoming reduced to NADH (gains 2 electrons & a hydrogen)

coenzyme

organic non-protein enzyme helper

NADH

• the reduced form of NAD⁺ 

• carries electrons to the electron transport chain.

• equivalent to 2.5 ATPs

Catabolism of glucose occurs in 3 phases:

• glycolysis 

• citric acid cycle 

• oxidative phosphorylation 

Glycolysis

• the first phase of aerobic respiration

• glucose is converted into 2 molecules of pyruvate

  • 6-carbon sugar splits into 2 3-carbon sugars 

• takes 10 reactions

• happens in cytosol

Is glycolysis anaerobic or aerobic?

anaerobic, as it can occur without oxygen, although it is part of aerobic respiration.

What do you invest into glycolysis and how many ATP & NADH do you get out?

invest 2 ATP and get out 4 ATP and 2 NADH

Pyruvate to CoA linking reaction

1. pyruvate transported into mitochondria 

2. one carbon cut off releasing CO₂

3. coenzyme A attached to left over 2 carbons = acetyl CoA 

4. NADH is made 

   1. essentially one CO₂ and one NADH is released

   2. remaining 2 carbon atoms form acetyl CoA

Pyruvate

A three-carbon molecule that is the end product of glycolysis.

Citric Acid Cycle

• the second major phase of aerobic respiration

• processes acetyl CoA and releases CO2.

  • pyruvate is converted in acetyl CoA

    • links glycolysis to citric acid cycle 

• has 8 steps 

• starts w/ oxaloacetate and ends w/ oxaloacetate

What is released with the citric acid cycle per turn? per glucose?

• 1 ATP

• 3 NADH

• 1 FADH

• 2 CO₂

  • 2 ATP’s released per glucose since w/ glucose it spins twice

2 major ways ATP is made:

• 90% oxidative phosphorylation 

• 10% substrate- level phosphorylation

Substrate-Level Phosphorylation

The process of producing ATP by adding a phosphate group to ADP through enzyme reactions.

Electron Transport Chain

• series of large membrane proteins

• in the inner mitochondrial membrane

• electron carriers → take electrons from NADH

  • transfer electrons

  • pump protons out of mitochondria to create a gradient

• no direct ATP production

What 2 carriers are most active in electron transport chains and account for the most energy extracted from food?

NADH and FADH⁺

• start process of making ATP

Proton Gradient

The difference in proton concentration across the mitochondrial membrane, used to drive ATP synthesis.

• active energy source in chemiosmosis

Chemiosmosis

• proton coupling

  • protions gather in mitochondrial intermembrane space

  • proton motitive force = the proton gradient

    • proton moves back acrosss membrane passing therough ATP synthase

ATP Synthase

An enzyme that produces ATP from ADP and inorganic phosphate, utilizing the proton gradient to drive phosphorylation of ATP

Oxidative Phosphorylation

The phase of aerobic respiration that produces the most ATP, involving the electron transport chain and chemiosmosis.

Respiratory efficiency 

• effectiveness of a respiratory system in converting energy from nutrients into usable ATP, often measured by the yield of ATP per glucose molecule

  • 34% of energy in a glucose molecule is transferred to ATP making abt 32-38 ATP

What makes the # of ATP vary?

• leaky mitochondrial membrane

• different paths through the electron transport chain

• getting cytosilic NADH inside mitochondrion

Fermentation

• anaerobic respiration 

  • occurs w/o oxygen 

• coupled w/ glycolysis to produce ATP and regenerate NAD+.

Fermentation Types

The two main types are alcohol fermentation (producing ethanol) and lactic acid fermentation (producing lactate).

Facultative Anaerobes

Organisms that can switch between aerobic respiration and fermentation based on oxygen availability

• only our muscles can use, we can’t 

• include yeast & bacteria

Obligate Anaerobes

Organisms that can only perform fermentation or anaerobic repiration and cannot survive in the presence of oxygen.

Other things that can be catabolized: 

fats (glycerol & 3 fatty acids), proteins (amino acids), and carbohydrates all feed into same respiration pathways 

Feedback Regulation

Mechanisms that regulate metabolic pathways based on the levels of substrates or products, such as ATP and citrate.

• if ATP drops, respiration speeds up

• if ATP is high, respiration slows down

  • most common mechanism for control

Allosteric Inhibition

Regulation where a molecule binds to an enzyme at a site other than the active site, affecting the enzyme's activity.

AMP

Adenosine monophosphate; an indicator of low energy charge in the cell

• allosteric enhancer