Chapter 11: Catabolism - Energy Release and Conservation

Heteretrophs

Use organic molecules as their carbon source

Autotrophs

use Co2 as sole or principal carbon source

phototrophs

obtain energy from light

Chemotrophs

obtain energy from oxidation of chemical compounds

lithotrophs

use reduced inorganic substances as an electron source

organotrophs

extract electrons from reduced organic substances

three major products of catabolic reactions

1. ATP

2. Electron Carriers (Reducing Power)

3. Precursor metabolites

What are examples of the final electron acceptors in anaerobic respiration?

Nitrate, sulfate, CO2

Fermentation

A process that uses an endogenous electron acceptor, not an ETC, and produces various products

Four main Stages of glucose catabolism

1. Glycolysis

2. Brdige Reaction

3. Krebs Cycle

4. ETC

Function of glycolysis

converts glucose into pyruvate and generates ATP and NADH

What is the bridge reaction?

Converts pyruvate into acetyl-CoA

What is the main function of the Krebs cycle?

Extracts electrons from acetyl-coA and transfers them to NAD+ and FAD

What does the ETC do?

Uses electrons to generate ATP via oxidative phosphorylation

Net yield of EMP?

2 ATP / glucose

Unique features of EDP?

Found in Pseudomonas and replaces 6-Carbon phase of EMP

What is the function of the PPP?

Generates NADPH and ribose-5-phosphate for biosynthesis

Two other names for the TCA

Citric Acid Cycle and Krebs Cycle

How many turnsm of the TCA cycle are required to fully oxidize 1 molecule of glucose?

2

What are the products of 1 Acetyl-CoA entering the TCA Cycle?

2CO2, 3NADH, 1FADH2 and 1 GTP

How many ATP molecules are directly synthesized from glucose oxidation to CO2?

Four

Where does most ATP production occur?

ETC

What are the 3 hydrogen pumps in the mitochondrial ETC?

Complex I, III and IV

What is the chemiosmotic hypothesis?

Proton movement across membrane generates a PMF that drives ATP synthesis

Maximum theoretical ATP yield in eukaryotic aerobic respiration?

32 ATP

Common terminal electron acceptors in anaerobic respiratoin?

Nitrate, Sulfate, Co2, Metals and organic molecules

How does ATP yield in anaerobic respiration compare to aerobic?

It’s lower

Why does fermentation occur?

No available ETC to take electrons from NADH

How is ATP produced in fermentatoin?

By substrate-level phosphorylation

How are carbohydrates catabolized?

Broken down into monomers that enter gylcolytic pathways

How are lipids catabolized?

Triglycerides are hydrolyzed into glycerol and fatty acids. Fatty acids broken down by beta-oxidatoin

How are proteins catabolized?

Hydrolyzed into amino acids by proteases than deaminated to enter metabolic pathways

What do chemolithotrophs oxidize for electrons?

Inorganic molecules

What is nitrification?

Oxidation of ammonia to nitrate by nitrifiying bacteria

Primary electron acceptor in chemolithotrophy

oxygen

What are the 2 stages of photosynthesis?

1. Light reactions

2. dark reactoins

What do light reactions produce?

ATP and NADPH

What is the function of dark reactions?

Use ATP and NADPH to fix CO2 into organic molecules

What is the difference between oxygenic and anoxygenic photosynthesis?

Oxygenic produces oxygen, anoxygenic doesnt

Bacteriorhodopsin

Protein used by microbes for light-driven proton pumping without an ETC

Characteristics of Anoxygenic Photosynthesis

• cyclic

• PS 1

• ATP

Characteristics of oxygenic photosynthesis

• noncyclic

• PS 1 and 2

• ATP , NADPH and O2

Whart are the 2 types of heterotrophs?

saprophytics and parasitic

What is the function of precursor metabolites?

provides carbon skeleton for biosynthesis

What are the two types of chemoorganotrophic metabolism?

Respiration and fermentation

Where is the ETC located in eukaryotes?

mitochondrial inner membrane

Where is the ETC located in bacteria and archaea?

plasma membrnae

What are the two types of carrier proteins in the ETC?

flavins and quinones

What is the electron acceptor in fermentation?

pyruvate or a derivative

Propionic acid produces

swiss cheese

lactic acid produces

yogurt

butyric acid produces

acetone a

acetic acid produces

vinegar

what happens to glycerol from lipid breakdown?

glycolysis

what enzyme breaks down proteins?

protease

how are fatty acids broken down?

beta-oxidation pathway

what enzyme breaks down lipids?

lipases

deamination

removal of the amino group from amino acids

3 major groups of chemolithotrophs?

hydrogen oxidizers

nitrogen oxidizers

sulfur oxidizers

What are the accessory pigments?

Carotenoids and phycobilns