Microbio Test 2 Chapter 6

Why do microbes need metabolism?

• Energy source for microbes

• Cell structures, macromolecules, nutrient source, needs energy source (glucose often, sugars) break down energy source into energy to drive building process

  • Releases waste products (acids, CO2)

• Microbes break down molecules to get energy

  • Break down energy = catabolism (cats like to knock things down= break down)

• Microbes build up molecules to make essential cell structures

  • Build up macromolecules = anabolism

Metabolism definition

the total sum of all biochemical and chemical reactions that occur inside a bacterium to extract energy from the environment, build cellular components, and sustain life

Catabolic

• Starts with larger molecules

  • Glucose

• Ends with smaller products

  • CO2

• Releases energy, molecules break down

• ADP → ATP 

Anabolic

• Starts with smaller molecules

  • Elements and catabolism products

• Ends with larger products

  • Phospholipids and membrane

• Synthesizes molecules

• Energy is needed and used 

• ATP → ADP using energy 

ATP role in metabolic reactions

• ATP: most common source of energy in all cells 

  • Adenosine triphosphate, nucleotide! (ribose sugar, carb backbone, A nucleotide base, 3 phosphates attached to sugar)

  • Nucleotide

  • “Energy currency” of cells

  • Stores energy in the bonds between phosphate molecules (high energy bonds) when adding or removing phosphates it can store or release energy

  • Cells cycle between ATP (3 phosphate) and ADP (2 phosphate)

  • Unstable high energy bonds in ATP → removes one phosphate, releases energy that can be used by cell to build anabolic reactions, becomes ADP 

  • ADP → ATP by adding a phosphate onto chain energy stored in ATP molecule and output of catabolic reactions 

Electron carriers role in metabolism

• Intermediate molecules that hold onto energy in catabolic reaction in order to make ATP 

• Electrons are shared between compounds to form a chemical bond

• Electrons move from low electron affinity to high electron affinity (how strong a molecule can hold onto electrons)

• Helps cell to make largest amount of ATP possible

• Electron donor → Electron acceptor 

  • Low electron affinity (donor) energy source, donates electron

  • High electron affinity (acceptor) 

• Oxidation = removal of electron

• Reduction = gain of electron

  • Memory tip: reduced = getting more negative = gained electrons (negatively charged)

  • Happen together, electrons are moving 

  • When an electron moves between molecules, a proton (H+) follows it

    • Hydrogen = H+ + e-

• Can recycle back and forth

• NADH can be oxidized back to NAD+, loses electrons

• B is the electron acceptor and gains the e- and H+ it is reduced

Enzymes role in metabolism

• Enzymes accelerate chemical reactions

• Catalysts that accelerate the rate of chemical reactions

• Work by lowering the activation energy of a reaction, make it easier for the cell to do the reaction, much less energy needed to do reaction because it facilitates the reaction

Precursor metabolites role in metabolism

• Intermediate molecules in metabolic pathways

• Can be turned into macromolecule subunits

• Use some intermediates to create molecules

Describe how an enzyme works using the terms active site, enzyme- substrate complex, cofactor, activation energy

An enzyme binds to a substrate at its active site, forming an enzyme-substrate complex. A cofactor may help the enzyme function. The enzyme lowers the activation energy, speeding up the reaction. Products are released, and the enzyme can be reused.

Parts of an enzyme

• Proteins 

• Shape of protein binds a specific substrate (Active site)

• When substrate binds to enzyme, called the enzyme substrate complex 

• Enzyme helps the substrate be converted into whatever product → the molecule no longer fits → product released

  • After product is released, enzyme in original shape until another substrate binds and makes another products

  • Continuous cycle until runs out of substrate to make products 

• Sometime needs more help, cofactor

  • Attached non-protein component that helps the enzyme work

• Sometimes substrates have to wait to go through enzymatic reactions, can determine how quickly reaction can occur

• Temp + pH reason bacteria cannot survive at high temp/ pH because without enzymes bacteria cannot survive

What is the purpose of glycolysis?

Break down 1 glucose (6C) into 2 pyruvate (3C) molecules to produce ATP, NADH, and precursor metabolites

What does glycolysis require and produce?

Input: 1 glucose, 2 ATP invested, 2 NAD+, ADP +Pi

Output: 2 pyruvate, 2 NADH, 4 ATP (net 2 ATP), and metabolic intermediates used as precursors

Where does glycolysis occur?

Prokaryotes: cytoplasm

Eurkaryotes: cytosol

What is the purpose of the TCA (Krebs) cycle?

Oxidize acetyl-CoA to CO2 while producing reduced electron carriers (NADH and FADH2) and precursor metabolites

What is the purpose of glycolysis

Break down 1 glucose into 2 pyruvate molecules to produce ATP, NADH, and precursor metabolites.

What does glycolysis require and produce

Requires glucose, 2 ATP, 2 NAD+, and ADP + Pi. Produces 2 pyruvate, 2 NADH, and 4 ATP (net gain of 2 ATP).

Where does glycolysis occur

Prokaryotes: cytoplasm. Eukaryotes: cytosol.

What is the purpose of the TCA (Krebs) cycle

Break down acetyl-CoA to produce NADH, FADH2, ATP, and precursor metabolites.

What does the TCA cycle produce per glucose

2 ATP, 6 NADH, 2 FADH2, and 4 CO2. Pyruvate oxidation before the cycle also produces 2 NADH and 2 CO2.

Where does the TCA cycle occur

Prokaryotes: cytoplasm. Eukaryotes: mitochondrial matrix.

What is the purpose of the electron transport chain (ETC)

Use electrons from NADH and FADH2 to create a proton motive force that drives ATP production.

What does the ETC require and produce

Requires NADH, FADH2, and a terminal electron acceptor such as oxygen. Produces a proton gradient and regenerates NAD+ and FAD. ATP synthase uses the gradient to make ATP.

Where does the ETC occur

Prokaryotes: cytoplasmic membrane. Eukaryotes: inner mitochondrial membrane.

What is the purpose of the pentose phosphate pathway

Produce NADPH for biosynthesis, ribose-5-phosphate for nucleotides, and precursor metabolites.

What does the pentose phosphate pathway produce

Its oxidative phase produces 2 NADPH and 1 CO2 per glucose-6-phosphate, along with sugar phosphates. Produces 0 ATP directly.

Where does the pentose phosphate pathway occur

Prokaryotes: cytoplasm. Eukaryotes: cytosol.

What is the purpose of fermentation

Regenerate NAD+ from NADH so glycolysis can continue producing ATP without respiration.

What does fermentation require and produce

Uses pyruvate or a derivative and NADH. Produces NAD+ and products such as lactic acid or ethanol. Glycolysis produces a net 2 ATP per glucose; fermentation adds no ATP directly.

Where does fermentation occur

Prokaryotes: cytoplasm. Eukaryotes: cytosol.

What is proton motive force (PMF)

Stored energy from a difference in proton (H+) concentration and electrical charge across a membrane.

How does proton motive force produce ATP

The ETC pumps H+ across a membrane. H+ flows back through ATP synthase, providing energy to convert ADP + Pi into ATP through chemiosmosis.

How many ATP can a bacterium produce from 1 glucose during aerobic respiration

Traditional theoretical maximum: 38 ATP total (2 glycolysis + 2 TCA + 34 oxidative phosphorylation). Actual yields vary.

How many ATP are produced from 1 glucose during fermentation

Net 2 ATP, both produced during glycolysis.

Calculating ATP