Test 2 More Ch 5 SG

Microbial Metabolism

Microbial metabolism- the set of controlled chemical reactions that occur in a microorganism.

• The primary goal of metabolism is the reproduction of the organism.

Why should we care about microbial Metabolism?

• How to create effective therapies against microbes

• Use microorganisms to make or break down compounds as we want

• Atovaquone- selectively kills parasites that causes malaria by interfering with the metabolism

Metabolism

• Catabolic pathways- break larger molecules into smaller products

• Anabolic pathways- synthesize larger molecules from smaller ones

• ATP- the energy currency of the cell

• Oil: Oxidation involves loss

• RIG: Reduction involves gain

Enzymes

• Chemical reactions occur when bonds are broken or formed between atoms

• In catabolic reactions, a bond must be destabilized before it breaks

• In anabolic reactions, reactants collide with sufficient energy for bonds to form between them

• Enzymes are organic catalysts that accelerate chemical reactions without being consumed in the process.

  • They are essential for metabolic pathways.

• Enzymes lower the activation energy of a chemical reaction

  • Cells have a wide variety of enzymes that are proteins

• Most enzymes are complete and functional by themselves and do not need cofactors

• Other enzymes are inactive if not bonded to nonprotein cofactors

• Binding of apoenzyme and its cofactor(s) yeilds holoenyme

• Robozymes- An RNA molecule that speeds things up

  6 Types of Enzyme Activity

• Hydrolases: Break down of something with water as a by-product

• Isomerases: Rearrange atoms within a molecule.

• Polymerases: Join two molecules together.

• Lyases: Split molecules without using water.

• Oxidoreductases: Transfer electrons between molecules.

• Transferases: Move functional groups from one molecule to another.

  • The enzyme active site- it has a specific shape that perfectly fits the shape of substrate

Factors that influence the rate of enzymatic reactions

1. Temperature

2. pH

3. Enzyme and substrate concentrations

4. Presence of inhibitors

   • Temperature, pH and other conditions can cause enzymes (proteins) to denature and become inactive

Enzyme Inhibitors

• Inhibitors- substances that decrease or block enzyme activity

  • Substances that block an enzyme's active site

  • Do not denature enzymes

  • Two Types of inhibitors

    • Competitive & Non-competitive

• Inhibitors & activators- control enzyme reactions

  • Substances that change an enzyme's active site

  • Do not denature enzymes

  • Can activate or inhibit an enzyme

• Feedback inhibition: The end product of a pathway inhibits an earlier step, regulating the pathway's activity.

  • This can be effective method by shutting off an enzymatic reaction

Glycolysis

• Glycolysis- the process by which glucose is broken down to produce energy

  • Glucose- most common carbohydrate used

  • Catabolized by 2 processes

    • cellular respiration and fermentation

• Glucose first goes through glycolysis

  • Occurs in the cytoplasm of most cells

  • Splits 6-carbon glucose into 2 3-carbon sugar colecules

• Glycolysis consists of 10 steps grouped into three stages

  • Three Stages of cellular respiration

    1. Energy-investment- Breaking ATP, using energy

    2. Lysis- Breaking the 6 carbon glucose into 2 3 carbon molecules

    3. Energy conserving- You gain 4 ATP

       • After glycolysis you have gained 2 ATP per glucose and 2 NADH

Cellular Respiration

• 3 Stages

  1. Synthesis of acetyl-CoA

  2. Krebs cycle

  3. Final series of redox reactions (electron transport)

The Krebs cycle

• Occurs in the cytosol of prokaryotes and matrix of mitochondira in eukayotes

• 6 types of reactions in Krebs cycle

  1. Anabolism of citric acid

  2. Isomerization reactions

  3. Hydration reaction

  4. Redox reactions

  5. Decarboxylation

  6. Substrate-level

The Krebs cycle products for one molecule of glucose

• Two molecules of ATP

• Two molecules of FADH2

• Six molecules of NADH

• Four molecules of CO2Redox Reactions in Metabolism