Microbio 4000 Chapter 7 Key Concepts

What types of environmental energy do microbes use

Light, organic, and inorganic compounds

How do cells use catabolism and anabolism to power the other

Cells may use catabolism to process glucose into pyruvate which may be used for TCA or reduced end products.

What are the three ways cells transfer energy to ATP

Glycolysis, TCA, and ETC.

Redox reactions

Reducing agents lose electrons and are oxidized
Oxidizing agents gain electrons and are reduced

Electron carriers

Molecules that can be reduced and oxidized to move electrons.
They are used for capturing nutrients, ATP production, biosynthesis, maintaining redox balance

How do cells benefit from multistep pathways

Multistep pathways allow for intermediates to be used for multiple processes and improve efficiency.

Enzymes

Made up of proteins, speed up chemical reactions by lowering activation energy, affected by temperature, pH, coenzymes, concentration, enzymes are regulated by feedback by inhibiting certain processes to maintain balance.

Glycolysis

Input: 1 Glucose, 2 ATP

Output: 4 ATP (via SLP), 2 NADH, 2 pyruvate, intermediates

Prepatory step

Input: 2 pyruvate (per molecule of glucose)

Output: 2 NADH, 2 CO2, 2 Acetyl-CoA, intermediates

TCA

Input: 2 Acetyl-CoA

Output: 4 CO2, 6 NADH, 2 FADH2, 2 ATP (via SLP), intermediates

How are electrons and energy transferred in respiration

Electrons are transferred from glycolysis, TCA, and pyruvate oxidation to NAD+ and FAD. NADH and FADH2 enter ETC and transfer the electron which is used for proton pumping.

How does ETC work

Electrons are transferred to a series of oxireductase enzymes, releasing enrgy that generates the PMF. The PMF drives ATP production by oxidative phosphorylation

Why are microbial ETCs diverse

Bacteria do not have mitochondria, ETC occurs in cell membrane. This means the arrangement and number of complexes may vary between microbial species. Cytochrome C also may vary in location (membrane, periplasm, or in a complex). Microbes also vary in energy intake and carbon source which can also change how their ETC is formed. All cells do not use Cytochrome c oxidase, some may use ubiquinol oxidase or nitrate reductase.

When and why do cells use fermentation?

When oxygen is unavailable, ETC may not be working, and ATP is needed. Pyruvate is the final electron acceptor. The benefit is that there is another way to produce ATP even without using oxygen. Common products are lactic acid and ethanol. Microbes help humans by breaking down the fiber we cannot to smaller sugars.

When is O2 required and not required in microbial metabolism

Required: aerobic respiration (final electron acceptor)
Not required: anarobic respiration and fermentation

Pentose Pathway

Break down glucose into pentose
Yields: 2 NADPH and 1 ATP, intermediates used for nucleic acids and amino acids

Entner-Doudoroff Pathway

Yields 1 NADPH and 1 ATP, pyruvate still produced, needed to metabolize certain sugars

How are cells able to use alternative sources of carbon

Cells may have a wide variety of different enzymes to break down different carbon sources such as amylase, lipase, and protease.

For biosynthesis, where do substrates or starting metabolites often come from?

Substrates or starting metabolites often come from intermediates of other multi-step pathways. This helps to promote efficiency and balance.

How do lithotrophs harvest energy from their environment?

They harvest electron energy from inorganic sources using the ETC.

What are diversities between phototrophs

Oxygenic: use H2O and release O2 when converting light energy
Anoxygenic: use H2, H2S, No O2 release when cconverting light energy

Chemosynthesis

conversion of inorganic molecules into carbon sources

How is chemosynthesis similar and different to photosynthesis

Both lead to the production of sugars like glucose. They are different because photosynthesis uses sunlight, and produces O2 while chemosynthesis requires inorganic compounds and produces CO2.

Calvin Cycle

Input: 3 CO2, 18 ATP, 12 NADPH
Output: 2 G3P