CH 13

Created by erethorma 

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What molecules can a cell use to make ATP?

Glucose and other carbohydrate. Proteins and triglycerides.

Which molecule is the most important and why?

Glucose because (all) enzymatic pathways involved in ATP production start with glucose

Where does Glycolysis occurs?

(in the) cytoplasm. (it's a process that doesn't require O2).

Give examples of cell types that produce all of their ATP via glycolysis

RBC because they don't have mitochondria.
Skeletal muscle - when O2is depleted, cells must use only glycolysis.
Many bacteria and protists in anaerobic environments.

What happens after glycolysis?

Pyruvate and NADH are transported into mitochondria (inside mitochondrial membrane/matrix). For each NADH transported, 1 ATP hydrolyzed.

Transition reaction

Occurs inside the mitochondria. Pyruvate transfers acetyl group to CoA (coenzyme A) to make acetyl CoA. 1 NADH produced per pyruvate. 1 CO2 left over per pyruvate. Acetyl CoA passes the acetyl group on to the Krebs cycle (citric acid cycle/tricarboxylic acid cycle).

electron transport chain. What about the carriers?

NADH and FADH produced, the high energy electrons are taken and thrown into the high energy complex known as the electron transport chain.
The energy that is released from this is used to produce ATP; this process also uses O2 gas/

What is the problem with continous glycolysis. What is the solution?

Cells that continuously run glycolysis will eventually run out of NAD+. Glycolysis will no longer run, ATP production completely stops. Fermentation.

Give information about Fermentation.

Pyruvate and NADH utilized to regenerate NAD+. Very inefficient use of energy, but allows ATP to be produced. The main products is NAD+ and the other product can vary.

What are the other products of fermentation?

Other product varies with organism which typically isn't even utilized by that organism and doesn't matter.
Yeast - produces ethanol and CO2 used for brewing and bread making.
Bacteria - many alcohols and acids produced as a fermentation product.
Human skeletal muscle - lactic acid.

What is anaerobic respiration?

Anaerobic respiration - anaerobic organisms can undergo this to produce ATP with an ETC.
Uses something besides O2 as a final acceptor.

Where do all the reactions (glycolysis, acetyl CoA production, and the citric acid cycle) take place in an aerobic bacteria? What does the aerobic bacteria lack?

(All of these reactions take place in a single compartment of the) cytosol. (It has no) mitochondria.

Energy utilization from Triglycerides.

C-C-C fatty acid tail.
Fatty acids released from glycerol.
Glycerol is converted into glyceraldehyde 3 phosphate.
Fatty acids go through B (beta) oxidation .
Cycle shortens a fatty acid by two carbons for each round.
Cycle yields NADH and FADH2 (used by electron transport system).
Overlaps with Krebs cycle.
Utilizes NADH and FADH2 to power ETC.

Energy utilization from Proteins

Some amino acids are transported into the mitochondria where they are converted into acetyl CoA or one of the other intermediates of the Krebs cycle.
Polypeptides broken down to amino acids.
Amino acid then deanimated.
Amine group removed.
NH2 can pick up an hydrogen (single proton).
Produces NH3 - ammonia (NH3).
Urea produced from amine group before ammonia allowed to accumulate.
Urea removed from individual cells into blood.
Urinary system removes urea.

Electron Transport Drives the Synthesis of the Majority of the ATP in Most Cells

The electron carriers NADH and FADH2 transfer the electrons they have gained by oxidizing other molecules to the ETC (embedded in the inner membrane of the mitochondrion in eukaryotic cells/ in the plasma membrane of bacteria)
As the electrons pass through the series of electron acceptor and donor molecules that form the chain, they fall to successively lower energy states.
Energy released is used to drive H+ across the membrance (proton gradient)
This drives ATP synthesis (addition of ADP to Pi)
At the end of the chain, the electrons are added to O2 and ultimately combine with protons (H+) to produce water

Oxidative Phosphorylation - oxygen-requiring generation of ATP

In total, the complete oxidation of a molecule of glucose to H2O and CO2 produces about 30 molecules of ATP

Glycolysis and the citric acid cycle lie in the center of metabolism

Cell's metabolism is very complex but stable
Control mechanisms allows for homeostasis

Gluconeogenesis - synthesis of glucose

Pathway that builds glucose, pyruvate, lactate, etc used to begin the pathway
For most of the pathway reactions, the exact same enzymes can be used as glycolysis

Most of the glycolysis reactions are reversible... (add more info)

These require different enzymes
Pyruvate → phosphoenol pyruvate
Requires 2 reactions (and therefore 2 enzymes)
Fructose 1,6 bisphosphate → fructose 6 phosphate
Glucose 6 phosphate → glucose
Steady equilibrium between these two in the liver (another place that it is stored is muscle cells)

Glycogenesis

Building of glycogen (storage of glucose)

Glycogenolysis

Glucose is released from glycogen

Insulin

High glucose in the blood causes insulin to lower glucose levels by glycogenesis

Glucagon

Low glucose in the blood causes glucagon to raise glucose levels by glycogenolysis

Fats

Makes a better storage material than glycogen (because the oxidation of a gram of fat releases about twice as much energy as the oxidation of a gram of glycogen
Most humans store only enough glycogen for a day of normal activity
Fat is stored in water-insoluble triacylglycerols in specialized adipose tissue
Plants store sugars as starch

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