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Chapter 7
How Cells Harvest Energy
37
Biology
Undergraduate 1
10/10/2010

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Term
Dehydrogenations
Definition
The electron lost in a redox reaction is not just an electron but also a hydrogen atom.
Term
Redox Reactions for ATP
Definition
Used to take energy from food sources and convert them to ATP
Term
Aerobic Respiration
Definition
When the final electron acceptor is oxygen in cellular respiration.
Term
Anaerobic Respiration
Definition
When the final electron acceptor is an inorganic molecule other than oxygen.
Term
Fermentation
Definition
When the final electron acceptor is an organic molecule.
Term
Substrate Level Phosphorylation
Definition
ATP is created by transferring a phosphate group directly to ADP from a phosphate bearing intermediate, or substrate. Glycolysis does this.
Term
Oxidative Phosphorylation
Definition

ATP synthesized by the enzyme ATP synthase, using an energy from a proton gradient. This gradient is formed by high-energy electrons from the oxidation of glucose passing down the ETC. These are then donated to oxygen. 

Formula:

ADP + Pi -> ATP 

Term
Photophosphorylation
Definition
Energy from sunlight is used to provide energy for ATP synthesis.
Term
Mitochondria
Definition
Powerhouse of the cell
Term
Intermembrane Space
Definition
Between the two mitochondrion membranes
Term
Crista
Definition
Inner membrane folded
Term
Mitochondrial Matrix
Definition
Space inside inner membrane
Term
Mitochondria Key Notes
Definition
Surrounded by double membrane (Outer and Inner mitochondria membranes)
Term
Cellular Respiration
Definition
The Complete oxidation of glucose. Glucose is a reduced organic molecule that stores chemical energy in the C-H bond.
Term
Steps of Glycolysis
Definition
Glucose Priming->Cleavage and rearrangement-> Oxidation-> ATP generation 
Term
Step 1 Of Glycolysis
Definition
Glucose Priming- 3 Reactions change glucose into a compound that can be cleaved into 2 3-carbon phosphorylated molecules. 2 of these reactions transfer a phosphate from ATP, uses 2 ATP molecules. (Needs energy to start) Glucose 6C to 2Pyruvate (3C)
Term
Step 2 of Glycolysis
Definition
Cleavage and Rearrangement- The 6carbon product (2Pyruvate/Glucose) of step 1 is split into 2 3-carbon molecules. 1 is G3P, the other is an isomerase of it. 
Term
Step 3 of Glycolysis: Oxidation & ATP Formation
Definition
2 Electrons are transferred from G3P to NAD+ to form NADH. A molecule of Pi is added to G3P to form BPG. The phosphate incorporated will be transferred to ADP and then through Substrate Level Phosphorylation allow for ATP to form. Then to formATP four reactions convert BPG into pyruvate and then two ATP molecules are formed per G3P formed in step 2.
Term
Summary of Glycolysis
Definition

Substrates- 1 Glucose, 2 ATP used, 2 NAD+ 4 ADP, 2 Pi.

Products- 2 Pyruvate (3C each), 2 ADP, 2NADH, 4 ATP

Overall Net Formed: 2 Pyruvate, 2 NADH, 2ATP

Term
Recycling NAD+ and using Pyruvate 
Definition
NADH needs to reproduce NAD+, which means if it has oxygen it will use aerobic respiration and eventually go to the Acetyl CoA and the Krebs Cycle, but if it does not have oxygen it will go to fermentation and produce. This is the same with 
Term
Pyruvate Oxidation
Definition

A redox reaction overall with 1 Glucose that makes 2 Pyruvate which then creates:

2 Acetyl CoA

2 CO2

2 NADH

Term
The Krebs Cycle Overview
Definition

- 2-carbon acetyl CoA combines with 4-carbon oxaloacetate which makes 6-carbon citrate. 

- Goes through multiple step electron-yielding oxidation reactions, during which two CO2 molecules split, restoring oxaloacetate.

- This oxaloacetate keeps going from cycle to cycle. The electrons made from this cycle are transferred to electron carried and used by the ETC to drive proton pumps that generate ATP.

 

Term
Krebs Cycle: Segment A
Definition
1 Reaction- The Acetyl-CoA (2C) and Oxaloacetate (4C) produce Citrate (6C). CoA is given off.
Term
Krebs Cycle: Segment B
Definition
5 Reactions- Reduces citrate to a 5-carbon intermediate and then to 4-carbon succinate. Two NADH and and one ATP are produced.
Term
Krebs Cycle: Segment C
Definition
3 Reactions- The 4 Carbon Succinate molecule undergoes 3 reactions to become oxaloacetate. One NADH is produced; FAD is also a cofactor that is reduced to created FADH2
Term
Krebs Cycle Summary
Definition

Input:

- 2 Acetyl-CoA's (From 2 pyruvates which came from one glucose)

- 6 NAD+ (3 Per Pyruvate)

- 2 FAD (1 Per Pyruvate)

- 2 ADP (1 Per Pyruvate)

 

Output:

- 6 CO2(2 Per Pyruvate)

- 6 NADH (3 Per Pyruvate)

- 2 FADH2 (1 Per Pyruvate)

- 2 ATP (1 Per Pyruvate)

Term
Oxidation of Glucose (Glycolysis + Krebs)
Definition

Glucose + 10NAD+ 2FAD + 4ADP + 4Pi ->

6CO+ 10NADH + 2FADH+ 4ATP

Term
Electron Transport Chain
Definition
Gained electrons during FADHand NADH redox reactions. The NADH takes the electrons to the inner mitochondrial membrane, whereh they transfer electrons to series of membrane associated proteins of the ETC.
Term
Process in ETC Chain for NADH
Definition
 NADH Hydrogenase is the first of the proteins to receive the electrons (is a complex). The carrier ubiquinone (q) then passes it through the bccomplex. Each complex in chain pumps out a proton into the intermembrane space. Then electrons carried by carrier protein cytochrome c to the cytochrome oxidase complex. Here a molecule of oxygen is broken down by 4 of the electrons carried here. The two oxygens separately combine with 4 protons to form water. 
Term
Process in ETC Chain Contiuned
Definition
This feeds its electrons directly to ubiquinone. Overall electrons move from high energy to low energy. 5 Proton pumps are activated and cause a proton gradient to form between the intermembrane space and matrix.
Term
Chemiosmosis
Definition
Utilizes electrochemical gradient to produce ATP. Because of the negative matrix compared with the intermembrane space, positive protons are attracted. Protons pass through ATP Synthase enzyme which takes energy from proton gradient and creates ATP from ADP and P1. Called chemiosmosis because ATP is driven by a diffusion force similar to osmosis. 
Term
Oxidation of 1 Glucose Molecule
Definition
Produces 38 ATP, Net Production of 36 ATP (Theoretical). Actual production is 30 ATP molecules.
Term
Regulation of Glucose Catabolism
Definition

ATP- Inhibits phosphofructokinase (Enzyme in glycolysis).

NADH- Inhibits oxidation of pyruvate

High Levels of ATP- Inhibit citrate synthetase.

Term
Anaerobic Respiration
Definition
Oxidation without CO2
Term
Methanogens
Definition

COis the final electron acceptor

CO-> CH4

Term
Sulfur Bacteria
Definition
Inorganic sulfate is the final electron acceptor. Produces H2S.
Term
Fermentation
Definition
Organic molecule is the final electron acceptor. Accepts the electron from NADH and the purpose of this is to use glycolysis to still produce the 2 ATP, yet mainly regenerate NADfor future glycolysis.
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