Biology Chapter 7 Flashcards

Questions and Answers

Distinguish between fermentation and cellular respiration.

Fermentation is the partial degradation of sugars or other organic fuel without oxygen while cellular respiration uses oxygen.

What is the summary equation for cellular (aerobic) respiration? Write the specific chemical equation for the degradation of glucose.

C6H12O6 + 6O2 ---------> 6CO2 + 6H2O + energy

Define oxidation and reduction.

Oxidation is the loss of an electron; reduction is gain of an electron.

How are redox reactions involved in energy exchanges?

Electrons are transferred from one atom to another, or move to a lower energy orbital on the covalent bond of an atom. Signup and view all the answers

What is the role of NAD+ in cellular respiration?

NAD+ acts as an electron and hydrogen carrier in some oxidation-reduction reactions. Signup and view all the answers

Explain the role of the electron transport chain in cellular respiration.

NADPH passes electrons to the electron transport chain, contributing to the formation of water. Signup and view all the answers

Name the three stages of cellular respiration and state where each occurs in a eukaryotic cell.

Glycolysis occurs in the cytosol, citric acid cycle and oxidative phosphorylation occur in the mitochondrial matrix. Signup and view all the answers

How does the carbon skeleton of glucose change during glycolysis?

The glucose ring opens and it is cleaved into two 3-carbon molecules known as glyceraldehyde. Signup and view all the answers

Why is ATP required for the preparatory steps of glycolysis?

Two molecules of ATP are consumed as glucose is split into two three-carbon sugars. Signup and view all the answers

Where do substrate-level phosphorylation and the reduction of NAD+ occur in glycolysis?

Substrate-level phosphorylation occurs in reactions 7 and 10 of glycolysis. Signup and view all the answers

Describe where pyruvate is oxidized to acetyl CoA and how this links glycolysis to the citric acid cycle.

Pyruvate is oxidized in the mitochondria and links glycolysis to the citric acid cycle through acetyl CoA. Signup and view all the answers

What are the products of the citric acid cycle and why is it called a cycle?

Products include CO2, NADH + H+, and FADH2; it is called a cycle because oxaloacetate is regenerated. Signup and view all the answers

At what point is glucose completely oxidized during cellular respiration?

Glucose is completely oxidized when all energy is transferred to the 6 NADH and 2 FADH2. Signup and view all the answers

Distinguish between substrate-level phosphorylation and oxidative phosphorylation.

Substrate-level phosphorylation involves direct transfer of a phosphate group; oxidative phosphorylation uses the proton motive force. Signup and view all the answers

Explain how the exergonic 'slide' of electrons is involved in energy production.

Electrons moving to lower energy states release energy, which is harnessed for ATP synthesis. Signup and view all the answers

Study Notes

Fermentation vs. Cellular Respiration

Fermentation occurs without oxygen, partially degrading organic fuels like sugars.
Cellular respiration requires oxygen and fully breaks down glucose.

Summary Equation for Cellular Respiration

General formula: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy.
Specific chemical equation reflects the complete conversion of glucose.

Oxidation and Reduction

Oxidation: Loss of electrons.
Reduction: Gain of electrons.

Role of Redox Reactions

Electrons transfer between atoms, often moving to lower energy states during covalent bond alterations.

NAD+ in Cellular Respiration

NAD+ acts as an electron and hydrogen carrier.
It is a site for dehydrogenase enzymes to transfer electrons during oxidation-reduction reactions.

Electron Transport Chain

Electrons are passed from NADPH to the electron transport chain.
This process culminates in the formation of water by combining electrons with hydrogen ions and oxygen.

Stages of Cellular Respiration

Stages: Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation.
Glycolysis occurs in the cytosol; Citric Acid Cycle and Oxidative Phosphorylation occur in the mitochondrial matrix.

Changes in Glucose During Glycolysis

The glucose ring opens, and glucose is cleaved into two straight-chain 3-carbon molecules (glyceraldehyde).

ATP in Glycolysis Preparatory Steps

Two ATP are consumed when glucose splits into glyceraldehyde 3-phosphate.
This conversion leads to the production of two NADH and four ATP through substrate-level phosphorylation.

Substrate-Level Phosphorylation in Glycolysis

Takes place in Reactions 7 and 10 where substrates transfer phosphate to ADP to form ATP.
Phosphate groups originate from ATP hydrolysis in endergonic reactions.

Oxidation of Pyruvate to Acetyl CoA

Occurs in the presence of oxygen for aerobic respiration.
NADH is involved, linking glycolysis to the Citric Acid Cycle through acetyl CoA production.

Products of the Citric Acid Cycle

Produces CO2, NADH + H+, and FADH2.
It is termed a cycle as citrate is formed from acetyl CoA and oxaloacetate, then oxidized back to regenerate oxaloacetate.

Complete Oxidation of Glucose

Glucose is fully oxidized when energy has been transferred to 6 NADH and 2 FADH2.

Substrate-Level vs. Oxidative Phosphorylation

Oxidative phosphorylation uses a proton motive force (PMF) to produce ATP via ATP synthase.
Substrate-level phosphorylation directly synthesizes ATP through the transfer of phosphate groups during glycolysis.

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Description

Explore key concepts in Chapter 7, focusing on cellular respiration and fermentation. These flashcards provide definitions and equations related to aerobic respiration and fermentation processes, helping you understand energy production in living organisms.