Biochemistry Lecture 23: Glycolysis and Gluconeogenesis
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is glycosidic bond primarily associated with?

  • Protein structure
  • Nucleic acid binding
  • Lipid metabolism
  • Carbohydrate structure (correct)

Which of the following lectures focuses on the structure of membranes?

  • Carbohydrates in cell-cell interactions
  • Transporters, ion channels, receptors
  • Lipid structure: fatty acids, phospholipids, sphingolipids
  • Membranes and membrane proteins (correct)

What subject is covered in the session after 'Enzyme structure and specificity'?

  • Regulation of enzyme activity
  • Mechanisms of rate enhancement (correct)
  • Enzymes Inhibition
  • Transport mechanisms in cells

What is the primary role of the glycolytic pathway in metabolism?

<p>To convert glucose into usable energy (D)</p> Signup and view all the answers

What type of fats are characterized by a hydrocarbon chain and a carboxylic acid group?

<p>Fatty acids (A)</p> Signup and view all the answers

Which of the following is a primary focus during the discussion on 'Enzymes as targets in disease'?

<p>Inhibition of enzyme action (B)</p> Signup and view all the answers

What is a crucial function of NAD+ in glycolysis?

<p>To receive electrons during fermentation (B)</p> Signup and view all the answers

During which session are carbohydrates discussed in relation to cell-cell interactions?

<p>Carbohydrates in cell-cell interactions, proteoglycans, bacterial cell wall (D)</p> Signup and view all the answers

Which of the following statements about ATP generation in glycolysis is true?

<p>A net gain of ATP occurs through substrate-level phosphorylation. (A)</p> Signup and view all the answers

Which type of biomolecule is cholesterol categorized under?

<p>Lipids (D)</p> Signup and view all the answers

Gluconeogenesis primarily occurs in which organ?

<p>Liver (D)</p> Signup and view all the answers

What is the primary topic of the session on November 4th?

<p>Introduction to metabolism (B)</p> Signup and view all the answers

What is the main purpose of the regeneration of NAD+ during fermentation?

<p>To allow glycolysis to continue (A)</p> Signup and view all the answers

What is generated as a byproduct of anaerobic fermentation in glycolysis?

<p>Lactic acid or ethanol (C)</p> Signup and view all the answers

How is gluconeogenesis powered within a cell?

<p>By ATP and GTP hydrolysis (A)</p> Signup and view all the answers

Which chapter from 'Stryer, Biochemistry' outlines the glycolytic pathway?

<p>Chapter 16 (D)</p> Signup and view all the answers

What is the primary location in the body where gluconeogenesis occurs?

<p>Liver (B)</p> Signup and view all the answers

Which process is characterized by the hydrolysis of four ATP and two GTP molecules?

<p>Gluconeogenesis (D)</p> Signup and view all the answers

What commonly serves as a starting point for gluconeogenesis?

<p>Lactate (B)</p> Signup and view all the answers

What is the primary role of ATP in the cell?

<p>To drive energy-requiring processes (B)</p> Signup and view all the answers

Where does the final step of converting pyruvate to acetyl groups occur?

<p>In mitochondria (B)</p> Signup and view all the answers

What effect does the balance between glycolysis and gluconeogenesis have on glucose levels?

<p>Synthesizes glucose when energy reserves are high (B)</p> Signup and view all the answers

What type of energy input do the bypass reactions in gluconeogenesis require?

<p>Chemical energy in the form of ATP and GTP (D)</p> Signup and view all the answers

What byproduct is produced alongside NADH during the reactions involving acetyl CoA?

<p>Water and carbon dioxide (D)</p> Signup and view all the answers

Which organelles are specifically mentioned as being capable of digesting large molecules within cells?

<p>Lysosomes (A)</p> Signup and view all the answers

How does the liver respond when energy reserves are low?

<p>Increases gluconeogenesis (C)</p> Signup and view all the answers

Which metabolic intermediate indicates sufficient energy reserves in the liver?

<p>Citrate (A)</p> Signup and view all the answers

In which part of the cell does oxidative phosphorylation primarily occur?

<p>In mitochondria (C)</p> Signup and view all the answers

What is the relationship between gluconeogenesis and glycolysis?

<p>They are regulated to balance glucose consumption and synthesis. (C)</p> Signup and view all the answers

What is mainly produced in Stage 1 of ATP formation?

<p>Large amounts of ATP (D)</p> Signup and view all the answers

What role does oxygen play in the reactions involving acetyl?

<p>It is required for aerobic respiration (A)</p> Signup and view all the answers

What is the main function of the reducing power expressed as NADH in cellular processes?

<p>To drive ATP synthesis (B)</p> Signup and view all the answers

What is the primary function of gluconeogenesis?

<p>To generate glucose from pyruvate (A)</p> Signup and view all the answers

Which steps in glycolysis are bypassed during gluconeogenesis?

<p>Steps 1, 3, and 10 (B)</p> Signup and view all the answers

What does gluconeogenesis require in terms of energy?

<p>It requires input of energy (B)</p> Signup and view all the answers

What is the role of fructose 1, 6-bisphosphate in the context of glycolysis?

<p>It is cleaved to form two 3-carbon sugars (A)</p> Signup and view all the answers

Which enzyme is specifically associated with gluconeogenesis?

<p>Fructose 1, 6-bisphosphatase (B)</p> Signup and view all the answers

Which of the following statements is true regarding gluconeogenesis?

<p>It creates two energy carriers for each glucose produced (C)</p> Signup and view all the answers

Which molecule is a substrate for gluconeogenesis?

<p>Lactate (C)</p> Signup and view all the answers

What type of protein is associated with glucose 6-phosphatase to enhance its activity?

<p>Ca2+-binding stabilizing protein (D)</p> Signup and view all the answers

What is the overall change in Gibbs free energy (ΔG°') for gluconeogenesis?

<p>248 kJ mol⁻¹ (211 kcal mol⁻¹) (A)</p> Signup and view all the answers

How many ATP equivalents are utilized in the process of gluconeogenesis when converting pyruvate to glucose?

<p>6 (C)</p> Signup and view all the answers

What is the stoichiometry of gluconeogenesis involving pyruvate?

<p>1 glucose + 4 ADP + 2 GDP + 1 NAD + 6 Pi + 2 H (A)</p> Signup and view all the answers

What by-products are produced during the reversal of glycolysis?

<p>2 NADH and 2 ATP (B)</p> Signup and view all the answers

Which process has a lower Gibbs free energy change when converting pyruvate to glucose?

<p>Gluconeogenesis (A)</p> Signup and view all the answers

Which of the following statements about glucose synthesis from pyruvate is true?

<p>It requires the input of energy. (D)</p> Signup and view all the answers

In terms of energy cost, what is a significant aspect of gluconeogenesis compared to glycolysis?

<p>Gluconeogenesis requires hydrolysis of high-phosphoryl-transfer-potential molecules. (D)</p> Signup and view all the answers

What is produced alongside glucose during gluconeogenesis from pyruvate?

<p>ADP and Pi (A)</p> Signup and view all the answers

Flashcards

Carbohydrate structure

The arrangement of atoms in sugars (monosaccharides, polysaccharides), and the bonds between them (glycosidic bonds).

Lipid structure

The arrangement of atoms in fats, oils, and related molecules, like fatty acids, phospholipids, sphingolipids, and cholesterol.

Enzyme structure and specificity

How proteins known as enzymes fold into specific shapes, which allows them to bind to molecules in a targeted way.

Enzyme inhibition

Mechanisms that prevent enzymes from working correctly, often with a connection to diseases or treatments.

Signup and view all the flashcards

Enzyme regulation

Processes that control the activity of enzymes, to make sure they're only working when needed and at the right level.

Signup and view all the flashcards

Glycolysis and gluconeogenesis

Metabolic pathways. Glycolysis breaks down sugar and gluconeogenesis builds it.

Signup and view all the flashcards

Membranes and Membrane Proteins

The structure and function of cell membranes and the proteins embedded within them.

Signup and view all the flashcards

Transporters, ion channels, receptors

The proteins that move molecules, ions, and carry signals across cell membranes.

Signup and view all the flashcards

Cellular Respiration

The process by which cells break down glucose to produce energy in the form of ATP. It involves a series of chemical reactions that occur in three main stages: glycolysis, the citric acid cycle, and oxidative phosphorylation.

Signup and view all the flashcards

Glycolysis

The first stage of cellular respiration that occurs in the cytoplasm. It breaks down glucose into pyruvate, producing a small amount of ATP and NADH.

Signup and view all the flashcards

Citric Acid Cycle

The second stage of cellular respiration that occurs in the mitochondria. It completes the breakdown of glucose, generating more ATP, NADH, and FADH2.

Signup and view all the flashcards

Oxidative Phosphorylation

The third and final stage of cellular respiration that occurs in the mitochondria. It uses the reducing power of NADH and FADH2 to generate a large amount of ATP by harnessing the energy from electron transport and proton gradients.

Signup and view all the flashcards

ATP

Adenosine triphosphate, the main energy currency of cells. It is used to power many cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis.

Signup and view all the flashcards

NADH and FADH2

Electron carriers that transport electrons during cellular respiration. They are produced in glycolysis and the citric acid cycle and used to power oxidative phosphorylation.

Signup and view all the flashcards

Mitochondria

Organelles responsible for cellular respiration. They contain the enzymes needed for the citric acid cycle and oxidative phosphorylation.

Signup and view all the flashcards

ATP Production in the Mitochondria

The majority of ATP production during cellular respiration occurs in the mitochondria through oxidative phosphorylation.

Signup and view all the flashcards

ATP Generation in Glycolysis

ATP is generated through substrate-level phosphorylation, where a phosphate group is directly transferred from a substrate molecule to ADP (adenosine diphosphate), forming ATP.

Signup and view all the flashcards

NAD+ Regeneration in Fermentation

Fermentation regenerates NAD+ from NADH, which is essential for glycolysis to continue. It allows the cell to produce ATP even without oxygen.

Signup and view all the flashcards

Gluconeogenesis

A metabolic pathway that synthesizes glucose from non-carbohydrate sources, like pyruvate, lactate, or amino acids, primarily in the liver.

Signup and view all the flashcards

Purpose of Gluconeogenesis

Gluconeogenesis ensures a steady supply of glucose for the brain and other tissues that rely primarily on glucose for energy, especially during fasting or starvation.

Signup and view all the flashcards

Substrate-Level Phosphorylation

A way to generate ATP by directly transferring a phosphate group from a high-energy molecule to ADP, forming ATP.

Signup and view all the flashcards

Fermentation

Metabolic process that regenerates NAD+ from NADH, allowing glycolysis to continue in the absence of oxygen. It produces byproducts like lactic acid or ethanol.

Signup and view all the flashcards

Bypass Reactions

Four enzymatic reactions that are essential for gluconeogenesis and bypass irreversible steps in glycolysis.

Signup and view all the flashcards

Why is Gluconeogenesis Needed?

To maintain blood glucose levels when dietary intake is insufficient, especially during fasting or prolonged exercise.

Signup and view all the flashcards

Irreversible Steps in Glycolysis

Steps 1, 3, and 10 in glycolysis are irreversible, requiring specific bypass reactions in gluconeogenesis.

Signup and view all the flashcards

Energy Input in Gluconeogenesis

Gluconeogenesis requires energy input in the form of ATP and GTP, unlike glycolysis which produces ATP.

Signup and view all the flashcards

Glucose 6-phosphatase

An enzyme bound to the membrane that removes phosphate from glucose 6-phosphate, allowing glucose to exit the liver.

Signup and view all the flashcards

Regulation of Gluconeogenesis

Gluconeogenesis is tightly regulated by hormones like insulin and glucagon, which influence key enzymes.

Signup and view all the flashcards

Energy Carriers in Glycolysis and Gluconeogenesis

Since each glucose molecule is split into two 3-carbon sugars, all reactions involving these sugars require twice the number of energy carriers (ATP, GTP, etc.).

Signup and view all the flashcards

What is the primary source of glucose for the brain?

Brain cells mainly rely on glucose for energy. They cannot utilize fat for energy and depend on a constant supply of glucose.

Signup and view all the flashcards

Where does gluconeogenesis occur?

In mammals, gluconeogenesis primarily takes place in the liver.

Signup and view all the flashcards

Why does gluconeogenesis need energy?

Gluconeogenesis requires energy input in the form of ATP and GTP to synthesize glucose. This is because the process reverses the energy-yielding glycolysis.

Signup and view all the flashcards

What happens to lactate produced by muscles?

Lactate, a byproduct of muscle exertion, is taken up by the liver and converted back into glucose.

Signup and view all the flashcards

What role does pyruvate play in gluconeogenesis?

Pyruvate, a product of glycolysis, can be used as a starting material for gluconeogenesis.

Signup and view all the flashcards

Why is the balance between glycolysis and gluconeogenesis important?

The body must carefully regulate these pathways to ensure energy balance: breaking down glucose when energy is needed and building it when stores are low.

Signup and view all the flashcards

How does gluconeogenesis contribute to blood glucose levels?

Gluconeogenesis contributes to maintaining stable blood glucose levels, ensuring a constant supply for tissues like the brain.

Signup and view all the flashcards

Gluconeogenesis Stoichiometry

The net reaction for gluconeogenesis requires 6 nucleoside triphosphates (4 ATP, 2 GTP) and 2 NADH to synthesize one molecule of glucose from two pyruvates.

Signup and view all the flashcards

Glycolysis Stoichiometry

Glycolysis produces 2 ATP and 2 NADH per glucose molecule broken down into two pyruvate molecules.

Signup and view all the flashcards

Gluconeogenesis vs. Glycolysis

Gluconeogenesis synthesizes glucose from pyruvate, requiring energy input (ATP, GTP, NADH), while glycolysis breaks down glucose to pyruvate, producing energy (ATP, NADH).

Signup and view all the flashcards

Net Energy Cost of Gluconeogenesis

Gluconeogenesis requires a net input of 4 high-energy phosphate bonds (ATP) per glucose molecule synthesized.

Signup and view all the flashcards

Why is Gluconeogenesis Important?

Gluconeogenesis provides a source of glucose when dietary intake is insufficient or when glycogen stores are depleted.

Signup and view all the flashcards

Fueling the Brain

The brain primarily relies on glucose for energy. Gluconeogenesis ensures a continuous supply even when blood sugar is low.

Signup and view all the flashcards

Gluconeogenesis and the Liver

The liver plays a major role in gluconeogenesis, converting pyruvate from other sources (e.g., amino acids) into glucose.

Signup and view all the flashcards

Study Notes

Lecture 23: Glycolysis and Gluconeogenesis

  • Glycolysis is an anaerobic pathway, occurring before oxygen was abundant.
  • Glycolysis does not require oxygen.
  • Glycolysis converts glucose to pyruvate.
  • The process has many steps, each catalyzed by a different enzyme.
  • Glycolysis has two phases: the energy investment phase and the energy generation phase.
  • The energy investment phase takes up two ATP molecues and the energy generation phase produces four, yielding a net gain of 2 ATP.
  • NAD+ is crucial for glycolysis, as it is required for the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.
  • Pyruvate has several fates, including fermentation or oxidation to produce more ATP.
  • Gluconeogenesis is the process that replenishes blood glucose, creating glucose from non-carbohydrate molecules like lactate or amino acids.
  • Gluconeogenesis is not a simple reversal of glycolysis, but it uses several different enzymes for the 3 key irreversible steps of glycolysis.

Metabolic Pathways

  • Key metabolic pathways include glycolysis, the citric acid cycle, and oxidative phosphorylation, each critical for energy production and biosynthesis.
  • Metabolic pathways are a series of linked reactions in which components are systematically built or broken down.
  • ATP is an energy currency, linking energy-releasing pathways with energy-requiring pathways.

Glucose as a Fuel

  • Almost all organisms use glucose for fuel.
  • In mammals, glucose is the primary fuel for the brain and red blood cells under non-starvation conditions.
  • Glucose's stability as a hexose, combined with its availability from prebiotic conditions, likely contributed to its crucial role in metabolism across all life forms.
  • Glucose is the most stable hexose and is readily available for biochemical processes.

Glycolysis Steps

  • Detailed steps converting glucose to pyruvate are outlined, focusing on enzymes and high energy connections.
  • Each step in glycolysis is facilitated by a specific enzyme.
  • Specific intermediates in glycolysis are vital for energy production and overall metabolic control.

Pyruvate's Fates

  • Pyruvate can undergo fermentation (alcoholic or lactic acid).
  • Pyruvate can be completely oxidized through pyruvate processing and the citric acid cycle. Fermentation occurs without oxygen.
  • Oxidizing pyruvate to acetyl CoA occurs specifically in the presence of oxygen.

Gluconeogenesis

  • The process of creating glucose from non-carbohydrate sources is called gluconeogenesis.
  • Gluconeogenesis is required for maintaining blood glucose levels.
  • Gluconeogenesis bypasses the three irreversible steps of glycolysis. Many of the steps in gluconeogenesis are the reverse of glycolysis.

Key Scientists

  • Louis Pasteur, Eduard Buchner were pioneers in understanding fermentation and early glycolysis processes.
  • Sir Arthur Harden and William John Young elucidated critical aspects of the reactions.
  • Otto Meyerhof and Jakub Karol Parnas and Gustav Embden were responsible for linking multiple aspects of the reactions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Lecture 2. Glycolysis and Gluconeogenesis PDF

Description

This quiz focuses on Lecture 23, covering the key processes of glycolysis and gluconeogenesis. Understand the stages of glycolysis, the importance of NAD+, and the distinct mechanisms involved in gluconeogenesis. Test your knowledge of these fundamental metabolic pathways.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser