BIO-249 Lecture Exam 5: Energy & Oxidative Metabolism

1. In a sentence or two, describe metabolism.

2. What is anabolism and catabolism?

3. When energy is created or released, what unit of measurement is used to measure that energy within the body and within a cell?

• Metabolism: Balance of energy storage and usage

  • the totality of all chemical reactions in the body

• Catabolism: energy RELEASING (decomposition reactions)

  • big molecule → smaller molecules

• Anabolism: energy consuming (synthesis reactions)

  • CREATING bonds to make BIGGER molecules

• Energy unit: ATP or calories

What are the reactants and products of cellular respiration?

• Reactants

  1. Glucose

  2. O₂

  3. ADP

• Products

  1. H₂O

  2. CO₂

  3. ATP (cellular energy)

1. In a sentence or two, describe the basic chemical process (very abstract) of ATP synthesis.

2. What is phosphorylation?

3. In 2-4 sentences, describe the differences between substrate-level phosphorylation and oxidative phosphorylation

• ATP Synthesis

  • Energy ise produced at the chemical level

  • 2 ways of making ATP (substrate-level phosphorylation and oxidative phoshorylation)

• Phosphorlyation: adding a phosphate group to a molecule

• Substrate-level Phosphorylation

  1. Using an enzyme to add a phosphate group to ADP

  2. Occurs in the cystol & mitochondrial matrix

  3. Very little ATP produced

• Oxidative Phosphorylation

  1. Uses the Electron Transport System (proteins that “pump” protons)

  2. Uses the H+ gradient and ATP Synthase to create ATP

  3. ONLY in the mitochondrial matrix

  4. LOTS of ATP

  5. Requires O₂

1. What are the 3 general steps to cellular respiration?

2. Which step produces the most ATP?

3. Of each of those steps, which ones use substrate-level phosphorylation and oxidative phosphorylation?

• Cellular Respiration STEPS

  1. Glycolysis

     • Substrate-level phosphorylation (ADP → ATP)

  2. Citric Acid Cycle

     • substrate-level phosphorylation

     • produces NADH & FADH₂

  3. Electron Transport Chain

     • MAKES THE MOST ATP

     • oxidative phosphorylation (uses O₂)

1. What is the activation energy of a reaction?

2. How do enzymes accelerate chemical reactions? HINT: the answer involves the activation energy of the chemical reaction energy.

• Activation Energy

  • energy required for a chemical reaction to occur

• Enzyme Function

  • LOWERS the activation energy of a reaction

  • Reaction occurs FASTER

1. What is a chemical reaction pathway (chemical pathways for short)?

2. In a chemical reaction pathway, what are the reactants, products, and intermediates?

• Chemical Reaction Pathway: series of steps that transform reactants into products

  • Reactants: before reactions

  • Products: final result

  • Intermediates: produced & consumed after the beginning

How can chemical reactions be reversed?

Enzymes

• In a couple of sentences, describe how chemical processes/reactions are controlled by enzymes.

  • Be prepared to predict how chemical pathways will change if enzyme activity changes.

1. Regulators

   • If the enzyme is present, the reaction will occur

   • No enzyme = no reaction

2. Time

   1. reduce the reaction time

   2. Increase reaction rate

3. Enzyme Activity Changes

   

1. In 2-4 sentences, generally describe glycolysis.

2. Where does it occur in the cell?

3. Does it require oxygen to occur?

4. What are the reactants and products?

• Glycolysis Function: first step of cellular respiration

• Occurs in the cytoplasm

• does NOT need O₂

• Reactants

  1. Glucose

• Products

  1. Pyurvate

  2. NADH (high energy electron carrier)

  3. ATP

1. In the absence of oxygen, what happens to pyruvate and what is that process called?

2. How much more ATP does that process make?

3. How much ATP in total is created in anaerobic respiration (glycolysis + lactic acid fermentation) from one glucose molecule?

• Lactic Acid Fermentation: allows glycolysis to continue WITHOUT O₂ to CREATE MORE NAD+

  • Reactants

    1. Pyruvate

    2. NADH

  • Products

    1. NAD+

    2. Lactate (lactic acid)

  • NO ATP PRODUCED/USED (fermentation is only used to make more NAD+ !!!!)

• 2 ATP produced from glycolysis & lactic acid fermentation

1. In 2-4 sentences, generally describe the citric acid cycle.

2. Where does it occur in the cell?

3. How is oxygen involved in the citric acid cycle, and do the actual chemical reactions require oxygen to occur?

• Citric Acid Cycle: a repeating pathway to produce as much NADH & FADH₂ as possible

• occurs in the mitochondrion

• O₂ needs to be present for pyruvate to ENTER the mitochondria & for the citric acid cycle to run

• O₂ is NOT chemically needed, just physically (needs to be present)

1. What is the initial reactant to the Citric acid cycle?

2. What are the by-products of the citric acid cycle?

• Reactants

  1. Pyruvate (product from glycolysis)

• By-products

  1. NADH

  2. FADH₂

  3. ATP

  4. CO₂

1. In 2-4 sentences, generally describe the electron transport chain.

2. Where can it be found in the cell?

• Electron Transport Chain: uses oxidative (oxygen) phosphorylation to produce ATP from electrons

• Occurs in the mitochondria

1. How is oxygen used in the ETC part of cellular respiration?

2. What are the reactants and products of the electron transport system?

• O₂ in the ETC: last electron acceptor

  • O₂ + electrons + H^{+ _→} H₂O

• Reactants:

  1. NADH: electron carrier

  2. FADH₂: electron carrier

  3. O₂: LAST electron acceptor

• Products

  1. ATP 🙂

  2. H₂O

Why is the double membrane of the mitochondria required for the electron transport system?

• Double membrane creates a concentration gradient for H+

• H+ protein pumps on the inner membrane

  • accept electrons from NADH & FADH₂

1. What is NADH and FADH₂?

2. How are the electrons from NADH and FADH₂ used to create ATP?

• NADH & FADH₂: electron carriers

• Electrons and H+ are dumped into the electron transport chain proteins → H₊ gradient is created → H+ facilitated diffusion powers ATP Synthase to create ATP

• H+ gradient powers ATP Synthase

In a couple of sentences, describe what glycogen is.

Long-term storage for glucose, is a polysaccharide

1. What is glycogenesis?

2. Under what situations does glycogenesis occur?

3. What are the reactants and products of glycogenesis?

4. Which types of cells typically undergo glycogenesis?

• Glycogenesis: storing glucose into glycogen for long-term storage

• Occurs when cells are full of ATP & don’t need to do cellular respiration → fed state

• Reactant: glucose → Product: glycogen

• Liver & skeletal muscle cells perform glycogenesis

1. What is glycogenolysis?

2. Under what situations does glycogenolysis occur?

3. What are the reactants and products of the process?

4. Which types of cells typically use glycogenolysis?

• Glycogenolysis: breaking down glycogen into glucose

• Occurs when

  1. Blood sugar levels are low

  2. need glucose for cellular respiration

• Reactant: glycogen → Product: glucose

• Skeletal muscles & liver cells

1. What is glyconeogenesis?

2. Under what situations does glyconeogenesis occur?

3. What are the reactants and products of the process?

4. Which types of cells typically use glyconeogenesis?

• Glyconeogenesis: using non-glucose molecules to create glucose

• Occurs when glucose is scarce

• Reactants

  1. Lactate

  2. Amino Acids

  3. Glycerol

  4. Pyruvate

• Product: glucose

• Kidney but MOSTLY liver cells do glyconeogenesis

Which type of lipid is used for energy?

Triglycerides are broken up and used in cellular respiration for energy

How can glycerol and the fatty acid chains be used in cellular respiration?

• Glycerol: glycolysis via lipolysis

• Fatty Acid Chains: citric acid cycle via lipolysis FIRST, then beta oxidation

Beta oxidation process, reactants, and products

• Beta oxidation: fatty acid chains are broken down into acetyl CoA for the citric acid cycle, NOT FOR GLYCOLYSIS

• Occurs AFTER lipolysis (breaking down triglycerides into glycerol & fatty acid chains)

• Reactant: Fatty Acid Chains

• Product:

  1. Acetyl CoA

  2. NADH

  3. FADH₂

1. What is lipogenesis?

2. What are its reactants and product?

3. What chemical processes do the reactants come from in the cell?

4. Can carbohydrates ultimately be turned into fat using lipogenesis?

• Lipogenesis: creating triglycerides from acetyl CoA, fatty acid chains, and glycerol

• Reactants:

  1. Fatty Acids

  2. Glycerol

  3. Acetyl CoA

  4. Pyruvate

  5. Come from (glycolysis) cellular respiration

• Products

  • Triglycerides

• YES, carbohydrates can be turned into fat

What is lipolysis?

• Decomposition of triglycerides into glycerol and fatty acids

• Catabolic reaction

1. Can amino acids be used in cellular respiration?

2. If so, which part of cellular respiration can use converted amino acids?

3. What is deamination?

• Deamination: transformation of an amino acid to an organic acid so it can be USED in cellular respiration

• Used in

  1. Glycolysis (some amino acids)

  2. Citric Acid Cycle

• DEAMINATION IS IRREVERSIBLE

1. Be able to describe how various non-glucose molecules can become glucose using the pathways of cellular respiration. Note: This is basically describing gluconeogenesis by specifically describing the chemical pathways taken in cellular respiration.

1. Lipids (triglycerides)

   • Lipolysis:

     • Reactant: triglyceride

     • Product: glycerol & fatty acid chains

     • Glycerol for glycolysis

   • Beta oxidation

     • Fatty Acid →acetyl CoA for the citric Acid cycle

2. Amino Acids

   • Deamination

     • Reactant: some amino acids

     • Product: pyruvate OR citric acid cycle intermediates

3. Glycogen

   • glycogenolysis

   • Reactant: glycogen

   • Product: glucose

   • Used for glycolysis

When does the fed and fasted state occur in the human body?

• Fed State: 4 hours since the start of eating

• Fasted Sate: after 4 hours

1. Describe the movement and processing of carbohydrates, triglycerides, and amino acids during the fed state.

2. Make sure to explain what happens in the liver, skeletal muscle organs, adipose tissue, and all other cells.

1. GI Tract (absorbing nutrients from the small intestine)

   • Glucose

     • glycogenesis (glucose → glycogen)

       • Skeletal muscle cells

       • Liver cells

     • Lipogenesis (glucose → triglycerides)

       • Adipose tissue

       • Liver cells

   • Amino Acids

     • Storage

       • Muscles

       • Liver

     • Deamination

       • amino acids into triglycerides

   • Glycerol & Fatty Acids

     • Lipogensis: (glycerol & fatty acids → triglycerides)

       • adipose tissue

1. How do nutrients like glucose and amino acids travel from the GI tract to other parts of the body? Be specific.

2. Why can’t this work for fatty acids?

• Glucose & amino acids: bloodstream

  • Secondary active transportation INTO intestinal cells

  • facilitated diffusion OUT of the cell

  • Passive diffusion into the blood capillaries

  • Hepatic portal vein → Liver

  • Rest of the systemic circuit

• Fatty acids are nonpolar & hydrophobic → don’t mix well with water

1. How are cholesterol and fatty acids transported throughout the body?

2. What molecular structure is used?

• Lympathic system: transport chylomicrons (lipid packages) to the body

• Lipoproteins: transport larger lipids throughout the body

• Describe the movement and processing of carbohydrates, triglycerides, and amino acids during the fasted state.

• Make sure to explain what happens in the liver, skeletal muscle organs, adipose tissue, brain, and other cells.

• Proteins: deamination

  • protein → amino acids

  • liver cells

• Carbohydrates: glycogenolysis

  • glycogen → glucose

  • Muscle & Liver cells

• Lipids:

  • lipolysis

    • Triglycerides → glycerol & fatty acids

    • glycerol → glucose

    • adipose tissue & liver

  • beta oxidation

    • fatty acids → acetyl CoA

1. What hormone triggers the fed state, and which hormone triggers the fasted state?

2. Where do both hormones come from (Be specific)?

• Fed State Hormone: insulin

  • too much blood sugar from food → need to decrease blood sugar → store it

  • Glycogenesis: glycogen synthesis

  • Lipogensis: fat synthesis

  • Protein synthesis

• Fasted State Hormone: glucagon

  • LOW blood sugar → NEED to increase it → breakdown stuff

  • glycogenolysis: breakdown glycogen

  • gluconeogensis

    • amino acids, triglycerides, pyruvate, lactate, etc into glucose

  • Ketogenesis