Metabolism Basics and Cellular Respiration

Practice flashcards covering the basics of metabolism, ATP production, glycolysis, the Krebs cycle, beta oxidation, amino acid catabolism, the electron transport chain, and ketosis based on lecture notes.

What is metabolism?

The sum of all chemical reactions in the body that transform metabolites through enzyme-controlled pathways.

What are metabolites?

Chemicals that are processed step-by-step in metabolic pathways.

What do enzymes do in metabolism?

They catalyze one reaction at a time and pass the product to the next enzyme.

What are metabolic maps?

Diagrams showing the complex pathways of thousands of metabolic reactions.

What is anabolism?

The process of building molecules, tissues, and energy reserves like fat.

What is catabolism?

The process of breaking down molecules to produce energy (ATP).

What happens if the body's energy reserves run out?

The body begins breaking down its own tissues for energy.

What do anabolic steroids promote?

Excessive anabolism (building of tissues).

In chemistry, what does "burning" refer to?

A reaction with oxygen that releases energy.

What does carbon become when it is burned?

Carbon dioxide ($CO_2$).

What does hydrogen become when it is burned?

Water ($H_2O$).

Why can't the human body burn fuel like a fire?

Flames and extreme heat would damage living tissues.

What is ATP?

Adenosine triphosphate, which is the cell's main energy molecule.

What are the three components of ATP?

Adenine, ribose, and three phosphate groups.

Where is the energy in ATP stored?

In the bonds between the phosphate groups.

What is the result of breaking a phosphate bond in ATP?

Energy is released for cellular work.

What is the body's real fuel?

ATP.

Do cells run directly on carbohydrates and fats?

No. Carbohydrates and fats are used to produce ATP.

Why can't dietary ATP provide energy directly to cells?

ATP cannot cross cell membranes because its negatively charged phosphates are repelled by negatively charged phospholipid membranes.

Where must ATP be made?

Inside each individual cell.

What is the literal meaning of glycolysis?

Breakdown of sugars; from "glyco-" (sugar) and "-lysis" (breakdown or destruction).

What molecule starts the glycolysis process?

Glucose.

What molecule is the end product of glycolysis?

Pyruvate.

How many ATP are invested and produced during glycolysis?

$2$ ATP are invested and $4$ ATP are produced.

What is the net ATP gain from glycolysis?

$2$ ATP per glucose.

Where does glycolysis occur within the cell?

Cytoplasm.

Does glycolysis require oxygen?

No. It is anaerobic.

Is glycolysis considered an efficient process?

No. It produces relatively little ATP.

What types of activities rely mainly on glycolysis?

Sprinting, jumping, punching, and other explosive movements.

What happens to pyruvate before it enters the Krebs cycle?

It is converted into acetyl-CoA.

Where does the conversion of pyruvate to acetyl-CoA take place?

During transport into the mitochondria.

What is the role of Coenzyme A (CoA)?

It carries acetyl groups.

What are the other names for the Krebs cycle?

Citric acid cycle and TCA cycle.

What molecule enters the Krebs cycle?

Acetyl-CoA.

What is the final carbon-containing product of the Krebs cycle?

Carbon dioxide ($CO_2$).

Where does the Krebs cycle occur?

Mitochondria.

Is the Krebs cycle aerobic or anaerobic?

Aerobic; it requires oxygen.

What types of activities rely mainly on the Krebs cycle?

Walking, jogging, and other endurance activities.

What is beta oxidation?

The breakdown of fatty acids for energy.

Where does beta oxidation occur?

Mitochondria.

Does beta oxidation require oxygen?

Yes.

What are fatty acids broken into during beta oxidation?

Two-carbon units, which become acetyl-CoA.

Does fat metabolism produce more or less ATP than glucose?

More ATP.

Why is aerobic exercise necessary to burn fat effectively?

Beta oxidation requires oxygen.

What three parts make up an amino acid?

Amino group, carboxyl group, and R group.

What is deamination?

Removal of the amino group from an amino acid.

What waste product is formed from the removed amino group?

Urea, which is removed from the body in urine.

What happens to the carbon skeleton of an amino acid after deamination?

It is burned for energy, entering metabolism at glycolysis or the Krebs cycle.

What is the electron transport chain (ETC)?

The final and most productive stage of aerobic ATP production.

Where is the ETC located?

Inner mitochondrial membrane.

Which molecules donate electrons to the ETC?

NADH and $FADH_2$.

What is the final electron acceptor in the ETC?

Oxygen.

What forms when oxygen accepts electrons in the ETC?

Water ($H_2O$).

Which enzyme is responsible for making ATP in the ETC?

ATP synthase.

What powers the ATP synthase enzyme?

The flow of hydrogen ions ($H^+$) down their concentration gradient.

Where is the majority of ATP produced in the cell?

Electron transport chain.

What happens to fat breakdown during starvation?

Fat breakdown (beta oxidation) increases as glucose becomes scarce.

Can fats be converted into glucose?

No.

Why does acetyl-CoA accumulate during starvation?

The Krebs cycle cannot process it fast enough.

What are the three types of ketone bodies mentioned?

Acetoacetate (the first formed), acetone, and $\beta\text{-hydroxybutyrate}$.

Can the brain use ketone bodies?

Yes, during prolonged starvation.

How does a keto diet mimic starvation?

By severely restricting carbohydrates.

What is ketosis?

A metabolic state in which ketone bodies become a major fuel source.

What is the body's immediate usable energy source?

ATP.

Which metabolic pathway is anaerobic?

Glycolysis.

Which metabolic pathways are aerobic?

Krebs cycle, beta oxidation, and electron transport chain.

What molecule connects glycolysis to the Krebs cycle?

Acetyl-CoA.