Carbohydrates, Metabolism

Question 1

is defined as the “ability to do work”.

Question 2

Animals need energy to?

Answer 2

carry out all the body processes required to maintain life.

Question 3

Without energy, an animal is?

Answer 3

unable to move, to digest its food, to reproduce, to grow, or even to breathe.

Question 4

are the major source of energy in the ani- mal’s diet.

Answer 4

Carbohydrates

Question 5

plays a prominent role in energy metabolism.

Answer 5

Hydrogen

Question 6

During the catabo- lism of glucose (C6H12O6) by the animal, hydrogen is transferred from?

Answer 6

glucose to hydrogen receptors

Question 7

During the catabolism of glucose (C6H12O6) by the animal, hydrogen is transferred from glu- cose to hydrogen receptors, such as?

Answer 7

• nicotinamide adenine dinucleotide (NAD+)
• flavin adenine dinucleotide (FAD)

Question 8

nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) are oxidized in the reactions of the respiratory chain inside the ? to release energy.

Answer 8

mitochondria

Question 9

In biological systems, oxidation of hydrogen is coupled with the synthesis of

Answer 9

adenosine triphosphate (ATP)

Question 10

is the readily available form of energy (“molecular energy currency unit”) in the

Answer 10

ATP

Question 11

ATP has three components:

Answer 11

a nitrogenous base (adenine), the sugar ribose, and the triphosphate

Question 12

Energy is stored within the PO4 bonds, and the release of each phosphate bond generates?

Answer 12

eight kcal of energy.

Question 13

is the compound used as an energy source in bio- chemical reactions.

Answer 13

ATP

Question 14

What is the first use of absorbed glucose in the animal body?

Answer 14

The first use of absorbed glucose is to form glycogen, which is stored in the liver and muscles.

Question 15

How is glycogen used when needed?

Answer 15

Glycogen can be rapidly broken down into glucose through a process called glycogenolysis to maintain stable blood sugar levels.

Question 16

What happens to glucose after glycogen storage?

Answer 16

After glycogen storage, glucose can be oxidized to produce energy.

Question 17

What happens to excess glucose if glycogen storage is full?

Answer 17

Excess glucose is converted into fat and stored in adipose tissue.

Question 18

How is glucose converted into fat?

Answer 18

Glucose is first broken down into a substance called pyruvate through a process called glycolysis, which is then used to make fat.

Question 19

What is the first step in the process of deriving energy from glucose?

Answer 19

Glycolysis

Question 20

Where does glycolysis occur in the cell?

Answer 20

In the cell’s cytoplasm

Question 21

What does glycolysis produce from glucose?

Answer 21

Glycolysis breaks down glucose into pyruvate and produces a small amount of ATP and other molecules.

Question 22

What is the second step in the process of deriving energy from glucose?

Answer 22

The tricarboxylic acid (TCA) cycle, also known as the citric acid or Krebs cycle.

Question 23

Where does the TCA cycle take place in the cell?

Answer 23

In the cell’s mitochondria.

Question 24

What happens to pyruvate during the TCA cycle?

Answer 24

Pyruvate is further broken down.

Question 25

What does the TCA cycle produce?

Answer 25

The TCA cycle produces more ATP and other molecules that help carry energy to different parts of the cell.

Question 26

What are the final products of glucose metabolism?

Answer 26

Carbon dioxide and water.

Question 27

What is the overall purpose of glycolysis and the TCA cycle?

Answer 27

To convert glucose into carbon dioxide and water while capturing energy for the cell’s functions.

Question 28

Enzymes for glycolysis are located in the?

Answer 28

cytosol of the cell

Question 29

What is the 3-carbon end product of glycolysis in aerobic conditions (with oxygen)?

Answer 29

Pyruvate

Question 30

What is the 3-carbon end product of glycolysis in anaerobic conditions (without oxygen)?

Answer 30

Lactic acid

Question 31

Fructose can be converted to ? by hexokinase

Answer 31

fructose-6-phosphate

Question 32

Fructose can be converted to fructose-6-phosphate by?

Answer 32

hexokinase

Question 33

Why is glucose-6-phosphate (G6P) important in glycolysis?

Answer 33

G6P is a key molecule that continues through the glycolysis pathway to produce energy for the cell.

Question 34

Glycolysis has two phases:

Answer 34

an energy investment phase requiring the input of ATP (preparatory phase) and an energy realization phase (pay off) where ATP is made

Question 35

What does hexokinase do to glucose?

Answer 35

Hexokinase uses ATP to add a phosphorus group to glucose.

Question 36

What does glucose become after hexokinase adds a phosphorus group?

Answer 36

Glucose becomes glucose-6-phosphate (G6P) after hexokinase adds a phosphorus group.

Question 37

Why is glucose changed into glucose-6-phosphate (G6P)?

Answer 37

Glucose is changed into G6P to help the cell use it for energy or store it for later.

Question 38

What are the products of glycolysis, and what roles do they play in other metabolic pathways?

Answer 38

1. Pyruvate: Enters the Krebs cycle (TCA cycle) to produce energy.
2. Amino acids: Produced through transamination, important for protein synthesis.
3. Glucose-6-phosphate: Used in glycogen synthesis for glucose storage.
4. NADPH and dihydroxyacetone phosphate:
   - NADPH: Vital for fatty acid synthesis and triglyceride formation.
   - Dihydroxyacetone phosphate: Used for synthesizing glycerol, the backbone of fat molecules.