Carbohydrates, Metabolism Flashcards
is defined as the “ability to do work”.
Animals need energy to?
carry out all the body processes required to maintain life.
Without energy, an animal is?
unable to move, to digest its food, to reproduce, to grow, or even to breathe.
are the major source of energy in the ani- mal’s diet.
Carbohydrates
plays a prominent role in energy metabolism.
Hydrogen
During the catabo- lism of glucose (C6H12O6) by the animal, hydrogen is transferred from?
glucose to hydrogen receptors
During the catabolism of glucose (C6H12O6) by the animal, hydrogen is transferred from glu- cose to hydrogen receptors, such as?
- nicotinamide adenine dinucleotide (NAD+)
- flavin adenine dinucleotide (FAD)
nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) are oxidized in the reactions of the respiratory chain inside the ? to release energy.
mitochondria
In biological systems, oxidation of hydrogen is coupled with the synthesis of
adenosine triphosphate (ATP)
is the readily available form of energy (“molecular energy currency unit”) in the
ATP
ATP has three components:
a nitrogenous base (adenine), the sugar ribose, and the triphosphate
Energy is stored within the PO4 bonds, and the release of each phosphate bond generates?
eight kcal of energy.
is the compound used as an energy source in bio- chemical reactions.
ATP
What is the first use of absorbed glucose in the animal body?
The first use of absorbed glucose is to form glycogen, which is stored in the liver and muscles.
How is glycogen used when needed?
Glycogen can be rapidly broken down into glucose through a process called glycogenolysis to maintain stable blood sugar levels.
What happens to glucose after glycogen storage?
After glycogen storage, glucose can be oxidized to produce energy.
What happens to excess glucose if glycogen storage is full?
Excess glucose is converted into fat and stored in adipose tissue.
How is glucose converted into fat?
Glucose is first broken down into a substance called pyruvate through a process called glycolysis, which is then used to make fat.
What is the first step in the process of deriving energy from glucose?
Glycolysis
Where does glycolysis occur in the cell?
In the cell’s cytoplasm
What does glycolysis produce from glucose?
Glycolysis breaks down glucose into pyruvate and produces a small amount of ATP and other molecules.
What is the second step in the process of deriving energy from glucose?
The tricarboxylic acid (TCA) cycle, also known as the citric acid or Krebs cycle.
Where does the TCA cycle take place in the cell?
In the cell’s mitochondria.
What happens to pyruvate during the TCA cycle?
Pyruvate is further broken down.
What does the TCA cycle produce?
The TCA cycle produces more ATP and other molecules that help carry energy to different parts of the cell.
What are the final products of glucose metabolism?
Carbon dioxide and water.
What is the overall purpose of glycolysis and the TCA cycle?
To convert glucose into carbon dioxide and water while capturing energy for the cell’s functions.
Enzymes for glycolysis are located in the?
cytosol of the cell
What is the 3-carbon end product of glycolysis in aerobic conditions (with oxygen)?
Pyruvate
What is the 3-carbon end product of glycolysis in anaerobic conditions (without oxygen)?
Lactic acid
Fructose can be converted to ? by hexokinase
fructose-6-phosphate
Fructose can be converted to fructose-6-phosphate by?
hexokinase
Why is glucose-6-phosphate (G6P) important in glycolysis?
G6P is a key molecule that continues through the glycolysis pathway to produce energy for the cell.
Glycolysis has two phases:
an energy investment phase requiring the input of ATP (preparatory phase) and an energy realization phase (pay off) where ATP is made
What does hexokinase do to glucose?
Hexokinase uses ATP to add a phosphorus group to glucose.
What does glucose become after hexokinase adds a phosphorus group?
Glucose becomes glucose-6-phosphate (G6P) after hexokinase adds a phosphorus group.
Why is glucose changed into glucose-6-phosphate (G6P)?
Glucose is changed into G6P to help the cell use it for energy or store it for later.
What are the products of glycolysis, and what roles do they play in other metabolic pathways?
- Pyruvate: Enters the Krebs cycle (TCA cycle) to produce energy.
- Amino acids: Produced through transamination, important for protein synthesis.
- Glucose-6-phosphate: Used in glycogen synthesis for glucose storage.
- NADPH and dihydroxyacetone phosphate:
- NADPH: Vital for fatty acid synthesis and triglyceride formation.
- Dihydroxyacetone phosphate: Used for synthesizing glycerol, the backbone of fat molecules.
