Biochemistry of Glucose Metabolism

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Questions and Answers

What is the primary reason glucose is phosphorylated within cells?

To facilitate the breakdown of glucose into smaller molecules.

To prevent glucose from leaving the cell. (correct)

To create a positive charge on the glucose molecule.

To increase the stability of glucose.

Which of the following statements accurately describes the role of phosphorylation in blood glucose regulation?

Phosphorylation decreases as blood glucose levels decrease.

Phosphorylation levels have no impact on blood glucose levels.

Phosphorylation increases as blood glucose levels decrease. (correct)

Phosphorylation levels remain constant regardless of blood glucose levels.

Why is phosphate commonly used for energy transfer within cells?

Phosphate is highly reactive and easily forms bonds with other molecules.

Phosphate is readily available within cells.

Phosphate is the most efficient form for storing energy.

Phosphate has a high transfer potential, making it suitable for exchanging energy between molecules. (correct)

What happens when a molecule has two phosphate groups located close together?

The molecule is likely to be broken down by an enzyme. Signup and view all the answers

What is the primary function of amination in the context of glucose?

To modify glucose into a derivative with a different function. Signup and view all the answers

What is the preferred position for adding an amine group to glucose?

Carbon 2 Signup and view all the answers

What is the significance of adding an acetic acid group to the amino group at position 2 of glucose?

It is the first step in a metabolic pathway for producing a specific compound. Signup and view all the answers

Why is phosphorylation considered important for preparing fructose for breakdown?

It destabilizes the molecule, making it easier to break down. Signup and view all the answers

What is the primary function of the extracellular matrix (ECM)?

To provide structural support and organization to tissues Signup and view all the answers

What are the three main classes of biomolecules found in the extracellular matrix?

Structural proteins, specialized proteins, and heteropolysaccharides Signup and view all the answers

Which of the following is NOT a function of the extracellular matrix?

Regulation of cellular metabolism Signup and view all the answers

What is the defining structural feature of glycosaminoglycans (GAGs)?

They are composed of repeating disaccharide units. Signup and view all the answers

Which of the following is NOT a characteristic of glycosaminoglycans due to their negative charge?

High resistance to enzymatic degradation Signup and view all the answers

What is the name of the acidic sugar found in glycosaminoglycans?

Glucuronic acid Signup and view all the answers

Which of these is NOT a type of glycosaminoglycan?

Keratin Signup and view all the answers

What is the main reason for the negatively charged nature of glycosaminoglycans?

The presence of acidic sugars like glucuronic acid Signup and view all the answers

What is the primary function of aggrecan in the context of trauma?

Aggrecan acts as a buffer, absorbing and releasing water to manage stress. Signup and view all the answers

Which of the following is NOT a function of glycoproteins?

DNA replication Signup and view all the answers

What is the main structural difference between blood groups A, B, AB, and O?

The specific sugar present at the non-reducing end of the oligosaccharide chain. Signup and view all the answers

In the context of blood transfusions, what is the primary concern regarding blood group incompatibility?

The risk of the recipient's immune system attacking and destroying the donated red blood cells. Signup and view all the answers

Which of the following is a key characteristic of mucopolysaccharidoses (MPS)?

Accumulation of complex glycosaminoglycans (GAGs) within lysosomes, leading to various symptoms. Signup and view all the answers

What is the specific enzyme deficiency that causes Hurler's syndrome (MPS Type I)?

α-L-iduronidase Signup and view all the answers

What is the role of L-fucose in the context of blood group antigens?

L-fucose forms the basis of the oligosaccharide chain and is modified to create different blood group antigens. Signup and view all the answers

Which of the following is NOT a common characteristic of mucopolysaccharidoses (MPS)?

Increased risk of developing autoimmune disorders. Signup and view all the answers

What distinguishes a chiral carbon atom in amino acids?

It is bonded to four different atoms or groups. Signup and view all the answers

Why are amino acids designated as alpha (α) amino acids?

Their amine and carboxyl groups are attached to the second carbon. Signup and view all the answers

Which group of amino acids includes aspartate and glutamate?

Acidic charged side chains Signup and view all the answers

What characteristic do nonpolar neutral side chains in amino acids share?

They consist of hydrocarbon components. Signup and view all the answers

Which of the following amino acids is essential and must be obtained from the diet?

Methionine Signup and view all the answers

What role do R groups (side chains) play in the function of proteins?

They influence the charge and polarity of proteins. Signup and view all the answers

Which of the following is NOT a basic charged side chain amino acid?

Threonine Signup and view all the answers

Which of the following characteristics best describes acidic amino acids?

Tend to give H+ to the solution. Signup and view all the answers

What happens to the pH of the stomach during digestion?

It becomes more acidic. Signup and view all the answers

What does pKa represent in the context of amino acids?

The negative logarithm of the acid dissociation constant. Signup and view all the answers

What is the typical pKa range for the carboxyl group (COOH) and amine group (NH3+) of amino acids?

2.34 and 9.69 Signup and view all the answers

Why are amino acids generally considered neutral at a physiological pH of 7.4?

The charges of the carboxyl and amine groups balance each other. Signup and view all the answers

What determines the overall charge of an amino acid with a charged R-side chain?

The pH of the surrounding environment. Signup and view all the answers

Why are amino acids that have no charged R-side chain considered 'neutral' in terms of charge?

They have a net charge of zero at physiological pH. Signup and view all the answers

How does the pKa of a group relate to its tendency to release and acquire protons?

The lower the pKa, the more readily a group releases a proton. Signup and view all the answers

Which statement correctly explains the significance of pKa values in determining the overall charge of an amino acid?

PKa values are used to predict the charge of the R-side chain and its contribution to the overall charge of the amino acid. Signup and view all the answers

What causes the peptide bond to have an intermediate length between a single and a double bond?

The bond exhibits resonance, with electron movement between the nitrogen, carbon, and oxygen atoms. Signup and view all the answers

Why is the peptide bond considered to be not truly covalent?

The bond has a strong ionic component due to the unequal sharing of electrons between the nitrogen and oxygen atoms. Signup and view all the answers

Why is the oxygen atom in a peptide bond considered to be more electronegative than nitrogen and carbon?

Oxygen has a smaller atomic radius, leading to a stronger attraction for electrons. Signup and view all the answers

Which of the following correctly describes the direction of electron flow in a peptide bond due to resonance?

From nitrogen to carbon to oxygen. Signup and view all the answers

What is the key consequence of the electron movement in the peptide bond due to resonance?

The formation of a permanent dipole moment within the peptide bond. Signup and view all the answers

Which of the following accurately describes the two different forms of the peptide bond?

The charged form has a positive charge on the nitrogen atom and a negative charge on the oxygen atom, while the neutral form has no charges. Signup and view all the answers

Why is the end of a peptide chain referred to as the C-terminus?

The end of the chain is characterized by a carboxyl group. Signup and view all the answers

Which of the following statements best explains the concept of resonance in the context of the peptide bond?

The electrons are continuously fluctuating between the nitrogen, carbon, and oxygen atoms, leading to partial charges. Signup and view all the answers

Study Notes

Biochemistry Study Notes

Biochemistry is the study of chemical processes within and relating to living organisms.
Macromolecules are large molecules consisting of similar building blocks.
Lipids, carbohydrates, proteins, and nucleic acids are the four major classes of biological macromolecules.
Carbohydrates are composed of monomers like sugars and are a major fuel source for metabolism.
Carbohydrates include monosaccharides (simple sugars), disaccharides (double sugars), and polysaccharides (complex sugars)
Polysaccharides function as both sources of energy (starch) and storage forms (glycogen).

Carbohydrate Structure

Carbohydrates are literally "hydrates of carbon" and can be classified as polyhydroxy aldehydes or ketones.
Sugars are carbohydrates that are soluble in water and sweet in taste.
Carbohydrates have many functions including a source of energy, storage of energy, and as structural components
Monosaccharides, a simple sugar, includes glucose, fructose, galactose.
Disaccharides are two monosaccharides linked together by a glycosidic bond and include sucrose, maltose and lactose.
Polysaccharides are multiple monosaccharides linked together and include starch, glycogen, and cellulose.

Carbohydrate Classification

The classification of carbohydrates is based on the number of carbon atoms (triose, tetrose, pentose, hexose) as well as on the functional group (aldehyde or keto).
Aldoses have an aldehyde group.
Ketoses have a ketone group.
Important monosaccharides in metabolism include glucose, fructose, and galactose.

Carbohydrates in Metabolism

Monosaccharides are the primary fuel for metabolism.
Plants store energy in the form of starch, whereas animals store it as glycogen.
Carbohydrates are converted into simpler units like glucose for metabolism, supplying energy to all living cells in plants and animals.

Isomers

Isomers have the same chemical formula but a different arrangement of atoms.
Stereoisomers are isomers that differ in spatial arrangement.
Enantiomers are non-superimposable mirror images.
Epimers are stereoisomers that differ in the configuration around one chiral carbon only.
Glucose and fructose are examples of isomers and epimers.

Structural Components

Carbohydrates form structural components in organisms such as plant fibers (cellulose), insect/crustacean exoskeletons (chitin), and bacterial cell walls.

Other Functions

Some carbohydrates are part of RNA and DNA components.
Some carbohydrates are conjugated with proteins and lipids.
Carbohydrates are involved in some cell-cell interactions and recognition events.

Other Categories

Oligosaccharides: The link between the two or more monosaccharides is the glycosidic bond. Oligosaccharides are small chains of monosaccharides (2-10)
Polysaccharides are long chains of many monosaccharides

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Description

This quiz explores key concepts related to the metabolism of glucose, focusing on phosphorylation, amination, and the role of the extracellular matrix in cellular functions. Delve into the biochemical processes that regulate energy transfer and the structure of biomolecules involved. Test your understanding of these essential metabolic pathways.