Life Sciences 120 Flashcards #5

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Questions and Answers

Which molecule is not a carbohydrate?

Nucleic Acid

Lipid (correct)

Carbohydrate

Protein

Which of the following statements about monosaccharide structure is true?

Monosaccharides can be classified according to the spatial arrangement of their atoms.

Peptidoglycan is a polysaccharide found only in bacteria.

True

Which complex carbohydrate contains only α-1,4-glycosidic linkages?

Amylose Signup and view all the answers

Which of the following complex carbohydrates is listed with its correct function?

Cellulose: structural component of plant cell walls Signup and view all the answers

Which polysaccharide contains a modified monosaccharide?

Peptidoglycan Signup and view all the answers

You isolate an organic molecule that contains C, H, O, N, and S. This molecule _____?

could be a glycoprotein Signup and view all the answers

What is the difference between an aldose sugar and a ketose sugar?

the position of the carbonyl group Signup and view all the answers

Which of the following linkages would you expect to find at a branch point in glycogen or amylopectin?

α-1,6-glycosidic linkage Signup and view all the answers

What is the major structural difference between starch and glycogen?

the amount of branching that occurs in the molecule Signup and view all the answers

Which of these best reflects the following relationship: monosaccharide versus polysaccharide?

Glucose versus Glycogen Signup and view all the answers

Which of the following molecules would you expect to have the most free energy per gram?

One with carbon and hydrogen atoms only Signup and view all the answers

Bacteria, insects, and plants use carbohydrates to build structures. Which of the following is true of structural carbohydrates?

Structural carbohydrates are long strands of monomers; the strands are chemically linked together to form a network. Signup and view all the answers

What would be the most appropriate control for testing Kawakubo's hypothesis about glycoprotein?

Grow H. pylori in a test tube with glycoprotein that has its terminal NAG removed. Signup and view all the answers

Which statement best summarizes a key difference in the structure of polysaccharides that function in energy storage versus structural support?

Built from α-glycosidic linkages; form straight chains that bond with adjacent chains. Signup and view all the answers

Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive allele of an X-linked gene in humans. A woman whose father suffered from G6PD marries a normal man. (a) What proportion of their sons is expected to be G6PD? (b) If the husband was not normal but was G6PD deficient, would you change your answer in part (a)?

(a) 1/2; (b) no Signup and view all the answers

The _____ functional group can always be found in a carbohydrate molecule.

carbonyl Signup and view all the answers

Which of the following classes of macromolecules always contains a carbohydrate portion?

nucleic acids Signup and view all the answers

A monosaccharide that has the chemical formula C5 H10 O5 would be characterized as a _____.

pentose Signup and view all the answers

A glycosidic linkage is a covalent bond that links two _____.

monosaccharides Signup and view all the answers

Both carbohydrates and fats are used as fuel in cells, but fats store twice as much energy per gram as carbohydrates. Which statement best explains why?

Fats have more C-H bonds with high free energy, and fewer bonds with low free energy. Signup and view all the answers

Carbohydrates that function as structural molecules withstand pulling and pushing forces well. Which structural feature best explains why?

Structural polysaccharides exist as sets of long, parallel strands that are linked to one another. Signup and view all the answers

Where are carbohydrates found in relationship to the cell?

They are found both inside and outside the cell. Signup and view all the answers

Which of the following chemical bonds have the lowest free energy?

C-O bonds Signup and view all the answers

Different types of glycosidic linkage cause glucose polymers to form a helix (e.g., in glycogen) versus a straight chain (e.g., in cellulose). Which statement best explains why?

The geometry of the α-1,4-glycosidic linkage results in a flipped orientation of adjacent glucose monomers; the β-1,4-glycosidic linkage does not. Signup and view all the answers

Study Notes

Carbohydrates and Their Classes

Lipids are not carbohydrates; they are hydrophobic polymers.
Monosaccharides are classified by the spatial arrangement of their atoms.
Peptidoglycan is a polysaccharide exclusive to bacteria, confirming its unique presence.

Complex Carbohydrates

Amylose consists of a-1,4-glycosidic linkages of glucose.
Cellulose serves as the structural component of plant cell walls.
Peptidoglycan contains modified monosaccharides like N-acetylglucosamine and N-acetylmuramic acid.

Organic Molecules

A molecule containing C, H, O, N, and S could potentially be a glycoprotein, as both sugars and proteins share these elements.
Aldose sugars differ from ketose sugars based on the carbonyl group’s position.
Glycogen and amylopectin contain α-1,6-glycosidic linkages at branching points.

Energy Storage and Structure

Starch and glycogen differ significantly in their branching; starch has less branching than glycogen.
Monosaccharides relate to polysaccharides through examples such as glucose (monosaccharide) and glycogen (polysaccharide).
Molecules with only carbon and hydrogen atoms hold the most free energy per gram.

Functional Aspects of Carbohydrates

Structural carbohydrates are characterized by long monomer strands formed into networks.
The human stomach contains a carbohydrate-based antibiotic that inhibits H.pylori, linked to peptic ulcers and stomach cancer.
An appropriate experimental control to test hypotheses about antibiotics would involve growing H.pylori with glycoprotein lacking terminal N-acetylglucosamine (NAG).

Polysaccharide Structures

Polysaccharides for energy storage have different linkages from those that provide structural support; energy storage is typically built from α-glycosidic linkages, forming helical chains.
In a genetic scenario involving G6PD deficiency, sons from a carrier woman and a normal man have a 1/2 chance of being G6PD deficient.
The carbonyl group is a fundamental feature in carbohydrate molecules.

Macromolecule Composition

Nucleic acids always contain a carbohydrate portion within their structure.
Monosaccharides characterized by the formula C5H10O5 are classified as pentoses.
Glycosidic linkages are covalent bonds joining two monosaccharides.

Energy Storage

Fats store twice as much energy per gram compared to carbohydrates due to a higher number of high-energy bonds and fewer low-energy bonds.
Structural polysaccharides are resilient due to their formation into long, parallel strands interconnected to withstand mechanical forces.

Cellular Distribution and Bond Energy

Carbohydrates can be found inside and outside the cell, indicating diverse roles in cellular activities.
C-O bonds are the chemical bonds with the lowest free energy, which may influence metabolic processes.
Glucose polymers exhibit different structures (helixes vs. straight chains) due to variations in the type of glycosidic linkage, affecting their geometric orientation.

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Test your knowledge on carbohydrates, lipids, and monosaccharides with these flashcards from Life Sciences 120. Each card presents a question to help reinforce key concepts in biochemistry. Perfect for studying or review.