Biology Chapter: Chemical Basis of Life

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Questions and Answers

What percentage of the dry weight of the human body is constituted by a few key elements?

75%

100%

90% (correct)

50%

Which of the following elements is NOT mentioned as being important in cells?

Carbon

Calcium

Oxygen (correct)

Iodine

What type of biomolecules serve as the building blocks for proteins?

Nucleotides

Amino acids (correct)

Monosaccharides

Fatty acids

Which of the following macromolecules are considered biopolymers?

Proteins and nucleic acids Signup and view all the answers

What is the primary role of carbohydrates in biological systems?

Energy storage Signup and view all the answers

Why is carbon considered a unique element of life?

It can form infinite number of compounds. Signup and view all the answers

What aspect of carbon allows for the formation of unbranched and branched chain structures?

The ability to form C-C chains Signup and view all the answers

Which biomolecule serves as the fundamental basis of structure and function in cells?

Protein Signup and view all the answers

Which of the following best describes lipids?

They are not strictly biopolymers. Signup and view all the answers

What constitutes the building block of ribonucleic acid (RNA)?

Ribonucleotides Signup and view all the answers

Which of the following is true regarding prokaryotic cells?

They possess a relatively simple structure. Signup and view all the answers

What is the primary function of glycogen in cells?

Storage form of energy for short-term needs Signup and view all the answers

What is the major component that contributes to more than 60% of the chemical composition in a normal human body weighing 65 kg?

Water Signup and view all the answers

Which biomolecule acts as a repository of hereditary information?

Deoxyribonucleic acid (DNA) Signup and view all the answers

What structural components are lipids primarily associated with?

Structural components of membranes Signup and view all the answers

What is the building block of proteins?

Amino acids Signup and view all the answers

Which of the following diseases is associated with a defect in lysosomal hydrolases?

Inclusion cell (I-cell) disease Signup and view all the answers

What is the primary function of lysosomes in a cell?

Digestion of cellular substances Signup and view all the answers

What role does catalase play in peroxisomes?

Protection from toxic H2O2 Signup and view all the answers

What type of cellular organelles are peroxisomes classified as?

Single membrane organelles Signup and view all the answers

Which of the following enzymes is NOT found in lysosomes?

Catalase Signup and view all the answers

The accumulation of which pigment has been implicated in the aging process?

Lipofuscin Signup and view all the answers

Which of the following statements about lysosomes is true?

They are involved in the degradation and recycling of cellular compounds. Signup and view all the answers

What happens to the degraded products of lysosomal activity?

They leave lysosomes and are excreted. Signup and view all the answers

What is the primary biochemical importance of glyceraldehyde?

It acts as an intermediate in glycolysis. Signup and view all the answers

Which monosaccharide is primarily a component of RNA?

D-Ribose Signup and view all the answers

What is the role of D-Ribulose in biological processes?

It is an important metabolite in the hexose monophosphate shunt. Signup and view all the answers

Which of the following sugars is found as a constituent of DNA?

D-Deoxyribose Signup and view all the answers

Which sugar is recognized as the 'sugar fuel' of life?

D-Glucose Signup and view all the answers

What is the main biochemical importance of D-Xylose?

Involved in the function of glycoproteins. Signup and view all the answers

Which monosaccharide undergoes excretion in urine as a result of essential pentosuria?

L-Xylulose Signup and view all the answers

What is the significance of D-Erythrose in carbohydrate metabolism?

It is an intermediate in carbohydrate metabolism. Signup and view all the answers

What is maltose composed of?

Two D-D-glucose units Signup and view all the answers

Which coenzyme is identified as a component of lipids?

Glycerol Signup and view all the answers

What type of bond connects the units in maltose?

D (1 → 4) glycosidic bond Signup and view all the answers

How are amino sugars formed?

By replacing hydroxyl groups with amino groups Signup and view all the answers

Which compound is a sweetener often used in sugarless products?

Xylitol Signup and view all the answers

Which monosaccharide derivative is commonly found in cell membranes?

Myo-inositol Signup and view all the answers

Which aldehyde group is involved in reducing reactions in sugars?

C1 of the second glucose Signup and view all the answers

What characterizes the structure of D-Glucosamine?

It has a hydroxyl group replaced by an amino group Signup and view all the answers

Study Notes

The Chemical Basis of Life

Carbon is the most predominant element in living organisms, contributing to the formation of countless complex compounds due to its ability to form stable covalent bonds and chains.
Life is composed of lifeless chemical molecules, with even a single bacterial cell containing thousands of different types of molecules.
Organic compounds, such as amino acids, nucleotides, and monosaccharides, serve as the fundamental building blocks for complex biomolecules, including proteins, nucleic acids, and polysaccharides, respectively.

Major Biological Macromolecules

Proteins: Primarily responsible for the structure and function of cells, encompassing both static and dynamic roles.
DNA (Deoxyribonucleic acid): Acts as the repository of hereditary information, containing the genetic code.
RNA (Ribonucleic acid): Essential for protein biosynthesis, playing a key role in the translation of genetic information into proteins.
Polysaccharides (e.g., glycogen): Serve as a storage form of energy to meet immediate cellular demands.
Lipids: Act as a long-term energy reservoir and key structural components of cell membranes.

Cellular Organization

Macromolecules assemble into supramolecular structures, such as membranes, which further organize into organelles, cells, tissues, organs, and ultimately, the complete organism.

Cellular Diversity

Prokaryotes: Lack a well-defined nucleus and exhibit a relatively simple structural organization. Examples include bacteria.
Eukaryotes: Possess a defined nucleus and a more complex cellular structure.

Lysosomes

Lysosomes are spherical vesicles, enclosed by a single membrane, functioning as the "digestive tract" of the cell.
They contain hydrolytic enzymes that break down cellular components, including proteins, lipids, carbohydrates, and nucleic acids.
Lysosomal enzymes play a critical role in maintaining cellular homeostasis by degrading and recycling cellular components.
Dysfunctional lysosomal activity can lead to various disorders, such as arthritis and muscle diseases.

Peroxisomes

Peroxisomes, also known as microbodies, are single-membrane bound organelles involved in various important cellular processes.
They contain the enzyme catalase, which protects the cell from the toxic effects of hydrogen peroxide (H2O2) by converting it to water (H2O) and oxygen (O2).
Peroxisomes are involved in the breakdown of long-chain fatty acids, and the synthesis of plasmalogens and glycolipids.
Plant cells contain glyoxysomes, a specialized type of peroxisome involved in lipid metabolism.

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Description

This quiz focuses on the fundamental chemical basis of life, emphasizing the role of carbon and the various organic compounds that form the building blocks of biological macromolecules. Participants will explore essential molecules such as proteins, DNA, and RNA, and their significance in cellular structure and function.