Questions and Answers
What is the non-proteinous substance called that can be a prosthetic group or cofactor?
Prosthetic group or cofactor
Which of the following is an example of a prosthetic group in hemoglobin?
Denaturation of proteins can be reversible.
True
What are the two major nucleic acids found in cells?
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What is the term for nucleotides that contain ribose sugar?
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Match the nitrogenous bases to their categories:
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Each nucleotide is made of a pentose sugar, a phosphate group, and a ______.
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What type of bond forms between nucleotides?
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What is the main function of DNA?
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How many types of RNA are there?
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Which of the following is not a major class of compounds that constitute life?
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Water makes up 90% of the weight of cells.
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What role does water play in living organisms?
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The chemical formula for carbohydrates is (CH2O)[]
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What is the basic structure of lipids?
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What are the functions of carbohydrates?
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Ice has a higher density than liquid water.
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The highest latent heat of vaporization of water is [] calories g-1.
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Which of the following is a disaccharide?
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Match the following types of carbohydrates with their descriptions:
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List the three common hexose sugars.
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Lipids are generally formed from fatty acids and [].
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Proteins are made up of amino acids.
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What are the four levels of protein structure?
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Match the types of proteins with their characteristics:
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Study Notes
Molecules of Life
- Life is formed from five major classes of compounds: Water, Carbohydrates, Lipids, Proteins, and Nucleic acids.
- Water is essential for life, constituting 90% of cell mass.
Importance of Water
- Acts as an inert medium for chemical reactions within living organisms.
- Facilitates transport of nutrients within and between cells.
- Helps dissipate heat and regulates temperature, impacting biological systems' evolution.
Structure of Water
- Composed of two hydrogen atoms covalently bonded to one oxygen atom.
- Has a polar covalent bond due to the electronegativity difference between oxygen and hydrogen.
Unique Properties of Water
- Polar molecule, liquid at room temperature, and serves as a universal solvent for polar compounds.
- Low viscosity, high surface tension, and ability to undergo capillary action.
- High specific heat capacity allows regulation of internal temperatures in cells and environments.
- Ice expands when frozen, making it less dense than liquid water, which is crucial for aquatic life.
Carbohydrates
- Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio with the formula (CH₂O)n.
- Functions include energy source, storage, structural components in cells (e.g., cell walls), and involvement in nucleic acids.
Types of Carbohydrates
- Monosaccharides: Simple sugars (e.g., glucose, fructose) characterized by sweetness and water solubility.
- Disaccharides: Two monosaccharides linked by glycosidic bonds (e.g., maltose, sucrose, lactose).
- Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose) that are not sweet, do not dissolve in water, and cannot crystallize.
Characteristics of Polysaccharides
- Starch: Used for energy storage in plants; consists of amylose and amylopectin.
- Cellulose: Structural component of plant cell walls; not easily digestible.
- Glycogen: Energy storage in animals; branched structure for rapid mobilization.
Lipids
- Organic compounds predominantly made of carbon, hydrogen, and some oxygen.
- Functions include energy storage, structural support in cell membranes, protection of organs, insulation, and waterproofing functions.
Types of Lipids
- Triglycerides (fats and oils): Made from glycerol and fatty acids.
- Phospholipids: Key components of cell membranes, containing hydrophilic heads and hydrophobic tails.
- Steroids: Characterized by a specific ring structure; include hormones like estrogen and testosterone.
Proteins
- Composed of 20 different amino acids, containing carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur and phosphorus.
- Amino acids link via peptide bonds to form polypeptides, which fold into functional proteins.
- Four levels of protein structure: primary, secondary (α-helix and β-pleated sheets), tertiary, and quaternary.
Functions of Proteins
- Serve in defence, catalysis (enzymes), transport, storage, and structural roles in cells and organisms.
Nucleic Acids
- Composed of nucleotides that include a pentose sugar, phosphate group, and nitrogenous base.
- Two key types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
- DNA contains deoxyribose and nitrogen bases adenine, thymine, cytosine, and guanine; RNA contains ribose and uracil in place of thymine.
- Nucleotides link through phosphodiester bonds to form long chains.
Summary of Nucleic Acid Structure
- The backbone consists of alternating sugars and phosphate groups, forming the structural foundation of DNA and RNA.
These notes summarize the foundational elements of life and their functions, outlining the essential roles of water, carbohydrates, lipids, proteins, and nucleic acids in biological systems.
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Description
Explore the essential components that constitute life in this chapter. Learn about the five major classes of compounds, including water, carbohydrates, lipids, proteins, and nucleic acids. Understand the significance of water as the medium of life and its role in cellular composition.
