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Questions and Answers
What are molecules consisting only of carbon and hydrogen called?
What are molecules consisting only of carbon and hydrogen called?
Why do hydrocarbons make good fuels?
Why do hydrocarbons make good fuels?
Which of the following functional groups would make a molecule more basic?
Which of the following functional groups would make a molecule more basic?
What is the empirical formula for carbohydrates?
What is the empirical formula for carbohydrates?
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What characteristic differentiates structural isomers from stereoisomers?
What characteristic differentiates structural isomers from stereoisomers?
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Which macromolecule does not follow the monomer–polymer relationship?
Which macromolecule does not follow the monomer–polymer relationship?
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What is the molecular composition of a water molecule?
What is the molecular composition of a water molecule?
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What reaction is responsible for building polymers from monomers?
What reaction is responsible for building polymers from monomers?
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What is the key feature of carbohydrates in terms of energy storage?
What is the key feature of carbohydrates in terms of energy storage?
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What property of water results in its high surface tension?
What property of water results in its high surface tension?
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What causes the phenomenon of cohesion in water?
What causes the phenomenon of cohesion in water?
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What happens when water is placed in a narrow glass tube?
What happens when water is placed in a narrow glass tube?
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Why is carbon considered the framework of biological molecules?
Why is carbon considered the framework of biological molecules?
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What type of bonding primarily characterizes water's polarity?
What type of bonding primarily characterizes water's polarity?
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Which atom in a water molecule is more electronegative?
Which atom in a water molecule is more electronegative?
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What is a key characteristic of water's adhesion?
What is a key characteristic of water's adhesion?
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What is the primary role of disaccharides in plants and animals?
What is the primary role of disaccharides in plants and animals?
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Which of the following disaccharides is known as 'milk sugar'?
Which of the following disaccharides is known as 'milk sugar'?
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What are the links between glucose molecules in starch called?
What are the links between glucose molecules in starch called?
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What happens to adults regarding the enzyme lactase?
What happens to adults regarding the enzyme lactase?
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Which sugar is known to taste significantly sweeter than glucose?
Which sugar is known to taste significantly sweeter than glucose?
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What is a common method for storing sugars in organisms?
What is a common method for storing sugars in organisms?
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What is the primary function of polysaccharides?
What is the primary function of polysaccharides?
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How do the linkages in cellulose differ from those in starch?
How do the linkages in cellulose differ from those in starch?
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Study Notes
Biology 1 "BIO131"
- Course taught by Dr. Ahmed Deghidy
- PhD in Molecular Biology
- At Alex U, Alexandria, Egypt
Water: A Vital Compound
- Water molecules are composed of one oxygen atom and two hydrogen atoms.
- Oxygen shares an electron with each hydrogen atom.
- Water's polarity results from oxygen's greater electronegativity.
- This creates partial negative charges near oxygen and partial positives near hydrogen.
- Water has a simple molecular structure.
Water molecules are cohesive
- Cohesion is water's tendency to adhere to other water molecules due to hydrogen bonding.
- Cohesion is responsible for water's surface tension.
- Surface tension is the force that allows insects to glide on water.
- High surface tension is due to hydrogen bonding between water molecules.
Water molecules are adhesive
- Water's polarity allows it to adhere to other polar molecules.
- Adhesion is the attraction of water to other substances.
- Water adheres to surfaces like glass, causing water to rise in narrow tubes (capillary action).
- Adhesion strength is greater than gravity in narrow tubes.
Properties of Water
- Cohesion: Hydrogen bonds hold water molecules together.
- High specific heat: Water absorbs or releases heat when bonds break or form, minimizing temperature changes.
- High heat of vaporization: Many hydrogen bonds must break for water to evaporate, cooling body surfaces.
- Lower density of ice: Water molecules in ice are spaced further apart due to hydrogen bonding, making ice less dense than liquid water.
- Solubility: Polar water molecules attract ions and polar compounds, making them soluble.
The Chemical Building Blocks of Life
- Biological molecules are primarily composed of carbon atoms bonded to other carbon atoms or atoms of oxygen, nitrogen, sulfur, phosphorus, or hydrogen.
- Carbon atoms can form up to four covalent bonds.
- This allows for diverse structures in biological molecules.
- Molecules consisting only of carbon and hydrogen are hydrocarbons (e.g., gasoline).
- Hydrocarbons make good fuels due to high energy stored in C-H bonds.
Functional groups
- Differences in molecular properties of biological molecules are primarily due to functional groups.
- Functional groups give specific chemical properties to molecules.
- Ex1: Amino groups make molecules more basic.
- Ex2: Carboxyl groups make molecules more acidic.
- Hydroxyl
- Carbonyl
- Carboxyl
- Amino
- Sulfhydryl
- Phosphate
Biological macromolecules
- Macromolecules include carbohydrates, lipids, nucleic acids, and proteins.
- Polymers are large molecules made from repeating subunits (monomers).
- Polymers are built via dehydration reactions (water is lost).
- Polymers are broken down via hydrolysis reactions (water is added).
- Lipids are macromolecules that don't strictly follow monomer-polymer relationships, forming through dehydration reactions linking fatty acids to glycerol.
Carbohydrates
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Carbohydrates contain carbon, hydrogen, and oxygen in a 1:2:1 ratio.
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Their empirical formula is (CH₂O)ₙ.
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They're excellent energy storage molecules due to numerous C-H bonds.
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Simplest carbohydrates are monosaccharides (e.g., glucose, fructose, galactose).
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Disaccharides are formed from two monosaccharides bonded together (e.g., sucrose, lactose).
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Polysaccharides are long chains of monosaccharides (e.g., starch, cellulose, glycogen).
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Starch: A storage polysaccharide consisting of unbranched chains of α-glucose monomers.
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Cellulose: A structural polysaccharide consisting of unbranched chains of β-glucose monomers. Cellulose is difficult for most animals to digest.
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Glycogen: An animal storage polysaccharide, branched, with more branches than plant starch.
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Description
Test your knowledge on the vital compound, water, in this quiz for Biology 1. Explore the unique properties of water including cohesion, adhesion, and its molecular structure. Understand how these properties impact biological systems and everyday life.
