Biology Chapter Water and Proteins

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Questions and Answers

What percentage of our body weight is made up of water?

Water makes up 2/3 of our body weight.

Why is water referred to as the universal solvent?

Water is called the universal solvent due to its ability to dissolve many organic and inorganic compounds.

What is meant by the term 'high heat capacity' in relation to water?

High heat capacity refers to water's ability to absorb and retain heat, allowing it to remain liquid over a wide range of temperatures.

Explain the role of water in chemical reactions within the body.

Water is involved in most chemical reactions, either as a reactant or the medium where reactions occur. Signup and view all the answers

What defines a solution, and what is its relation to water?

A solution is a uniform distribution of a solute in a solvent, and water often acts as the solvent in biological solutions. Signup and view all the answers

What are the seven major functions of proteins?

<ol> <li>Support, 2. Movement, 3. Transport, 4. Buffering, 5. Metabolic Regulation, 6. Coordination and Control, 7. Defense.</li> </ol> Signup and view all the answers

Describe the structure of an amino acid.

An amino acid consists of a central carbon, a hydrogen atom, an amino group (-NH2), a carboxylic acid group (-COOH), and a variable side chain (R group). Signup and view all the answers

What happens to ionic compounds like sodium chloride when they are dissolved in water?

Ionic compounds like sodium chloride dissociate into ions, with water molecules forming hydration spheres around the ions. Signup and view all the answers

What process forms a peptide bond between amino acids?

A peptide bond is formed by dehydration synthesis between the amino group of one amino acid and the carboxylic acid group of another. Signup and view all the answers

Define hydrophilic molecules and give an example.

Hydrophilic molecules are organic molecules that dissolve in water, such as sugar. Signup and view all the answers

List and briefly describe the four levels of protein structure.

<ol> <li>Primary structure - order of amino acids; 2. Secondary structure - hydrogen bonds form; 3. Tertiary structure - folds the secondary structure; 4. Quaternary structure - several tertiary structures together.</li> </ol> Signup and view all the answers

Why is maintaining the concentration of electrolytes in body fluids important?

An imbalance in electrolyte concentrations can seriously disturb vital body functions. Signup and view all the answers

What indicates a double covalent bond between atoms?

A double covalent bond is indicated by a double line (==). Signup and view all the answers

How do nonpolar covalent bonds differ from polar covalent bonds?

Nonpolar covalent bonds share electrons equally, while polar covalent bonds share electrons unequally, leading to an asymmetrical charge. Signup and view all the answers

How does the shape of a protein relate to its function?

The unique shape of a protein determines its specific function, enabling it to perform particular roles within the cell. Signup and view all the answers

What is a characteristic of water that contributes to its ability to dissolve ionic compounds?

Water is a polar molecule, which allows it to interact with both positive and negative ions. Signup and view all the answers

What roles do enzymes play in cells?

Enzymes are proteins that catalyze biochemical reactions, making cellular functions more efficient. Signup and view all the answers

What is the primary function of nucleic acids?

Nucleic acids store and process information at the molecular level. Signup and view all the answers

What role do hydrogen bonds play in the properties of water?

Hydrogen bonds cause surface tension in water, which influences its interactions with small particles. Signup and view all the answers

Define the terms 'reactants' and 'products' in a chemical reaction.

Reactants are the chemicals that go into a reaction, while products are the chemicals that come out. Signup and view all the answers

Why are proteins considered pivotal in biological systems?

Proteins are essential for determining cell shape, tissue properties, and performing nearly all cell functions. Signup and view all the answers

What happens to energy during chemical reactions?

Energy is transformed from one form to another during chemical reactions, with some energy being lost as heat. Signup and view all the answers

What type of energy is associated with molecular bonds?

The chemical energy in a molecular bond is a form of potential energy. Signup and view all the answers

How does the concept of energy conservation apply to chemical reactions?

Energy cannot be created or destroyed but can only change forms in chemical reactions. Signup and view all the answers

What characterizes hydrophobic molecules and provide an example of such a molecule.

Hydrophobic molecules are nonpolar and do not react with water; examples include fats and oils. Signup and view all the answers

Describe the relationship between hydrogen ion concentration and pH.

The pH scale has an inverse relationship with hydrogen ion concentration; more H+ ions result in lower pH. Signup and view all the answers

What does a pH of 7.0 indicate about a solution?

A pH of 7.0 indicates that the solution is neutral, meaning concentrations of H+ and OH- ions are balanced. Signup and view all the answers

What are acids and how do they affect pH in body fluids?

Acids are solutes that release hydrogen ions (H+) in solution, lowering the pH of body fluids. Signup and view all the answers

Explain the concept of alkalosis and its cause.

Alkalosis is caused by an excess of hydroxide ions (OH-) in body fluids, which raises the pH. Signup and view all the answers

What ions affect the acidity of solutions and why?

Only compounds containing H+ or OH- ions affect acidity because they influence the concentration of these ions in solution. Signup and view all the answers

What is the role of hydrogen ions (H+) in physiological processes?

Hydrogen ions (H+) are very reactive and essential for many physiological processes. Signup and view all the answers

What happens to cells and tissues when there is an excess of hydrogen ions in the body?

An excess of hydrogen ions damages cells and tissues, alters proteins, and interferes with normal physiological functions. Signup and view all the answers

What distinguishes saturated fatty acids from unsaturated fatty acids?

Saturated fatty acids have no double covalent bonds in the carbon chain, while unsaturated fatty acids contain one or more double bonds. Signup and view all the answers

What roles do triglycerides play in the human body?

Triglycerides serve as an energy source, provide insulation, and offer protection for organs. Signup and view all the answers

Identify two functions of steroids within the body.

Steroids regulate metabolism and serve as essential components of cell membranes. Signup and view all the answers

How do phospholipids contribute to cell membrane structure?

Phospholipids have hydrophilic heads and hydrophobic tails, allowing them to form bilayers that constitute cell membranes. Signup and view all the answers

What are eicosanoids, and from which acid are they derived?

Eicosanoids are signaling molecules derived from arachidonic acid. Signup and view all the answers

Differentiate between monoglycerides and diglycerides.

Monoglycerides consist of one fatty acid attached to glycerol, while diglycerides have two fatty acids attached. Signup and view all the answers

Why are proteins considered the most important class of molecules in the human body?

Proteins are essential for all body functions, as they are involved in structure, function, and regulation of tissues and organs. Signup and view all the answers

What is the significance of the number of double bonds in fatty acid chains?

The number of double bonds influences the shape, fluidity, and function of the fatty acids and the lipids they form. Signup and view all the answers

Study Notes

Chemical Bonds and Reactions

A double covalent bond shares 2 electron pairs, indicated by a double line (==).
Carbon dioxide (CO2) contains two double covalent bonds.
Nonpolar covalent bonds feature equal electron sharing, like in oxygen (O2), leading to symmetrical shapes.
Polar covalent bonds occur with unequal electron sharing, as seen in water (H2O), creating a dipole with partial positive and negative charges.
Hydrogen bonds are weak attractions between polar molecules, crucial for the structure of proteins and DNA.
Water's hydrogen bonds contribute to surface tension, affecting interactions with particles.
Reactants are substances that enter a chemical reaction; products are the outcomes, with metabolism encompassing all biological reactions.

Water and Its Properties

Water comprises approximately two-thirds of body weight and is vital for chemical and physiological processes.
Unique properties of water arise from its polarity and hydrogen bonding:
- Solubility: Water is a universal solvent, making it capable of dissolving many organic and inorganic substances.
- Reactivity: Most bodily reactions either utilize water or occur in aqueous solutions.
- High heat capacity: Water maintains a liquid state across various temperatures due to its capacity to absorb heat.
- Lubrication: Minimal friction between water molecules promotes smooth interactions.
Electrolytes, such as NaCl, dissociate in water and are essential for physiological functions.
Hydrophilic compounds readily dissolve in water, while hydrophobic substances, like fats, do not.

pH and Body Regulation

The concentration of hydrogen ions (H+) in solutions is measured using the pH scale; higher H+ concentrations indicate acidic conditions (pH < 7), while lower concentrations indicate basic conditions (pH > 7).
Pure water has a neutral pH (7.0).
Acids release H+ ions, lowering pH, whereas bases remove H+ ions, raising pH.
Body fluid pH must be carefully regulated to prevent acidosis (excessive acidity) or alkalosis (excessive alkalinity).

Lipids

Five main classes of lipids exist:
- Fatty acids consist of carbon chains and vary by saturation levels: saturated (no double bonds), monounsaturated (one double bond), and polyunsaturated (multiple double bonds).
- Eicosanoids derive from arachidonic acid, affecting injury and hormone regulation.
- Glycerides include monoglycerides, diglycerides, and triglycerides, serving as energy sources and insulation.
- Steroids feature four carbon rings, with cholesterol found in cell membranes and various hormones.
- Phospholipids and glycolipids create cell membranes with hydrophilic heads and hydrophobic tails.

Proteins

Proteins, composed of carbon, hydrogen, oxygen, and nitrogen, are critical for all bodily functions.
Functions of proteins include:
- Support through structural proteins.
- Movement via contractile proteins.
- Transport through transport proteins.
- Buffers for pH regulation.
- Metabolic regulation by enzymes.
- Coordination and control through hormones.
- Defense as antibodies.
Proteins consist of amino acids, each containing a central carbon, hydrogen, an amino group, a carboxylic acid group, and a variable side chain (R group).
Peptide bonds form between amino acids, creating polypeptides that fold into specific shapes essential for function.
The four levels of protein structure include primary, secondary, tertiary, and quaternary structures.

Nucleic Acids

Nucleic acids are large organic molecules made of carbon, hydrogen, oxygen, nitrogen, and phosphorus, responsible for storing and processing molecular information.

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Description

Test your knowledge of the vital roles of water and proteins in biological systems. This quiz covers the composition of body weight, the significance of water as a solvent, and the functions of proteins. Perfect for students looking to deepen their understanding of biology concepts.