Biology 1&2

What are the essential elements in living organisms?

The most important elements in living organisms are Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S).

What is the smallest unit of an element that maintains chemical properties?

An atom is the smallest unit of an element that maintains its chemical properties.

What are the components of an atom?

An atom consists of a nucleus containing protons and neutrons, and electron shells that contain electrons.

Why is Carbon important in organic chemistry?

Carbon is the basis of organic chemistry due to its four valence electrons, allowing it to form four covalent bonds, which enable the creation of long chains, branches, rings, and complex three-dimensional structures.

Name some biological molecules that are carbon-based.

Examples of carbon-based biological molecules include carbohydrates, lipids, proteins, and nucleic acids.

What is a covalent bond?

A covalent bond forms when atoms share electrons, making it a strong bond.

What are some examples of covalent bonds?

Examples include C–C bonds in organic molecules, peptide bonds in proteins, glycosidic bonds in carbohydrates, and phosphodiester bonds in DNA.

What is an ionic bond?

An ionic bond forms between atoms with opposite charges, such as Na⁺ and Cl⁻ forming NaCl.

Where do ionic interactions occur in biological systems?

Ionic interactions occur between charged groups, important for protein folding and enzyme-substrate interactions.

What are hydrogen bonds?

Hydrogen bonds are weak attractions between a hydrogen atom attached to an electronegative atom and another electronegative atom.

What common atoms are involved in hydrogen bonds?

Common atoms include oxygen and nitrogen.

What are some examples of hydrogen bonds in biology?

Examples include water molecules, DNA base pairing, and protein structure.

Why are weak interactions important in biology?

Weak interactions, though individually small, collectively create stable biological structures essential for life.

What properties of water result from hydrogen bonds?

Hydrogen bonds create cohesion, surface tension, and a high boiling point in water.

How do hydrogen bonds contribute to DNA structure?

Hydrogen bonds hold complementary DNA bases together, with adenine pairing with thymine and guanine with cytosine.

What role do hydrogen bonds play in protein structure?

Hydrogen bonds stabilize the structure of α-helices and β-sheets in proteins.

What are hydrophobic interactions?

Hydrophobic interactions occur when nonpolar molecules avoid contact with water, contributing to the formation of cell membranes and protein folding.

What are van der Waals forces?

Van der Waals forces are very weak attractions caused by temporary changes in electron distribution, important for molecular recognition and protein interactions.

What is the strength ranking of different types of interactions in biology?

Covalent bonds are strong, ionic interactions are medium, hydrogen bonds are weak, hydrophobic interactions are weak, and van der Waals forces are very weak.

What percentage of the human body is made up of water?

Water makes up approximately 60–70% of the human body.

What are the two main properties of water?

The properties of water are due to its polarity and hydrogen bonding.

What type of molecule is water?

Water is a polar molecule.

What are the characteristics of the oxygen and hydrogen atoms in a water molecule?

Oxygen is slightly negative, and hydrogen is slightly positive.

What is a hydrophilic substance?

Hydrophilic substances are those that dissolve in water, such as salts, sugars, and amino acids.

What is a hydrophobic substance?

Hydrophobic substances do not dissolve in water, such as oils and lipids.

What is cohesion in relation to water?

Cohesion refers to the attraction between water molecules, caused by hydrogen bonds.

Why is cohesion important in biology?

Cohesion is important for the movement of water in plants and for creating surface tension.

What is adhesion in relation to water?

Adhesion is the attraction between water and other surfaces.

Why is adhesion significant in biology?

Adhesion is significant for capillary action in plants.

What is specific heat capacity in relation to water?

Water has a high specific heat capacity, meaning it requires a lot of energy to change its temperature.

Why is the high specific heat capacity of water important?

It prevents rapid temperature changes and helps maintain body temperature.

What is evaporative cooling?

Evaporative cooling is a process where water requires large amounts of energy to evaporate, helping cool the body during sweating.

List four important roles of water in biological systems.

Water is important because it is polar, a solvent, a temperature stabilizer, and a participant in chemical reactions.

What is an acid?

An acid is a substance that releases hydrogen ions (H⁺), for example, HCl → H⁺ + Cl⁻.

What is a base?

A base is a substance that accepts hydrogen ions or releases hydroxide ions (OH⁻), for example, NaOH → Na⁺ + OH⁻.

What does the pH scale range from?

The pH scale ranges from 0 to 14.

What does a pH value of less than 7 indicate?

A pH value of less than 7 indicates an acidic solution.

What does a pH value of 7 indicate?

A pH value of 7 indicates a neutral solution.

What does a pH value greater than 7 indicate?

A pH value greater than 7 indicates a basic solution.

Why is pH important for biological systems?

pH is important because proteins and enzymes require specific pH conditions; changes in pH can alter protein shape.

Give an example of a protein that works under acidic conditions.

Stomach enzymes work in acidic conditions.

What is a buffer?

A buffer prevents large changes in pH.

What is an important biological buffer?

The bicarbonate buffer system.

What is the normal range for blood pH maintained by the bicarbonate buffer system?

The bicarbonate buffer system maintains blood pH around 7.35–7.45.

What are some high-yield concepts related to buffers and pH?

1. Carbon forms four bonds.
2. Hydrogen bonds stabilize DNA and proteins.
3. Hydrophobic interactions create cell membranes.
4. Water is polar because oxygen is more electronegative than hydrogen.
5. Buffers maintain stable pH.
6. Weak interactions are individually weak but biologically essential.

What is a common misconception about hydrogen bonds?

Hydrogen bonds are strong bonds. This is false; they are weak individually but important in large numbers.

What is a common misconception about lipids?

Lipids dissolve easily in water. This is false; lipids are hydrophobic.

What is a common misconception about biological molecules?

All biological molecules are made only of carbon and hydrogen. This is false; they also contain oxygen, nitrogen, phosphorus, and sulfur.

What should you know for IMAT about biological macromolecules?

The four major groups of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids, including their basic building blocks, bonds, structures, biological functions, and examples found in humans and other organisms.

What are carbohydrates?

Carbohydrates are organic molecules made mainly of carbon (C), hydrogen (H), and oxygen (O).

What is the general formula for carbohydrates?

The general formula for carbohydrates is (CH₂O)ₙ.

What are the main functions of carbohydrates?

Carbohydrates are important for energy production, energy storage, and structural support.

What are monosaccharides?

Monosaccharides are the simplest carbohydrates and cannot be broken down into smaller carbohydrates.

What is glucose?

Glucose is the most important monosaccharide in biology, serving as the main cellular energy source.

How do cells utilize glucose?

Cells break down glucose during cellular respiration, leading to ATP production.

Why does the brain rely heavily on glucose?

The brain relies on glucose as a primary energy source.

What are disaccharides?

Disaccharides are formed by joining two monosaccharides.

What type of bond is formed between monosaccharides in disaccharides?

The bond formed is a glycosidic bond, created by a condensation reaction.

What is an example of a disaccharide and its components?

Sucrose is a disaccharide made of glucose and fructose.

What is starch and its function?

Starch is a polysaccharide that serves as energy storage in plants, made of glucose molecules.

What is glycogen and where is it stored?

Glycogen is a polysaccharide found in animals, stored mainly in the liver and skeletal muscle, and functions for rapid glucose storage and release.

What is cellulose and its function in plants?

Cellulose is a polysaccharide found in plant cell walls that provides strength and rigidity.

Why can't humans digest cellulose?

Humans cannot digest cellulose because they lack the enzyme cellulase.

What are the two main functions of polysaccharides?

The two main functions of polysaccharides are energy storage and structural support.

What is chitin and where is it found?

Chitin is a polysaccharide found in fungal cell walls and arthropod exoskeletons.

What is the function of chitin?

Chitin provides structural support.

What is the type and function of glucose?

Glucose is a monosaccharide that provides immediate energy.

What is the type and function of glycogen?

Glycogen is a polysaccharide that serves as animal energy storage.

What is the type and function of starch?

Starch is a polysaccharide that serves as plant energy storage.

What is the type and function of cellulose?

Cellulose is a polysaccharide that provides plant structure.

What is the type and function of lipids?

Lipids are a diverse group of molecules mainly composed of carbon, hydrogen, and oxygen; they are nonpolar, hydrophobic, and insoluble in water.

What is one key function of lipids?

Lipids store large amounts of energy; one gram of fat stores approximately twice as much energy as carbohydrates.

What role do phospholipids play in biology?

Phospholipids are primarily involved in the formation of the plasma membrane.

How do lipids help with insulation?

Fat beneath the skin reduces heat loss and protects organs.

What are steroid hormones derived from?

Some hormones, such as testosterone, estrogen, and cortisol, are derived from lipids.

Is the statement 'The storage carbohydrate in humans is starch' true or false?

False; humans store glucose as glycogen.

Is the statement 'Cellulose is a source of energy for humans' true or false?

False; humans cannot digest cellulose.

What are the components of fatty acids?

Fatty acids consist of a carboxyl group (-COOH) and a hydrocarbon chain.

What are saturated fatty acids?

Saturated fatty acids contain no double bonds, have straight chains, pack tightly, and are usually solid at room temperature.

Give an example of a saturated fatty acid.

Butter fat.

What are unsaturated fatty acids?

Unsaturated fatty acids contain one or more double bonds, have a bent structure, are less tightly packed, and are usually liquid at room temperature.

Give an example of an unsaturated fatty acid.

Olive oil.

What are triglycerides?

Triglycerides are the most common type of fat, consisting of one glycerol molecule and three fatty acids bonded by ester bonds.

What is the primary function of triglycerides?

The primary function of triglycerides is long-term energy storage.

What are phospholipids?

Phospholipids are the main component of cell membranes, consisting of a glycerol, two fatty acid tails, and a phosphate group.

What does it mean for phospholipids to be amphipathic?

Amphipathic means they have both a hydrophilic head that likes water and hydrophobic tails that avoid water.

What is the significance of the phospholipid bilayer?

The phospholipid bilayer forms spontaneously due to the amphipathic nature of phospholipids, critical for cell membrane structure.

What are proteins made of?

Proteins are polymers made of amino acids.

List some functions of proteins.

Functions of proteins include enzymes, structural support, transport, movement, defense, and signaling.

What do all amino acids contain?

All amino acids contain an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group).

What is a peptide bond?

A peptide bond is formed between amino acids through a condensation reaction, linking them together.

What is the primary structure of a protein?

The primary structure is the amino acid sequence of a protein.

What characterizes secondary structure in proteins?

Secondary structure involves local folding caused by hydrogen bonds, forming α-helices and β-sheets.

What is tertiary structure in proteins?

Tertiary structure is the complete three-dimensional shape of one polypeptide, maintained by various interactions like hydrogen bonds and ionic interactions.

What is quaternary structure in proteins?

Quaternary structure refers to the combination of two or more polypeptide chains, as seen in hemoglobin.

What is protein denaturation?

Denaturation is the loss of normal protein shape, caused by high temperature, extreme pH, or chemical changes, leading to loss of function.

Give an example of protein denaturation.

An example of denaturation is egg white becoming solid when cooked.

What do nucleic acids do?

Nucleic acids store and transmit genetic information.