Topic 1: Biological molecules

What are monomers?

Small units that are the components of larger molecules, such as monosaccharides, amino acids, and nucleotides.

What are polymers?

Molecules made from many monomers joined together.

What is a condensation reaction?

A chemical reaction where monomers are joined together, eliminating a water molecule.

What is hydrolysis?

The process of adding water to break a chemical bond between two molecules.

What are carbohydrates made of?

Molecules consisting only of carbon, hydrogen, and oxygen, formed into long chains of sugar units called saccharides.

What is a monosaccharide?

A single sugar unit, such as glucose, galactose, or fructose.

What is a disaccharide?

A molecule formed by the condensation of two monosaccharides.

What is a polysaccharide?

A molecule formed from many monosaccharides joined together.

What is the main substrate for respiration?

Glucose.

What is maltose?

A disaccharide formed by the condensation of two glucose molecules.

What is sucrose?

A disaccharide formed by the condensation of glucose and fructose.

What is lactose?

A disaccharide formed by the condensation of glucose and galactose.

What is glycogen?

The main energy storage molecule in animals, formed from many alpha glucose molecules joined by glycosidic bonds.

What are the two types of starch?

Amylose (unbranched) and amylopectin (branched).

What is cellulose?

A polysaccharide composed of long, unbranched chains of beta glucose, important for plant cell walls.

What is the function of microfibrils in cellulose?

They provide strength to the cell wall by forming strong cross-linkages through hydrogen bonds.

What does Benedict's reagent test for?

The presence of reducing sugars.

What is the procedure for testing reducing sugars with Benedict's reagent?

Mix food sample with Benedict's reagent, heat, and observe color change to brick red for a positive result.

What is the test for non-reducing sugars?

Hydrolyze the sample with dilute hydrochloric acid, neutralize, and retest with Benedict's reagent.

What is the chemical test for starch?

Iodine/potassium iodide, which turns blue/black if starch is present.

What are lipids?

Biological molecules made of carbon, hydrogen, and oxygen, soluble only in organic solvents.

What are the main types of lipids?

Triglycerides and phospholipids.

What is the general formula for monosaccharides?

(CH2O)n where n is any number from three to seven.

What is the significance of glycogen's structure?

Its large number of side branches allows for rapid energy release.

What makes starch suitable for energy storage?

It is insoluble, compact, and can be easily hydrolyzed to release alpha glucose.

What role does cellulose play in plant cells?

It prevents cell walls from bursting under osmotic pressure, maintaining turgidity.

What are triglycerides made of?

One molecule of glycerol and three fatty acids joined by ester bonds.

What distinguishes saturated lipids from unsaturated lipids?

Saturated lipids do not contain carbon-carbon double bonds, while unsaturated lipids do.

Why are unsaturated fats liquid at room temperature?

The presence of double bonds allows them to bend, preventing tight packing.

What is a key property of triglycerides related to energy storage?

They have a high ratio of energy-storing carbon-hydrogen bonds to carbon atoms.

How do triglycerides benefit animals in terms of mass?

They have a low mass to energy ratio, allowing for efficient energy storage with less mass to move.

What is the role of triglycerides in water potential of cells?

Being large and non-polar, they are insoluble in water, thus not affecting the water potential of cells.

What do triglycerides release when oxidized?

They release water, providing an important source of water for organisms in dry environments.

What is the structure of phospholipids?

One fatty acid of a triglyceride is substituted by a phosphate-containing group.

What is the significance of the hydrophilic and hydrophobic parts of phospholipids?

The hydrophilic heads are attracted to water, while the hydrophobic tails repel water, allowing for bilayer formation.

What does a cloudy-white color indicate in the emulsion test?

The presence of lipids.

What are amino acids?

The monomers from which proteins are made, containing an amino group, carboxylic acid group, and a variable R group.

What type of bond forms between amino acids?

Peptide bonds formed in condensation reactions.

What is the primary structure of a protein?

The order and number of amino acids in a protein.

What are the two types of secondary structures in proteins?

Alpha helix and beta pleated sheet.

What maintains the tertiary structure of proteins?

Disulfide bridges, ionic bonds, and hydrogen bonds.

What is the difference between globular and fibrous proteins?

Globular proteins are compact (e.g., enzymes), while fibrous proteins are long (e.g., keratin).

What does the Biuret test detect?

The presence of peptide bonds in proteins.

How do enzymes increase the rate of reaction?

By lowering the activation energy of the reaction they catalyze.

What is the active site of an enzyme?

The area of the enzyme that binds to the substrate.

What is the induced fit model?

The model describing how the enzyme's active site changes shape to fit the substrate upon binding.

How does temperature affect enzyme activity?

Reaction rate increases to an optimum temperature, then decreases as the enzyme denatures.

What does pH measure?

The hydrogen ion concentration in a solution.

What is the formula to calculate pH?

pH = -log10[H+].

What is the pH of a hydrogen ion concentration of 1x10-9?

pH of 9

How does pH affect enzymes?

pH can disrupt the bonds in the tertiary structure of the enzyme.

What is the effect of increasing enzyme concentration on the rate of reaction?

The rate of reaction increases until substrate concentration becomes the limiting factor.

What happens when substrate concentration increases?

The rate of reaction increases until enzyme concentration becomes the limiting factor.

What is the effect of competitive reversible inhibitors on enzyme activity?

As their concentration increases, the rate of reaction decreases because active sites are blocked.

How do non-competitive reversible inhibitors affect enzymes?

They decrease the rate of reaction by altering the shape of the enzyme.

What is the primary function of DNA?

DNA holds genetic information.

What is the role of RNA in protein synthesis?

RNA transfers genetic information from DNA to ribosomes.

What are the components of a DNA nucleotide?

Deoxyribose sugar, a phosphate group, and one of the nitrogen bases: adenine, cytosine, guanine, or thymine.

What are the components of an RNA nucleotide?

Ribose sugar, a phosphate group, and one of the nitrogen bases: adenine, cytosine, guanine, or uracil.

How do nucleotides join together?

By phosphodiester bonds formed in condensation reactions.

What is the structure of a DNA molecule?

A double helix composed of two polynucleotides joined by hydrogen bonds between complementary bases.

What is the base pairing rule in DNA?

Adenine pairs with Thymine and Guanine pairs with Cytosine.

Why is DNA considered a stable molecule?

The phosphodiester backbone protects reactive bases, and C-G pairings provide additional stability.

What is semi-conservative replication of DNA?

A process that ensures genetic continuity by producing two identical strands from one original strand.

What role does DNA helicase play in DNA replication?

It separates the two strands of DNA by breaking hydrogen bonds between complementary bases.

What is ATP and its main components?

Adenosine triphosphate, consisting of ribose, adenine, and three phosphate groups.

What happens during the hydrolysis of ATP?

Energy is released when ATP is converted to ADP and a phosphate molecule.

How does ATP provide energy for cellular processes?

It releases energy quickly due to the unstable bonds between phosphate groups.

What is the role of water in metabolic reactions?

Water acts as a metabolite in condensation and hydrolysis reactions.

Why is water considered a polar molecule?

Due to the uneven distribution of charge, with a slight negative charge near the oxygen atom.

What is the significance of water's high specific heat capacity?

It minimizes temperature fluctuations in living organisms.

What is the latent heat of vaporization of water?

It requires a lot of energy to evaporate water, providing a cooling effect with minimal water loss.

What are some essential inorganic ions in biological systems?

Hydrogen ions (pH), Iron ions (hemoglobin), Sodium ions (co-transport), Phosphate ions (DNA and ATP).

How do hydrogen ions affect pH levels?

Higher concentrations of hydrogen ions result in lower pH levels.