Biology Chapter 5: Carbohydrates and DNA Structure

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Questions and Answers

What type of reaction occurs when monomers are joined together to form polymers?

Redox reaction

Condensation reaction (correct)

Hydrolysis reaction

Dehydration synthesis

Which of the following correctly describes monosaccharides?

They consist of long chains of sugar units.

They contain only carbon and oxygen atoms.

They are primarily structural molecules in plants.

They can be combined to form disaccharides. (correct)

Which disaccharide is formed from two glucose molecules?

Maltose (correct)

Fructose

Lactose

Sucrose

What type of bond is formed between two monosaccharides during a condensation reaction?

Glycosidic bond Signup and view all the answers

What type of glucose is used to form cellulose?

Beta glucose Signup and view all the answers

Which polysaccharide is primarily utilized for energy storage in animals?

Glycogen Signup and view all the answers

Which of the following statements about hydrolysis is correct?

It breaks chemical bonds by adding water. Signup and view all the answers

What is the general formula for common monosaccharides?

(CH2O)n Signup and view all the answers

What effect do competitive reversible inhibitors have on the rate of reaction?

They decrease the rate of reaction by temporarily blocking active sites. Signup and view all the answers

Which component is NOT part of a DNA nucleotide?

Ribose sugar Signup and view all the answers

How do non-competitive reversible inhibitors affect enzyme activity?

They alter the shape of the enzyme but not the active site. Signup and view all the answers

What is the structure of DNA in terms of its composition?

A double helix made of two polynucleotides with hydrogen bonds between bases. Signup and view all the answers

Which base pairing is correct for DNA structure?

Adenine pairs with Thymine. Signup and view all the answers

What is the significance of semi-conservative replication in DNA?

It produces two new DNA strands from one original strand. Signup and view all the answers

Which factor contributes to the stability of DNA?

The phosphodiester backbone protecting the nitrogenous bases. Signup and view all the answers

What role does RNA play in relation to DNA?

It transfers genetic information from DNA to ribosomes for protein synthesis. Signup and view all the answers

What characteristic of unsaturated fats allows them to remain liquid at room temperature?

Presence of carbon-carbon double bonds Signup and view all the answers

Which property of triglycerides makes them excellent energy storage molecules?

They possess a high ratio of energy storing carbon-hydrogen bonds. Signup and view all the answers

What does the hydrophilic nature of the heads in phospholipids allow them to do in an aqueous environment?

Hold at the surface of the cell membrane Signup and view all the answers

What is the primary purpose of the emulsion test?

To identify the presence of lipids Signup and view all the answers

Which of the following statements is true regarding the storage of triglycerides?

They release water when oxidized, providing moisture in dry environments. Signup and view all the answers

What is created when a triglyceride's fatty acid is replaced by a phosphate-containing group?

Phospholipid Signup and view all the answers

What role do glycolipids play in relation to phospholipids?

They are important for cell recognition on the cell surface. Signup and view all the answers

Why are non-polar lipids advantageous for storage in cells?

They do not affect the water potential of cells. Signup and view all the answers

What is the significance of water's large latent heat of vaporisation?

It aids in cooling with minimal water loss. Signup and view all the answers

What indicates the presence of a peptide bond in a solution?

A purple coloration Signup and view all the answers

How do hydrogen ions affect pH levels in a solution?

Higher concentrations of hydrogen ions lower the pH. Signup and view all the answers

Which factor affects the rate of enzyme-controlled reactions by altering the enzyme's tertiary structure?

Hydrogen ion concentration (pH) Signup and view all the answers

What happens to the rate of reaction when the temperature exceeds the optimum temperature for an enzyme?

It decreases as the enzyme becomes denatured Signup and view all the answers

Which ion is a crucial component of haemoglobin?

Iron ions Signup and view all the answers

How does enzyme concentration affect the rate of reaction beyond a certain point?

Plateaus as substrate concentration becomes limiting Signup and view all the answers

What role do sodium ions play in cellular processes?

They are involved in the co-transport of glucose and amino acids. Signup and view all the answers

What model describes how an enzyme's active site adapts to fit a substrate?

Induced fit model Signup and view all the answers

What effect does water's strong cohesion have in plants?

It allows for effective transport of water in xylem. Signup and view all the answers

Which enzyme is known to function best in very acidic conditions?

Pepsin Signup and view all the answers

What is the primary role of enzymes in biochemical reactions?

To lower the activation energy of the reaction Signup and view all the answers

What formula is used to calculate the pH of a solution?

pH = -log10[H+] Signup and view all the answers

What are amino acids primarily composed of?

An amino group, carboxylic acid group, and a variable R group Signup and view all the answers

Which type of bond forms between amino acids during a condensation reaction?

Peptide bond Signup and view all the answers

What determines the primary structure of a protein?

The order and number of amino acids Signup and view all the answers

Which structure of a protein is characterized by alpha helices and beta pleated sheets?

Secondary structure Signup and view all the answers

Which type of bond is the strongest in maintaining protein structure?

Disulfide bridges Signup and view all the answers

What is the purpose of the Biuret test?

To test for the presence of peptide bonds in a protein Signup and view all the answers

Which of the following describes a globular protein?

Compact and folded into a spherical shape Signup and view all the answers

Which structure of a protein involves multiple polypeptides coming together?

Quaternary structure Signup and view all the answers

Study Notes

Biological Molecules

Monomers are small units forming larger molecules (e.g., monosaccharides, amino acids, nucleotides).
Polymers are large molecules made from many monomers joined together.
Condensation reactions join monomers, eliminating a water molecule.
Hydrolysis breaks down polymers, adding a water molecule.

Carbohydrates

Carbohydrates are made of carbon, hydrogen, and oxygen.
Monosaccharides are single sugar units (e.g., glucose).
Disaccharides are two monosaccharides joined (e.g., maltose).
Polysaccharides are many monosaccharides joined (e.g., glycogen, starch, cellulose).
Glycosidic bonds link monosaccharides in condensation reactions.
Glucose has alpha and beta isomers.
Common monosaccharides include glucose, galactose, and fructose.

Disaccharides

Formed by condensation of two monosaccharides.
Examples include maltose (glucose + glucose), sucrose (glucose + fructose), and lactose (glucose + galactose).
A glycosidic bond is formed in a condensation reaction.

Polysaccharides

Formed from many glucose units joined together.
Glycogen is the main energy storage molecule in animals.
Starch is an energy storage molecule in plants, composed of amylose and amylopectin.
Amylose is unbranched.
Amylopectin is branched.
Cellulose forms plant cell walls.
It consists of beta glucose linked together by 1,4 and 1,6 glycosidic bonds.

Biochemical Tests

Benedict's reagent: used to test for reducing sugars.
- Reducing sugars reduce Cu2+ to Cu+ forming a brick-red precipitate.
Hydrochloric acid and sodium hydrogencarbonate are used to test for non-reducing sugars; HCl hydrolyzes the disaccharides into monosaccharides.
Iodine/potassium iodide: used to detect starch.
- A positive result is a blue-black colour change from an orange-brown colour.

Lipids

Lipids are made of carbon, hydrogen, and oxygen, insoluble in water.
Triglycerides are made of one glycerol molecule and three fatty acids.
Fatty acids can be saturated (no C=C double bonds) or unsaturated (one or more C=C double bonds).
Phospholipids have a hydrophilic head and hydrophobic tails, crucial for cell membranes.

Proteins

Proteins are made from amino acids linked by peptide bonds.
The primary structure of a protein is the sequence of amino acids.
Secondary structures include alpha helices and beta pleated sheets.
Tertiary structure is the overall 3D shape of a protein.
Proteins contain peptide bonds.
The Biuret test is used to detect proteins.

Enzymes

Enzymes are proteins that catalyse biochemical reactions.
Enzymes have an active site that binds to a substrate, forming an enzyme-substrate complex.
The induced fit model describes how the enzyme's active site changes shape to bind the substrate more effectively.
Enzymes lower activation energy.

Factors Affecting Enzyme Activity

Temperature: Optimum temperature exists for enzyme activity. Beyond this, enzymes denature.
pH: Enzymes have an optimum pH range.
Substrate concentration: Increasing substrate concentration increases the rate until the enzyme is saturated.
Enzyme concentration: Increasing enzyme concentration increases the rate until the substrate becomes limiting.
Inhibitors: Competitive and non-competitive inhibitors can reduce enzyme activity.

Nucleic Acids

DNA and RNA are nucleic acids; polymers of nucleotides.
Nucleotides consist of a pentose sugar, a nitrogenous base, and a phosphate group.
DNA is a double helix; RNA is a single strand.
DNA stores genetic information; RNA transfers information from DNA to ribosomes for protein synthesis.
DNA nucleotides contain deoxyribose; RNA nucleotides contain ribose.

ATP

Adenosine triphosphate (ATP) is a nucleotide derivative, a source of readily available energy in cells.
ATP releases energy when hydrolysed to ADP and phosphate.
ATP is crucial for various metabolic activities.
ATP synthase catalyses the formation of ATP.

Water

Water is a polar molecule.
Water has high specific heat capacity and high latent heat of vaporization.
Water is a good solvent for polar and charged molecules.
Water is essential for many biological processes.
Water is involved in various transport processes.
Water is crucial for regulating temperature.

Inorganic Ions

Inorganic ions play critical roles in biological processes.
Examples include hydrogen ions (affect pH), iron (part of haemoglobin), sodium (co-transport), and phosphate (part of DNA, ATP).

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Description

Test your knowledge on carbohydrates, including the formation of polymers from monomers and the characteristics of monosaccharides and disaccharides. Additionally, this quiz explores key concepts of DNA structure and the roles of RNA in genetic processes. Perfect for students studying biology at an advanced level.