AQA A Level Biology Topic 1: Carbohydrates and Monosaccharides

Covalent bonds are formed between the phosphate group of one nucleotide and the deoxyribose sugar of the next nucleotide, linking them together. These bonds create the sugar-phosphate backbone of DNA.

Unwinding is the process where DNA helicase separates the two strands of the DNA double helix by breaking the hydrogen bonds between the nitrogenous bases. This creates a replication fork, allowing access to each strand for copying.

Free nucleotides, each composed of a phosphate group, a deoxyribose sugar, and a nitrogenous base, are added to the exposed bases on the original DNA strands, using complementary base pairing rules (A with T and C with G).

Phosphodiester bonds are formed between the phosphate group of one nucleotide and the deoxyribose of another. These bonds form the backbone of the DNA molecule.

DNA helicase is an enzyme that breaks the hydrogen bonds between the two DNA strands, separating them. This creates a replication fork, allowing access to each strand for copying.

DNA polymerase forms phosphodiester bonds between nucleotides, linking them together to create a new DNA strand. This is a fundamental part of DNA replication.

Breaking hydrogen bonds does not involve a specific type of reaction. It's a process of separating the bonds, requiring energy.

DNA polymerase joins adjacent nucleotides, using the original DNA strands as templates, to create new DNA strands with the same sequence. Replication proceeds in a 5' to 3' direction.

ATP consists of a ribose sugar, an adenine base, and three phosphate groups. The bonds between the phosphate groups store energy, making ATP a key energy carrier in cells.

ATP is broken down by hydrolysis, a process that involves the addition of a water molecule. This breaks the bond between the second and third phosphate groups, releasing energy and forming ADP (adenosine diphosphate) and inorganic phosphate (Pi).

ATP hydrolase is the enzyme that catalyzes the hydrolysis of ATP, speeding up the reaction and releasing energy for cellular processes.

Inorganic phosphate (Pi) is released during ATP hydrolysis. This phosphate group can be transferred to other molecules, phosphorylating them to make them more chemically reactive. This is important for many cellular processes, like enzyme activation and signal transduction.

ATP is resynthesized by the addition of a phosphate group to ADP, catalyzed by ATP synthase. This process requires energy, often provided by processes like cellular respiration or photosynthesis.

ATP hydrolysis releases energy that can be used to power energy-requiring reactions in cells, like muscle contraction, protein synthesis, and active transport. This makes it a vital energy source for all living organisms.

ATP is a suitable immediate source of energy for cells because it releases energy in relatively small, manageable amounts, with minimal loss as heat. This allows cells to efficiently control and utilize energy for specific processes.

ATP hydrolysis releases energy from the breaking of the phosphate bond, not from the creation of energy. Energy is simply being converted from one form to another.

ATP is not a long-term storage form of energy. It's an immediate, readily available source of energy. Cells primarily use carbohydrates, fats, and proteins for long-term energy storage.

Water molecules exhibit strong cohesion due to their polarity and the formation of hydrogen bonds between them. The oxygen atom has a partial negative charge, while the hydrogen atoms have partial positive charges, allowing them to form weak bonds with each other.

Water's ability to be stored within cells is a function of its solvent properties, not a property of water itself that's important in biology.

Hydrogen bonds are essential for water's high specific heat capacity. These bonds require a lot of energy to break, meaning water can absorb and store a large amount of heat before its temperature changes significantly.

Water's high latent heat of vaporization is important for evaporative cooling. This is critical for organisms to maintain a stable internal temperature. When water evaporates, it absorbs a large amount of heat, helping to cool the organism.

Hydrogen bonds allow water to form a dynamic network of molecules that can effectively surround and dissolve a wide range of polar and ionic solutes. This is essential for transporting nutrients and removing waste products in living organisms.

Water's high specific heat capacity plays a vital role in regulating temperature in living organisms, ensuring a stable internal environment for biochemical reactions. It also moderates temperature fluctuations in aquatic ecosystems.

Hydrogen bonds between water molecules contribute to water's high latent heat of vaporization. These bonds need to be broken for water to transition from liquid to gas (evaporation). This energy requirement makes water act as an effective coolant.

A polymer is a large molecule formed by the joining of many smaller, repeating units called monomers. These units are linked together by covalent bonds.

Ribose is a five-carbon sugar that's part of RNA. It has a hydroxyl group attached to the 2' carbon atom, while deoxyribose lacks that hydroxyl group.

The main structural difference between α-glucose and β-glucose is the position of the hydroxyl group on the first carbon atom. In α-glucose, it's below the plane of the ring, while in β-glucose, it's above the plane.

Condensation reaction is the process of joining two monosaccharides together to form a disaccharide. This reaction involves the removal of a water molecule.

Sucrose, a common table sugar, is a disaccharide composed of glucose and fructose.

A glycosidic bond is a type of covalent bond that joins two monosaccharides together in a disaccharide. It's formed between the anomeric carbon of one sugar and a hydroxyl group on the other sugar.

Polysaccharides are large, complex carbohydrates formed by the condensation of many monosaccharides. They are important for energy storage (e.g., starch and glycogen) and structural support (e.g., cellulose and chitin).

A dimer is a molecule formed by the joining of two identical or similar monomers. In the context of sugars, a dimer is a disaccharide formed by the condensation of two monosaccharides.

Non-competitive inhibitors bind to an allosteric site on an enzyme, a site different from the active site. This binding causes a conformational change in the enzyme, reducing its affinity for the substrate and slowing down the rate of reaction.

Increasing the concentration of a non-competitive inhibitor will decrease the rate of reaction because it reduces the enzyme's affinity for the substrate. As more inhibitor binds, the enzyme becomes less effective at catalyzing the reaction.

Increasing substrate concentration will not alter the rate of reaction in the presence of a non-competitive inhibitor because the inhibitor affects the enzyme's structure and function permanently. Even with more substrate, the enzyme's activity remains reduced.

The induced fit model describes how an enzyme's active site undergoes a conformational change upon substrate binding to become complementary. This dynamic interaction allows for a more precise fit and enhances the catalytic efficiency of the enzyme.

High or low pH can disrupt the hydrogen and ionic bonds that maintain the tertiary structure of an enzyme, leading to denaturation. Similarly, extreme temperatures can also cause denaturation, affecting the enzyme's active site and reducing its functionality.

The rate of reaction will remain constant, regardless of the substrate concentration, due to the inhibitory effect of non-competitive inhibitors. The enzyme's activity is permanently reduced, even if more substrate is available.

Non-competitive inhibitors decrease the maximum velocity (Vmax) of the reaction by reducing the enzyme's affinity for the substrate. Even at high substrate concentrations, the enzyme's catalytic efficiency is reduced due to the inhibitor's binding.

Non-competitive inhibitors do not affect the Michaelis constant (Km) of the reaction. Km is the substrate concentration at half the maximum velocity, and non-competitive inhibitors do not affect the binding affinity between the enzyme and substrate.