1 Biological Molecules: 2 Nucleic Acids Flashcards
What is water?
A major component of cells.
Why is water dipolar?
Oxygen atom has a slight negative charge whilst hydrogen atoms have a slight positive charge.
What is the importance of water in metabolism?
It’s a metabolite in many metabolic reactions including condensation and hydrolysis reactions.
Chemical reactions take place in an aqueous medium.
A major raw material in photosynthesis.
What is the importance of water in solvents?
Water readily dissolves other substances: gases such as oxygen and carbon dioxide, wastes such as ammonia and urea, inorganic ions and small hydrophilic molecules such as amino acids and monosaccharides and ATP.
Enzymatic reactions take place in solution.
What is water’s importance in relation to its specific heat capacity?
It has a relatively high heat capacity, buffering changes in temperature.
Because water molecules stick together due to hydrogen bonding, it takes more energy to separate and heat them.
Without hydrogen bonds, water would be a gas at rtp.
What is water’s importance in relation to its latent heat?
It has a relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation.
This makes sweating an effective cooling mechanism.
What is water’s importance in relation to its cohesion?
There is strong cohesion between water molecules.
This supports columns of water in the tube-like transport cells of plants.
A surface tension is produced where water meets air.
Where are inorganic ions normally?
In solution in the cytoplasm and body fluids of organisms.
Some are in high concentrations, others in very low concentrations.
What does DNA do?
Hold genetic information.
What does RNA do?
Transfer genetic information from DNA to the ribosomes.
What are ribosomes formed from?
RNA and proteins.
What is a nucleotide composed of?
A pentose sugar, a nitrogenous organic base, and a phosphate group.
What are the components of a DNA nucleotide?
Deoxyribose, a phosphate group, and one of the organic bases adenine, thymine, cytosine or guanine.
What are the components of a RNA nucleotide?
Ribose, a phosphate group, and one of the organic bases adenine, uracil, cytosine or guanine.
What does the condensation reaction between two nucleotides form?
A phosphodiester bond.
What is the structure of a DNA molecule?
A double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs.
What is a RNA molecule?
A relatively short polynucleotide chain.
What does the semi-conservative replication of DNA ensure?
Genetic continuity between generations of cells.
What is the process of semi-conservative replication of DNA?
- DNA helicase breaks the hydrogen bonds between complementary bases, causing the double helix to unwind to form two single strands.
- Each strand acts as a template strand. Complementary base pairing means that free DNA nucleotides are attracted to their complementary exposed bases.
- DNA polymerase catalyses the condensation reactions that join adjacent nucleotides, forming phosphodiester bonds. Hydrogen bonds form between the bases.
What is a molecule of ATP made of?
Adenine, ribose, and three phosphate groups.
What does the hydrolysis of ATP produce?
ADP (adenosine diphosphate) and Pi (an inorganic phosphate group).
What is the hydrolysis of ATP catalysed by?
ATP hydrolase.
What can the hydrolysis of ATP be used for?
Energy-requiring reactions within cells.
What can the inorganic phosphate group released during the hydrolysis of ATP be used for?
To phosphorylate other compounds, often making them more reactive.
