3.8 Nucleic acids Flashcards
What are nucleotides?
- The monomers that are used to form nucleic acids.
- Made up of a pentose monosaccharide, a phosphate group and a nitrogenous base.
What are nucleic acids?
- Large polymers formed from nucleotides.
- Contain the elements carbon, hydrogen, nitrogen, phosphorus and oxygen.
What is an individual nucleotide made of?
- A pentose monosaccharide, containing five carbon atoms
- A phosphate group, an inorganic molecule that is acidic and negatively charged.
- A nitrogenous base: A complex organic molecule containing one or two carbon rings in its structure as well as nitrogen.
How are nucleotides linked together to form polypeptides?
By condensation reactions. The phosphate group at the fifth carbon of the pentose sugar of one nucleotide forms a covalent bond with the hydroxyl group at the third carbon of the pentose sugar of an adjacent nucleotide.
What are phosphodiester bonds?
Phosphodiester bonds forms a long, strong sugar phosphate ‘backbone’ with a base attached to each sugar. The phosphodiester bonds are broken by hydrolysis, the reverse of condensation, releasing the individual nucleotides.
Whar two groups can bases be divided into?
Pyramidines and purines
What are pyramidines?
The smaller bases, which contain single carbon ring structures- thymine, and cytosine
What are purines?
The larger bases, which contain double carbon rings structures- adenine and guanine
What does RNA contain?
- RNA (ribonucleic acid) contains nucleotides with a ribose sugar (5 C sugar/pentose sugar)
- A RNA nucleotide also has a phosphate group and one of four different bases.
- In RNA, uracil (a pyramidine) replaces thymine as a base.
- An RNA molecule is made up of a single polynucleotide chain.
How can you phosphorlyate a nucleotide?
You add one or more phosphate groups to it.
What is ADP & ATP?
- ADP (adenosine diphosphate) contains the base adenine, the sugar ribose and two phosphate groups.
- ATP (adenosine triphosphate) contains the base adenine, the sugar ribose and three phosphate groups.
How does ADP form ATP?
- ATP is synthesised frim ADP and inorganic phosphate, using the energy from an energy releasing reaction.
- The ADP is phosphorylated to form ATP and a phosphate bond is formed.
- Energy is stored in the phosphate bond.
- When this energy is needed by a cell, ATP is broken back down into ADP and an inorganic phosphate.
- Energy is released from the phosphate bond and used by the cell.
What types of cell activity requires energy?
- Synthesis : e.g of large molecules such as proteins
- Transport: e.g pumping molecules or ions across cell membranes by active transport.
- Movement: E.g protein fibres in muscle cels that cause muscle contraction
What are the properties of ADP?
- Small : Moves easily into, out, within cells.
- Water soluble: Energy requiring processes happen in aqueous solutions.
- Easily regenerated: Can be recharged with energy
- Releases energy in small quantities: Quantities are suitable to most cellular needs, so that energy is not wasted as heat.
- Contains bonds between phosphates with intermediate energy: large enough to be useful for cellular reactions but not so large that energy is wasted as heat.
How many hydrogen bonds form between adenine and thymine?
2
