3.8 Nucleic Acids Flashcards
What are Nucleic acids?
Large molecules that are found in the cell nuclei. There are two types of Nucleic Acid: DNA and RNA, and both have roles in storage and transfer of genetic information and the synthesis of proteins
What elements make up Nucleic acids? What are their monomers?
C, H, O, N, P
Nucleic acids are large polymers made form many nucleotides linked together in a chain
What three components makes up a nucleotide?
- a pentose monosaccharide
- a phosphate group, and inorganic negatively charged molecule that is acidic
- a nitrogenous base
How are nucleotides joined together to form a polymer?
Linked together by condensation reactions to form a polynucleotide.
The phosphate group on the fifth carbon of the pentose sugar of one nucleotide forms a covalent bond, called a phosphodiester bond, with the hydroxyl group at the third carbon of the pentose sugar of an adjacent nucleotide.
This forms a long, strong sugar-phosphate backbone
The phosphodiester bonds are broken by hydrolysis
Describe DNA nucleotides
The nucleotides in DNA (deoxyribonucleic acid) all contain:
- the pentose sugar called deoxyribose
- each DNA nucleotide contains a phosphate group
- the base on each of DNA’ s nucleotides can vary through, the 4 possible bases: adenine (A), Thymine (T), cytosine (C), guanine (G)
A molecule of DNA contains two polynucleotide chains - each chain is made up of many nucleotides joined together by phosphodiester bonds
Describe RNA nucleotides
RNA structure?
RNA (ribonucleic acid) nucleotides:
- contain a ribose sugar
- a phosphate group
- one of 4 possible bases : adenine (A), uracil (U), cytosine (C), guanine (G)
An RNA molecule is made of a single polynucleotide chain
What two types of bases are there present in DNA and RNA molecules? What are their differences?
Two types of bases present in RNA and DNA nucleotides: purines and Pyrimidines
Adenine and Guanine are both purines. A purine base contains 2 carbon-nitrogen rings joined together
Cytosine, thymine and uracil are pyrimidines. A Pyrimidine base contains only one carbon-nitrogen base. So Pyrimidines are smaller than purine bases.
What are ADP and ATP? Their differences?
ADP and ATP are phosphorylated nucleotides (one or more phosphate groups have been added to it).
ADP contains the base adenine, the sugar ribose, and two phosphate groups.
ATP contains the base adenine, ribose sugar and three phosphate groups
Describe synthesis of ATP?
Through phosphorylation:
ATP is synthesised from ADP and an inorganic phosphate (Pi). The ADP is phosphorylated to form ATP and a phosphate bond is formed.
Energy is stored in the phosphate bond.
ATP is broken back down into ADP and inorganic phosphate, when energy is needed by the cell, and energy is released from the phosphate bond.
Describe DNA structure?
DNA is composed of two polynucleotide strands joined together to form a double-helix shape. The two strands join together by hydrogen bonding between the bases. Complementary base pairing occurs (A-T, C-G).
Two hydrogen bonds form between adenine and thymine, and three hydrogen bonds form between cytosine and guanine.
The two polynucleotide strands are anti parallel (they run in opposite directions). Two anti parallel strands to twist to from a DNA double-helix.
Why and How is DNA purified and extracted?
- break up/ sample in a mortar and pestle- this breaks down the cell walls
- mix the sample with detergent - this breaks down the cell membrane, releasing the contents into the solution
- add salt- this breaks the hydrogen bonds between the DNA and water molecules
- add protease enzyme- this will break down the proteins associated with the DNA in the nuclei
- add a layer of alcohol (ethanol) on top of the sample- alcohol causes the DNA to precipitate out of the solution
- the DNA will be seen as white strands forming between the layer of the sample and the layer of alcohol. The DNA can be picked up by ‘spooling’ it on the glass rod
Properties of ATP?
Properties that make ATP suited to carry out its function of energy transfer:
- small: moves easily into and out of and within cells
- water soluble: energy requiring processes occur in aqueous environments
- releases energy in small quantities: quantities are suitable to most cellular needs, so that energy is not wasted as heat
- easily regenerated: can be recharged quickly with energy (phosphorylation occurs rapidly)
