Nucleic acids 3.8 Flashcards
what are nucleic acids and where are they found
nucleic acids are large molecules that were discovered in cell nuclei - hence their name
what are the 2 types of nucleic acid and what is there function
- DNA, store and transfer genetic information
- RNA, code for proteins via translation of DNA
what elements do nucleic acids contain
contain the elements carbon, hydrogen, oxygen, nitrogen and phosphorus
whats the structure of nucleic acids
They are large polymers formed from many nucleotides (monomers) linked together in a chain
what is an individual nucleotide made up of
-A pentose monosaccharide (sugar), containing 5 carbon atoms
-A phosphate group, -PO4 (2-), an inorganic molecule that is acidic and negatively charged
-A nitrogenous base , a complex organic molecule containing 1 or 2 carbon rings in its structure as well as nitrogen
what links nucleotides together and what polymer is formed
what bond
nucleotides are linked together by condensation reactions to form a polymer called a polynucleotide
how does one nucleotide bond to another
The phosphate group at the 5th carbon of the pentose sugar of one nucleotide forms a covalent bond with the hydroxyl group at the 3rd carbon of the pentose sugar adjacent nucleotide
what is the covalent bond between 2 nucleotides called
these bonds are called phosphodiester bonds
what does deoxyribose mean
a sugar with 1 fewer oxygen atoms that ribose
what are the 4 different bases that are found in DNA
thymine, adenine, cytosine, guanine
what 2 groups can the 4 bases for DNA be separated into
Pyrimidines-the smaller bases, which contain single carbon ring structures (thymine and cytosine)
Purines-the larger bases, which contain double carbon ring structures (adenine and guanine)
what is the structure of DNA
it is made up of 2 strands of polynucleotides coiled into a helix, known as there DNA double helix
what bonds hold nucleotides together in a DNA molecule
hydrogen bonds
how would you refer to the structure of the polynucleotides in a double helix
The 2 parallel stands are arranged so that they run in opposite directions- they are said to be antiparallel
what does the pairing between bases allow
the pairing between the bases allows DNA to be copied and transcribed-key properties required of the molecule of heredity
what bases bond to which bases and how many hydrogen bonds form between each
adenine and thymine are both able to from 2 hydrogen bonds and always join with each other
cytosine and guanine form 3 hydrogen bonds and so also only bind to each other
if a base only bonds to a specific base what it is called
such as the bonding of DNA bases
this is known as complementary base pairing
what type of base bonds to what type of base and what does this arrangement mean
a small pyrimidine base always binds to a larger purine base
this arrangement maintains a constant distance between the DNA ‘backbones’, resulting in parallel polynucleotide chains
what does complementary base pairing mean for the number of bases
DNA always has equal amounts of adenine and thymine and equal amounts of cytosine and guanine
what part of the DNA carries the genetic information of an organism
it is the sequence of bases along a DNA strand that carries the genetic information in the form of a code
what is the function of Ribonucleic acid (RNA)
plays an essential role in the transfer of genetic information from DNA to the proteins that make up the enzymes and tissues of the body
what is a gene
A gene is a section of DNA located at a particular site on a DNA molecule, called its locus.
how do you get around the problem of DNA being to big to get out of the nucleus
- gene is transcribed into short messenger RNA which can leave nucleus
what base differs between RNA and DNA nucleotides
the thymine base is replaced with the base uracil
what are the similarites between thymine and uracil and what does this mean for RNAs function
- like thymine, uracil is a pyrimidine (1 carbon ring)
^forms 2 hydrogen bonds with adenine - base pairing rules apply when RNA nucleotides bind to DNA to make copies of sections of DNA
what’s the difference between the RNA polymers formed and the DNA polymers formed
the RNA polymers formed are small enough to leave the nucleus and travel to the ribosomes
what happens to RNA molecules after protein synthesis
after protein synthesis the RNA molecules are degraded in the cytoplasm
The phosphodiester bonds are hydrolysed and the RNA nucleotides are released and reused
what bonds are in RNA polymers
the same as DNA polymers, phosphodiester
explain the process to extract DNA from plant material
- grind sample to break down cell walls.
- Mix sample with detergent, this breaks down the cell membrane
- 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 solution
- The DNA will be seen as white strands forming between the layer of sample and layer of alcohol
