Nucleic acids 3.8

Question 1

what are nucleic acids and where are they found

Answer 1

nucleic acids are large molecules that were discovered in cell nuclei - hence their name

Question 2

what are the 2 types of nucleic acid and what is there function

Answer 2

• DNA, store and transfer genetic information
• RNA, code for proteins via translation of DNA

Question 3

what elements do nucleic acids contain

Answer 3

contain the elements carbon, hydrogen, oxygen, nitrogen and phosphorus

Question 4

whats the structure of nucleic acids

Answer 4

They are large polymers formed from many nucleotides (monomers) linked together in a chain

Question 5

what is an individual nucleotide made up of

Answer 5

-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

Question 6

what links nucleotides together and what polymer is formed

what bond

Answer 6

nucleotides are linked together by condensation reactions to form a polymer called a polynucleotide

Question 7

how does one nucleotide bond to another

Answer 7

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

Question 8

what is the covalent bond between 2 nucleotides called

Answer 8

these bonds are called phosphodiester bonds

Question 9

what does deoxyribose mean

Answer 9

a sugar with 1 fewer oxygen atoms that ribose

Question 10

what are the 4 different bases that are found in DNA

Answer 10

thymine, adenine, cytosine, guanine

Question 11

what 2 groups can the 4 bases for DNA be separated into

Answer 11

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)

Question 12

what is the structure of DNA

Answer 12

it is made up of 2 strands of polynucleotides coiled into a helix, known as there DNA double helix

Question 13

what bonds hold nucleotides together in a DNA molecule

Answer 13

hydrogen bonds

Question 14

how would you refer to the structure of the polynucleotides in a double helix

Answer 14

The 2 parallel stands are arranged so that they run in opposite directions- they are said to be antiparallel

Question 15

what does the pairing between bases allow

Answer 15

the pairing between the bases allows DNA to be copied and transcribed-key properties required of the molecule of heredity

Question 16

what bases bond to which bases and how many hydrogen bonds form between each

Answer 16

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

Question 17

if a base only bonds to a specific base what it is called

such as the bonding of DNA bases

Answer 17

this is known as complementary base pairing

Question 18

what type of base bonds to what type of base and what does this arrangement mean

Answer 18

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

Question 19

what does complementary base pairing mean for the number of bases

Answer 19

DNA always has equal amounts of adenine and thymine and equal amounts of cytosine and guanine

Question 20

what part of the DNA carries the genetic information of an organism

Answer 20

it is the sequence of bases along a DNA strand that carries the genetic information in the form of a code

Question 21

what is the function of Ribonucleic acid (RNA)

Answer 21

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

Question 22

what is a gene

Answer 22

A gene is a section of DNA located at a particular site on a DNA molecule, called its locus.

Question 23

how do you get around the problem of DNA being to big to get out of the nucleus

Answer 23

• gene is transcribed into short messenger RNA which can leave nucleus

Question 24

what base differs between RNA and DNA nucleotides

Answer 24

the thymine base is replaced with the base uracil

Question 25

what are the similarites between thymine and uracil and what does this mean for RNAs function

Answer 25

• 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

Question 26

what’s the difference between the RNA polymers formed and the DNA polymers formed

Answer 26

the RNA polymers formed are small enough to leave the nucleus and travel to the ribosomes

Question 27

what happens to RNA molecules after protein synthesis

Answer 27

after protein synthesis the RNA molecules are degraded in the cytoplasm
The phosphodiester bonds are hydrolysed and the RNA nucleotides are released and reused

Question 28

what bonds are in RNA polymers

Answer 28

the same as DNA polymers, phosphodiester

Question 29

explain the process to extract DNA from plant material

Answer 29

• 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