biological molecules (nucleic acids)

Question 1

what is a nucleic acid

Answer 1

a polymer chain of nucleotides

Question 2

what does a nucleotide consist of

Answer 2

a pentose sugar, nitrogenous base and a phosphate

Question 3

what are the four possible bases in DNA

Answer 3

adenine, thymine, cytosine and guanine

Question 4

which bases are purine

Answer 4

adenine and guanine

Question 5

which bases a pyrimidine

Answer 5

cytosine and thymine

Question 6

what is the difference between purine and pyrimidine

Answer 6

purine has two carbon-nitrogen rings compared to one

Question 7

which base changes in RNA

Answer 7

thymine turns into uracil

Question 8

what is the difference between DNA and RNA

Answer 8

DNA is a double stranded polynucleotide whereas RNA is a single stranded polynucleotide

Question 9

what are ADP and ATP

Answer 9

phosphorylated nucleotides

Question 10

how is ATP synthesised

Answer 10

through using energy from respiration to create a bond between an inorganic phosphate and an ADP molecule. ATP synthase aids this reaction

Question 11

how is ATP used as an energy store

Answer 11

it is used as an effective short term energy store as the third phosphate bond can be broken to release energy into cells immediately and then can be phosphrlated into ATP again. However the phosphate bonds are unstable meaning they cant stay in the body for too long successfully.

Question 12

what sugar does ATP use

Answer 12

ribose

Question 13

what is an phosphoester bond

Answer 13

the bond between the phosphate and the sugar creating the sugar phosphate backbone at the 5th carbon

Question 14

what is a phosphdiester bond

Answer 14

it links two nucleotides together by the 3rd carbon

Question 15

how does a DNA strand form

Answer 15

when complementary bases join together by hydrogen bonding, two between A,T and three between C,G. they are anitparralel so the strands twist making the double helix.

Question 16

what does anitparraelll mean

Answer 16

running in opposite directions so one is 5 prime and one is 3 prime

Question 17

what is the 1st step of DNA replication

Answer 17

DNA helicase breaks the hydrogen bonds between bases

Question 18

what is the 2nd step

Answer 18

each original strand acts as a template where free floating nucleotides join exposed bases, they join to the one complementary to them.

Question 19

what is the third step

Answer 19

DNA joins nucleotides by phosphodiester bonds to create two new strands, hydrogen bonds form between bases meaning the double helix shape forms

Question 20

what does semi conservative mean

Answer 20

one strand of each DNA is from the original

Question 21

what is a triplet code

Answer 21

3 bases which code for an amino acid

Question 22

what are the three types of RNA

Answer 22

messenger, transfer and ribosomal

Question 23

what is the genetic code

Answer 23

sequence of codons which code for specific amino acids

Question 24

what does non overlapping mean

Answer 24

each codon is separate to the next

Question 25

what does degenerate mean

Answer 25

each amino acid can be coded for in different ways by different codons

Question 26

what does universal mean

Answer 26

the same codons code for the same amino acids in all organisms

Question 27

what is the first step of transcription

Answer 27

RNA polymerase attaches to the DNA strand, the hydrogen bonds break between the strands meaning two separate strands are formed (DNA helicase breaks the bonds)

Question 28

what is the second step

Answer 28

free RNA nucleotides line up against the complementary bases creating a complementary copy of the template DNA strand

Question 29

what is the third step

Answer 29

the mRNA is assembled by the RNA polymerase, the DNA hydrogen bonds reform meaning it returns to normal

Question 30

what is the first step of translation

Answer 30

the mRNA is held in the ribosome and complementary anticodons from tRNA are linked by bases. the tRNA carries an amino acid which has the same codon sequence as the orginal DNA sequence

Question 31

what is the second step

Answer 31

a second tRNA anticodon attaches in the same way, rRNA catalyses the formation of peptide bonds between the amino acids. After the bond is created the tRNA moves away leaving the amino acid in the chain

Question 32

what is the third step

Answer 32

a third tRNA makes the second one leave in the same way, this process repeats creating polypeptide chain until there is a stop codon