Nucleic acids

Question 1

what are nucleic acids

Answer 1

conatin C,H,O,N and P formed from many nucleotides linked in a chain

Question 2

how are nucleotides made up

Answer 2

pentose monosaccharide (sugar)
phosphate group acidic and negatively charged
nitrogenous base1,2 carbon rings as well as nitrogen

Question 3

nucleotide bonds

Answer 3

5th carbon phosphate group reacts with 3rd carbon OH group to form phosphodiester bonds many nucleotides form a sugar phosphate backbone
broken by hydrolysis which releases Individual nucleotides

Question 4

DNA

Answer 4

deoxyribose sugar 1 less O atom than ribose

Question 5

who types of bases

Answer 5

purines: larger bases , double carbon ring structure (A,G)
pyrimidines- smaller base, single carbon ring structure (T and (C)

Question 6

How do the bases react

Answer 6

A-T
G-C

Question 7

double helix DNA

Answer 7

made of two stand of polynucleotides wrapped around each other strands are held by H bonds . Each strand has a phosphate group 3’ at one end and a OH 5’ group at the other. Strands are antiparallel meaning they run in opposite directions

Question 8

what are the base pair rules

Answer 8

adenine and thymine = 2 H bonds
Cytosine and guanine = 3 H bonds
complementary base pairing

Question 9

how does the pairing aid the structure

Answer 9

small pyrimidine always pairs with larger paring maintains distance with backbones(parallel)

Question 10

who determined the structure of DNA

Answer 10

Watson and Crick 1953

Question 11

RNA?

Answer 11

transfer of genetic material from DNA, DNA too long a molecule ant cannot leave the nucleus during protein synthesis

Question 12

what is the pentose sugar in RNA

Answer 12

ribose

Question 13

What is thymine replaced by in RNA

Answer 13

Uracil which is a pyrimidine 2 H bonds with adenine

Question 14

Semi-conservative replication

Answer 14

Double helix unwinds
H bonds holding complementary bases are broken
free nucleotides pair with the complementary bases( activated)
H bonds form between the two bases and phosphodiester bonds hold together the nucleotides
two molecules of DNA produced one old strand and a new one (semi-conservative)

Question 15

which enzyme unwinds the strand

Answer 15

DNA helicase travels along the backbone and breaks any H bonds between bases

Question 16

what enzyme catalyses the formation of phosphodiester bonds

Answer 16

DNA polymerase

Question 17

what are replication errors

Answer 17

when an incorrect bases are matched and incorrect sequence occurs in newly copied strand(mutation)

Question 18

genetic code, DNA

Answer 18

DNA codes for sequence of amino acids to form proteins (genetic code)

Question 19

Triplet code

Answer 19

Every 3 bases is called a codon(triplet code) which codes for an amino acid
a section of DNA that codes for an entire protein is called a gene

Question 20

degenerate code

Answer 20

one codon acts as a start codon if its in the middle of the gene it codes for (methionine) and 3 stop codons that don’t code for amino acid signal chain end
code is non-overlapping(each base in sequence only read once)
many codons can code for the same amino acid so degenerate

Question 21

what is transcription

Answer 21

the formation of a smaller molecule that carries the genetic code for proteins synthesis

Question 22

sense and antisense strands

Answer 22

when the two strands unwind one sense strand that does code for proteins 5’ to 3’ and an anti sense strand that doesn’t code for proteins 3’ to 5’ which acts as a template so the complementary strand forms the sense strand

Question 23

what happens to thymine

Answer 23

replaced with uracil that binds with adenine

Question 25

how are the nucleotides joined

Answer 25

RNA polymerase , transcription stops at the end of the gene and short Mrna detaches and leave nuclear pore. DNA double helix reforms

Question 26

what are ribosomes made of

Answer 26

proteins and ribosomal Rrna
maintains structural stability of protein synthesis sequence

Question 27

Translation

Answer 27

after leaving nucleus RNA binds to specific place on small ribosome subunit is it is held in place for translation
Trna(transfer rRNA) have complementary bases called anticodons on one side of the molecule that bind to the RNA using normal base pair rules, it also has an amino acid on its other end that corresponds to the codon
As the trna molecules bind to the complementary bases and bring amino acids the begin for form the primary sequence of the amino acid chain
2 trnas can be bound at a time
the amino acids form peptide bonds with the aid of the enzyme peptidyl transferase(rRNA component of ribsomes)

Question 28

ATP

Answer 28

adenosine triphosphate
nitrogenous base, pentose sugar, 3 phosphate groups
base always adenine and 3 phosphate groups

Question 29

how does ATP release energy

Answer 29

small amount of energy required to release the last phosphate but it releases a lot of energy when done
30.6KJ mol-1

Question 30

ATP hydrolysis equation

Answer 30

ATP + H2O -> ADP +Pi + energy

Question 31

ATP as an energy store

Answer 31

very instable so its not a good long term store fats and carbs are better energy stores, break down of these molecules(energy released) used to form ATP. phosphorylation is the attachment of a phosphate group made to ADP(condensation releases water)
ATP - ADP conversion happening constantly so cells don’t need a large store for it ( good immediate energy store)

Question 32

properties of ATP

Answer 32

small- moles easily in and out of cells
water soluble- energy requiring reactions happen in aqueous environments
energy released in small quantities- used for cellular needs and is not wasted as heat
easily regenerated- recharged with energy