2.1.3 - nucleotides and nucleic acids🧬

Question 1

RNA

Answer 1

ribonucleic acid

Question 2

DNA

Answer 2

deoxyribonucleic acid

Question 3

differences between DNA and RNA

Answer 3

DNA has a deoxyribose sugar, RNA has a ribose sugar
DNA has bases A,T,C,G and RNA has bases A,U,C,G
DNA is double stranded, RNA is single stranded

Question 4

nucleotide

Answer 4

monomer - contains phosphate, sugar and a base

Question 5

purine

Answer 5

adenine and guanine, larger double ring structures

Question 6

pyrimadine

Answer 6

thymine and cytosine, smaller single ring structures

Question 7

phosphodiester bond

Answer 7

the bond formed between phosphate group of one nucleotide and a sugar of another

Question 8

how do nucleotides become polynucleotides?

Answer 8

• condensation reactions

Question 9

base pairing rules

Answer 9

A and T always pair and can form 2 H bonds
G and C always pair and can form 3 H bonds

Question 10

antiparallel

Answer 10

subunits of the sugar phosphate backbones run in opposite directions of eachother
one runs in 3’ to 5’ direction and vice versa
necessary so bases can pair up in the middle

Question 11

how is the structure of DNA related to its function?

Answer 11

• coiled into a compact shape so lots of genetic info can be stored in a small space
• specific sequence of bases acts as a genetic code
• double stranded means that it more stable, protecting the genetic code from damage.

Question 12

why do cells require energy?

Answer 12

• synthesis of large molecules
• transport
• movement

Question 13

ATP

Answer 13

Adenosine tri-phosphate
contains adenine, ribose and 3 phosphate groups

Question 14

products of ATP hydrolysis

Answer 14

forms ADP and Pi

Question 15

semi conservative replication

Answer 15

in each new DNA double helix, one strand is from the original molecule and one strand is new

Question 16

steps of DNA replication

Answer 16

• two strands unwind and separate, exposing the bases and breaking H bonds, using the enzyme DNA Helicase
• free nucleotides from the nucleus line up next to the exposed bases (complimentary base pairing)
• new H bonds form, and new phosphodiester bonds form, using DNA polymerase

Question 17

movement of DNA polymerase

Answer 17

3’ to 5’ direction

Question 18

leading strand

Answer 18

the strand that is continuously replicated

Question 19

lagging strand

Answer 19

the strand that has to be copied in sections as it unwinds (ozaki fragments)

Question 20

gene

Answer 20

sequence of DNA that codes for a protein and thus determines a trait

Question 21

mRNA

Answer 21

single stranded RNA molecule made in the nucleus during transcription, which carries the genetic code from DNA in the nucleus, to the ribosomes

Question 22

tRNA

Answer 22

has one end called an anticodon and amino acid binding site at the other end
found in ribosomes, where is involved in translation

Question 23

rRNA

Answer 23

ribosmal RNA
makes up major part of ribosomes and helps catalyse the formation of peptide bonds between amino acids

Question 24

triplet code

Answer 24

each amino acid is coded for by a sequence of 3 bases

Question 25

transcription stages

Answer 25

- DNA helicase unwinds the strands - template strand is used to make an MRNA copy of the DNA - free mRNA nucleotides join using RNA polymerase, forming the backbone - once enzyme has passed a section, the DNA reforms

Question 26

translation stages

Answer 26

- mRNA attaches to ribosome - anticodons on the tRNA line up to codons on mRNA (base pairing) - other end of tRNA willl have the specific amino acid attached - peptide bonds form between the amino acids - the ribosome will move along, forming a polypeptide chain - happens until a STOP codon on the mRNA

Question 27

degenerate code

Answer 27

multiple codons encode a single amino acid

Question 28

non overlapping code

Answer 28

base triplets do not share their bases, each triplet is distinct from the next

Question 29

universal code

Answer 29

all known living organisms use the same genetic code

Question 30

steps of DNA extraction pag

Answer 30

1. grind the sample in mortar and pestle (break cell walls) 2. mix sample with detergent (disrupts membrane) 3. add salt (breaks H bonds) 4. add protease enzymes (breaks down proteins 5. add layer of ehanol - the DNA will then precipitate out of solution