Nucleotides And Nucelic Acids

Question 1

Nucleotide

Answer 1

C H O N P
Pentose sugar
Nitrogenous base
Phosphate

Question 2

Ribose sugar

Answer 2

Deoxyribose in DNA
Ribose in RNA

Question 3

ATP

Answer 3

Three phosphates, adenosine base and ribose sugar
Provides energy for cellular chemical reactions
Energy stored in phosphate bond
ADP + Pi –> ATP uses energy
ATP –> ADP + Pi releases energy

Question 4

Polynucleotides

Answer 4

Phosphodiester bonds between sugar and phosphate molecules making sugar-phosphate backbone
Two strands join via hydrogen bonds complimentary base pairing
C-G ×3
A-T ×2
Two antiparrallel strands twist to form double helix

Question 5

Purify DNA

Answer 5

Break up cells using a blender
Mix detergent salt and distilled water and broken cells
Heat at 60°C for 15 minutes
Place in ice bath to cool
Filter mixture
Add protease enzymes to break down dna proteins
Dribble cold ethanol down side of tube
Leave for few minutes
DNA forms white precipitate

Question 6

DNA replication

Answer 6

DNA helicase breaks h bonds between two polynucleotide strands
Each strand acts as a template
Free floating DNA nucleotides join to exposed bases by complimentary base pairing
Nucleotides joined by DNA polymerase, reforming sugar phosphate backbone
Each new DNA contains one new and one old strand

Question 7

Semi conservative replication

Answer 7

Really accurate
Conserves genetic information

Question 8

Genes

Answer 8

Sequence of DNA nucleotides coding for a polypeptide
Order of bases determines order of amino acids
Coded for by a triplet

Question 9

Types of RNA

Answer 9

mRNA- carries genetic code from nucleus to cytoplasm
tRNA- amino acids binding sites and anticodon carrying amino acids to ribosomes
rRNA- forms two subunit, catalyses peptide bond formation

Question 10

mRNA importance

Answer 10

DNA too large to fit through nuclear pores
mRNA copies important section and is small enough to leave

Question 11

Genetic code

Answer 11

Sequence of triplets in DNA coding for amino acids
Each triplet is read in sequence separately
Degenerate- more triplets than amino acids
Have start and stop codons
Universal- same in all living things

Question 12

Transcription

Answer 12

RNA polymerase breaks hydrogen bonds between antiparrallel polynucleotide starnds
One strand is used to make mRNA copy
RNA polymerase lines up free RNA nucleotides and join via complimentary base pairing
Joined together to form mRNA molecule (phosphodiester bond formation)
RNA polymerase moves along DNA strand until stol coding is reached
Hydrogen bonds between antiparralelll dna strands reform
Mrna moves out via nuclear pore and attaches to ribosome

Question 13

Translation

Answer 13

mRNA attaches to ribosome and tRNA carry amino acids to ribosome
tRNA molecule with anticodon complimentary to start coding attaches by complimentary base pairing
Second tRNA attaches in same way
rRNA catalyses formation of peptide bond between two amino acids
Trna continue to artach until stop codon is reached
Polypeptide chain detaches and folds