Lecture 4 Flashcards
What are the 4 main groups of molecules involved in living systems?
Nucleic acids, Proteins, Carbohydrates, Lipids.
2 types of nucleic acids?
DNA (Deoxyribonucleic acid).
RNA (Ribonucleic acid).
By what process is DNA converted to RNA?
Transcription.
By what process is RNA converted to protein?
Translation.
Are nucleotides monomers or polymers?
Monomers.
Are DNA and RNA molecules polynucleotides or mononucleotides?
Polynucleotides.
3 parts of a nucleotide?
3 phosphate groups,
Sugar,
Nitrogenous base.
What is the sugar in RNA?
Ribose.
What is the sugar in DNA?
Deoxyribose.
What molecules are purines?
Adenine, Guanine.
What molecules are pyrimidines?
Cytosine, Thymine, Uracil.
Difference between deoxyribose and ribose?
1 oxygen not present in deoxyribose. (2’ Carbon has another H instead of OH).
What are the monomers used in the synthesis of nucleic acids?
Nucleoside triphosphates.
What is the backbone of DNA and RNA made of?
Sugar units linked by phosphate groups.
Hydroxyl on carbon-3’ of one sugar is joined to hydroxyl group on carbon-5’ of the next by?
Phosphodiester link.
What will be on the ends of a polynucleotide chain?
Unreacted 5’ phosphate.
Unreacted hydroxyl group on 3’.
In which direction is the base sequence of a polynucleotide chain written?
5’ to 3’.
What encodes the genetic information?
Sequence of bases along the backbone.
What did Watson and Crick analyse in 1953?
X-ray diffusion patterns from DNA fibres.
What 4 things did Watson and Crick deduce?
- Cross pattern typical of a helical structure (density of fibres suggested 2 DNA strands in helix).
- 10 residues per turn (as layer line spacing 1/10).
- Helical rise was 0.34nm as repeat distance was 3.4nm.
- DNA bases must form specific pairs (sugars must be same distance apart to establish constant diameter).
What bonds are present in DNA?
Hydrogen bonds between 2 strands, van der waals bonds between successive bases.
Do both strands run in the same direction in DNA?
No, opposite.
As each DNA strand acts as a template for the other during replication, what word describes both strands with respect to one another?
Complementary.
Do the phosphate groups and sugars lie on the inside or the outside? What’s on the outside?
Outside, next to water environment.
