Lecture 12: DNA introduction Flashcards
Why is DNA a better candidate for the genetic material than protein?
- It is CONSISTENT among members of the same species
- It is STABLE: does not change with environmental conditions
- Longer life duration
What is the relationship between A,T,G,C
Chargaff’s Rule: A=T, G=C
What are the major differences between RNA and DNA?
RNA has URACIL instead of Thymine RNA has ribose sugar instead of deoxyribose RNA more flexible than DNA; can loop RNA can be single stranded RNA can spontaneously form hairpins
What does the structure of DNA look like? (Level of organisation)
DNA strand > wraps histones (protein) = nucleosome
Nucleosomes coil around each other, forming CHROMATIN, which together form chromosomes
What are major and minor “groves”?
DNA helix has a slight tilt; all depends on the distance of the backbone; MAJOR=close, MINOR=far
Difference between parental, template and daughter DNA strands?
Parental = the two original strands Template= each of the original, used in replication Daughter= after replication, the helices are called this
What are the different forms of DNA?
3 forms: A, B and Z form. A&B= right handed helices
Z form = left handed helix
What cellular processes involve RNA?
Transcription, translation, DNA synthesis (RNA primers), reverse translation
Which base pairs is stronger, and how many bonds does it have?
G and C
3 Hydrogen bonds
What bond can occur between phosphate and pentose of neighboring nucleotide?
Covalent bonds
Name the purines and the pyrimidines
Purine: A and G
Pyrimidine: T, C, U
What does a nucleotide consist of?
- Phosphate
- Base
- Pentose sugar
What is the difference between the pentose sugar in RNA and DNA?
RNA: ribose
DNA: deoxyribose
Labeling of 5’ and 3’ ends
Start at the carbon where the base attaches; then move in a clock wise manner. (Note that 5’ is not in the ring)
What are the different forms of DNA?
A, B and Z.
A and B: right hand helix
Z: left hand helix
