L4 DNA structure Flashcards
What is DNA made up of?
Made up of DNA nucleotides
What 3 things makes up a DNA nucleotide?
A nitrogenous base
Deoxyribose sugar
Phosphate group
What did Erwin Chargaff do? (1951)
He used paper chromatography to separate and isolate the nucleobase components of DNA from a number of species
What are chargaff’s rules?
The amount of Adenine is equal to the amount of thymine
The amount of guanine is equal to the amount of cytosine
What did Maurice Wilkins and Rosalind Franklin (1952) discover?
They used X-ray crystallography to determine the structure of DNA and concluded that:
- X pattern = helix
- Regular pattern = repeating, even syructure
- Distance of one turn = 3.5nm
What were the main features of Watson and Crick’s model? (5)
A-T and G-C hydrogen-bonded base pairs
Antiparallel strands
Right-handed double helix
One helical turn every 10.5 bp
Major and minor grooves
What would happen if you mispaired two purines or two pyrimidines together?
It would cause distortion in the DNA molecule
Out of purines and pyrimidines, which one has a double carbon ring?
Purines - 2 carbon rings (Adenine and Guanine)
Pyrimidines - 1 carbon ring (Thymine and Cytosine)
Are DNA structures mainly right handed or left handed helices?
Right - handed helices
What is a histone?
A histone is a protein that provides a structural support for a chromosome.
It’s a fundamental component of chromatin, the complex of DNA and protein that packages genetic material in the nucleus of eukaryotic cells
Are eukaryotic chromosomes linear or circular ?
Linear molecules, held in the nucleus of the cell
What is the function of a centromere?
Centromere = the specialised chromosomal region where spindle microtubules assemble and direct the equal segregation of chromosomes during mitosis and meiosis
What do telomeres do?
They protect the ends of linear chromosomes
What are the structural components of plasmids?
- Plasmids are small, circular DNA molecules found in bacteria.
- Size typically a few thousand bp
- Can carry a variety of advantageous genes such as antibiotic resistance cassettes
What are DNA binding proteins?
They are proteins that have DNA binding domains that allow them to bind to specific or general sequences of single or double stranded DNA
