1 - Intro To DNA Flashcards
What is the structure of DNA?
- Right handed double helix
- Antiparallel complementary strands held together by hydrogen bonds between complementary base pairs
- 2-deoxyribose
- Phosphodiester backbone
- Polar due to 5’ 3’ ends
- Major/minor groove
What is chromatin?
DNA wrapped around histones (octomer of proteins) , which can then condense to form chromosomes
What is the structure of euchromatin and heterochromatin?
Euchromatin: Light. Beads on a string, when DNA being replicated. Less dense as acetylated.
Heterochromatin: Dark, solenoids packed to form a 30nm fibre. Dense as methylated. Gene not expressed like this
What is the name of DNA and a histone together?
Where do proteins for DNA replication bind to DNA?
Major groove as easily accessible
What is the process of forming a chromosome?
- DNA wraps around histones to form nucleosomes and beads on a string
- Nucleosomes wrap around one another and form solenoids
- Solenoids join together to become fibres
- Fibres zigzag over one another to become highly condensed loops
What is the genome?
- Entired DNA sequence
- 24 chromosomes, 2 sex 22 auto
What are nucleosides?
- Sugar and base, no phosphate
- Adenosine, Guanosine, Uridine, Deoxythymidine, Cytidine
What are the two classifications of nucleotide bases?
- Purines (2 C ring): A,G
- Pyrimidines (1 C ring): T,C,U
How would you find a gene on a chromosome if you knew the exact position?
LOOK AT THE BANDING PATTERNS
Why can C only bind to G?
- 3 hydrogen bonds
- All bonds of nearly equal distance
Why is DNA antiparallel?
Ensure the bases are close together and in the middle so they can form hydrogen bonds
What is the nomenclature of DNA?
- Left to right 5’ to 3’
- Complementary is 3’ to 5’
What is the cell cycle and where are the checkpoints?
What is the equation for DNA replication?
(dNMP)n + dNTP –> PPi + (dNMP)n+1