Fundamentals Of DNA, RNA And Proteins Flashcards
(12 cards)
What are examples of purines (2 carbon ring structure)
Adenosine and Guanin
Examples of pyrimidines (one carbon ring structure)
Cytosine and thymine
How many h bonds between each of the base pairings
A-T - 2 hydrogen bonds
C-G - 1 hydrogen bond
How is DNA packaged into a cell
Nucleosome - DNA wrapped around histone core. Linked dna between histones secures dna around nucleosome forming a chromatosome
Chromatosome - structural unit of chromatin made up of nucleosome
Chromatin - condensed dna packaged into a compact structure
Chromosome - most condensed structure. DNA supercoiled around histone
In what direction is dna replicated
5’ to 3’ end
What things are used in process of dna replication
- Topoisomerase
- Single strand binding proteins
- DNA polymerase
- sliding clamps
- Helicase
- DNA primase
- Okazaki fragments
- DNA lipase
What is the histone core structure like
H2A-H2B DIME
H3-H4 DIMER
Histone is positively charged and DNA is negatively charged so it attracts eachother
Topoisomerase function
- DNA coil needs to be straightened out
- Topoisomerase breaks and rejoins dna to unwind the super coil structure to allow easy access
Single strand binding protein function
Prevents DNA forming hairpin on the lagging strand
Keeps phosphate backbone straight and nucleotides to be exposed and allow dna polymerase to access it
DNA polymerase
Synthesises new strand
Moves 5’ to 3’
Catalyses the addition of deoxyribonucleotide
Alters shape to covelantly bind the new nucleotides onto the growing strand
Sliding clamps
Protein complex that encircles the dna strand
They do:
Enhance productivity by helping dna polymerases remain attached to the dna strand
Helps recruit other proteins to help replication
Regulates dna repair and replication by signalling and recruiting repair
Helicase
Moves along dna and uses atp to split apart the 2 strands
Exposes nucleotide to allow new strand to be made
