DNA / RNA Flashcards
What charge is on DNA backbone, and what is structure?
Negative charge.
Phosphodiester bonds; phosphate to sugar, with bases attached.
DNA - deoxyribose
RNA - ribsoe
What are the nitrogenous bases in DNA? What can they pair with?
Purine: Guanine and adenine
Pyrimidines: Thymine and cytosine
How do the bases stack?
Due to hydrophobic interactions. A&T 2 bonds, C&G 3 bonds. Major and Minor groove based on where the sugars are attached: C-G backbone Major, A-T backbone Minor.
What is the point of major groove?
It’s ideal size for protein to bind. Proteins nuteralise the negatively charged dna.
What makes up the human genome?
22 pairs of autosomes and 1 pair of sex chromosomes (2 x 22 + 2 x sex chromosomes) = 46 chromosomes in total.
What are histones?
DNA binding protein. 4 different histones come together creating octameric complex (positively charged).
Histone H2A, H2B, H3 & H4
Histone octamer and two turns of DNA is called an nucleosome (the building block of chromosomes).
What is the start codon?
AUG - met
What is the structure of tRNA?
5’ end and 3’ end (attached amino acid). 3D folded. Contain three anticodon loops to code each amino acid.
How are amino acids attached to tRNA?
Aminoacyl-tRNA synthases (v.big enzymes) are responsible for attaching the correct amino acid to the tRNA molecule. Catalyses bond between tRNA and amino acid with ATP. This high energy bond is later broken, the energy used to bind amino acids together. Specific binding sites and shaped enzymes to ensure correct binding.
Structure of ribosome?
80+ proteins, 4 RNA molecules. Three active sites in the complex (tRNA and mRNA bind simultaneously).
Active sites: E, P, A. (left to right).
Large unit: 49 proteins and 3 RNA.
Small unit: 33 proteins and 2 RNA.
What are the ribosomal site names, what do they do?
A - aminoactyl-tRNA (amino acid with tRNA)
P - peptidyltransferase (peptide bond formation between two aminoacyl-tRNA).
E - exit (shifts along, empty tRNA leaves the unit).
How do antibiotics work with translation?
They can inhibit translation.
What is miRNA?
Control translation.
Bind to mRNA for rapid degradation (extensive match) or translation reduction/pause and eventual degradation (less extensive match).
miRNA therefore had a lot of control of what proteins are produced, and c an be utilised to turn off and turn down protein production in clinical applications. They are also used as biomarkers (present in disease). Patterns can be observed for diagnostics.
