DNA Flashcards
simple flow of DNA (central dogma)
- DNA replication -> DNA
-transcription-> RNA -translation-> Protein
purposes of DNA
CODE FOR:
- regulate exchange of DNA
-energy transfer
- protein synthesis
- pass traits to next generation
Label DNA
- phosphate group
- Phosphodiester bond
- ribose sugar
- nitrogenous base
- hydrogen bond
differences between RNA and DNA
DNA:
- deoxyribose sugar
- A, T, C and G
- double stranded
- more stable
RNA:
- ribose sugar
- A, U, C, G
- single stranded
- less stable
What are purines
- A and G (pure as gold)
- two rings of nitrogen
what are pyramidines
- C and T (CH3 at 5-carbon), and Uracil (H atom at 5-carbon position)
- One ringed
How is DNA named
- sugar
- base
- number of phosphates (always 1)
e.g. deoxyadenosinemonophosphate
how is RNA named
- base
- number of phosphate groups (always 1)
e.g. adenosinemonophosphate
how many bonds between A and T vs C and G
2 for AT
3 for CG
why is DNA changed to RNA for protein synthesis?
- so it is small enough to fit through nuclear pores and only contains useful coding info (exons)
what is transcription
- process by which RNA is transcribed from DNA
what is:
tRNA
rRNA
mRNA
t = transfer RNA (pol 3)
m = messenger (pol II)
r = ribosomal (pol 1)
where does transcription occur
nucleus or nucleoid
Explain process of transcription
- RNA polymerase binding - binds to promotor region in non-coding area
- Initiation - RNA polymerase unwinds DNA and moves in 3’ to 5’ direction. Adds complimentary nucleoside trophosphates (e.g. GTP) onto template strand (synthesising RNA in 5’ to 3’ direction), forms phosphodiester bonds between them
- Elongation - continuation
- Termination - at end of gene, stop sequence read, termination signal received by polymerase. hairpin structure forms
- RNA pol detaches
template vs coding strand
BOTH are genes (sections of DNA), not the whole DNA strand itself
template - complimentary to code wanted
coding - contains actual code we want in mRNA
how can O2 be damaging to cells
forms Reactive oxygen species which damage molecules
What are the 5 types of bacteria based on O2 use
- obligate aerobes - require O2
- microaerophiles - require low levels of O2
- faculative anaerobes - aerobic or anaerobic
- arotolerant anaerobes - tolerate O2, don’t use
- obligate anaerobes - anaerobic only!
characteristics of mRNA
- less stable
- highly specific
- variable in size
- very little 2° structure
Role and characterisitics of tRNA
recognises mRNA code, and carries amino acid to site of protein synthesis
-stable
- small
- consiiderable 2° stuurcture
characteristics of rRNA
- stable
- produced in nucleolus
- considerable 2° structure
What is translation
- process where RNA is translated into an amino acid sequence with a protein code
Explain process of Translation
- aminoacylation occurs, mRNA travels out of nuclear pores to cytoplasm
- Initiation - bidning of mRNA and aminoacyl-tRNA to ribosome (binding site) ribosome assembles around it
- Elongation - codon recognition in tRNA, brings AA and binds via anticodon, enzyme peptidyl transferase catalsyses formation of peptide bonds. First tRNA leaves, more tRNA enter (next codon read)
- Termination - a release factor enters ribosome, binds to A site, release factor accepted by ribosome and termination. Full polypeptide made
what is aminoacylation?
- process of amino acids binding to tRNA
- tRNA synthase used to bind them at 3’end
what are the subunits of bacterial vs eukaryotic ribosomes
bacterial = 50S and 30S
eukaryotic = 60S and 40S
what is the mRNA binding site?
where small subunit will bind to mRNA (codon)
what is the aminoacyl site
holds tRNA carrying next amino acid
what s peptydyl site
holds tRNA carrying gorwing polypeptide chain
why is genertic code degenerate
codons can code for more than 1 amino acid
how to use genetic code table
read mRNA from 5’ to 3’
AUG = start codon
UGA, UAA and UAG = terminator
hoow should you wriite genetic sequence once found?
- with NH2 before start codon
- include all code including start and stop codons
- finsih with COOH
e.g NH2 met Arg Leu Asn COOH
