From Gene to Protein Flashcards
Transcription vs. Translation
DNA -> RNA = Transcription
RNA -> Protein = Translation
Transcription location
Euks: Nucleus
Proks: Cytosol
Translation Location
Euks: Cytosol
Proks: Cytosol
Reverse Transcriptase
RNA -> DNA = Reverse Transcription
Retrovirus way of infection.
Ratio of Genes to RNA molecules
1 gene: 1 RNA molecule (mRNA, tRNA, rRNA)
RNA synthesis needs?
Needs:
-template strand (1 only)
-Nucleotides (UTP, ATP, CTP, GTP)
-RNA Pol II (Acts as helicase as well)
-Topoisomerase
-ssDNA binding protein
-Promoter (includes TATA box)
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3 types of RNA
- mRNA - dictates A.A. sequence, ‘protein recipe or blueprint’
- tRNA - transfers A.A. to ribosome for assembly
- rRNA - combines w/ proteins to make ribosome, “workbench” for translation. Transcribed in Nucleus.
Ends of eukaryote strand
5’ cap: A modified (methylated) guanine after transcription of the first 20-40 nucleotides have been transcribed.
Poly-A tail @ 3’ end: 50-250 more adenine nucleotides.
Introns and Exons
Introns stay in the nucleus (leave the RNA). Intervening sequences, cut out & removed.
Exons exit nucleus (stay in mRNA transcript), spliced together.
Codon
3 nucleotide sequence. Used for stopping, coding proteins, and starting
Anticodon
On tRNA, responses to mRNA in the _____(?).
How do tRNA get their amino acids?
Aminoacyl-tRNA synthetase
Transcription Factors
Proteins that control the rate of transcription of genetic information from DNA to messenger RNA by binding to specific DNA sequences called enhancers or silencers
RNA Pol II
An enzyme that pried the 2 strands of DNA apart. Joins together RNA nucleotide complementary to a DNA strand. Doesn’t need a helicase. Also do not need a primer, unlike DNA polymerase.
Ribosomes in RNA and protein production
2 pieces, small and large. small attaches first, has 3 sites, Aminoacyl, Peptidyl and exit. The large piece attaches next, also has 3 sites for tRNA to attach to. Contains peptidyl transferace, (an aminoacyl transferace).
Ribosome site names
E - Exit site
P - Peptidyl
A - Aminoacyl
Order goes A -> P -> E
polyadenylation signal
AAUAAA. In eukaryotes, RNA pol II transcribes a sequence on the DNA called the polyadenylation signal. Called a signal because once this stretch of six RNA nucleotides appears, it is immediately bound by certain proteins in the nucleus. Then, at a point about 10-35 nucleotides downstream from the polyadenylation signal, these proteins cut the RNA transcript free from the polymerase.
Starting codon
AUG, Methianine
Ending codons
UAA
UAG
UGA
(Almost universal)
Downstream
Toward DNA Pol II
UTR purpose
Regulation. Untranslated Region
Ribozyme
An RNA molecules that acts as an enzyme, only one per ribosome. i.e. peptidyl transferace.
Peptidyl Transferace
An aminoacyl transferace that serves as the primary enzymatic function of the ribosome. Breaks covalent bonds of amino acids to tRNAs. (double check me on that).
Point mutation
Mutation involving 1 nucleotide
Missense Mutation
Change one amino acid to another. Can still be a silent mutation.
Nucleotide-pair substitution
Replacing one nucleotide and its partner with another pair of nucleotides
Silent mutation
When the mutation has no observable effect on the phenotype.
Insertion and Deletion mutations
Additions or losses of nucleotide pairs in a gene.
Frameshift Mutation
Whenever the number of nucleotides inserted or deleted are not multiples of three.
Aminoacyl tRNA synthetase
An enzyme that joins amino acids to the appropiate tRNA.
Releasing Factor
Bonds to stopping codon
Nonsense Mutation
Mutations causes an early stop codon. Terminating early. Substitution only.
Transcription Initiation Complex
RNA pol II + Transcription factors bound to promoter
