DNA synthesis Flashcards
Restriction Enzyme
Typically produced by bacteria that can cleave DNA moles at or near a specific sequence of bases. Predictably cleave sequences that they recognize as palindromic.
Reverse transcriptase
An enzyme used to generate complementary DNA from a RNA template.
mRNA
Single-stranded RNA molecule that is complementary to one of the DNA strands of a gene. Carries codes from the DNA in the nucleus to ribosomes in the cytoplasm.
tRNA
Type of RNA molecule that helps decode a mRNA sequence into a protein
rRNA
Responsible for reading the order of amino acids and linking amino acids together.
What is transcription and where does it occur?
Transcription is the conversion from DNA to RNA. This occurs in the nucleus.
What is translation and where does it occur?
Translation is the conversion of RNA into protein. This occurs in the cytoplasm.
How are nucleotides attached to each other?
Phosphodiester bonds join one nucleotide to another. Holds a polynucleotide chain together by joining a phosphate group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the pentose sugar of the next nucleotide
Operator
Genetic sequence which allows proteins responsible for transcription to attach to the DNA sequence. Regulates the production of a certain portion of the DNA.
Operon
Genes that get transcribed when the operator is bound
Represssor proteins
Bind to the operator and can block transcription factors from binding to the operator.
Degenerate Code
Multiple codons encode for the same amino acid. Sequence lacks the distinction of one codon per amino acid with instead multiple possible codon combinations for a specific amino acid.
Anticodon
Translation machinery responsible for making sure the sequence of codons is correct. These anticodon are part of the tRNA and attach to codons based on base-pairing rules.
Wobble effect
Loose bond between third position of a codon and anticodon
Missense codons
A mutation that changes a position in the codon. Depending on the position changed and the specific nucleotide substitution, a missense codon may or may not encode for a different amino acid. A change in the nucleotide in a third wobble position may not affect the outcome of the amino acid.
Nonsense codons
Type of codon mutation responsible for ending the polypeptide sequence prematurely.
What are the special codons?
AUG - encodes for methionine which is a start codon. UAA, UAG and UGA are stop codons. (remember U Are Amazing, U Are Great, U Get A’s)
Ribozyme
Enzyme that is comprised of RNA which assists in splicing
Small nuclear RNA(snRNA)
Class of ribozyme that combines with small nuclear ribonucleoproteins (snRNPs) which assist in splicing
Spliceosome
snRNPs and other associated proteins together that perform splicing by pinching off introns from the RNA transcript into a loop that is removed and joining the ends of the remaining exons
Importance of Introns
Introns are no-coding regions. Offer support to the transcript as it is transported out of the nucleus and assist in the control of gene expression by influencing a variety of protein products depending on splicing sites and the inclusion or omission of particular exons.
What are the three sites in a Ribosome and what do they do?
A (aminoacyl) site: Provide space for a new approaching tRNA with attached amino acid and corresponding anticodon to match the next codon in the mRNA sequence:
P (peptidyl) site: Two amino acids held adjacent to each other, one attached to a tRNA in the A site, and one attached to a tRNA in the P site, ribozyme catalyzes peptidyl transferase activity, which transfers the P site amino acid onto the A site amino acid.
E (exit) site: A tRNA moved into the E site, having just released its amino acid, is then free to dissociate from the ribosome and mRNA.
What are post-translation modifications of proteins in translation
- Chaperone proteins can assist in the process of folding
- It can include the addition of sugars, lipids or phosphate groups to the amino acids of the polypeptide.
- Proteins can be cleaved with the removal of leading sequences to produce their final forms.
