Sac 1 Flashcards
Define recombinant
DNA that has been formed artificially by combining components from different organisms
Define transform
The process where a cell takes up foreign DNA and takes it up into its own plasmid or genome
Define transgenic
An organism that contains genes from another species through genetic engineering
Define Synthesis
The process of creating a complex compound substance from simpler materials (making something new from other parts)
Define vector
A vehicle, such as a plasmid or virus, used to transfer genetic material into a cell
What is the purpose of a coding strand in transcription?
Has the coded info to be sent out to a ribosome to be used to make a protein
What is the purpose of a non-coding (template) strand of DNA in transcription?
RNA polymerase attaches to this strand to create mRNA.
What is RNA polymerase?
An enzyme of quaternary structure that unwinds the DNA (unzips)
What is a trinucleotide?
3 consecutive nucleotides
Process of transcription: STEP 1
- RNA polymerase enzymes run along the template strand in a 3’ to 5’ direction, unzipping the DNA
Process of transcription: STEP 2
As the RNA polymerase runs along, it creates the mRNA copy of the template strand, which has the same code as the coding strand, built in a 5’ to 3’ direction
Process of transcription: STEP 3
After the process is finished, the coding strand will join back on to the template strand, and a the strip of DNA is left as well as pre-mRNA
What is pre-mRNA?
The primary transcript of RNA from transcription. Still has both exons and introns.
Methyl
CH3
What is a poly-A tail?
Series of adenine nucleotides attached to the 3’ end of mRNA
Steps of RNA processing:
- Introns (Irrelevant) get cut out and exons get joined together
- Methyl cap gets added to 5’ end
- Poly-A tail gets added to 3’ end
Define codon
Sequence of 3 nucleotides in mRNA and coding strand of DNA
Definitely anti-codon
Sequence of 3 unpaired nucleotides in tRNA
Process of translation: STEP 1
mRNA leaves the nucleus, goes out into the cytoplasm and goes into a ribosome (AKA attaches to) 5’ end first
Process of translation: STEP 3
Inside the ribosome, the anticodon of tRNA attaches to the specific corresponding codon of the mRNA
Process of translation: STEP 2
The tRNA carries amino acids to the ribosome and each anticodon is specific to a type of amino acid
Process of translation: STEP 4
Once the anticodons of the tRNA have attached to the mRNA, the attached amino acids form a peptide bond with each other
What does universal mean?
The genetic code is the same in all organisms (AGTCU)
Process of amino acid condensation polymerisation:
- Hydroxyl group breaks off
- Hydrogen breaks off
- The two make water (H2O)
- Residues form a peptide bond
- Polypeptide breaks off
Define degenerate
Most amino acids can be coded for by more than one codon
Define unambiguous
Each codon specifies only one amino acid
Define chaperone
A protein that assists the folding of a polypeptide into its tertiary structure
Define methylation
Adding a methyl (CH3) group
What is post-translational modification?
Once a polypeptide is synthesised it can be differentiated out
Purpose of gene regulation
Some genes need to be switched off to save energy as protein synthesis is very energy expensive. Others may need to be turned off to allow the cell to differentiate for particular functions
Tryptophan
The rarest of the 20 naturally occurring amino acids
How does the trp operon work?
Tryptophan is very energy expensive to make so when there is enough in the cell, the tryptophan will attach to a repressor. This changes the repressors shape, making it complimentary to the operator. It attaches to the operator and stops the polymerase from producing any more tryptophan
Polymerase enzymes
Enzymes that build a polymer by going along the template strand of DNA and synthesising the polymer of DNA in a 5’ to 3’ direction and amplify the synthesis of DNA
Ligase
AKA molecular glue. Repairs the sugar-phosphate bond to create continuous strand of DNA
Endonucleases
AKA molecular scissors. Breaks the sugar-phosphate bonds, either leaving sticky or blunt ends. Cut DNA at a specific sequence
Restriction endonucleases
Cut a section of DNA with a specific palindromic repeat
What are plasmids?
Vectors used to transport foreign DNA into bacterial cells. Small seperate DNA molecules that replicate independently and are used for genetic engineering
Region of origin (ROI)
Section of DNA that works like a promoter region
