Protein Synthesis Flashcards
(31 cards)
What are ribosomes made from
rRNA and ribosomal protein
Where does translation occur
Cytoplasm
Where does transcription occur in eukaryotes
Nucleus
Where doe’s transcription occur in prokaryotes
Cytoplasm
Transcription process
- DNA helicase attaches to DNA, hydrogen bonds broken so strands separate
- Only one strand act as a template
- RNA nucleotides attracted to exposed bases
- Attraction according to base pair ruling is Uracil+Adenine.Cytosine+Guanine
- RNA polymerase join’s nucleotide together forming phosphodiester bonds through condensation reaction
- PremRNA is spliced to remove introns
Structure of tRNA
- cloverleaf shape
- 75 nucleotides
- single stranded
- held by Hydrogen bonds
- amino acid binding site
- anti codon region
What are introns
Non coding base sequence of DNA found within a gene
What are exons
Coding base sequence of DNA found within a gene
Definition Gene
Sequence of Nucleotides that code for the primary structure of a polypeptide chain
Compare Eukaryotes vs Prokaryotes
Eukaryotes:
- linear
- associated with histones
- contains introns
Prokaryotes:
- circular
- not associated with histones
- contains no introns
Compare DNA and mRNA
DNA:
- longer
- contains deoxyribose
- thymine in DNA
- double standard
- has hydrogen bonds
-has introns
mRNA:
- shorter
- contains ribose
- uracil in mRNA
- single stranded
- has no hydrogen bonds
-has no introns
What is splicing
When pre mRNA is spliced to remove introns and recombines exons forming mature mRNA
What translation process
- mRNA binds to ribosomes
- Ribosomes finds start codon
- The idea of 2 codon binding site
- Allows tRNA complimentary anticodon bind to codon
- Catalyses peptide bonds between amino acids using energy from ATP
- tRNA is released as ribosomes moves along mRNA to the next codon
- Ribosomes releases polypeptide to RER when stop codon has reached
Definition of universal
The same 3 bases codes in mRNA and DNA codes for the same amino acid in all organisms
The mechanism of transcription and translation is ————— found in all organisms
Universal
Definition of non-overlapping
Each base is read once in a triplet
Definition of degenerate
More than one triplet codes for each amino acid
Definition of gene mutation
- The change to a single base in a DNA base sequence of a gene.
- Mutation occurs randomly and spontaneously
Gene mutation in DNA may result a change in what
Primary structure
If primary structure changes due to mutation what are the consequences
-May alter secondary structure (change position of weak hydrogen bonds affecting alpha helices and beta pleated sheets)
-May alter tertiary structure ( change in weak hydrogen bonds, ionic bonds between the R groups of amino acids and disulphide bonds)
- altering binding site and active site of enzymes making proteins not functional
What are the 3 different mutations
Substitution
Deletion
Addition
If substitution changes amino acid sequence what are the consequences
- Alters tertiary structure and function
- May code for stop codon,
which shortens the polypeptide chain, may not perform intended function
What is silent mutation
Does not change amino acid coded for, so has no effect on polypeptide chain
What type of mutation is ‘silent mutation’
Substitution
