Gene Expression and Protein Synthesis Part 2 - (Week 4) Flashcards
Why was the one gene-one polypeptide hypothesis revised?
- some proteins are not enzymes
More details on proteins:
- polymers consisting of amino acids linked by peptide bonds
- composed of several polypeptides, having their own gene
What happens in the flow of gentic infromation from genes to proteins?
- info from genes is located in the specific sequences of nucleotides
- DNA inherited by an organism leads to specific traits by ditacting the synthesis of proteins
- proteins are links between genotype & phenotype
What is gene expression?
- process by which DNA directs protein synthesis (transcription & translation)
Genetic information can be provided by DNA or RNA. True of False?
True - the translation of RNA into protein = unidirectional
What happens in the central dogma?
- info cannot be transferred from protein to protein to nucleic acid
- can be transferred between nucleic acid to nuclei acid and from nucleic acid to protein
- info in nucleic acid can be perpetuated or transferred
- transfer of info into a polypeptide = irreversible
What is a genome?
- complete set of genetic instructions for any organism (RNA/DNA)
- copied during the process of replication
- coding system for genetic info = same in all living organsims
What are the basic principles of transcription and translation?
- RNA = bridge between genes & proteins for which they code
- ribosomes are the sites of translation
What is transcription?
- synthesis of RNA using info in DNA
mRNA for protein coding genes
What is translation?
- synthesis of a polypeptide using info in the mRNA (in ribosomes)
What happens to mRNA produced by transcription in proakaryotes?
- it is immediately transferred without more processing (coupled)
What happens to mRNA produced by transcription in eukaryotes?
- nuclear envelope separates transcription site from translation
- mRNA = modified through RNA processing to yield mature mRNA that can be used for protein synthesis
How many nucleotides bases are there in DNA?
Four
How many nucleotides correspond to an amino acid?
Five
What is the flow of information from gene to protein based on?
A triple code - series of 3-nucleotides
What is the code of a gene transcribed into?
- a complementary three-nucleotide code of mRNA - a codon
- then translated into a chain of amino acids - froming a polypeptide
What is a codon?
A triplet RNA code
Out of the 64 possible codons, how many are stop/termination codons?
- 3, which are universally the same in almost all living organisms
- also 61 sense codons
What does it mean when the genetic code is “degenerate”?
- more than 1 codon may specify a particular amino acid (but not ambiguous)
Why do codons need to be read in the correct reading frame? (correct groupings)
- in order for the specified polypeptide to be produced
The amino acids are specified by each codon in their 3-letter abbreviation. True or False?
True - written in 5’ to 3’
How has the genetic code evolved?
- shared by the simplest bacteria to the most complex animals (universal)
- they can be transcribed & translated after being transplanted from one species to another
- the same codons are assigned to the same amino acids and START & STOP signals in the vast majority of genes in animals, plants & microorganisms (with some exceptions)
