Genes, Transcription and Translation Flashcards
Polypeptide
A polymer consisting of a chain of amino acid residues joined by peptide bonds
Gene
A length of DNA that codes for one (or more) polypeptides
Genome
The entire DNA sequence of an organism.
The human genome consists of 3 billion nucleotide base pairs
Protein
A large polypeptide - usually about 100 or more amino acids.
Some proteins consist of one polypeptide chain, some consist of more than one
Transcription
The creation of a single stranded mRNA copy of the DNA coding strand
Translation
The assembly of polypeptides (proteins) at ribosomes
Mutation
A change in the amount of, or arrangement of, the genetic material in a cell
DNA mutation
Changes to the gene due to changes in nucleotide base sequences
Gene mutation
Changes to DNA due to changes in nucleotide base sequences
Allele
Alternative version of a gene
Genetic code
The sequence of nucleotide bases on a gene that provides a code with instructions for construction of polypeptides/proteins
Operon
A length of DNA made up of structural genes and control sites
Homeobox genes
Homeotic genes that control the development of the body plan of an organism
Apoptosis
Programmed cell death
Lac Z codes for…
Beta galactosidase
Lac Y codes for…
Lactose permease
What is the function of the repressor protein in lac operon?
It binds to the operator region and blocks the promotor region so RNA polymerase can’t bind, so genes Z and Y can’t be transcribed
What is the role of lactose in lac operon?
Binds to the repressor at another site.
Causes its shape to change so it moves away from the operator, and leaves the promotor region free for RNA polymerase to bind
Z and Y genes are transcribed
Explain the advantages to E. coli bacteria having a lac operon system to induce enzyme formation
The bacteria only make enzymes when lactose is present in the culture medium.
The enzymes are inducible.
Therefore resources are not wasted in making unnecessary enzymes
What kind of system is lac operon?
Inducible negative
