Genomes, genes and alleles Flashcards
Gene expression
The process by which functional products, such as proteins, are produced through two stages: Transcription and Translation.
Gene regulation
The process by which cells can either turn on or off gene expression.
State the function of RNA polymerase
Copies DNA template strand into pre-mRNA via complementary base pairing
template strand
It is the strand of DNA that is copied into a pre-mRNA transcript during transcription.
Genome
All the genetic information (DNA) in an individual or cell.
Transcription followed by RNA processing.
Step 1: DNA unwinds and RNA polymerase attaches to the promoter region (+ context).
Step 2: DNA template strand is copied into pre-mRNA via complementary base pairing using RNA polymerase.
Step 3: pre mRNA undergoes RNA processing. Introns are removed, a 5’ methyl G cap and 3’ poly-A tail are added to form mRNA.
Step 4: mRNA from the _________ gene leaves the nucleus and goes to a ribosome.
Describe RNA processing
Introns are removed, a 5’ methyl-G cap and a 3’ poly-A tail are added to form mRNA
What is the purpose of a 5’ methyl cap and 3’ poly A tail?
5’ Methyl-G cap (which is added to the 5’ end) protects the mRNA from enzyme degradation and allows the ribosome to bind to the mRNA to begin translation. Poly-A tail (added to the 3’ end) also protects the mRNA from enzyme degradation and allows the mRNA to leave the nucleus.
Translation
Ribosomes read the mRNA code for (context)
tRNA brings the correct and specific amino acid to the ribosome.
tRNA anticodons are complementary and specific to mRNA codons. Step 4: Amino acids are joined together by peptide bond in a condensation polymerisation reaction to form a (context) polypeptide
Ribosome
Translates the mRNA into (context) polypeptide
mRNA codons
Groups of three RNA bases that code for specific amino acids or represent “End” of Translation.
tRNA anticodon
A group of three RNA bases found in a tRNA. It is complementary to a particular mRNA codon, allowing the tRNA molecule to bind to its complementary mRNA codon in the mRNA molecule.
Degenerate code
It refers to the fact that multiple codons can code for the same amino acid
Mutation
A change in the genetic code (in the DNA sequence).
Point mutations
Mutations that involve a single base change in the DNA sequence.
Examples: Substitution, Insertion, and Deletion.
Silent mutation
the mutated codon codes for the same amino acid as the original codon.
Missense mutation
the mutated codon codes for a different amino acid than the original codon.
Nonsense mutation
the mutated codon becomes a stop codon.
Frameshift mutation
A deletion or addition of bases in the DNA sequence that changes the reading frame of the DNA. It often results in multiple changes in the amino acid sequence
Gene
The hereditary unit, which is a section of DNA occupying a specific location on a chromosome. It determines the characteristic of an organism by directing the formation of a protein.
Allele
Variation of a gene at a particular gene locus.
Genotype
The allele combination of an individual
Homologous chromosomes
Chromosomes that have identical gene loci.
Homozygous
having two of the same allele for a gene at a specific gene locus.
