What is Gene Expression?
The process where genetic information from a gene (DNA section) is used to create a functional product, usually a protein (polypeptide).
What is a Triplet in the context of genetics?
Three consecutive bases on the DNA template strand that codes for one amino acid.
What is a Codon?
Three consecutive bases on the mRNA strand that are complementary to an anticodon found on a tRNA molecule.
What is an Anticodon?
Three consecutive bases on the tRNA molecule that are complementary to an mRNA codon.
What does Degeneracy (Redundancy) in the genetic code refer to?
The code has multiple codons (64) for most of the 20 amino acids, acting as a buffer against some point mutations.
What occurs during Transcription?
Making an mRNA copy of a gene in the nucleus.
What is the role of RNA polymerase in Transcription?
It uses the DNA template strand to build a complementary, single strand of mRNA.
What happens to mRNA after Transcription?
mRNA leaves the nucleus and goes to the ribosome.
What is Translation?
Making a polypeptide chain from the mRNA code at the ribosome in the cytoplasm.
What initiates Translation?
The mRNA attaches to a ribosome at the start codon.
What do tRNA molecules do during Translation?
They carry specific amino acids and match with complementary mRNA codons.
What occurs at the end of Translation?
Translation ends at a stop codon, releasing the polypeptide.
Why is the final 3D shape of proteins significant?
It determines their function.
Define Mutation.
A permanent change in the DNA base sequence.
What is a Mutagen?
An environmental agent (e.g., UV radiation, chemicals) that increases the rate of mutations.
What is a Point Mutation?
A change in one base.
What is a Silent Mutation?
A substitution that still codes for the same amino acid, leaving the protein unaffected.
What is a Missense Mutation?
A substitution that codes for a different amino acid, potentially changing the protein’s shape and function.
What is a Nonsense Mutation?
A substitution that creates a premature STOP codon, resulting in a significantly shorter, non-functional protein.
What are Frameshift Mutations?
Insertion or deletion of one or two bases that shifts the entire reading frame of the codons.
What is a Metabolic Pathway?
A series of enzyme-controlled reactions where the product of one reaction becomes the substrate for the next.
What is the relationship between Gene, Enzyme, and Phenotype?
Each gene codes for a specific enzyme, and enzymes control the steps in the pathway to produce the final phenotype.
How can a mutation affect metabolic pathways?
A mutation that makes an enzyme dysfunctional will block the pathway, preventing the final product from being made.
How can the environment affect phenotype?
Environmental factors can affect the expression of a gene without changing the DNA sequence.
