DNA Structure & Replication
What enzyme “unzips” DNA during replication?
Helicase
What molecule carries the genetic code from nucleus to ribosome?
mRNA
What type of mutation changes one base but does NOT change the amino acid?
Silent Mutation
What does PCR stand for?
Polymerase Chain Reaction.
What enzyme does CRISPR–Cas9 use to cut DNA?
Cas9 endonuclease.
DNA is described as “semi-conservative.” What does this mean?
Each new DNA molecule contains one original strand and one newly synthesized strand.
Where does translation occur?
At the Ribosomes
What is gene flow?
The movement of alleles into or out of a population due to migration.
What is recombinant DNA technology?
Combining DNA from two different species.
What is a guide RNA?
RNA that directs Cas9 to a specific DNA sequence.
Name the enzyme that builds the new DNA strand.
DNA Polymerase III
What is a codon?
A three-base sequence on mRNA that codes for an amino acid.
Name one example of a population event that causes genetic drift.
Bottleneck or founder effect.
Give one advantage and one disadvantage of artificial insemination.
Advantage: Predictable offspring traits.
Disadvantage: reduced genetic variation long-term
How does the gene in BT cotton protect the plant against pests?
The Bt gene (from Bacillus thuringiensis) is inserted, allowing the plant to produce a toxin that kills specific insect larvae—mainly caterpillar pests—when they feed on it.
Why does the lagging strand form Okazaki fragments?
Because DNA polymerase can only add nucleotides in the 5’ → 3’ direction.
Explain the role of tRNA.
It carries specific amino acids to the ribosome and matches anticodons to codons.
Why do mutations in germline cells have greater evolutionary significance?
They can be inherited by offspring.
Describe one ethical concern related to Biotechnology.
- playing "God"
- increased research and understanding
etc.
How does PCR work
1. increase temp to 95, break the two strands.
2. decrease temp to 55, allow primers to attach near target gene
3. increase temp to 72 degrees, DNA polymerase activates to make complementary gene
Describe the role of primers in DNA replication.
They provide a short RNA sequence for DNA polymerase to extend.
Describe the steps of RNA processing in eukaryotes.
Splicing to remove introns, adding poly-A tail, adding 5’ cap.
How does changes in non-coding regions still affect phenotype.
Mutations in these regions can alter when, where, or how much a gene is expressed, which can change the resulting phenotype even though the coding sequence is unchanged.
Compare gene cloning and whole-organism cloning in terms of purpose and process, and outline one social advantage and one social disadvantage of whole-organism cloning.
Purpose:
• Gene cloning copies a specific gene for research, medicine, or biotechnology.
• Whole-organism cloning produces a genetically identical individual.
Process:
• Gene cloning uses recombinant DNA inserted into vectors (e.g., plasmids) and replicated in host cells.
• Whole-organism cloning uses SCNT — a somatic nucleus placed into an enucleated egg, then stimulated to develop.
Social advantage:
• Can preserve valuable or endangered organisms.
Social disadvantage:
• Raises concerns about animal welfare, identity issues, or the acceptability of cloning individuals.
Describe how recombinant DNA is inserted into a host organism.
Gene of interest is cut and inserted into a vector (e.g., plasmid, virus), which delivers the gene into the host’s genome.