Gene-ius at work
What are the three components of a DNA nucleotide?
A phosphate group, a deoxyribose sugar and a nitrogenous base.
What is the term for a DNA segment that contains information to produce a functional product?
Gene
What does PCR stand for?
Polymerase chain reaction
What is a disease-causing agent called?
Pathogen
What is the genetic makeup of an organism called?
Genotype
Which nitrogenous base pairs with adenine in DNA, and which pairs with guanine?
Adenine pairs with thymine; guanine pairs with cytosine.
Which parts of eukaryotic pre-mRNA are removed during RNA processing?
Introns
Which enzyme joins DNA fragments together?
DNA ligase
Which type of immunity provides a rapid, non-specific first line of defence?
Innate immunity
What is the observable expression of an organism's characteristics called?
Phenotype
What are the three main stages in eukaryotes involved in using the information in a protein-coding gene to produce a protein?
Transcription, RNA processing and translation.
What type of protein binds to specific DNA sequences to regulate transcription?
Transcription factor
During gel electrophoresis, which electrode does DNA move towards?
Positive electrode
Which cells differentiate into plasma cells that secrete antibodies?
B lymphocytes
What process causes advantageous, heritable traits to become more common in a population?
Natural selection
A DNA template strand contains the sequence 3′–TAC GGA CTT–5′. What is the complementary mRNA sequence?
5′–AUG CCU GAA–3′.
Cells can produce more protein products than genes they contain. How is this possible?
Alternative splicing.
What two components are needed when constructing recombinant DNA?
Restriction enzyme and target DNA
Why does a vaccinated person often produce antibodies more rapidly following later exposure to the same antigen?
Memory B/T cells enable a faster secondary immune response.
A population of insects contains pesticide-resistant and susceptible individuals. Explain why resistance alleles may increase in frequency after repeated pesticide use.
Resistant insects are more likely to survive and reproduce, passing resistance alleles to offspring.
A mutation changes a codon in a gene but does not change the amino acid encoded. Name the type of mutation and the property of the genetic code responsible.
Silent mutation and degenerate.
If trp levels are high in E. coli, how does the cell lower these levels?
Repression - trp binds to repressor protein that prevents transcription
OR
Attenuation - double trp in the mRNA code results in a terminator hairpin loop
In CRISPR-Cas9 gene editing, explain the roles of guide RNA and Cas9.
Guide RNA directs Cas9 to the target DNA, and Cas9 cuts it.
A virus infects a body cell and begins reproducing inside it. Which immune cells can recognise and destroy the infected cell, and how do they recognise it?
Cytotoxic T cells, MHC class I
Two geographically isolated populations accumulate genetic differences over many generations. Explain how they could eventually become separate species.
Variation in original species, different selection pressures, no gene flow.