Bristol University Genetics and Molecular Biology Questionnaire
I’m working on a Genetics exercise and need support.
Q1
All female dung beetles lack horns. But in some species, males have horns and in others they do not.Parrett et al (Ecology Letters (2019) 22:1629-1637) studied species persistence in 34 species of dung beetles living in progressively more disturbed environments.The presence and size of male horns were strongly associated with the persistence of the species in changing habitats.In the most disturbed environments only those species with large horned males survived.
- Why do male dung beetles have horns in only some species?
- Dung beetle species do not compete with each other.Knowing this formulate a hypothesis for the survival of horned species in highly disturbed environments.
- If very small populations of bird species are introduced to new environments those with brightly coloured aggressive males rarely become established but those with less brightly coloured and aggressive males do. Why might this be?
Q2
Budd and Campbell (Mol Cell Biol (1993) 13:496-505) studied DNA replication in yeast (Saccharomyces cerevisiae).P2-12, a novel mutant was isolated which grew normally at 20°C but would not incorporate 3H thymidine or form colonies at 37°C.Analysis of the DNA produced at the higher temperature showed no chromosomal replication.However, multiple short stretches (~20 base pairs) of RNA associated with chromosomal DNA could be recovered from the mutant.
- What type of mutant is P2-12 and why are they especially useful in genetics?
- Describe the major similarities and differences between DNA replication in Escherichia coli and yeast
- How does DNA replication differ between yeast and humans?
- In which gene do you think P2-12 is mutant. Give your reasoning.
Q3
Yamamoto et al (EMBO J (1989) 8:3543-3552) identified a novel locus for eye colour in Drosophila melanogaster called claret eye (cla).The original claCM mutant is a recessive lethal.When crossed against another recessive allele for eye colour vermillion that allele behaves as a dominant.
- What type of mutant is the claCM allele? Explain your reasoning and how you would test your prediction.
- claCM mutants also give rise to a chromosomal phenotype of mixed translocated and non-translocated chromosomes with duplications and deletions of genetic material.Describe the methods by which these chromosomal changes are visualised.Why are these particular easy to perform in Drosophila?
- Proteins can often have multiple functions.Besides eye colour what function do you think may be played by the claret eye protein? Justify your answer.
Q4. The gene for Escherichia coli glutathione reductase encodes a protein 450 amino acids in length and consists of at least one of each of the essential amino acids. The homologous mitochondrial gene in H sapiens produces a protein 522 amino acids in length and the primary transcript has a minimum length of 3034 nucleotides.
- How many unique aminoacyl tRNA synthetases and subsequent tRNA types are needed to produce this protein?
- Detail the steps that are involved in charging a tRNA with its cognate amino acid.
- Compare and contrast the major features involved in translating these genes in their host organisms.
- Detail a methodology of regulation for one of these genes describing the final effect on the gene product.
