|| BS22620 |
|| EXPLORING GENETICS |
|| 2001/2002 |
|| Dr Glyn Jenkins |
|| Semester 2 |
|| BS10510 |
| Course delivery
|| Lecture || 30 Hours |
|| Practical || 15 Hours (5 x 3 hours) |
|| Exam || 3 Hours One 3-hour theory paper || 100% |
|| Resit assessment || 3 Hours One 3-hour theory paper || |
The course revolves around the gene and has six interrelated sections:
Concept of the Gene: This section describes how our concept of the gene has been influenced
by key discoveries and experiments to the present day. It gives prominence to Benzer's fine structure analysis of the rII locus of T4 bacteriophage, complementation, recombination, colinearity of genes and proteins, and the molecular structure of eukaryotic genes.
Genomic Environment of the Gene: This sections deals with the C-value paradox and the biochemical means by which the complexity of eukaryotic genomes may be assayed. It describes in detail the various classes of DNA components in a typical genome of a eukaryote, including centromeres, telomeres, repetitive sequences and transposable elements.
Meiosis and Recombination of the Gene: This section begins with a comparison between mitosis and meiosis and follows with a description of premeiotic events. The ultrastructure and behaviour of chromosomes at each substage of meiosis is described in detail, with particular emphasis upon homology, chromosome pairing and synapsis. The chiasmatype theory is reviewed with supporting evidence, before a detailed description of the distribution of chiasmata, both within and between chromosomes and chromatids. Gene conversion in Ascobolus immersus is considered before reciprocal and non-reciprocal recombination are integrated into Holliday's molecular model. Mitotic recombination is contrasted, with reference to Drosophila melanogaster and the parasexual cycle of Aspergillus nidulans.
Mapping of the Gene: This section recaps on the discovery of linkage before launching into the theoretical aspects of a worked example of three-point linkage analysis in Drosophila melanogaster. It covers also molecular marker maps, deletion mapping, chromosome mapping and the applications of such exercises.
Cytoplasmic Inheritance of the Gene: Non-Mendelian inheritance patterns are interpreted in terms of cytoplasmic inheritance in the classic examples of variegation in Mirabilis jalapa and the petite mutants of yeast. Consideration is also given to the molecular structure of the genomes of chloroplasts and mitochondria, and the endosymbiosis hypothesis.
Chromosome Environment of the Gene: Conventions on chromosome number, morphology, nomenclature and karyotyping introduce a major section on variation in chromosome number. The nature and consequences at mitosis and meiosis of aneuploidy and euploidy are considered. The classic experiment of Karpachenko prefaces a section on allopolyploidy, in which the origin, genetic segregation and evolution of this condition are described. Supernumerary B-chromosomes are briefly alluded to. Variation in chromosome structure is introduced by a description of the consequences of different types of chromosome breakage. Deficiencies, duplications, inversions and translocations are covered, with emphasis upon the mechanical and genetical problems arising during meiosis.
The practicals integrate with, and complement several of the sections above, covering meiosis in Allium ursinum, and three-point linkage analysis in Drosophila melanogaster and Aspergillus nidulans.
On completion of this module, students should be able to
interpret the structure, complexity and behaviour of genes ,chromosomes and genomes
explain the way in which these underpin and impinge upon a variety of biological systems.
Aims and objectives
The aim of this module is to consolidate and build upon some of the
genetics principles laid down in the level 1 module Introductory Genetics, and to provide a
sound knowledge base for the advanced specialised modules in genetics and molecular
biology in Level 3.
** Recommended Text
Brown, T.A.. (1999)
Genomes. Oxford: Bios Scientfic Publishers.
John, B.. (1990)
Meiosis. Cambridge University Press.
Lewin, B.. (1999)
Genes VII. Oxford University Press.
Rees, H. & Jones, R.N.. (1977)
Chromosome genetics. Arnold.
Stickberger, M.W.. (1985)
Genetics. 3rd. Macmillan, New York.
** Should Be Purchased
Griffiths, A.J.F., Miller, J.H., Suzuki, D.T., Lewontin, R.C. & Gelbart, W.M.. (1996)
An introduction to genetic analysis. 6th. Freeman, New York.
Klug, W.S. & Cummings, M.R.. (2000)
Concepts of genetics. 6th. Prentice Hall.