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PLNT3140 Introductory Cytogenetics
Lecture 1, part 1 of 2

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September 7, 2017

SETTING THE EUKARYOTIC CONTEXT


Learning Checklist:

1. Be able to list differences between prokaryotes and eukaryotes

2. Introduction to the microscope


Mendelian genetics originated with the discovery of single genes - single units of inheritance.  Cytology originated in the study of chromosomes, which carry genes. For many decades, cytogenetics employed the methods of microscopy to learn about inheritance on a macroscopic scale. One therefore had the choice of working with one gene at a time using phenotypes, or to observe the whole genome at a time under the microscope. Until recent decades, the best one could do was to map a given gene to a particular chromosomal band, a very gross level of mapping.

Modern cytogenetics attempts to bring together:

At the same time, the methods of cytogenetics really only applied to organisms with large cells and chromosomes. Bacterial genetics was not amenable to study under the light microscope.

The distinction between prokaryotes and eukaryotes is one of the most fundamental concepts in biology.


Today, we distinguish between the bacteria, which are prokaryotes, and the higher organisms, which are eukaryotes.  Prokaryotes are comparatively simple organisms, with all cellular processes taking place in a single compartment. Eukaryotes are highly organized, with specialized organelles which compartmentalize key cellular functions. Cytogenetics, then is a science devoted specifically to eukaryotes. It is therefore critical for us to have a clear picture of the nature of the eukaryotic cell, the differences between eukaryotic cells and prokaryotic cells, and in particular, the differences between eukaryotic chromosomes and prokaryotic chromosomes.

The Tree of Life
from http://tolweb.org/tree/home.pages/aboutoverview.html
The Tree of Life navigation picture is licensed under the Creative Commons Attribution-No Derivative Works License - Version 3.0.


Hedges SB, Marin J, Suleski M, Paymer M, Kumar S (2015) Tree of Life Reveals Clock-Like Speciation and Diversification Mol. Biol. Evol. 32:835-845 doi:10.1093/molbev/msv037


IN CLASS EXERCISE: PROKARYOTES VS. EUKARYOTES

Recurrent themes:

These are the main take home concepts of this course. In one way or another, everything in this course relates, in some way, to these themes.


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PLNT3140 Introductory Cytogenetics
Lecture 1, part 1 of 2

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