Theoretical Genetics topic 4.3

Welcome to the section on Theoretical Genetics. Before I start this section of Topic 4 I should like to share THIS article with you. It tells of the production of a synthetic chromosome placed into a Eukaryotic cell – yeast. This is I am sure the first of many such chromosomal modifications. The question to ask now I suppose is who is going to decide what is and is not morally and ethically permissible?


During this section we will look at THIS slideshare from the excellent I-Biology Website. If you want some practice with monohybrid crosses then check out THIS website and if you want practice with Pedigree charts check out this link.

So just how do we produce Gametes which are unique – Meiosis?


I can remember when I was at school learning about Meiosis that my Biology teacher was forever going on about Meiosis and why it was just sooooo important for a species to produce offspring with different blends of alleles. Hopefully, by the time we have covered this section you will all appreciate both the importance of Meiosis, and you will be able to explain why Meiosis is often referred to as a “Reduction Division”.

We will also look at how Meiosis can go wrong, and the consequences of this; Down’s syndrome will be studied as an example.

Again we will get to play ‘Doctor’ and will learn to use the technique of Karyotyping to “diagnose” chromosome abnormalities, though obviously knowing that an unborn child has genetic abnormalities does raise many ethical implications (look back to the last post and the article on Fetus food).

Mr Taylor has produced this excellent SlideShare presentation on Meiosis from I-Biology, and we will use this site to practice Karyotyping Karyotyping Activity.

By the end of this section you should also be able to use the following key words correctly:-

haploid, diploid,  homologous chromosomes, crossing over, non-disjunction, karyotyping,trisomy


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AHL Photosynthesis

Before we start this section you have to ask yourself do you actually know the information we studied about photosynthesis in topic 3? If the answer is no go back and remind yourself of the standard level information first.

To help us to understand the process we will use this presentation from I-Biology. We will use this animation from Mc Graw Hill to help us understand the light dependent reactions. We will compare the light dependent reactions in the chloroplasts with the electron transport chain and oxidative phosphorylation that occurs in respiration. Why might the similarities be significant? Respiration can be seen here.


K Key terms: photosynthesis, chloroplast, membrane, stroma, chlorophyll, thylakoid, granum, light-dependent, light-independent, photophosphorylation, chemiosmosis, protons, photoactivation, electron transport, photosystem, photolysis, cyclic, non-cyclic, reduction, NADP+, NADPH, RuBP, carboxylase, ribulose, glycerate-3-phosphate, triose phosphate, regeneration, carbohydrates, action, absorption, spectrum, pigment, limiting factor.