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In I/GCSE Biology, it is important to remember the topic regarding bacteria and DNA. Let's get started!!!! 😁
Inside Bacteria
Do you remember the previous post regarding the plant and animal cells in I/GCSE Biology? Can you distinguish them with bacteria?
Inside bacteria, we can see:
- No nucleus
- Chromosomal DNA – carries most of the genes
- Some have extra circles of plasmid DNA containing additional genes
- Cell membrane
- Some have flagellum to help them move
- Many have a cell wall for protection, but this is made out of a different substance to plant cell walls
- Ribosomes
DNA
- The nucleus contains chromosomes.
- A chromosome consists of a string of genes.
- A gene is a short piece of DNA that codes for a specific protein. Each gene is a length of DNA.
- DNA is formed of two strands that twist into a double helix.
- The two strands are joined with bases.
- Weak hydrogen bonds between the base pairs hold the DNA strands together.
- Four bases are: A = adenine T = thymine, C = cytosine G = guanine
Look at the digrams showing DNA below to have a clear concept!
DNA Discovery
In I/GCSE Biology, don't forget to study DNA discovery!
- Maurice Williams and Rosalind Franklin studied the structure of DNA using x-rays.
- Franklin studied x-ray photos to work out how the atoms were grouped.
- James Watson and Francis Crick interpreted data from other scientists including Franklin to build the double helix model.
The Human Genome Project
- Genome – complete set of DNA plus genes
- Scientists in 18 different countries collaborated to decode the human genome, the order of bases on all the human chromosomes
And we're done with this topic! Well Done!
Drafted by Alyssa (Biology)
References:
- "IGCSE Biology Notes", https://lh5.googleusercontent.com/0wkp5SYbprApyhDfyNvskJbgNlU4QOUX3sCxohOs9MBHOjXtaOY3hn-jKlF6lgXjXK4yBsL25PYY3RIWF9zZjGcT_X8rNUw1OwS2yyb6kBGVH5H5K1BDqfh--2WJir8iGcvgU8Ki
- "4.2 An Overview of Basic Genetics", https://open.lib.umn.edu/app/uploads/sites/206/2018/10/4.2-Deconstructed-DNA-2-01-974x1024.png
- "Structure of DNA", https://ib.bioninja.com.au/_Media/crystallograph4_med.jpeg
- "The Human Genome Project". Photo from the internet.