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In this post, we're looking at the topic of genetic in I/GCSE Biology. Let's get started! 😆
What are genes?
In I/GCSE Biology, you should be able to know what genes are!
Do you know the difference between DNA and genes in I/GCSE Biology?
- A GENE ➡️ a short section of DNA.
- Genes carry instructions that control how you develop and function
- they are long molecules of a molecule called DNA.
- Each gene codes for a specific protein by specifying the order in which AMINO ACIDS must be joined together.
These proteins can be:
- STRUCTURAL PROTEIN: Gives the body structure, rigidity and strength
- E.g. Skin, Hair, Muscles etc
- FUNCTIONAL PROTEIN: Enables the body to function
- E.g. Enzymes, Antibodies etc.
Variation
In I/GCSE Biology, variation is commonly asked in the exam!
- GENOTYPE – The genetic makeup of an organism. The different characteristics that an individual inherits, E.g. whether you have dimples or not.
- PHENOTYPE – The observable characteristics the organism has. How the environment changes an individual, E.g. cutting the skin may cause a scar.
IDENTICAL TWINS have the same set of genotype however any differences between them is because of environment.
CONTINOUS VARIATION shows when some characteristics are controlled by several genes working together
- e.g. eye colours and height
- For instance it was originally believed that eye colour was due to a single gene.
- It is now known that there are a number of genes coding for different pigments in the iris, mainly on chromosome 15 in humans.
- This means that there is enormous variation in eye colour.
And we're done with this topic! Well Done!
Drafted by Alyssa (Biology)
References:
- "Chromosomes & Chromatin", https://cellorganelles-kfaith.weebly.com/uploads/1/8/5/7/18578962/7871050_orig.png?250
- "Protein structure", https://cdn.kastatic.org/ka-perseus-images/71225d815cafcc09102504abdf4e10927283be98.png
- "Continuous, discontinous", https://biology-igcse.weebly.com/uploads/1/5/0/7/15070316/3615527_orig.png