GCSE Biology - Genetic Diagrams | Punett Squares

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*** WHAT'S COVERED ***
1. Introduction to Genetic Diagrams
* Showing combinations of alleles from two parents.
2. Representing Alleles
* Using letters (capital for dominant, lowercase for recessive).
* Example gene: mouse muscularity (Normal vs Muscular).
3. How to Draw Genetic Diagrams (5 Key Steps)
* Parents' phenotype and genotype.
* Gametes' genotype.
* Offsprings' genotype and phenotype.
4. Example 1: Crossing Homozygous Parents
* Homozygous normal (AA) crossed with homozygous muscular (aa).
* Determining gametes and offspring genotypes (all heterozygous Aa).
* Determining offspring phenotypes (all normal).
5. Introduction to Punnett Squares
* An alternative method for showing genetic crosses.
6. Example 2: Crossing Heterozygous Parents (using Punnett Square)
* Heterozygous (Aa) crossed with heterozygous (Aa).
* Determining offspring genotypes (AA, Aa, aa).
* Determining offspring phenotypes (Normal, Muscular).
7. Ratios and Probabilities
* Calculating phenotype ratios (e.g., 3:1 normal to muscular).
* Calculating probability (e.g., 25% chance of muscular offspring).
8. Example 2 Revisited: Using a Genetic Diagram
* Showing the heterozygous cross using the standard diagram format.
9. Important Considerations
* Most characteristics are controlled by multiple genes interacting.
* Environmental factors also influence phenotype.

*** CHAPTERS ***
0:00 What Genetic Diagrams Show
0:17 Representing Genes and Alleles (Dominant/Recessive)
1:02 Drawing a Genetic Diagram: The 5 Steps
1:15 Homozygous Cross - Parents
2:11 Determining Gametes
2:33 Offspring Genotypes and Phenotypes
3:21 Punnett Squares Explained
4:22 Heterozygous Cross - Punnett Square
4:59 Understanding Phenotype Ratios and Probabilities
5:37 Heterozygous Cross - Using a Genetic Diagram
6:26 Interactions & Environment

*** PLAYLISTS ***






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