Bio Reading 7 - Bio Reading 7 Why It Matters Sickle cell anaemia is a dominant allele It protected from malaria which is why this ended up occurring

Bio Reading 7 - Bio Reading 7 Why It Matters Sickle cell...

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Bio Reading 7Why It MattersSickle cell anaemia is a dominant alleleIt protected from malaria, which is why this ended up occurring10.1 - The Beginning of Genetics: Mendel’s Garden PeasBefore this, blending theory of inheritance which suggested that hereditary traits blend evenly in offspring through mixing of parent’s bloodMendel studied a variety of heritable characteristics called charactersA variation of a character is called a traitMendel recorded observations and noticed that blending did not occur, but parental traits were passed on10.1a – Mendel Chose True-Breeding Garden Peas for His ExperimentsPea plants were used because they were easy to growMale gametes are sperm nuclei produced in anthers of the flowerFemale gametes are egg cells produced in the carpel of flowersNormally, they self-fertilize, but Mendel prevented this so he could cross-pollinateMendel chose plants that were known to be true-breeding (create identical offspring)10.1b – Mendel First Worked with Single-Character CrossesCrossed purple flowers with white flowersFirst generation called F1 and P generation was parentsF2 generation was offspring of F1Found a 3:1 ratio of phenotype with more purple than white10.1c – Mendel’s Single-Character Crosses Led Him to Propose the Principle of SegregationMendel’s first hypothesis: The adult plants carry a pair of factors that govern the inheritance of each characterThe different versions of a gene that produce different traits of a character are called allelesMendel’s second hypothesis: If an individual’s pair of genes consist of different alleles, one allele is dominant over the other, recessive alleleWhen an organism carries two different alleles, the dominant allele is simply the one that determines the appearance of the organismDominant alleles do not directly inhibit recessive alleles. Recessive alleles were created by mutations that results in a non-functional enzymeMendel’s third hypothesis: the pairs of alleles that control a character segregate as characters are formed; half the gametes carry one allele, and the other half carry the other allele. This is now known as Mendel’s Principle of segregationGenotype is genetic constitution of an organismPhenotype refers to its outward appearance
10.1d – Mendel Could Predict Both Classes and Proportions of Offspring from His Hypothesis

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