Learning Science Channel: Heredity, Inheritance, and Variation

Introduction

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• Topics include biology, chemistry, earth science, and physics.
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Today's Topic: Heredity, Inheritance, and Variation

Heredity

• Definition: Transmission of genetic characters from parents to offspring.
• Natural process of passing characteristics and potentialities to the next generation.
• Example: Child inherits certain traits from both parents (e.g., eyes, nose, hair color).

Inheritance

• Definition: Acquisition of genetic qualities by offspring.
• Involves the combination of genetic material from two parents in sexual reproduction.
• Certain genes dominate the expression of traits over others.
• Example: Child's characteristics from each parent (e.g., eyes from father, lips from mother).

Genetic Variation

• Refers to differences among individuals or populations.
• Results from different gene sequences among individuals within a species.
• Example: Variations in eye color (blue, brown, green).

Genetic Vocabulary

Phenotype

• Definition: Observable physical properties of an organism (appearance, development, behavior).
• Examples: Pointed nose, blue eyes, straight hair.

Genotype

• Definition: Complete set of heritable genes or alleles passed down from parents.
• Examples: NN for pointed nose, Bb for blue eyes, SS for straight hair.
• Refers to alleles inherited for a particular gene.

Alleles

• Definition: Alternative forms of a gene in a genotype.
• Represented by letters (capital for dominant, lowercase for recessive).
• Examples: NN or nn for nose, Bb or bb for eyes.

Dominant and Recessive Traits

Dominant Traits

• Inherited characteristics that appear if contributed by a parent through a dominant allele.
• Represented by capital letters.
• Example: BB for brown eyes, DD for dimples.

Recessive Traits

• Weak, unexpressed traits in the phenotype of a heterozygous individual.
• Represented by lowercase letters.
• Example: bb for blue eyes, dd for no dimples.

Homozygous and Heterozygous Traits

Homozygous Traits

• Made up of two identical alleles.
• Examples: AA, FF, gg, ii.

Heterozygous Traits

• Made up of two different alleles.
• Examples: Aa, Ff, Gg, Ii.

Interactive Question

• Family scenario: Father is tall, mother is short, child is tall.
• Question: Is the mother's trait dominant or recessive?
• Invitation to answer in the comments.

Conclusion

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• Invitation to join future lessons.