Lesson Notes By Weeks and Term v4 - SHS 1
THE HUMAN BODY AND HEALTH
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THE HUMAN BODY AND HEALTH
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: General Science
Class: SHS 1
Term: 2nd Term
Week: 19
Grade code: 3.4.1.LI.2
Strand code: 4
Sub-strand code: 1
Content standard code: 3.4.1.CS.2
Indicator code: 3.4.1.LI.2
Theme: RELATIONSHIPS WITH THE ENVIRONMENT
Subtheme: THE HUMAN BODY AND HEALTH
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This lesson explores the fascinating science of heredity—why we inherit certain characteristics from our parents. Have you ever been told, "You have your mother's eyes" or "You walk just like your father"? These resemblances are not coincidences; they are the result of genetic information passed down through generations. In Ghana, understanding heredity is especially important for our health, as it helps us understand conditions like Sickle Cell Disease and albinism, which are present in our communities.
This section breaks down the essential vocabulary and processes for understanding Mendelian genetics. A. Fundamental Concepts of Heredity Heredity: The passing of physical or mental characteristics (traits) from parents to offspring (children). Genetics: The scientific study of heredity and the variation of inherited characteristics. Trait: A specific characteristic of an individual, like height, eye colour, or the ability to roll your tongue. Gene: A section of DNA that carries the instructions for a particular trait. Think of it as a "recipe" for a characteristic. For example, there's a gene for earlobe shape. Allele: The different forms or versions of a single gene. For the earlobe shape gene, the alleles might be "unattached earlobe" and "attached earlobe." We inherit one allele from each parent for every gene. Alleles are represented by letters (e.g., E and e). B. Dominant and Recessive Alleles Dominant Allele: This is the "stronger" allele. If an individual has at least one dominant allele, that is the trait that will be expressed (seen). It is represented by a capital letter (e.g., T for tallness). Recessive Allele: This is the "weaker" allele. This trait is only expressed if the individual has two copies of the recessive allele. It is represented by a lowercase letter (e.g., t for shortness).
Example: For the trait of tongue rolling, the ability to roll your tongue (R) is dominant over the inability to do so (r). If a person has the alleles RR or Rr, they can roll their tongue. Only a person with the alleles rr can not roll their tongue. C. Genotype vs. Phenotype Genotype: The actual genetic makeup or combination of alleles for a trait. It is represented by the letters. Examples: RR, Rr, rr. Phenotype: The observable physical characteristic or trait that is expressed as a result of the genotype. It is what you can actually see. Examples: "Can roll tongue," "Cannot roll tongue."
Let's connect them: | Genotype | Phenotype | | :--- | :--- | | RR | Can roll tongue | | Rr | Can roll tongue | | rr | Cannot roll tongue| D. Homozygous vs. Heterozygous Homozygous: When an individual has two identical alleles for a particular trait. Homozygous Dominant: Two capital letters (e.g., RR). Also called "purebred dominant." Homozygous Recessive: Two lowercase letters (e.g., rr). Also called "purebred recessive." Heterozygous: When an individual has two different alleles for a particular trait (e.g., Rr). Also called "hybrid." The dominant trait will be expressed. E. The Punnett Square: Predicting Outcomes
A Punnett square is a simple diagram used to predict the possible genotypes and phenotypes of offspring from a cross between two parents.