Lesson Notes By Weeks and Term - Senior Secondary 3

Biology of heredity 1

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TERM – 1ST TERM

WEEK FIVE

Class: Senior Secondary School 3

Age: 17 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: Biology Of Heredity 1

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Define heredity.
  2. Define Variation
  3. Discuss the process of transmission of hereditary traits from parents to offspring
  4. Identify the location of chromosomes in the body

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher introduces heredity and discuss the basics concepts used in genetic

Students pay

attention

STEP 2

EXPLANATION

Teacher explain Variation and describe the structure and location of chromosomes in the body

Students pay

attention and

participate

STEP 3

DEMONSTRATIO

N

Teacher discusses the process of transmission of hereditary traits from parents to offspring

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

 

The students

copy the note in

their books

 

NOTE

BIOLOGY OF HEREDITY 1

Heredity

Heredity is the passing of genetic traits or characteristics from parents to offspring through the transmission of genetic information, typically in the form of DNA and the expression of these inherited traits is influenced by a combination of genetic and environmental factors.This process is fundamental to the continuity of traits across generations in living organisms.

The following are basic genetic Concepts

  1. Gene: A segment of DNA that codes for a specific trait or function.
  2. Allele: Different forms of a gene, located at the same position on homologous chromosomes.
  3. Genotype: The genetic makeup of an organism, representing the combination of alleles for a particular trait.
  4. Phenotype: The observable physical or biochemical characteristics of an organism, determined by its genotype and influenced by the environment.
  5. Dominant: An allele that expresses its trait even if only one copy is present in the genotype.
  6. Recessive: An allele that is expressed only when two copies are present in the genotype.
  7. Homozygous: Having identical alleles for a particular gene (e.g., AA or aa).
  8. Heterozygous: Having different alleles for a particular gene (e.g., Aa).
  9. Genetic Variation: Differences in genetic material among individuals of a population.
  10. Mutation: A change in the DNA sequence, which can lead to variations in traits.
  11. Chromosome: Thread-like structures in the cell nucleus that carry genetic information.
  12. Crossbreeding: Breeding individuals from different populations or species to produce offspring with desirable traits.
  13. Pedigree: A diagram that shows the relationships and inheritance of traits within a family.
  14. Genetic Engineering: Manipulation of an organism's genes to achieve specific traits or outcomes.
  15. Mendelian Inheritance: The principles of heredity proposed by Gregor Mendel, including the laws of segregation and independent assortment.

Variation

Variation refers to the differences in traits or characteristics among individuals of the same species. It can result from genetic factors, environmental influences, or a combination of both, contributing to the diversity observed within populations.

Chromosomes - Location and Structures

Chromosomes are thread-like structures located in the cell nucleus, composed of DNA and proteins. They carry genetic information in the form of genes. Humans typically have 23 pairs of chromosomes, with one set inherited from each parent. The structures on chromosomes that determine specific traits are genes.


Process of Transmission of Hereditary Traits from Parents to Offspring

The process involves reproduction through sexual or asexual means. In sexual reproduction, specialized cells (gametes) with half the usual number of chromosomes fuse during fertilization, forming a zygote with a complete set of chromosomes. This zygote then undergoes cell division and differentiation, eventually developing into an organism with a combination of genetic material from both parents.

Probability in Genetics

Probability plays a crucial role in understanding the inheritance of traits. The principles of probability, as established by Mendel, help predict the likelihood of certain traits appearing in offspring. For example, in simple Mendelian inheritance, the chance of inheriting a dominant or recessive trait is determined by the probability of receiving specific alleles from each parent.

In more complex situations, such as dihybrid crosses or situations involving multiple genes, probability calculations become more intricate. The Punnett square is a tool commonly used to visualize and calculate probabilities in genetic crosses, aiding in the prediction of offspring genotypes and phenotypes.

EVALUATION: 1. What is heredity

  1. Describe the process of transmission of hereditary traits from parents to offspring
  2. How can you determine probability in genetics.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively