Science E-Learning: Chapter 5: Genetics (Gene, DNA and Chromosomes)

DAY 1: Cell Division
1. Gene, DNA and Chromosomes

Genes
Genes are sections of DNA that code for the production of protein and are arranged along the chromosomes.
Carry the inherited characteristics of a person.
Genes occurs in pairs, therefore each inherited characteristics is carried by two genes.
One gene from each pair comes from the father and the mother.
Example of inherited characteristics carried by genes are colour of the eyes, pattern of finger prints, type of hair, blood group and etc.
DNA (Deoxyribonucleic acids)
A double helix, made up of a series of genes to encode genetic information.
This determine the individual characteristics of an organism.
All the information in DNA is transmitted in the form of a genetic code.
Should any information not be followed, the baby will be born with physical or mental defects.
DNA molecule is very complicated and resembles a twisted ladder or staircase.

Chromosomes
Is a thread-like structure found in the nucleus of a cell.
Chromosomes and the genes on them are composed of DNA.
It exist in pair and are identical-->homologous.
A pair of chromosomes has genes arranged in the same way. As a result the genes also exist in pairs.
Human has two sets of chromosomes in the body(one set from the father and another set form the mother).

2. Mitosis

Mitosis is occur in somatic cells --> all cells body except reproductive cells.
Mitosis is the type of cell division that produces genetically identical cells.
During mitosis, DNA replicates in the parent cell, which divides to produce two new cells, each containing an exact copy of the DNA as in the parent cell.
This allows growth of multicellular organism from unicellular zygotes.
Mitosis is the basis of asexual reproduction --> the production of new individuals of a species by one parent organism.
Cells produced are diploid (2n).
Replacement of cells and repair of tissues is possible through mitosis. For example, cell replacement is rapid in the skin & in the lining of the gut.
Mitosis is actively carried out at the ends of plant shoots and roots.
Mitosis is divided into four phases.

To understand more about mitosis, please watch this video:https://www.youtube.com/watch?v=DwAFZb8juMQ

3. Meiosis

Meiosis is the process by which a nucleus divides by two divisions into four nuclei, each containing half the number of chromosome of the mother cell.
Resulting nuclei are haploid (n).
The cells produced are genetically different to the parent cell and to each other.
Occurs in 2 stages that is meiosis 1 and meiosis 2.
Produces genetic variation (caused by crossing over between homologous chromosome).
In animals, meiosis occurs in testes and ovaries, whereas in plants, it occurs in the anthers and ovaries.

To understand more about meiosis, please watch this video:https://www.youtube.com/watch?v=7EvtgLLuJpo

4. Formative Practice

DAY 2: Quiz

DAY 3: Inheritance

1. Inheritance

In order for you to do this activity, please read the subtopic Inheritance in your textbook.
Watch any video in the Youtube and do research in the internet to get more information about inheritance.
Answer the questions below in foolscap paper.

1. Diagram below shows the sex determination in human

2. Diagram below shows schematic diagram for hair types.

3. Draw a schematic diagram of:

Science E-Learning