Lesson Notes By Weeks and Term v4 - SHS 2
CELL STRUCTURE AND FUNCTIONS
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CELL STRUCTURE AND FUNCTIONS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Biology
Class: SHS 2
Term: 2nd Term
Week: 4
Grade code: 2.2.2.LI.3
Strand code: 2
Sub-strand code: 2
Content standard code: 2.1.2.CS.1
Indicator code: 2.2.2.LI.3
Theme: LIFE IN THE FUNDAMENTAL UNIT
Subtheme: CELL STRUCTURE AND FUNCTIONS
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Welcome, students! Today, we are going to explore the most important molecules in our bodies: DNA and RNA. Have you ever wondered why a mango seed always grows into a mango tree and not a pawpaw tree? Or why children often resemble their parents? The answer lies in a special instruction manual found inside every living cell. This manual is called DNA. In Ghana, understanding DNA helps us tackle important issues like sickle cell anaemia, a genetic disease common in our communities, and helps our scientists at places like the Crops Research Institute (CRI) in Kumasi to develop better, stronger crops like cassava and maize.
A. The Building Block: The Nucleotide
Imagine you are building a house with blocks. The most important molecules of life, nucleic acids (like DNA and RNA), are also built from small, repeating blocks. This block is called a nucleotide.
Every nucleotide, whether for DNA or RNA, has three parts: A Phosphate Group: This is a group containing a phosphorus atom bonded to oxygen atoms. It helps link nucleotides together to form a long chain. A Pentose Sugar: A sugar molecule with five carbon atoms. This is the "backbone" of the nucleic acid. A Nitrogenous Base: This is the most interesting part. It's a molecule containing nitrogen, and it holds the genetic code.
Think of it like a simple unit: Phosphate – Sugar – Base. B. DNA (Deoxyribonucleic Acid): The Master Blueprint