GRADE 12 LIFE SCIENCES – COMPLETE ACADEMIC NOTES PACK
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MODULE 1: LIFE AT THE MOLECULAR, CELLULAR & TISSUE LEVEL
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1. DNA: STRUCTURE, REPLICATION AND APPLICATIONS
• DNA (Deoxyribonucleic acid) is a double■stranded helical molecule that carries hereditary
information.
• The building blocks of DNA are nucleotides made of:
– A phosphate group
– A deoxyribose sugar
– A nitrogenous base (A, T, C or G)
• Base■pairing rule: A pairs with T; C pairs with G.
DNA REPLICATION (SEMI■CONSERVATIVE)
Steps:
1. DNA unwinds and unzips as hydrogen bonds break.
2. Free nucleotides attach to complementary bases.
3. Two identical DNA molecules form.
Importance:
• Ensures genetic continuity during mitosis and meiosis.
Applications:
• DNA profiling
• Genetic engineering
• Forensic investigations
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2. PROTEIN SYNTHESIS
Process includes:
• Transcription – Formation of mRNA in the nucleus.
• Translation – mRNA attaches to ribosome; tRNA brings amino acids; polypeptide chain forms.
, Importance:
• Determines phenotypes and cell functions.
--------------------------------
3. MITOSIS AND MEIOSIS
MITOSIS:
• Produces 2 identical diploid cells.
• Ensures growth and repair.
MEIOSIS:
• Produces 4 haploid gametes.
• Ensures genetic variation through crossing over and independent assortment.
Significance:
• Genetic diversity in populations.
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MODULE 2: DIVERSITY, CHANGE & CONTINUITY
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1. REPRODUCTIVE STRATEGIES IN VERTEBRATES
• Internal vs external fertilisation.
• Ovipary, ovovivipary and vivipary.
• Parental care increases survival likelihood of offspring.
--------------------------------
2. EVOLUTION
Natural selection:
• Variation exists within populations.
• Environmental pressure selects favourable traits.
• Organisms with favourable traits survive and reproduce.
Speciation:
-----------------------------
MODULE 1: LIFE AT THE MOLECULAR, CELLULAR & TISSUE LEVEL
-----------------------------
1. DNA: STRUCTURE, REPLICATION AND APPLICATIONS
• DNA (Deoxyribonucleic acid) is a double■stranded helical molecule that carries hereditary
information.
• The building blocks of DNA are nucleotides made of:
– A phosphate group
– A deoxyribose sugar
– A nitrogenous base (A, T, C or G)
• Base■pairing rule: A pairs with T; C pairs with G.
DNA REPLICATION (SEMI■CONSERVATIVE)
Steps:
1. DNA unwinds and unzips as hydrogen bonds break.
2. Free nucleotides attach to complementary bases.
3. Two identical DNA molecules form.
Importance:
• Ensures genetic continuity during mitosis and meiosis.
Applications:
• DNA profiling
• Genetic engineering
• Forensic investigations
--------------------------------
2. PROTEIN SYNTHESIS
Process includes:
• Transcription – Formation of mRNA in the nucleus.
• Translation – mRNA attaches to ribosome; tRNA brings amino acids; polypeptide chain forms.
, Importance:
• Determines phenotypes and cell functions.
--------------------------------
3. MITOSIS AND MEIOSIS
MITOSIS:
• Produces 2 identical diploid cells.
• Ensures growth and repair.
MEIOSIS:
• Produces 4 haploid gametes.
• Ensures genetic variation through crossing over and independent assortment.
Significance:
• Genetic diversity in populations.
--------------------------------
MODULE 2: DIVERSITY, CHANGE & CONTINUITY
--------------------------------
1. REPRODUCTIVE STRATEGIES IN VERTEBRATES
• Internal vs external fertilisation.
• Ovipary, ovovivipary and vivipary.
• Parental care increases survival likelihood of offspring.
--------------------------------
2. EVOLUTION
Natural selection:
• Variation exists within populations.
• Environmental pressure selects favourable traits.
• Organisms with favourable traits survive and reproduce.
Speciation:
