Chapter 20 Molecular Genetics Content  • The Structure of DNA  • The Role of DNA in Protein Synthesis  • Genes  • Genetic ...
Lesson Objectives <ul><li>At the end of this lesson, you should be able to:  </li></ul><ul><li>(a) outline the relationshi...
Recap
DNA <ul><li>Deoxyribonucleic acid  ( DNA ) is a molecule that carries genetic information  </li></ul><ul><li>This informat...
How is DNA organised in cells? <ul><li>Each DNA molecule consists of 2 parallel strands twisted around each other forming ...
 
How DNA is packed into a chromosome
Basic Unit of DNA <ul><li>is called a  nucleotide </li></ul><ul><li>A nucleotide is made up of   </li></ul><ul><li>Deoxyri...
4 types of nucleotides linked to form a polynucleotide instead of thymine double ring structure  single ring structure
Nucleotides are the building blocks of DNA <ul><li>Each gene is made up of a sequence of nucleotides </li></ul><ul><li>The...
Complementary base pairing  between polynucleotides <ul><li>Adenine (A) always binds with thymine (T) </li></ul><ul><li>Cy...
A DNA molecule <ul><li>is made up of 2 polynucleotide chains  </li></ul><ul><li>running in opposite directions ( anti-para...
 
A DNA molecule
Create a DNA model worksheet
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Chapter 20 Molecular Genetics Lesson 1 - Structure of DNA

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Chapter 20 Molecular Genetics Lesson 1 - Structure of DNA

  1. 1. Chapter 20 Molecular Genetics Content • The Structure of DNA • The Role of DNA in Protein Synthesis • Genes • Genetic Engineering and Medical Biotechnology
  2. 2. Lesson Objectives <ul><li>At the end of this lesson, you should be able to: </li></ul><ul><li>(a) outline the relationship between DNA, genes and chromosomes </li></ul><ul><li>(b) state the structure of DNA in terms of the bases, sugar and phosphate groups found in each of their nucleotides </li></ul><ul><li>(c) state the rule of complementary base pairing </li></ul>
  3. 3. Recap
  4. 4. DNA <ul><li>Deoxyribonucleic acid ( DNA ) is a molecule that carries genetic information </li></ul><ul><li>This information is important for cellular functions e.g. cell division and cell differentiation </li></ul><ul><li>Without DNA, cells would not be able to carry out these vital functions </li></ul><ul><li>Almost all cells contain DNA inside their nuclei </li></ul>
  5. 5. How is DNA organised in cells? <ul><li>Each DNA molecule consists of 2 parallel strands twisted around each other forming a double helix </li></ul><ul><li>A molecule of DNA is wrapped around proteins ( histone proteins) to form a single chromatin thread </li></ul><ul><li>During cell division, chromatin threads coil tightly into chromosomes inside the nucleus </li></ul>
  6. 7. How DNA is packed into a chromosome
  7. 8. Basic Unit of DNA <ul><li>is called a nucleotide </li></ul><ul><li>A nucleotide is made up of </li></ul><ul><li>Deoxyribose (a sugar) </li></ul><ul><li>A phosphate group </li></ul><ul><li>A nitrogen-containing base ( ATGC ) </li></ul><ul><li>A denine </li></ul><ul><li>T hymine </li></ul><ul><li>G uanine </li></ul><ul><li>C ytosine </li></ul>
  8. 9. 4 types of nucleotides linked to form a polynucleotide instead of thymine double ring structure single ring structure
  9. 10. Nucleotides are the building blocks of DNA <ul><li>Each gene is made up of a sequence of nucleotides </li></ul><ul><li>The sequence of nucleotides can vary </li></ul><ul><li>This results in many different genes </li></ul><ul><li>Since there are 4 different bases and hence 4 different nucleotides, for a gene made up of n nucleotides, there are 4 n different combinations of nucleotides </li></ul>
  10. 11. Complementary base pairing between polynucleotides <ul><li>Adenine (A) always binds with thymine (T) </li></ul><ul><li>Cytosine (C) always binds with guanine (G) </li></ul><ul><li>A denine </li></ul><ul><li>T hymine </li></ul><ul><li>G uanine </li></ul><ul><li>C ytosine </li></ul>
  11. 12. A DNA molecule <ul><li>is made up of 2 polynucleotide chains </li></ul><ul><li>running in opposite directions ( anti-parallel ) </li></ul><ul><li>The bases of one chain are bonded to those of the opposite chain according to the rule of base pairing </li></ul><ul><li>A-T = 2 hydrogen bonds </li></ul><ul><li>G-C = 3 hydrogen bonds </li></ul>
  12. 14. A DNA molecule
  13. 15. Create a DNA model worksheet

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