2. Psychology Fossils and Evolution Global Systems DNA and Inheritance
Topics Covered
Fossils and Evolution
Psychology
Global Systems

3. 1.1 DNA the molecule (page 2)
DNA and Inheritance
1.1 DNA the molecule (page 2)

4. Introduction

5. DNA DNA stands for Deoxyribonucleic acid
Found in the nucleus of cells.
It determines the characteristics of living things.
For example, hair colour, eye colour, bone structure, height.
They are instructions for making an animal or plant.
Ladder-like structure called a double helix.
A molecule of DNA is made up of millions of tiny subunits called nucleotides

6. Nucleotides

7. Nucleotides Each nucleotide consists of: Sugar Phosphate group
Pentose sugar
Nitrogenous base
Nucleotides
Phosphate
Sugar
Nitrogenous Base

8. DNA Structure
The phosphate and sugar form the backbone of the DNA molecule
The bases form the “rungs”
There are four types of nitrogenous bases:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Each base will only bond with one other specific base (Nitrogenous base pairing)
C and G always pair together and
T and A

9. Complementary Base Pairing
The order of one strand determines the order of the other.
This is known as the complementary base pairing.
The sequence of these nitrogen bases along the strands of DNA is the basis for all inherited characteristics.
Original Sequence
Complementary Sequence

10. Nitrogenous base pairing
Each base will only bond with one other specific base.
Cytosine and Guanine
Thymine and Adenine
That means, if there are 50 Cytosine's in a DNA molecule, there will also be 50 Guanines – as they come as a pair!
Nitrogenous base pairing

11. Modelling DNA activity
Your task is to construct a DNA molecule
Insure you label All parts of the DNA molecule including:
Nucleotide
Hydrogen Bond
DNA backbone
Original and Complementary sequence
*hint* there should be 12 labels in total
Answer the following questions
State the base pairing rule
Compare you model to others in the class. Are they the same? Describe the similarities and differences
Calculate the number of different variations of single DNA Strands that can be made using only the 10 bases you started off with

12. Prac #1 -Extracting DNA from peas
The following website is an useful resource to help answer the discussion questions

13. What is DNA?

14. The Genetic Code
Each strand of DNA contains thousands of sequences of bases A, T, G and C
This long sequence of bases is read in sets of three.
Each set of three is called a codon

15. There are 20 amino acids that can be used to make protein
The body can only make 11 amino acids. The others are too slow to synthesis therefore must be obtained through our diet.
Making a protein

16. The sequence of Amino Acids in a protein that determines its function.
The shape of the protein depends on its primary structure, which then determines the proteins properties and functions
Primary Structure

17. Roles of Proteins
Some proteins are enzymes (speed up reactions) Eg: digestive system
Act as messengers between cells
Make up cellular components such as muscle, hair and nails
Act as ‘gatekeepers ‘ which allow substances to enter and leave cells
Produce haemoglobin which transports oxygen to our cells.
Also involved in producing insulin which controls our blood sugar levels.

18. Enzymes: speed up chemical reactions
Enzymes of the digestive system
Enzymes: speed up chemical reactions

19. This diagram shows a cross section of four plasma membrane proteins performing different functions as gate keepers

20. Haemoglobin: transports oxygen to our cells

21. Insulin: controls blood sugar levels

22. DNA to Protein

23. How to make a protein? Step 1: DNA is copied into mRNA
The DNA triplets are COMPLEMENTARY to a group of 3 RNA bases, known as a codon
Cytosine (C) still pairs with Guanine (G)
Adenine (A) pairs with Uracil (U).
Eg. DNA: CAT TAC GTA GAA GTC CCA TAA
mRNA: GUA AUG CAU CUU CAG GGU AUU

24. How to make a protein? Step 2: mRNA is used to read the codon chart.
Three bases in a mRNA sequence is called a codon. Each codon is associated with an amino acid
You will use a codon chart to make this match
Abbreviate each amino acid (use first three letters)
mRNA: GUA AUG CAU CUU CAG GGU AUU
Amino acid: val met his leu glu gly iso
How to make a protein?

25. A codon chart is used to determine the amino acid sequence of a protein
There are 64 different codons and form these 20 different amino acids codes for 1000s if proteins.
The Codon Chart

26. The Codon Chart