From Gene to Protein. Wednesday, 26th July

Transcription

1 From Gene to Protein Wednesday, 26th July

2 Overview During this session, you will explore the following questions: What are the building blocks of DNA? What are proteins made of? How does genes get translated into proteins? BREAK Practical on the activity of enzymes Investigating the effect of substrate concentration and ph on the activity of catalase Analysing the effect of varying surface area

3 Macromolecules in the Cell

4 Macromolecules in the Cell (A) DNA (B) Haemoglobin (C) Phosphatidylcholine lipid molecule from a cell membrane (D) Branched complex carbohydrate

5 Macromolecules in the Cell Class of Biomolecules Proteins (most abundant) Nucleic acids Lipids Carbohydrates Main cell functions Catalysts Signal molecules Receptors for signal molecules Structural roles Information storage and transfer Storage of energy Structural roles Storage of energy Cell-to-cell communication

6 Structure of the cell

7 Nucleic Acids

8 Structure of DNA

9 Nucleotides codons amino acids 3 nucleotides form 1 codon 1 codon codes for one amino acid 1 start codon, ATG 3 stop codons, TAA, TAG, TGA

10 Other nucleotide functions Nucleotides act as: the precursors of DNA and RNA energy carriers (high energy carriers: e.g. ATP [universal currency of energy in biological systems], GTP [involved in protein biosynthesis as energy source], CTP and UTP) components of enzyme cofactors (e.g. adenine nucleotides are components of three major co-enzymes NAD+, FAD+ and CoA) regulators and chemical messengers (e.g. camp and cgmp)

11 Functions of RNA mrna (messenger RNA) contains the information of just one gene and is transported from the site of transcription to the ribosome. rrna (ribosomal RNA) has a structural function as part of the ribosomal complex. Plays a major part in how the mrna docks onto the ribosome. trna (transfer RNA) carrier of activated amino acids to the ribosome for protein synthesis.

12 DNA/RNA locations DNA Nucleus / nucleic-like zone Mitochondria Chloroplasts RNA Nucleus Mitochondria Chloroplasts Cytoplasm Ribosome

13 Endosymbiotic theory

14 Transcription

15 Overview of transcription

16 mrna synthesis

17 Translation

18 The ribosome

19 Protein synthesis

20 Protein folding machinery

21 Protein structure

22 Amino acids

23 Main motifs α-helices and β-sheets

24 Levels of protein organisation

25 General functions in the cell Catalytic activity (enzymes that accelerate thousands of biochemical reactions) Transport (e.g. haemoglobin of erythrocytes binds oxygen) Storage (e.g. myoglobin stores oxygen in muscles) Structure (e.g. collagen, keratin of hair and nails) Contraction (e.g. actin and myosin in the contractile system of skeletal muscle) Defence (e.g. immunoglobulins or antibodies) Regulation (e.g. insulin and glucagon regulate blood glucose levels) Stress response (e.g. heat shock proteins that promote correct refolding damaged proteins and or degradation of severely damaged proteins)

26 Enzymes

27 Advantages over chemical catalysts Operate at a much lower temperature and standard pressure Very substrate-specific Regulatable Much faster

28 Mechanism Stabilisation of transition state

29 Genetic engineering

30 Polymerase chain reaction (PCR)

31 Producing a recombinant protein

32 Case study: How to produce insulin in bacteria?

33 TIME FOR A BREAK CLASS RESTARTS AT 10:45

34 Practical Activity of Enzymes Decomposition of Hydrogen Peroxide by Catalase

35 Practical: Aims Through the experiments you will explore: The mechanism of enzyme activity The influence of the following factors on enyzme activity Enzyme concentration Substrate concentration ph Enzyme: CATALASE Function: Protection of the cell Mechanism: Breaking down hydrogen peroxide (H2O2)

36 Protocol Preparation of the potato pieces: Cut the potato in small pieces of similar size (ca. 1 cm 3 ) Add two pieces of potato into the beaker with vinegar and two into the tray containing baking soda Test Tubes A-G Label the test tubes Add three drops of detergent and two drops of food colouring into each test tube Add 5 ml of 3% H2O2 on top into each test tube, mix carefully Test Tubes H/I Label the test tubes Add three drops of detergent and two drops of food colouring into each test tube Add 5 ml of 3% H2O2 into tube H and 5 ml of 6% H2O2 into tube I, mix carefully