* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Unit 1.1 Molecules.pps
Transcriptional regulation wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Citric acid cycle wikipedia , lookup
Gene expression wikipedia , lookup
Butyric acid wikipedia , lookup
Metalloprotein wikipedia , lookup
Epitranscriptome wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Peptide synthesis wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Point mutation wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Protein structure prediction wikipedia , lookup
Genetic code wikipedia , lookup
Glyceroneogenesis wikipedia , lookup
Proteolysis wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Unit 1.1 Molecules Biology Department Watford Girls Grammar School Introduction For each of the following you should be able to: Describe the properties Know the general formulae & structure Understand the role in animals & plants •Water •Proteins •Carbohydrates •Nucleic acids •Lipids H + Water - O H Water is a polar molecule It forms weak hydrogen bonds It remains a liquid over a wide temperature range Water molecules stick to one another = cohesion (surface tension) Water molecules stick to other substances = adhesion (capillarity) + Water has a high specific heat capacity – so water can maintain a reasonably constant temperature (homeostasis) It has a high latent heat of vaporisation – so animals use water to cool themselves It is less dense as a solid (ice)… … and ice is a poor conductor Water is a good solvent It Carbohydrates Contain the elements Carbon Hydrogen & Oxygen There are 3 types: Monosaccharides Disaccharides Polysaccharides Monosacharides (CH2O)n If n=3, triose (glyceraldehyde) If n=5, pentose (fructose, ribose) If n=6, hexose (glucose, galactose) Monosaccharides are used for Energy Building C blocks C O C C C C Isomerism They can exist as isomers: & glucose OH OH Disaccharides Formed from two monosaccharides Joined by a glycosidic bond A condensation reaction: + glucose maltose glucose + galactose lactose glucose + fructose sucrose glucose Condensation reaction C C C O C C C C C C O OH OH C C C Condensation reaction C C C O C C C C C C O OH OH C C C Condensation reaction C C C O C C C C C C O O H2O C C C Condensation reaction C C C O C C1 C C C O 4C O C C A disaccharide 1,4 glycosidic bond C Polysaccharides Polymers formed from many monosaccharides Three important examples: Starch Glycogen Cellulose Starch Insoluble store of glucose in plants formed from two glucose polymers: Amylose -glucose 1,4 glycosidic bonds Spiral structure Amylopectin -glucose 1,4 and some 1,6 glycosidic bonds Branched structure Glycogen Insoluble compact store of glucose in animals -glucose units 1,4 and 1,6 glycosidic bonds Branched structure Cellulose Structural O O O O polysaccharide in plants -glucose 1,4 glycosidic bonds H-bonds link adjacent chains O Lipids Made up of C, H and O Can exist as fats, oils and waxes They are insoluble in water They are a good source of energy (38kJ/g) They are poor conductors of heat Most fats & oils are triglycerides Triglycerides Formed by esterification… …a condensation reaction between 3 fatty acids and glycerol: H C O H Glycerol H C O H H C O H Fatty acids Carboxyl group (-COOH) attached to a long non-polar hydrocarbon chain (hydrophobic): H O C O H H H C H C H C H H C H C H C H C H H H H H A saturated fatty acid (no double bonds) O C H H C C H O H H H C H C H C C H C H H H H H A monounsaturated fatty acid O C O H H H H C C C H H H C H H C C C H H H A polyunsaturated fatty acid Esterification H C O H H C O H C O H H H O C O H C H C H H C H C H H Glycerol Fatty acid H Esterification H C O H H C O H C O H H H O C O H C H C H H C H C H H Glycerol Fatty acid H Esterification H C O H H C O H C H H O C O H C H C H H C H C H Glycerol H O H Fatty acid H Esterification H C O H H C O H C H H O C O Ester bond H O H water H C H C H H C H C H H Esterification This happens three times to form a triglyceride: glycerol fatty acids Phospholipids One fatty acid can be replaced by a polar phosphate group: hydrophilic phosphate glycerol Hydrophobic fatty acids Functions of lipids Protection of vital organs To prevent evaporation in plants & animals To insulate the body They form the myelin sheath around some neurones As a water source (respiration of lipids) As a component of cell membranes Proteins Made from C H O N & sometimes S Long chains of amino acids Properties determined by the aa sequence Amino acids ~20 aa Glycine R=H Alanine R=CH3 R O H H N amine C H C O H carboxyl Peptide bonding H H R N C H C O O H H H R N C H C O O H Peptide bonding H H R N C H C O O H H H R N C H C O O H Peptide bonding H H R N C H C O H H H O R N C H C O O H Peptide bonding H H R N C C O H H R N C H C O O H Peptide bond H H O water A condensation reaction Peptide bonding H H R N C H R O C N H A dipeptide C H C O O H Primary structure The sequence of aa is know as the primary structure The aa chain is a polypeptide Secondary structure forms between the –COOH and the -NH2 of adjacent aa This results in the chains folding: H-bonding Secondary structure -helix -pleated sheet Tertiary structure Bonding between R-groups gives rise to a 3D shape H-bonds =O HNaffected by temp & pH Ionic bonds –NH3-COOaffected by pH Disulphide bridge --CH2S-SCH2affected by reducing agents Quaternary structure Some proteins have more than one polypeptide chain Each chain is held together in a precise structure eg Haemoglobin Types of proteins Fibrous proteins e.g. collagen Insoluble structural Globular proteins e.g.enzymes Soluble 3D shape Functions of proteins Enzymes – Transport – Movement – Cell recognition – Channels – Structure – Hormones – Protection – Amylase Haemoglobin Actin & myosin Antigens Membrane proteins Collagen & keratin Insulin Antibodies Nucleic acids DNA & RNA Made up of nucleotides: phosphate base pentose sugar Nucleotides 2 types of base: Pyrimidines - Cytosine C T Thymine Purines Adenine Guanine A G Complimentary base pairing Adenine will only bind with Thymine Cytosine will only bind with Guanine T A C G DNA structure nucleotide Condensation polymerisation of the deoxyribose nucleotides Replication During cell division the DNA must replicate The DNA double helix unwinds The exposed bases bind to free floating nucleotides in the nucleoplasm DNA polymerase binds the complimentary nucleotides Replication is semiconservative The genetic code The sequence of nucleotide bases forms a code Each ‘code word’ has three letter – a triplet code Each codon codes for a specific amino acid e.g: GGG = proline CGG = glycine ATG = tyrosine ACT = stop (no amino acid) Protein synthesis The DNA codes for proteins A copy of DNA (mRNA) is made in the nucleus (transcription) The mRNA is used to make a protein (translation) in the cytoplasm Transcription The DNA polymerase unwinds the DNA Free nucleotides join onto complimentary bases RNA polymerase links adjacent nucleotides The completed mRNA moves out of the nucleus Transcription Amino acid activation transferRNA: tRNA binds onto a specific amino acid Translation mRNA binds to a ribosome tRNA carries an amino acid to the ribosome Translation A second tRNA brings another aa The two aa’s bind The process repeats Translation A polypeptide chain forms Eventually a stop codon is reached The Human Genome Project A multinational project aimed at sequencing the entire human genome Visit the Human Genome Web site: www.ornl.gov/hgmis/project/about.html www.sanger.ac.uk Acknowledgements Animated cell models used by kind permission of The Virtual Cell website: Feel free to use this presentation for educational non-profit making purposes. Quiz a) b) c) d) 1. Which of the following is not an important property of water Its polar nature Its low specific heat capacity Its high latent heat of vaporisation Its low density in solid form Quiz a) b) c) d) 2. The general formula for a monosaccharide is: (CH2O)n (CHO)n C(H2O)n C nH 2O n Quiz a) b) c) d) 3. Sucrose is made up of glucose + fructose glucose + galactose glucose + glucose galactose + fructose Quiz a) b) c) d) 4. Amylopectin is made up of: -1,4 glycosidic bonds -1,4 & -1,4 glycosidic bonds -1,4 & 1,6 glycosidic bonds -1,4 & 1,6 glycosidic bonds Quiz a) b) c) d) 5. Formation of a triglyceride does NOT involve: A condensation reaction Esterification Polymerisation A reaction between 3 fatty acids & glycerol Quiz a) b) c) d) 6. The general formula of a saturated fatty acid is: CnH2nO2 Cn(H2O)n (CH2O)n (CH2)nO Quiz a) b) c) d) 7. Which of the following is not responsible for a proteins tertiary structure ionic bonding covalent bonding hydrogen bonding disulphide bonding Quiz a) b) c) d) 8. Which of these is not an amino acid: alanine cysteine glycine cytosine Quiz a) b) c) d) 9. Which process involves tRNA: transciption translation DNA replication gene mutation Quiz a) b) c) d) 10. The formation of RNA does not involve: ribose sugar thymine removal of water phosphate