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Unit 1.1 Molecules Biology Department Watford Girls Grammar School.

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Presentation on theme: "Unit 1.1 Molecules Biology Department Watford Girls Grammar School."— Presentation transcript:

1 Unit 1.1 Molecules Biology Department Watford Girls Grammar School

2 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 Carbohydrates Lipids Proteins Nucleic acids

3 Water 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) O H H + + -

4 Water It 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

5 Carbohydrates Contain the elements Carbon Hydrogen & Oxygen There are 3 types: Monosaccharides Disaccharides Polysaccharides

6 Monosacharides (CH 2 O) n If n=3, triose (glyceraldehyde) If n=5, pentose (fructose, ribose) If n=6, hexose (glucose, galactose) Monosaccharides are used for Energy Building blocks O CC C C C C

7 Isomerism They can exist as isomers: & glucose OH

8 Disaccharides Formed from two monosaccharides Joined by a glycosidic bond A condensation reaction: glucose + glucose maltose glucose + galactose lactose glucose + fructose sucrose

9 Condensation reaction O CC C C C CO CC C C C C OH

10 Condensation reaction O CC C C C CO CC C C C C OHOHOH

11 Condensation reaction O CC C C C CO CC C C C C O H2OH2O

12 O CC C C C CO CC C C C C O A disaccharide 1,4 glycosidic bond 41

13 Polysaccharides Polymers formed from many monosaccharides Three important examples: Starch Glycogen Cellulose

14 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

15 Glycogen Insoluble compact store of glucose in animals -glucose units 1,4 and 1,6 glycosidic bonds Branched structure

16 Cellulose Structural polysaccharide in plants -glucose 1,4 glycosidic bonds H-bonds link adjacent chains O O O O O

17 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

18 Triglycerides Formed by esterification… …a condensation reaction between 3 fatty acids and glycerol: Glycerol H C H C C H H H H O O O

19 Fatty acids Carboxyl group (-COOH) attached to a long non-polar hydrocarbon chain (hydrophobic): H H C H H C H H C H C O O H C H H C H H C H H C H H A saturated fatty acid (no double bonds)

20 HH C O O H C H H CC CC H C H H C H H A polyunsaturated fatty acid C O O H C H H C H H C H H C H C H H C H H C H H A monounsaturated fatty acid HH

21 Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Glycerol Fatty acid

22 Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Glycerol Fatty acid

23 Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Glycerol Fatty acid

24 Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Ester bond water

25 Esterification This happens three times to form a triglyceride: glycerol fatty acids

26 Phospholipids One fatty acid can be replaced by a polar phosphate group: glycerol Hydrophobic fatty acids hydrophilic phosphate

27 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

28 Proteins Made from C H O N & sometimes S Long chains of amino acids Properties determined by the aa sequence Amino acids H C H NC H H O O R ~20 aa Glycine R=H Alanine R=CH 3 amine carboxyl

29 Peptide bonding H C H NC H H O O R H C H NC H H O O R

30 H C H NC H H O O R H C H NC H H O O R

31 H C H NC H H O O R H C H NC H H O O R

32 C H NC H H O R H C H NC H H O H O O R water Peptide bond A condensation reaction

33 Peptide bonding C H NC H H O R H C H NC H O O R A dipeptide

34 Primary structure The sequence of aa is know as the primary structure The aa chain is a polypeptide Secondary structure H-bonding forms between the –COOH and the -NH 2 of adjacent aa This results in the chains folding:

35 Secondary structure -helix -pleated sheet

36 Tertiary structure Bonding between R-groups gives rise to a 3D shape H-bonds =O HN- Ionic bonds –NH 3 -COO- Disulphide bridge --CH 2 S-SCH 2 - affected by temp & pH affected by pH affected by reducing agents

37 Quaternary structure Some proteins have more than one polypeptide chain Each chain is held together in a precise structure eg Haemoglobin

38 Types of proteins Fibrous proteins e.g. collagen Insoluble structural Globular proteins e.g.enzymes Soluble 3D shape

39 Functions of proteins Enzymes – Transport – Movement – Cell recognition – Channels – Structure – Hormones – Protection – Amylase Haemoglobin Actin & myosin Antigens Membrane proteins Collagen & keratin Insulin Antibodies

40 Nucleic acids DNA & RNA Made up of nucleotides: phosphate pentose sugar base

41 Nucleotides 2 types of base: Pyrimidines - Cytosine C Thymine T Purines Adenine A Guanine G

42 Complimentary base pairing Adenine will only bind with Thymine Cytosine will only bind with Guanine TCGA

43 DNA structure nucleotide Condensation polymerisation of the deoxyribose nucleotides

44 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

45 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)

46 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

47 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

48 Transcription

49 Amino acid activation transferRNA: tRNA binds onto a specific amino acid

50 Translation mRNA binds to a ribosome tRNA carries an amino acid to the ribosome

51 Translation A second tRNA brings another aa The two aas bind The process repeats

52 Translation A polypeptide chain forms Eventually a stop codon is reached

53 The Human Genome Project A multinational project aimed at sequencing the entire human genome Visit the Human Genome Web site:

54 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.

55 Quiz 1. Which of the following is not an important property of water a) Its polar nature Its polar nature b) Its low specific heat capacity Its low specific heat capacity c) Its high latent heat of vaporisationIts high latent heat of vaporisation d) Its low density in solid formIts low density in solid form

56 Quiz 2. The general formula for a monosaccharide is: a) (CH 2 O) n (CH 2 O) n b) (CHO) n(CHO) n c) C(H 2 O) nC(H 2 O) n d) C n H 2 O nC n H 2 O n

57 Quiz 3. Sucrose is made up of a) glucose + fructose glucose + fructose b) glucose + galactoseglucose + galactose c) glucose + glucoseglucose + glucose d) galactose + fructosegalactose + fructose

58 Quiz 4. Amylopectin is made up of: a) -1,4 glycosidic bonds -1,4 glycosidic bonds b) -1,4 & -1,4 glycosidic bonds -1,4 & -1,4 glycosidic bonds c) -1,4 & 1,6 glycosidic bonds -1,4 & 1,6 glycosidic bonds d) -1,4 & 1,6 glycosidic bonds -1,4 & 1,6 glycosidic bonds

59 Quiz 5. Formation of a triglyceride does NOT involve: a) A condensation reaction A condensation reaction b) Esterification Esterification c) Polymerisation Polymerisation d) A reaction between 3 fatty acids & glycerol A reaction between 3 fatty acids & glycerol

60 Quiz 6. The general formula of a saturated fatty acid is: a) C n H 2n O 2C n H 2n O 2 b) C n (H 2 O) n C n (H 2 O) n c) (CH 2 O) n(CH 2 O) n d) (CH 2 ) n O(CH 2 ) n O

61 Quiz 7. Which of the following is not responsible for a proteins tertiary structure a) ionic bondingionic bonding b) covalent bondingcovalent bonding c) hydrogen bondinghydrogen bonding d) disulphide bondingdisulphide bonding

62 Quiz 8. Which of these is not an amino acid: a) alaninealanine b) cysteinecysteine c) glycineglycine d) cytosinecytosine

63 Quiz 9. Which process involves tRNA: a) transciptiontransciption b) translationtranslation c) DNA replicationDNA replication d) gene mutationgene mutation

64 Quiz 10. The formation of RNA does not involve: a) ribose sugarribose sugar b) thyminethymine c) removal of waterremoval of water d) phosphatephosphate

65 Answers Sorry, that is not the correct answer Click here to go back

66 Answers Sorry, that is not the correct answer Click here to go back

67 Answers Sorry, that is not the correct answer Click here to go back

68 Answers Sorry, that is not the correct answer Click here to go back

69 Answers Sorry, that is not the correct answer Click here to go back

70 Answers Sorry, that is not the correct answer Click here to go back

71 Answers Sorry, that is not the correct answer Click here to go back

72 Answers Sorry, that is not the correct answer Click here to go back

73 Answers Sorry, that is not the correct answer Click here to go back

74 Answers Sorry, that is not the correct answer Click here to go back

75 Answers Thats right – water has a high specific heat capacity Click here to go to the next question

76 Answers Thats right Click here to go to the next question

77 Answers Thats right Click here to go to the next question

78 Answers Thats right Click here to go to the next question

79 Answers Thats right Click here to go to the next question

80 Answers Thats right Click here to go to the next question

81 Answers Thats right Click here to go to the next question

82 Answers Thats right, cytosine is an organic base Click here to go to the next question

83 Answers Thats right Click here to go to the next question

84 Answers Thats right, in RNA thymine is replaced with uracil Click here to go back to the start Press escape to exit


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