Biomolecules Lecture Carbohydrates Lipids Proteins Nucleic Acids

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1 Biomolecules Lecture Carbohydrates Lipids Proteins Nucleic Acids

2 Carbohydrates

3 Monosaccharides 4 Examples: 1. Glucose 2. Fructose 3. Ribose 4. Deoxyribose

4 Glucose Structure

5 Function of Glucose

6 Fructose Structure

7 Function of Fructose Used by sperm cells as source of energy Converted to glucose and used as source of energy

8 Structure of Ribose and Deoxyribose deoxyribose

9 Function of Ribose Part of RNA nucleotides and ATP RNA RNA Nucleotide

10 Function of Ribose Part of RNA nucleotides and ATP ATP

11 Function of Deoxyribose Part of DNA nucleotides

12 Disaccharides 3 examples: Sucrose 2. Lactose 3. Maltose

13 Carbohydrate Synthesis/Hydrolysis

14 Carbohydrate Structure Glucose + Glucose Maltose

15 Sucrose Structure

16 Sucrose Function Once it is broken down, it is used as a source of energy

17 Lactose

18 Maltose

19 How sweet is sweet? We perceive a sweet taste when a chemical binds to the sweet receptor on the tongue The structure of a compound determines how well it fits into a receptor The more strongly the chemical binds to the receptor, the sweeter it is perceived to be The chemical can be sugar or another compound, such as aspartame

21 Polysaccharides 3 examples: Glycogen Starch Cellulose

25 STARCH GLYCOGEN CELLULOSE

26 26

27 Lipids 3 types of lipids: 1. Simple Lipids a) Neutral Lipids or Triglycerides (fats & oils) b) Waxes 2. Compound Lipids a) Phospholipids b) Sphingolipids c) Glycolipids 3. Derived Lipids a) Terpenes b) Steroids

28 1. Simple Lipids a) Neutral Lipids or Triglycerides (fats & oils) Fats and oils are composed of 2 types of subunits: glycerol and fatty acids.

29 Examples of Trigylcerides

30 Triglyceride

31 Triglyceride

32 Fats, and Oils Animal fats and vegetable oils are the most widely occurring lipids Closely related structures Have different appearances Animal fats are solids like butter and lard Vegetable oils are liquids like corn and peanut oil

33 Fats, and Oils Fats and oils are triglycerides, or triacylglycerols Triesters of glycerol with three long-chain carboxylic acids called fatty acids Fats are used by animals for long-term energy storage Less highly oxidized than carbohydrates Provide about six times as much energy as an equal weight of glycogen

34 Fats, and Oils Hydrolysis of a fat or oil with aqueous NaOH yields glycerol and three fatty acids Fatty acids are generally unbranched and contain an even number of carbon atoms between 12 and 20 If double bonds are present they are generally Z, or cis The three fatty acids of a specific triacylglycerol do not need to be the same A fat or oil is likely to be a complex mixture of many different triacyglycerols

35 Fats, and Oils Structures of some common fatty acids

36 Fats, and Oils Approximate composition of some fats and oils

37 Fats, and Oils Palmitic acid (C 16 ) and stearic acid (C 18 ) are the most abundant saturated fatty acids Oleic and linoleic acids (both C 18 ) are the most abundant unsaturated fatty acids Oleic acid is monounsaturated It has only one double bond Linoleic, linolenic, and arachidonic acids are polyunsaturated fatty acids They have more than one double bond

38 Fats, and Oils Linoleic and linolenic acids occur in cream and are essential to the human diet Infants grow poorly and develop skin lesions if fed a diet of nonfat milk for prolonged periods

39 Fats, and Oils Unsaturated fatty acids generally have lower melting points than their saturated counterparts Vegetable oils that have higher proportions of unsaturated to saturated fatty acids and have lower melting points Unsaturated fatty acids have C=C double bonds that make crystal formation more difficult thus lowering the melting point Saturated fatty acids have a uniform shape that allows them to pack together efficiently in a crystal lattice thus raising their melting point

40 Saturated Fats

41 Unsaturated Fats

42 Fats, and Oils Unsaturated fatty acids can be catalytically hydrogenated Catalytic hydrogenation is typically carried out at high temperature using a nickel catalyst Margarine and shortening are produced by hydrogenating soybean, peanut, or cottonseed oil until the proper consistency is obtained Hydrogenation is accompanied with cis-trans isomerization of the double bonds Produces fats with about 10% to 15% trans unsaturated fatty acids Dietary intake of trans fatty acids increases cholesterol levels in the blood increasing the risk of coronary artery disease

43 Trans Fats

44 Fats, and Oils The conversion of linoleic acid into elaidic acid

45 b. Waxes Waxes are mixtures of esters of long-chain carboxylic acids with long-chain alcohols Carboxylic acid usually has an even number of carbons from 24 through 36 Beeswax is the ester of the C 30 alcohol triacontan-1-ol and the C 16 acid hexadecanoic acid

46 2.Compound Lipids

47 a. Phospholipids

48 Phospholipids

49 Phospholipids Phospholipids are diesters of phosphoric acid, H 3 PO 4

50 Phospholipids Two general kinds of phospholipids Glycerophospholipids Based on phosphatidic acid Acyl group at C1 is usually saturated and the one at C2 is usually unsaturated The phosphate group at C3 is also bonded to an amino alcohol such as choline, ethanolamine, or serine Compounds are chiral at C2

51 Phospholipids Sphingomyelins Have sphingosine or a related dihydroxyamine as their backbone Abundant in brain and nerve tissue Major constituent of the coating around nerve fibers

Phospholipids Phospholipids occur widely in both plant and animal tissues Constitute approximately 50% to 60% of cell membranes Organize in cell membrane into a lipid

52 Phospholipids Phospholipids occur widely in both plant and animal tissues Constitute approximately 50% to 60% of cell membranes Organize in cell membrane into a lipid bilayer about 5.0 nm thick Nonpolar tails aggregate in the center of the bilayer Bilayer serves as barrier to passage of water, ions, and other components into and out or cells

55 Ceramides The amino group of sphingosine can form an amide bond with a fatty acid carboxyl, to yield a ceramide. In a ceramide, the NH 2 group in sphingosine is attached by an amide bond to a fatty acid General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 55

56 Sphingolipids Sphingolipids are similar to glycerophospholipids contain sphingosine, a fatty acid, phosphate, and an amino alcohol General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 56

57 Sphingomyelin Sphingomyelin is a sphingolipid found in nerve cells bonds the OH of a ceramide to a phosphate ester of choline General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 57

58 Glycosphingolipids Glycosphingolipids are sphingolipids that contain monosaccharides attached by a -glycosidic bond to the OH group of ceramide General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 58

59 Cerebrosides Cerebrosides contain galactose or glucose attached by a -glycosidic bond to the OH group of ceramide are found in the brain and the myelin sheath are important in cellular recognition and tissue immunity General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 59

60 Gangliosides Ganglia: Nerve tussues at CNS/PNS Gangliosides are sphingolipids that contain chains of two to seven monosaccharides are important in neurons are found on cell membrane surfaces act as receptors for hormones, viruses, and drugs can cause genetic diseases if they accumulate General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 60

61 c) Glycolipids Glycolipids are glycoconjugates of lipids. The term glycolipid designates any compound containing one or more monosaccharide residues bound by a glycosidic linkage. It is a structural lipid. They are generally found on the extracellular face of eukaryotic cellular membrane. General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 61

62 Types of Glycolipid 1. Cerebrosides-Cerebroside (from cerebro=brain) are glycolipids that are found primarily in the brain and peripheral (other areas of the body) nervous tissue. Function: Provide protective coating to each nerve and act as insulator. General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 62

63 Types of Glycolipids 2. Gangliosides- These glycolipids (glycosphingolipids) are neutral (uncharged). The gangliosides are acidic in ph and they are the more complex of the glycolipids. 3. Sulfoglycosphingolipids-These cerebrosides are also called sulfatides, They are simply cerebrosides with a sulfate residue on the sugar portion of glycolipid. Ocurrance: this particular lipid is found primarily in the medulated nerve fibres. General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 63

64 Functions of Glycolipid The glycolipids are an essential part of cell membranes. Glycolipids also help determine the blood group of an individual. Glycolipids act as receptors at the surface of the red blood cell. Some viruses, bacteria (eg., cholera) use glycolipids on their cell surface as well. This helps the immune system destroy and clear the pathogen from the body. General, Organic, and Biological Chemistry Copyright 2010 Pearson Education, Inc. 64

67 a. Terpenes /Terpenoids Terpenoids are a vast and diverse group of lipids found in all living organisms All contain a multiple of five carbons All derived biosynthetically from the five-carbon precursor isopentenyl diphosphate Terpenoids contain oxygen Terpenes are hydrocarbons

68 Terpenoids Monoterpenoids Contain 10 carbons Derived from two isopentenyl diphosphates Found primarily in plants, bacteria, and fungi Sesquiterpenoids Contain 15 carbons Derived from three isopentenyl diphosphates Found primarily in plants, bacteria, and fungi Diterpenoids Contain 20 carbons Derived from four isopentenyl diphosphates Found in both plants and animals Higher terpenoids Triterpenoid lanosterol (C 30 ) Precursor for steroid hormones Tetraterpenoid -carotene (C 40 ) is dietary source of vitamin A

69 b. Steroids

70 Examples of Steroids

71 Steroids Steroids are lipids derived from the triterpenoid lanosterol Structures are based on a tetracyclic ring system Four rings designated A, B, C, and D Numbering begins in A ring A, B, and C rings adopt chair conformations but do not undergo cyclohexane ring-flips

72 Steroids Steroid Hormones Steroids function as hormones in humans Hormones are chemical messengers that are secreted by endocrine glands and carried through the bloodstream to target tissues Two main classes of hormones Sex hormones Control maturation, tissue growth, and reproduction Adrenocortical hormones Regulate metabolic processes

73 Steroids SEX HORMONES Testosterone and androsterone are the two most important male sex hormones or androgens Responsible for development of male secondary sex characteristics during puberty Synthesized in the testes from cholesterol Androstenedione is used by athletes for muscle growth

74 Steroids Estrone and estradiol are the two most important female sex hormones, or estrogens Estrogens are synthesized in the ovaries from testosterone Responsible for development of female secondary sex characteristics and for regulation of menstrual cycle Progestin is another kind of sex hormone responsible for preparing the uterus for implantation of a fertilized ovum during pregnancy Progesterone is the most important progestin

75 Steroids ADRENOCORTICAL HORMONES Adrenocortical steroids are secreted by the adrenal glands Mineralocorticoids Control tissue swelling by regulating cellular salt balance between Na+ and K+ Glucocorticoids Involved in regulation of glucose metabolism and in the control of inflammation

76 Steroids SYNTHETIC STEROIDS Steroids synthesized in pharmaceutical laboratories for new applications and treatments Oral contraceptives Most birth-control pills are a mixture of two compounds 1. Synthetic estrogen, such as ethynylestradiol 2. Synthetic progestin, such as norethindrone Anabolic steroids Methandrostenolone (Dianabol) induces tissue building in a manner similar to natural testosterone

77 Biomolecules: Lipids and Their Metabolism Lipids classified into two broad types: 1. Those that contain ester linkages that can be hydrolyzed Include fats and waxes 2. Steroids which do not have ester linkages and cannot be hydrolyzed Includes cholesterol and other steroidal hormones

78 Proteins Proteins are made up of amino acids linked together

79 Proteins

81 Examples of Amino Acids

83 Protein Structure The function of a protein is a result of its 3-D structure 83

84 26.9 Protein Structure The primary structure of a protein is simply the amino acid sequence. The secondary structure of a protein describes how segments of the peptide backbone orient into a regular pattern. The tertiary structure describes how the entire protein molecule coils into an overall threedimensional shape. The quaternary structure describes how different protein molecules come together to yield large aggregate structures 84

Primary Structure of Proteins Metal ions can coordinate to: side chain functional groups backbone functional groups N- and C-terminal functional groups A

85 Primary Structure of Proteins Metal ions can coordinate to: side chain functional groups backbone functional groups N- and C-terminal functional groups A combination of donor atom types and geometric orientation that best matches the metal ion preferences will dictate where and how a particular metal ion binds

86 Secondary Structure of Proteins Dashed lines indicate hydrogen bonds These bonding interactions will compete with metal ion binding

87 Tertiary Structure of Proteins Additional side chain and backbone interactions contribute to protein folding and stability These interactions further limit the opportunities for metal ion binding

88 Protein Structure

89 Lactase Protein Structure

90 Protein Structure

91 Protein Movement

92 Protein Transport

93 LE 5-13c Protein Transport ATP

94 Protein Buffers Help maintain ph in our body

95 Protein Receptors Can Activate Molecules Messenger molecule Receptor Activated molecule

96 Protein Control

97 Protein Defense

98 Protein Enzymes

99 Enzyme Active Site

100 Nucleic Acids

101

102 DNA: Stores genetic code. That is it stores all of the recipes for making the proteins our body needs (cookbook) Controls when cells divide Regulates metabolism (when enzymes are made)

103 Genes: Instructions for making 1 protein (1 recipe )

104 RNA Structure

105 RNA Structure

106 RNA Function 1. Involved in protein synthesis 2. Can function as enzymes (called ribozymes)

107 mrna Has rewritten instructions for making proteins (rewritten recipe ) trna Carries amino acids (ingredients) as per instructions on mrna rrna Holds mrna and trna so that amino acids can be linked as per original recipe on DNA (mixing bowl)

108 DNA Nucleotide Nitrogenous Base Phosphate Group Sugar

109 DNA Nucleotide

110

111

112 RNA Structure

113 DNA vs RNA

114 DNA and RNA

115 RNA

Classification, functions and structure

Classification, functions and structure Elena Rivneac PhD, Associate Professor Department of Biochemistry and Clinical Biochemistry State University of Medicine and Pharmacy "Nicolae Testemitanu" Lipids