Macromolecules AP Biology 2018 Overview: The
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Macromolecules AP Biology 2018 Overview: The Molecules of Life Macromolecules large molecules composed of thousands of covalently connected atoms 4 Classes Carbohydrates Lipids Proteins Nucleic Acids Structure dictates function 1:
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01
Macromolecules AP Biology 2018<br>
02
Overview: The Molecules of Life Macromolecules
large molecules composed of thousands of covalently connected atoms
4 Classes
Carbohydrates
Lipids
Proteins
Nucleic Acids
Structure dictates function<br>
large molecules composed of thousands of covalently connected atoms
4 Classes
Carbohydrates
Lipids
Proteins
Nucleic Acids
Structure dictates function<br>
03
1: MACROMOLECULES are polymers, built from monomers Polymer
Long molecule consisting of many similar ”building blocks”
Monomer
Specific subunits joined together to construct a specific larger molecule
Covalently bonded
¾ classes of macromolecules are polymers
Carbohydrates
Proteins
Nucleic Acids<br>
Long molecule consisting of many similar ”building blocks”
Monomer
Specific subunits joined together to construct a specific larger molecule
Covalently bonded
¾ classes of macromolecules are polymers
Carbohydrates
Proteins
Nucleic Acids<br>
04
Dehydration Reaction Two monomers bond together
Loses a water molecule Hydrolysis Reaction Polymers disassembled into monomers
Absorbs a water molecule, breaking a bond
Reverse of a dehydration reaction The Synthesis and Breakdown of Polymers<br>
Loses a water molecule Hydrolysis Reaction Polymers disassembled into monomers
Absorbs a water molecule, breaking a bond
Reverse of a dehydration reaction The Synthesis and Breakdown of Polymers<br>
05
The Diversity of Polymers Thousands of different macromolecules in each cell
Macromolecules vary
Among cells
Among organisms
Among species
Between species
Huge variety of polymers can be built from a small amount of monomers HO<br>
Macromolecules vary
Among cells
Among organisms
Among species
Between species
Huge variety of polymers can be built from a small amount of monomers HO<br>
06
1.2) CARBOHYDRATES serve as fuel and building material Carbohydrates: sugars & their polymers
Monosaccharides: The simplest carbohydrates are monosaccharides, or single sugars
Polysaccharides: Polymers composed of many sugar building blocks<br>
Monosaccharides: The simplest carbohydrates are monosaccharides, or single sugars
Polysaccharides: Polymers composed of many sugar building blocks<br>
07
Monosaccharides: major fuel for cells & raw material for building molecules Molecular formulas are usually multiples of CH2O
Glucose (C6H12O6) most common monosaccharide
Monosaccharides are classified by
The location of the carbonyl group (as aldose or ketose)
The number of carbons in the carbon skeleton<br>
Glucose (C6H12O6) most common monosaccharide
Monosaccharides are classified by
The location of the carbonyl group (as aldose or ketose)
The number of carbons in the carbon skeleton<br>
08
Figure 5.3 Aldoses (Aldehyde Sugars) Ketoses (Ketone Sugars) Glyceraldehyde Trioses: 3-carbon sugars (C3H6O3) Dihydroxyacetone Pentoses: 5-carbon sugars (C5H10O5) Hexoses: 6-carbon sugars (C6H12O6) Ribose Ribulose Glucose Galactose Fructose<br>
09
Often drawn as linear skeletons
In aqueous (aq) solutions many sugars form rings<br>
In aqueous (aq) solutions many sugars form rings<br>
10
Figure 5.4 (a) Linear and ring forms (b) Abbreviated ring structure 1 2 3 4 5 6 6 5 4 3 2 1 1 2 3 4 5 6 1 2 3 4 5 6<br>
11
Disaccharide formed when dehydration reaction joins two monosaccharides
Glycosidic Linkage is the resulting covalent bond<br>
Glycosidic Linkage is the resulting covalent bond<br>
12
Figure 5.5 (a) Dehydration reaction in the synthesis of maltose (b) Dehydration reaction in the synthesis of sucrose Glucose Glucose Glucose Maltose Fructose Sucrose 1–4glycosidiclinkage 1–2glycosidiclinkage 1 4 1 2<br>
13
Polysaccharides polymers of sugars
storage and structural roles
Structure & function determined by
its sugar monomers
the positions of glycosidic linkages<br>
storage and structural roles
Structure & function determined by
its sugar monomers
the positions of glycosidic linkages<br>
14
Storage Polysaccharides Starch
Found in plants
consists entirely of glucose monomers
Store surplus starch as granules
Chloroplasts and other plastids
Plastids: plant organelle used for storage of starches, lipids, or pigments
The simplest form of starch is amylose<br>
Found in plants
consists entirely of glucose monomers
Store surplus starch as granules
Chloroplasts and other plastids
Plastids: plant organelle used for storage of starches, lipids, or pigments
The simplest form of starch is amylose<br>
15
Figure 5.6 (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Chloroplast Starch granules Mitochondria Glycogen granules Amylopectin Amylose Glycogen 1 m 0.5 m<br>
16
Glycogen: storage polysaccharide in animals
Humans and other vertebrates store glycogen mainly in liver and muscle cells<br>
Humans and other vertebrates store glycogen mainly in liver and muscle cells<br>
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Structural Polysaccharides Cellulose: major component of the tough wall of plant cells
polymer of glucose
Differ in glycosidic linkage
Differences based on two ring forms for glucose: alpha () and beta ()<br>
polymer of glucose
Differ in glycosidic linkage
Differences based on two ring forms for glucose: alpha () and beta ()<br>
18
Figure 5.7 (a) and glucose ring structures (b) Starch: 1–4 linkage of glucose monomers (c) Cellulose: 1–4 linkage of glucose monomers Glucose Glucose 4 1 4 1 4 1 4 1<br>
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glucose polymers are helical
glucose polymers are straight
H atoms on one strand can bond with OH groups on other strands
Parallel cellulose molecules held together this way are grouped into microfibrils
form strong building materials for plants<br>
glucose polymers are straight
H atoms on one strand can bond with OH groups on other strands
Parallel cellulose molecules held together this way are grouped into microfibrils
form strong building materials for plants<br>
20
Cell wall Microfibril Cellulosemicrofibrils in aplant cell wall Cellulosemolecules Glucosemonomer 10 m 0.5 m Figure 5.8<br>
21
Enzymes that digest starch by hydrolyzing linkages can’t hydrolyze linkages in cellulose
Cellulose in human food passes through the digestive tract as insoluble fiber
Some microbes use enzymes to digest cellulose
Many herbivores, from cows to termites, have symbiotic relationships with these microbes<br>
Cellulose in human food passes through the digestive tract as insoluble fiber
Some microbes use enzymes to digest cellulose
Many herbivores, from cows to termites, have symbiotic relationships with these microbes<br>
22
Chitin: found in the exoskeleton of arthropods
provides structural support for the cell walls of fungi<br>
provides structural support for the cell walls of fungi<br>
23
Figure 5.9 Chitin forms the exoskeletonof arthropods. The structureof the chitinmonomer Chitin is used to make a strong and flexiblesurgical thread that decomposes after thewound or incision heals.<br>
24
1.3) LIPIDS a diverse group of hydrophobic molecules The one class of large biological molecules that do not form polymers
Unifying feature is having little or no affinity for water
Hydrophobic due to their hydrocarbon makeup
form nonpolar covalent bonds
Fats, phospholipids, steroids are the most biologically important<br>
Unifying feature is having little or no affinity for water
Hydrophobic due to their hydrocarbon makeup
form nonpolar covalent bonds
Fats, phospholipids, steroids are the most biologically important<br>
25
Fats Constructed from two types of smaller molecules: glycerol and fatty acids
Glycerol: three-carbon alcohol with a hydroxyl (OH) group attached to each carbon
Fatty Acid consists of a carboxyl (COOH) group attached to a long carbon skeleton<br>
Glycerol: three-carbon alcohol with a hydroxyl (OH) group attached to each carbon
Fatty Acid consists of a carboxyl (COOH) group attached to a long carbon skeleton<br>
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Figure 5.10 (a) One of three dehydration reactions in the synthesis of a fat (b) Fat molecule (triacylglycerol) Fatty acid(in this case, palmitic acid) Glycerol Ester linkage<br>
27
Fats separate from water
water molecules form hydrogen bonds with each other
excluding the fats
Triglycerol: three fatty acids are joined to glycerol by an ester linkage
a.k.a: triglyceride<br>
water molecules form hydrogen bonds with each other
excluding the fats
Triglycerol: three fatty acids are joined to glycerol by an ester linkage
a.k.a: triglyceride<br>
28
Fats Cont’d Variety in Fats
Length (# of carbons)
Number of double bonds
Locations of double bonds
Saturated fatty acids: have the maximum number of hydrogen atoms possible and no double bonds
Unsaturated fatty acids have one or more double bonds<br>
Length (# of carbons)
Number of double bonds
Locations of double bonds
Saturated fatty acids: have the maximum number of hydrogen atoms possible and no double bonds
Unsaturated fatty acids have one or more double bonds<br>
29
Figure 5.11 (a) Saturated fat (b) Unsaturated fat Structuralformula of asaturated fatmolecule Space-fillingmodel of stearicacid, a saturatedfatty acid Structuralformula of anunsaturated fatmolecule Space-filling modelof oleic acid, anunsaturated fattyacid Cis double bondcauses bending.<br>
30
Saturated Fats: Fats made from saturated fatty acids
solid at room temperature
Most animal fats are saturated
Unsaturated Fats: made from unsaturated fatty acids
Called unsaturated fats or oils
Liquid at room temperature
Plant fats and fish fats are usually unsaturated<br>
solid at room temperature
Most animal fats are saturated
Unsaturated Fats: made from unsaturated fatty acids
Called unsaturated fats or oils
Liquid at room temperature
Plant fats and fish fats are usually unsaturated<br>
31
A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits
Hydrogenation: is the process of converting unsaturated fats to saturated fats by adding hydrogen
Hydrogenating vegetable oils also create unsaturated fats with trans double bonds
These trans fats may contribute more than saturated fats to cardiovascular disease<br>
Hydrogenation: is the process of converting unsaturated fats to saturated fats by adding hydrogen
Hydrogenating vegetable oils also create unsaturated fats with trans double bonds
These trans fats may contribute more than saturated fats to cardiovascular disease<br>
32
Essential Fatty Acids: unsaturated fatty acids that are not synthesized in the human body
Must be supplied in the diet
omega-3 fatty acids
required for normal growth
thought to provide protection against cardiovascular disease<br>
Must be supplied in the diet
omega-3 fatty acids
required for normal growth
thought to provide protection against cardiovascular disease<br>
33
Major function of fats: energy storage
Humans and other mammals store their fat in adipose cells
Adipose tissue also cushions vital organs and insulates the body<br>
Humans and other mammals store their fat in adipose cells
Adipose tissue also cushions vital organs and insulates the body<br>
34
Phospholipids Two fatty acids and a phosphate group are attached to glycerol
fatty acid tails are hydrophobic
phosphate group and its attachments form a hydrophilic “head”<br>
fatty acid tails are hydrophobic
phosphate group and its attachments form a hydrophilic “head”<br>
35
Figure 5.12 Choline Phosphate Glycerol Fatty acids Hydrophilichead Hydrophobictails (c) Phospholipid symbol (b) Space-filling model (a) Structural formula Hydrophilic head Hydrophobic tails<br>
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Phospholipid Bilayer: when are added to water, they self-assemble into a double layer, with the hydrophobic tails pointing toward the interior
The structure of phospholipids results in a bilayer arrangement found in cell membranes
Phospholipids are the major component of all cell membranes<br>
The structure of phospholipids results in a bilayer arrangement found in cell membranes
Phospholipids are the major component of all cell membranes<br>
37
Figure 5.13 Hydrophilichead Hydrophobictail WATER WATER<br>
38
Steroids Steroids: lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol: an important steroid, is a component in animal cell membranes
Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease<br>
Cholesterol: an important steroid, is a component in animal cell membranes
Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease<br>
39
Figure 5.14<br>
40
1.4) PROTEINS include a diversity of structures, resulting in a wide range of functions account for more than 50% of the dry mass of most cells
Functions include
structural support
Storage
transport
cellular communications
movement
defense against foreign substances<br>
Functions include
structural support
Storage
transport
cellular communications
movement
defense against foreign substances<br>
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Figure 5.15-a Enzymatic proteins Defensive proteins Storage proteins Transport proteins Enzyme Virus Antibodies Bacterium Ovalbumin Amino acidsfor embryo Transportprotein Cell membrane Function: Selective acceleration of chemical reactions Example: Digestive enzymes catalyze the hydrolysisof bonds in food molecules. Function: Protection against disease Example: Antibodies inactivate and help destroyviruses and bacteria. Function: Storage of amino acids Function: Transport of substances Examples: Casein, the protein of milk, is the majorsource of amino acids for baby mammals. Plants havestorage proteins in their seeds. Ovalbumin is theprotein of egg white, used as an amino acid sourcefor the developing embryo. Examples: Hemoglobin, the iron-containing protein ofvertebrate blood, transports oxygen from the lungs toother parts of the body. Other proteins transportmolecules across cell membranes.<br>
42
Figure 5.15-b Hormonal proteins Function: Coordination of an organism’s activities Example: Insulin, a hormone secreted by thepancreas, causes other tissues to take up glucose,thus regulating blood sugar concentration Highblood sugar Normalblood sugar Insulinsecreted Signalingmolecules Receptorprotein Muscle tissue Actin Myosin 100 m 60 m Collagen Connectivetissue Receptor proteins Function: Response of cell to chemical stimuli Example: Receptors built into the membrane of anerve cell detect signaling molecules released byother nerve cells. Contractile and motor proteins Function: Movement Examples: Motor proteins are responsible for theundulations of cilia and flagella. Actin and myosinproteins are responsible for the contraction ofmuscles. Structural proteins Function: Support Examples: Keratin is the protein of hair, horns,feathers, and other skin appendages. Insects andspiders use silk fibers to make their cocoons and webs,respectively. Collagen and elastin proteins provide afibrous framework in animal connective tissues.<br>
43
Enzymes: a type of protein that acts as a catalyst to speed up chemical reactions
Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life<br>
Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life<br>
44
Polypeptides Polypeptides: unbranched polymers built from the same set of 20 amino acids
Protein: a biologically functional molecule that consists of one or more polypeptides<br>
Protein: a biologically functional molecule that consists of one or more polypeptides<br>
45
Amino Acid Monomers Amino acids: organic molecules with carboxyl and amino groups
differ in their properties due to differing side chains
R groups<br>
differ in their properties due to differing side chains
R groups<br>
46
Figure 5.UN01 Side chain (R group) Aminogroup Carboxylgroup carbon<br>
47
Figure 5.16 Nonpolar side chains; hydrophobic Side chain(R group) Glycine(Gly or G) Alanine(Ala or A) Valine(Val or V) Leucine(Leu or L) Isoleucine (Ile or I) Methionine(Met or M) Phenylalanine(Phe or F) Tryptophan(Trp or W) Proline(Pro or P) Polar side chains; hydrophilic Serine(Ser or S) Threonine(Thr or T) Cysteine(Cys or C) Tyrosine(Tyr or Y) Asparagine(Asn or N) Glutamine(Gln or Q) Electrically charged side chains; hydrophilic Acidic (negatively charged) Basic (positively charged) Aspartic acid(Asp or D) Glutamic acid(Glu or E) Lysine(Lys or K) Arginine(Arg or R) Histidine(His or H)<br>
48
Amino Acid Polymers Linked by peptide bonds
Polypeptide: a polymer of amino acids
range in length from a few to more than a thousand monomers
Each has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus)<br>
Polypeptide: a polymer of amino acids
range in length from a few to more than a thousand monomers
Each has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus)<br>
49
Figure 5.17 Peptide bond New peptidebond forming Side
chains Back-bone Amino end(N-terminus) Peptidebond Carboxyl end(C-terminus)<br>
chains Back-bone Amino end(N-terminus) Peptidebond Carboxyl end(C-terminus)<br>
50
Protein Structure and Function Functional Proteins
consist of one or more polypeptides precisely
Twisted
Folded
Coiled into a unique shape<br>
consist of one or more polypeptides precisely
Twisted
Folded
Coiled into a unique shape<br>
51
The sequence of amino acids determines a protein’s three-dimensional structure
Structure determines function<br>
Structure determines function<br>
52
Figure 5.19 Antibody protein Protein from flu virus<br>
53
Four Levels of Protein Structure Primary Structure: unique sequence of amino acids
Secondary Structure: coils and folds in the polypeptide chain
Tertiary Structure: interactions among various side chains (R groups)
Quaternary Structure: results when a protein consists of multiple polypeptide chains<br>
Secondary Structure: coils and folds in the polypeptide chain
Tertiary Structure: interactions among various side chains (R groups)
Quaternary Structure: results when a protein consists of multiple polypeptide chains<br>
54
Figure 5.20a Primary structure Aminoacids Amino end Carboxyl end Primary structure of transthyretin<br>
55
Primary structure:
the sequence of amino acids in a protein
like the order of letters in a long word
determined by inherited genetic information<br>
the sequence of amino acids in a protein
like the order of letters in a long word
determined by inherited genetic information<br>
56
Figure 5.20b Secondarystructure Tertiarystructure Quaternarystructure Hydrogen bond helix pleated sheet strand Hydrogenbond Transthyretinpolypeptide Transthyretinprotein<br>
57
Secondary Structure:
result from hydrogen bonds between repeating constituents of the polypeptide backbone
Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet<br>
result from hydrogen bonds between repeating constituents of the polypeptide backbone
Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet<br>
58
Secondary structure Hydrogen bond helix pleated sheet strand, shown as a flatarrow pointing towardthe carboxyl end Hydrogen bond Figure 5.20c<br>
59
Tertiary Structure:
determined by interactions between R groups, rather than interactions between backbone constituents
hydrogen bonds
ionic bonds
hydrophobic interactions
Van der Waals interactions
Disulfide Bridges: strong covalent bonds that may reinforce the protein’s structure<br>
determined by interactions between R groups, rather than interactions between backbone constituents
hydrogen bonds
ionic bonds
hydrophobic interactions
Van der Waals interactions
Disulfide Bridges: strong covalent bonds that may reinforce the protein’s structure<br>
60
Figure 5.20f Hydrogenbond Disulfidebridge Polypeptidebackbone Ionic bond Hydrophobicinteractions andvan der Waalsinteractions<br>
61
Quaternary Structure:
when two or more polypeptide chains form one macromolecule
Collagen: a fibrous protein consisting of three polypeptides coiled like a rope
Hemoglobin: a globular protein consisting of four polypeptides
two alpha
two beta chains<br>
when two or more polypeptide chains form one macromolecule
Collagen: a fibrous protein consisting of three polypeptides coiled like a rope
Hemoglobin: a globular protein consisting of four polypeptides
two alpha
two beta chains<br>
62
Hemoglobin Heme Iron subunit subunit subunit subunit Figure 5.20i<br>
63
Sickle-Cell Disease: A Change in Primary Structure A slight change in primary structure can affect a protein’s structure and ability to function
Sickle-cell Disease: an inherited blood disorder resulting from a single amino acid substitution in the protein hemoglobin<br>
Sickle-cell Disease: an inherited blood disorder resulting from a single amino acid substitution in the protein hemoglobin<br>
64
Figure 5.21 PrimaryStructure Secondaryand TertiaryStructures QuaternaryStructure Function Red BloodCell Shape subunit subunit Exposedhydrophobicregion Molecules do notassociate with oneanother; each carriesoxygen. Molecules crystallizeinto a fiber; capacityto carry oxygen isreduced. Sickle-cellhemoglobin Normalhemoglobin 10 m 10 m Sickle-cell hemoglobin Normal hemoglobin 1 2 3 4 5 6 7 1 2 3 4 5 6 7 <br>
65
What Determines Protein Structure? Physical & chemical conditions can affect structure
Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel
Denaturation: loss of a protein’s native structure is called
A denatured protein is biologically inactive<br>
Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel
Denaturation: loss of a protein’s native structure is called
A denatured protein is biologically inactive<br>
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Figure 5.22 Normal protein Denatured protein De n tu r t on Re n t r t on a a i a u a i<br>
67
Protein Folding in the Cell It is hard to predict a protein’s structure from its primary structure
Most proteins probably go through several stages on their way to a stable structure
Chaperonins: protein molecules that assist the proper folding of other proteins
Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with misfolded proteins<br>
Most proteins probably go through several stages on their way to a stable structure
Chaperonins: protein molecules that assist the proper folding of other proteins
Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with misfolded proteins<br>
68
Figure 5.23 The cap attaches, causingthe cylinder to changeshape in such a way thatit creates a hydrophilicenvironment for thefolding of the polypeptide. Cap Polypeptide Correctlyfoldedprotein Chaperonin(fully assembled) Steps of ChaperoninAction: An unfolded poly-peptide enters thecylinder fromone end. Hollowcylinder The cap comesoff, and theproperly foldedprotein isreleased.<br>
69
X-ray crystallography: individual atoms of a single molecule diffracting off an X-ray
used to determine a protein’s structure
Nuclear Magnetic Resonance (NMR) spectroscopy
Uses radio waves to depict carbon & hydrogen atoms
which does not require protein crystallization
Bioinformatics: uses computer programs to predict protein structure from amino acid sequences<br>
used to determine a protein’s structure
Nuclear Magnetic Resonance (NMR) spectroscopy
Uses radio waves to depict carbon & hydrogen atoms
which does not require protein crystallization
Bioinformatics: uses computer programs to predict protein structure from amino acid sequences<br>
70
Figure 5.24 DiffractedX-rays X-raysource X-raybeam Crystal Digital detector X-ray diffractionpattern RNA DNA RNApolymerase II EXPERIMENT RESULTS<br>
71
1.5) NUCLEIC ACIDS store, transmit, and help express hereditary information Gene: amino acid sequence of a polypeptide that is programmed by a unit of inheritance
made of DNA, a nucleic acid made of monomers called nucleotides<br>
made of DNA, a nucleic acid made of monomers called nucleotides<br>
72
The Roles of Nucleic Acids There are two types of nucleic acids
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA: provides directions for its own replication
directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
Protein synthesis occurs on ribosomes<br>
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA: provides directions for its own replication
directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
Protein synthesis occurs on ribosomes<br>
73
Figure 5.25-3 Synthesis ofmRNA mRNA DNA NUCLEUS CYTOPLASM mRNA Ribosome Aminoacids Polypeptide Movement ofmRNA intocytoplasm Synthesisof protein<br>
74
The Components of Nucleic Acids Polynucleotides: the name given to nucleic acid polymers
Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups
Nucleoside: portion of a nucleotide without the phosphate group<br>
Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups
Nucleoside: portion of a nucleotide without the phosphate group<br>
75
Figure 5.26 Sugar-phosphate backbone 5 end 5C 3C 5C 3C 3 end (a) Polynucleotide, or nucleic acid (b) Nucleotide Phosphategroup Sugar(pentose) Nucleoside Nitrogenousbase 5C 3C 1C Nitrogenous bases Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Adenine (A) Guanine (G) Sugars Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components<br>
76
Nucleoside = nitrogenous base + sugar
There are two families of nitrogenous bases
Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring
Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring
In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose
Nucleotide = nucleoside + phosphate group<br>
There are two families of nitrogenous bases
Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring
Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring
In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose
Nucleotide = nucleoside + phosphate group<br>
77
Nucleotide Polymers Joined by covalent bonds
form between the Hydroxyl group on the 3 carbon of one nucleotide and the phosphate on the 5 carbon on the next
These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages
Sequence of bases along a DNA or mRNA polymer is unique for each gene<br>
form between the Hydroxyl group on the 3 carbon of one nucleotide and the phosphate on the 5 carbon on the next
These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages
Sequence of bases along a DNA or mRNA polymer is unique for each gene<br>
78
The Structures of DNA and RNA Molecules RNA molecules usually exist as single polypeptide chains
DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a double helix
In the DNA double helix, the two backbones run in opposite 5→ 3 directions from each other, an arrangement referred to as antiparallel
One DNA molecule includes many genes<br>
DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a double helix
In the DNA double helix, the two backbones run in opposite 5→ 3 directions from each other, an arrangement referred to as antiparallel
One DNA molecule includes many genes<br>
79
Nitrogenous Base Pairs:
Hydrogen bonded
adenine (A) to thymine (T)
guanine (G) to cytosine (C)
Called complementary base pairing
Can also occur between two RNA molecules or between parts of the same molecule
In RNA, thymine is replaced by uracil (U)
adenine (A) to uracil (U)<br>
Hydrogen bonded
adenine (A) to thymine (T)
guanine (G) to cytosine (C)
Called complementary base pairing
Can also occur between two RNA molecules or between parts of the same molecule
In RNA, thymine is replaced by uracil (U)
adenine (A) to uracil (U)<br>
80
Figure 5.27 Sugar-phosphatebackbones Hydrogen bonds Base pair joinedby hydrogen bonding Base pair joinedby hydrogenbonding (b) Transfer RNA (a) DNA 5 3 5 3<br>
81
DNA and Proteins as Tape Measures of Evolution The linear sequences of nucleotides in DNA molecules are passed from parents to offspring
Two closely related species are more similar in DNA than are more distantly related species
Molecular biology can be used to assess evolutionary kinship<br>
Two closely related species are more similar in DNA than are more distantly related species
Molecular biology can be used to assess evolutionary kinship<br>
82
The Theme of Emergent Properties in the Chemistry of Life: Higher levels of organization result in the emergence of new properties
Organization is the key to the chemistry of life<br>
Organization is the key to the chemistry of life<br>
83
Figure 5.UN02<br>
84
Figure 5.UN02a<br>
85
Figure 5.UN02b<br>
86
Figure 5. UN07<br>
87
Figure 5. UN08<br>
88
Figure 5. UN09<br>
89
Figure 5. UN10<br>
90
Figure 5. UN12<br>
91
Figure 5. UN13<br>