Chapter 04. *Lecture Outline. *See separate Image PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.

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1 hapter 04 *Lecture utline *ee separate Image oweroint slides for all figures and tables pre-inserted into oweroint without notes. opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. 1

2 4.2: Metabolic rocesses ellular metabolism There are two (2) types of metabolic pathways: Anabolism Larger molecules are made from smaller ones Requires energy atabolism Larger molecules are broken down into smaller ones Releases energy 2

3 Anabolism 2 Anabolism provides the materials needed for cellular growth and repair joins simple molecules to form larger molecules of glycogen Example: Dehydration synthesis Type of anabolic process Used to make polysaccharides, triglycerides, and proteins roduces water opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display Monosaccharide + Monosaccharide Disaccharide + Water 3

4 lycerol and fatty acid molecules join by dehydration synthesis in fat cells to form fat molecules. Three hydrogen atoms are removed from a glycerol molecule and an group is removed from each of the three fatty acid molecules. All this results in 3 water molecules and a single fat molecule. (next slide) 4

5 Anabolism opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. ( 2 ) 14 3 ( 2 ) 14 3 ( 2 ) 14 3 ( 2 ) ( 2 ) 14 3 ( 2 ) 14 3 lycerol + 3 fatty acid molecules Fat molecule (triglyceride) + opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. eptide bond 3 water molecules R N N N N 2 R R R Amino acid + Amino acid Dipeptide molecule + 5 Water

6 atabolism ydrolysis can decompose carbohydrates, lipids and proteins using a water molecule o, with dehydration synthesis molecules are joined together and the by product is water. BUT ydrolysis uses water to decompose bonds 6

7 atabolism atabolism breaks down larger molecules into smaller ones Example: ydrolysis A catabolic process Used to decompose carbohydrates, lipids, and proteins Water is used to split the substances Reverse of dehydration synthesis opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display Monosaccharide + Monosaccharide Disaccharide + 7 Water

8 The next slide shows amino acids breaking down into dipeptides by using 20 to decompose the bonds 8

9 atabolism opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. ( 2 ) 14 3 ( 2 ) 14 3 ( 2 ) 14 3 ( 2 ) ( 2 ) 14 3 ( 2 ) 14 3 lycerol + 3 fatty acid molecules Fat molecule (triglyceride) + opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. eptide bond 3 water molecules R N N N N 2 R R R Amino acid + Amino acid Dipeptide molecule + 9 Water

10 4.3: ontrol of Metabolic Reactions Metabolic reactions include hundreds of chemical changes that must occur in particular sequences. All cells conduct specialized metabolic processes. There are hundreds of very specific chemical changes that must occur in particular sequences. 10

11 Enzymes are a catalyst that is not absorbed and can be used over and over. EA enzyme is specific acting only on (its own) molecule called its UBTRATE. Each enzyme must be able to recognize its specific substrate. Also explained in next slide 11

12 Enzyme Action Enzymes ontrol rates of metabolic reactions Lower activation energy needed to start reactions Most are globular proteins with specific shapes Not consumed in chemical reactions ubstrate specific hape of active site determines substrate opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. ubstrate molecules roduct molecule Active site Enzyme Enzyme-substrate molecule complex (a) (b) (c) Unaltered enzyme molecule 12

13 Enzymes temporarily attach to the active sites on the substrate as the numbers increase the reaction speeds up. equences of enzymes are controlled reactions called metabolic pathways. Many enzyme names are derived from the names of their substrates with the suffix ase. Examples are: The lipid splitting enzyme is lipase The lactose splitting enzyme is lactase 13

14 Enzyme Action Metabolic pathways eries of enzyme-controlled reactions leading to formation of a product Each new substrate is the product of the previous reaction opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. ubstrate 1 Enzyme A ubstrate 2 Enzyme B ubstrate 3 Enzyme ubstrate 4 Enzyme D roduct Enzyme names commonly: Reflect the substrate ave the suffix ase Examples: sucrase, lactase, protease, lipase 14

15 Regulation of Metabolic athways Negative feedback Limited number of regulatory enzymes becomes ineffective at high concentrations opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. Inhibition ubstrate 1 Rate-limiting Enzyme A ubstrate 2 Enzyme B ubstrate 3 Enzyme ubstrate 4 Enzyme D roduct 15

16 ofactors and oenzymes ofactors Make some enzymes active Non protein component Ions or coenzymes Many enzymes are inactive until they combine with a particular cofactor oenzymes rganic molecules that act as cofactors Vitamins (see next slide) 16

17 This is why we need some vitamins and minerals. Many enzymes are inactive until they combine with a particular cofactor. Examples are things we are aware of such as: Vitamin A for skin Vitamin for collagen and absorbing iron Vitamin D for bones and teeth 17

18 Factors That Alter Enzymes Factors that alter enzymes: eat Radiation Electricity hemicals hanges in p hemicals with extreme p values can denature or alter the shape of the enzymes. Example: yanide denatures respiratory enzymes 18

19 4.4: Energy for Metabolic Reactions Energy is the capacity to change something; it is the ability to do work ommon forms of energy: eat ellular respiration is the process that Light transfers energy from molecules such ound as glucose and makes it available for Electrical energy cellular use Mechanical energy hemical energy Energy can be changed from one form to another. Through cellular respiration, energy is transferred from molecules to make it available for cellular use. 19

20 AT is the primary energy carrying molecule in the cell. AT = an adenine, a ribose, and 3 phosphates in a chain. The second and third phosphates are attached by a highenergy bond, and the chemical energy stored may be quickly transferred to another molecule. ells burn glucose in a process called oxidation. The energy released by oxidation of glucose is harnessed to promote cellular metabolism. In cells enzymes initiate oxidation by lowering the activation energy. By transferring energy to AT cells are able to capture almost half of the energy released in the form of chemical energy. 20

21 Adenosine triphosphate 21

22 AT Molecules Adenosine triphosphate (AT) carries energy in a form that the cell can use Each AT molecule has three parts: An adenine molecule A ribose molecule Three phosphate molecules in a chain opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. Energy transferred from cellular respiration used to reattach phosphate Energy transferred and utilized by metabolic reactions when phosphate bond is broken 22

23 Release of hemical Energy hemical bonds are broken to release energy We burn glucose in a process called oxidation ellular reaction includes aerobic (o2) and anaerobic (no o2) reactions. For each glucose molecule decomposed by cellular respiration up to 38 molecules of AT can be produced. 23

24 ellular Respiration occurs in a series of reactions: 1. lycolysis 2. itric acid cycle (Kreb s ycle) 3. Electron transport chain (ET) roduces arbon dioxide water AT (chemical energy) heat Includes: Anaerobic reactions (without 2 ) - produce little AT Aerobic reactions (requires 2 ) - produce most AT 24

25 The next three slides are about lycolysis. It means the breaking of glucose. It does not require o2. 6- carbon sugar glucose is broken down in the cytosol into two 3-carbon pyruvic acid molecules with a net gain of 2 AT and the release of high-energy electrons. 25

26 lycolysis eries of ten reactions Breaks down glucose into 2 pyruvic acid molecules ccurs in cytosol Anaerobic phase of cellular respiration Yields two AT molecules per glucose molecule ummarized by three main phases or events: 1. hosphorylation 2. plitting 3. roduction of NAD and FAD (Nicotinamide Adenine Dinucleotide plus ydrogen) (flavin adenine dinucleotide) 26

27 lycolysis opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. Event 1 - hosphorylation Two phosphates added to glucose Requires AT hase 1 priming hase 2 cleavage lucose 2 AT 2 AD Fructose-1,6-diphosphate arbon atom hosphate Event 2 plitting (cleavage) 6-carbon glucose split into two 3-carbon molecules (The electron carrier NAD is produced) Dihydroxyacetone lyceraldehyde phosphate phosphate hase 3 oxidation and 2 NAD + formation of 4 AD AT and release 2 NAD + + of high energy 4 AT electrons 2 yruvic acid 2 2 To citric acid cycle 2 Lactic acid and electron transport chain (aerobic pathway) 2 NAD NAD + 27

28 lycolysis Event 3 roduction of NAD and AT ydrogen atoms are released ydrogen atoms bind to NAD + to produce NAD NAD delivers hydrogen and high energy electrons to electron transport chain if oxygen is available AD is phosphorylated to become AT Two molecules of pyruvic acid are produced Two molecules of AT are generated opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. hase 1 priming hase 2 cleavage lucose AT 2 AD Fructose-1,6-diphosphate Dihydroxyacetone lyceraldehyde phosphate phosphate hase 3 oxidation and 2 NAD + formation of 4 AD AT and release 2 NAD + + of high energy 4 AT electrons 2 2 yruvic acid 2 2 To citric acid cycle 2 Lactic acid and electron transport chain (aerobic pathway) arbon atom hosphate 2 NAD NAD + 28

29 Anaerobic Reactions If oxygen is not available: Electron transport system cannot accept new electrons from NAD yruvic acid is converted to lactic acid lycolysis is inhibited AT production is less than in aerobic reactions opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. hase 1 priming hase 2 cleavage lucose AT 2 AD Fructose-1,6-diphosphate Dihydroxyacetone lyceraldehyde phosphate phosphate hase 3 oxidation and 2 NAD + formation of 4 AD AT and release 2 NAD + + of high energy 4 AT electrons 2 2 yruvic acid 2 2 arbon atom hosphate 2 NAD NAD + To citric acid cycle 2 Lactic acid and electron transport chain (aerobic pathway) 29

30 lycolysis continues as NAD + delivers electrons to the electron transport chain. This can only happen in the presence of o2 under anaerobic conditions the electron can t be unloaded or accept new electrons. NAD + delivers electrons and hydrogens back to the pyruvic acid in a reaction that forms lactic acid. If enough o2 is available this reaction will yield carbon dioxide and water and yield up to 36 AT molecules per glucose 30

31 Aerobic Reactions If oxygen is available: yruvic acid is used to produce acetyl oa itric acid cycle begins Electron transport chain functions arbon dioxide and water are formed Up to 36 molecules of AT are produced per each glucose molecule opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. igh energy electrons (e ) and hydrogen ions ( + ) ytosol Mitochondrion igh energy electrons (e ) and hydrogen ions (h + ) lucose 2 AT 2 AT yruvic acid yruvic acid xaloacetic acid igh energy electrons (e ) and hydrogen ions ( + ) 2 Acetyl oa 2e itric acid Electron transport chain AT 31

32 itric Acid ycle 1. one AT is produced directly for each citric acid molecule 2. for each citric acid molecule 8 ydrogen atoms with high energy electrons are transferred to ydrogen carriers. 5. as 6 carbon citric acid reacts to form the 4 carbon oxaloacetic acid two 2 molecules are produced page

33 itric Acid ycle Begins when acetyl oa combines with oxaloacetic acid to produce citric acid itric acid is changed into oxaloacetic acid through a series of reactions ycle repeats as long as pyruvic acid and oxygen are available opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. yruvic acid from glycolysis ytosol arbon atom NAD + hosphate 2 Mitochondrion oa oenzyme A NAD + + Acetic acid oa Acetyl oa (replenish molecule) xaloacetic acid itric acid (finish molecule) (start molecule) NAD + + oa NAD + Malic acid Isocitric acid For each citric acid molecule: ne AT is produced Eight hydrogen atoms are transferred to NAD + and FAD Two 2 produced Fumaric acid FAD 2 FAD NAD + itric acid cycle 2 NAD + + -Ketoglutaric acid 2 oa NAD + NAD + + uccinic acid uccinyl-oa oa AD + AT 33

34 The ydrogen and electron carriers that have been generated by glycolysis and citric acid cycle now hold most of the energy contained in the original glucose molecules. 34

35 Electron Transport hain NAD and FAD2 carry hydrogen and high energy electrons to the ET ET is a series of enzyme complexes located in the inner membrane of the mitochondrion Energy from electrons transferred to AT synthase AT synthase catalyzes the phosphorylation of AD to AT Water is formed (xygen is the final electron carrier ) opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. AD + AT synthase AT NAD + + Energy e FAD 2 NAD e Energy Energy FAD Electron transport chain 2e

36 Mitochondrion ytosol ummary of ellular Respiration lycolysis opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. The 6-carbon sugar glucose is broken down in the cytosol into two 3-carbon pyruvic acid molecules 1 with a net gain of 2 AT and release of high-energy electrons. igh-energy electrons (e ) lucose lycolysis 2 A T itric Acid ycle The 3-carbon pyruvic acids generated by glycolysis 2 enter the mitochondria. Each loses a carbon (generating 2 and is combined with a coenzyme to form a 2-carbon acetyl coenzyme A (acetyl oa). More high-energy electrons are released. yruvic acid yruvic acid igh-energy electrons (e ) 2 Acetyl o A Each acetyl 3 oa combines with a 4-carbon oxaloacetic acid to form the 6-carbon citric acid, for which the cycle is named. For each citric acid, a series of reactions removes 2 carbons (generating 2 2 s), synthesizes 1 AT, and releases more high-energy electrons. The figure shows 2 AT, resulting directly from 2 turns of the cycle per glucose molecule that enters glycolysis. igh-energy electrons (e ) xaloacetic acid itric acid cycle 2 A T itric acid 2 2 Electron Transport hain 4 The high-energy electrons still contain most of the chemical energy of the original glucose molecule. pecial carrier molecules bring the high-energy electrons to a series of enzymes that convert much of the remaining energy to more AT molecules. The other products are heat and water. The function of oxygen as the final electron acceptor in this last step is why the overall process is called aerobic respiration. 2 Electron transport chain 2e and A T 36

37 arbohydrate torage arbohydrate molecules from foods can enter: atabolic pathways for energy production Anabolic pathways for storage Remember some amino acids are scavenged? arbohydrate molecules can enter catabolic pathways and be used to supply energy R they can enter anabolic pathways and be stored as glycogen ( for energy later, this assures that cells throughout the body have a continual supply of glucose.) R react to form some twenty different amino acids. 37

38 arbohydrate torage Excess glucose stored as: lycogen (primarily by liver and muscle cells) Fat more carbs ingested than can be used onverted to amino acids opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. arbohydrates from foods ydrolysis Monosaccharides atabolic pathways Anabolic pathways Energy lycogen or Fat Amino acids 38

39 4.6: Nucleic Acids and rotein ynthesis Instruction of cells to synthesize proteins comes from a nucleic acid, deoxyribonucleic acid (DNA) Enzymes control the metabolic pathways essential for cell survival cells must have information for producing these specialized protein. The information is held in the sequences of building blocks of DNA.. The correspondence between a unit of DNA information and a particular amino acid is the genetic code 39

40 Enzymes control the metabolic pathways essential for cell survival. ells must have information for producing these specialized proteins. The information is held in the sequence of building blocks of DNA. The correspondence between a unit of DNA information and a particular amino acid is the genetic code. 40

41 A DNA sequence that contains the information for a protein is a gene. Enzymes are proteins that control metabolism at the chemical level. The complete set of genetic instructions is the genome. nly a small part of the human genome encodes protein. The rest controls which proteins are produced in a particular cell, under particular circumstances called gene expression. 41

42 enetic Information enetic information instructs cells how to construct proteins; stored in DNA ene segment of DNA that codes for one protein enome complete set of genes enetic ode method used to translate a sequence of nucleotides of DNA into a sequence of amino acids 42

43 tructure of DNA made of 2 strands of nucleotides which spiral (double helix) Each nucleotide contains: 5- sugar (deoxyribose), phosphate, and a nitrogenous base (adenine, guanine, cytosine, or thymine) The backbone of each strand is a sugarphosphate chain The bases of complementary strands hydrogen bond to each other: -, A-T DNA wrapped about histones forms chromosomes 43

44 44 tructure of DNA opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. B B B B B B B B B B B B B B B B B B B B B opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display.

45 A T tructure of DNA opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. (a) ydrogen bond Thymine (T) Adenine (A) T A ytosine () uanine () olynucleotide strands A A T egment of DNA molecule T A T A A (b) lobular histone proteins hromatin Interphase chromosome 45 Metaphase chromosome (c)

46 4.1 From cience to Technology DNA rofiling Frees A risoner age

47 DNA can be a double-edged sword. Where it rightfully exculpates some, like Timothy ole, it wrongfully inculpates others. Lydia Fairchild's DNA results did not match that of her own children when she applied for welfare. "Fairchild was not only denied government assistance,...she was now suspected of possibly acting as a paid surrogate mother and committing welfare fraud." he'd have lost custody of her kids, had her lawyer not researched the medical phenomena known as chimerism. ometimes two fertilized eggs meant to be twins fuse into "one fetus that carries two distinct genetic codes -- two separate strands of DNA." o while DNA from Lydia's hair and skin cells didn't match that of her kids, those from other body tissues, like her cervical cells, did match. er story is an example of overestimating the validity of DNA rulings. 47

48 ometimes DNA evidence only leads police on a wild goose chase. In ermany, there was a woman serial killer, whose trail was as prolific as it was unpredictable. er DNA showed up repeatedly at crime scenes, but she managed to evade police capture. he seemed almost ghostly to the puzzled authorities and frightened public - aving no other clues to her existence besides her reliably present DNA calling card. Turns out a little old lady who worked in the factory that made the DNA swabs was unknowingly contaminating them. ops. 48

49 DNA Replication ydrogen bonds break between bases Double strands unwind and pull apart New nucleotides pair with exposed bases ontrolled by DNA polymerase When a cell divides, each newly formed cell receives a copy of the entire genome(complete set of genes). All cells except the sperm and egg receive two copies of the genome in two sets of chromosomes. 49

50 As DNA replication begins, ydrogen bonds break between the strands and they unwind and separate DNA polymerase catalyzes the new pairing which results in two complete DNA molecules each with one new and one original strand. enetic information specifies how these ladders line up as well as information for determining which genes are accessed for their information. 50

51 DNA Replication opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. 2 2 phase roceed to division phase: genetic material replicates 1 phase: ell growth ytokinesis A T Remain specialized Apoptosis Restriction checkpoint 1 A riginal DNA molecule A A T A T A A T A T A T T A A T A A T A A Newly forming DNA molecules 51

52 enetic ode pecification of the correct sequence of amino acids in a polypeptide chain Each amino acid is represented by a triplet code of DNA bases The base sequence of a gene then determines the amino acid sequence in a polypeptide ince DNA stays in the nucleus, and proteins are made in the cytoplasm, DNA s code must be copied and carried to the cytoplasm. RNA molecules accomplish this transfer of the genetic code. 52

53 RNA Molecules ingle strand of nucleotides Each nucleotide contains: ribose, phosphate, base (A,,, and Uracil instead of Thymine) horter than DNA Different types: mrna (carries code from DNA to ribosome), trna (brings amino acids to ribosome), rrna (a component of ribosomes) 53

54 RNA Molecules rotein ynthesis involves 2 steps, each requiring RNA and enzymes Transcription occurs in the nucleus and is the process of copying DNA information into an RNA sequence Translation occurs at the ribosomes in the cytoplasm as the code is transferred to a growing chain of amino acids 54

55 Direction of reading code RNA Molecules Transcription of Messenger RNA (mrna): A section of DNA opens up (just where the gene coding for the particular protein is) mrna nucleotides pair up with the DNA bases on one side---uracil is used instead of thymine mrna moves away and DNA closes up ontrolled by RNA polymerase The mrna now goes through nuclear pore and attaches to a ribosome in the cytoplasm. opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. DNA RNA A U T A 55

56 rotein ynthesis Each trna molecule has an attachment point for a specific amino acid Each trna also has a region of 3 bases called an anticodon which is attracted to complementary mrna codons As the ribosome moves down the mrna strand, trna s bringing their amino acids are attracted to the mrna codons age

57 rotein ynthesis 57

58 rotein ynthesis opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. DNA double helix T A A T A T T A T A A T A T T A T A A T A T T A T A Nucleus DNA strands pulled apart ytoplasm T A A T Messenger A T RNA T U A T U A A A T A A T A A T T U A A A T T U A A A T Transcription (in nucleus) 2 mrna leaves the nucleus and attaches to a ribosome 1 DNA information is copied, or transcribed, into mrna following complementary base pairing Messenger RNA U Nuclear pore A A 3 Translation begins as trna anticodons recognize complementary mrna codons, thus bringing the correct amino acids into position on the growing polypeptide chain DNA strand T olypeptide chain 4 As the ribosome moves along the mrna, more amino acids are added Translation (in cytoplasm) Amino acids attached to trna A U U A A A 6 5 At the end of the mrna, the ribosome releases the new protein odon 1 odon 2 odon 3 odon 4 odon 5 odon 6 odon 7 trna molecules can pick up another molecule of the same amino acid and be reused Amino acids represented Methionine lycine erine Alanine Threonine Alanine lycine 58

59 rotein ynthesis opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. 1 The transfer RNA molecule for the last amino acid added holds the growing polypeptide chain and is attached to its complementary codon on mrna. 1 2 rowing 3 4 Next amino acid polypeptide 5 6 chain Transfer Anticodon RNA U U A U U A A A A A U 1 odons eptide bond 2 rowing 3 4 Next amino acid polypeptide 5 6 chain Transfer Anticodon RNA U U A U U A A A A A U 1 odons Messenger RNA A second trna binds complementarily to the next codon, and in doing so brings the next amino acid into position on the ribosome. A peptide bond forms, linking new amino acid to the growing polypeptide chain. The trna molecule that brought the 3 last A amino acid to the ribosome is released to the cytoplasm, and will be used again. The ribosome moves to a new position at the next codon on mrna. A new trna complementary to 4 the next codon on mrna brings the next amino acid to be added to the growing polypeptide chain U A U U A A A A A U Ribosome Transfer RNA U A U U A A A A A U Next amino acid Transfer RNA Messenger RNA Next amino acid Messenger RNA 59

60 4.2 From cience to Technology MicroRNAs ontrol ene Expression Instructions for using the blueprint they control specific sets of genes age

61 4.7: hanges in enetic Information nly about 1/10 th of one percent of the human genome differs from person to person o we are 99.9% the same. The other 1/10 % carry DNA that affects health and appearance. 61

62 Direction of reading code Nature of Mutations Mutations change in genetic information Result when: Extra bases are added or deleted Bases are changed May or may not change the protein (a) opyright The Mcraw-ill ompanies, Inc. ermission required for reproduction or display. ode for glutamic acid T T Mutation (b) ode for valine T A 62

63 If a change at the 4 th base of a DNA sequence results in a noticeable or detectable change & occurs in less than 1% of the population, it is considered a mutation. If there is no discernable change with the DNA variation it is called an N (single nucleotide polymorphism) 63

64 rotection Against Mutation Repair enzymes correct the mutations Mutations can occur spontaneously during the DNA replication or might be induced in response to exposure to chemicals or radiation called mutagens. ells can detect and correct using the DNA damage response. It restores the original DNA sequence. 64

65 Inborn Errors of Metabolism ccurs from inheriting a mutation that then alters an enzyme This creates a block in an otherwise normal biochemical pathway ince amino acids can connect in different ways they can avoid the bad connection. If one gene is damaged-the other may provide enough for some measure of normalcy. Time is a factor. Mutations in eggs and sperm will be replicated from the start, but some mutations occur much later and may have lesser effects. 65

66 4.3 From cience to Technology The uman Metabolome age 145 Refers to all of the small molecules that are part of metabolism in a cell, tissue, organ or an entire organism. 66

67 Important oints in hapter 4: utcomes to be Assessed 4.1: Introduction Describe the linked pathways of metabolism. 4.2: Metabolic rocesses ompare and contrast anabolism and catabolism. 4.3: ontrol of Metabolic Reactions Describe how enzymes control metabolic reactions. Explain how metabolic pathways are regulated. 67

68 Important oints in hapter 4: utcomes to be Assessed 4.4: Energy for Metabolic Reactions Explain how AT stores chemical energy and makes it available to a cell. 4.5: ellular Respiration Describe how the reactions of cellular respiration release chemical energy. Describe the general metabolic pathways of carbohydrate metabolism. 68

69 Important oints in hapter 4: utcomes to be Assessed 4.6: Nucleic Acids and rotein ynthesis Describe how DNA molecules store genetic information. Describe how DNA molecules are replicated. Explain how protein synthesis relies on genetic information. ompare and contrast DNA and RNA. Describe the steps of protein synthesis. 4.7: hanges in enetic Information Describe how genetic information can be altered. Explain how a mutation may or may not affect an organism. 69