Figure 1.3. Order. Response to the environment. Evolutionary adaptation. Reproduction. Regulation. Energy processing. Growth and development

Transcription

1 Figure 1.3 Order Response to the environment Evolutionary adaptation Reproduction Regulation Energy processing Growth and development

2 Theme: New Properties Emerge at Each Level in the Biological Hierarchy Life can be studied at different levels, from molecules to the entire living planet The study of life can be divided into different levels of biological organization

3 Figure 1.4 The biosphere Ecosystems Organs and organ systems Tissues Communities Organelles Cells Organisms Atoms Populations Molecules

4 Emergent Properties Emergent properties result from the arrangement and interaction of parts within a system Emergent properties characterize nonbiological entities as well For example, a functioning bicycle emerges only when all of the necessary parts connect in the correct way

5 The Power and Limitations of Reductionism Reductionism is the reduction of complex systems to simpler components that are more manageable to study For example, studying the molecular structure of DNA helps us to understand the chemical basis of inheritance

6 An understanding of biology balances reductionism with the study of emergent properties For example, new understanding comes from studying the interactions of DNA with other molecules

7 Theme: Organisms Interact with Other Organisms and the Physical Environment Every organism interacts with its environment, including nonliving factors and other organisms Both organisms and their environments are affected by the interactions between them For example, a tree takes up water and minerals from the soil and carbon dioxide from the air; the tree releases oxygen to the air and roots help form soil

8 Figure 1.5a

9 Figure 1.5 Sunlight Leaves absorb light energy from the sun. CO 2 Leaves take in carbon dioxide from the air and release oxygen. O 2 Cycling of chemical nutrients Leaves fall to the ground and are decomposed by organisms that return minerals to the soil. Water and minerals in the soil are taken up by the tree through its roots. Animals eat leaves and fruit from the tree.

10 Theme: The Cell Is an Organism s Basic Unit of Structure and Function The cell is the lowest level of organization that can perform all activities required for life All cells Are enclosed by a membrane Use DNA as their genetic information

11 A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles

12 Concept 1.2: The Core Theme: Evolution accounts for the unity and diversity of life Nothing in biology makes sense except in the light of evolution Theodosius Dobzhansky Evolution unifies biology at different scales of size throughout the history of life on Earth

13 Classifying the Diversity of Life Approximately 1.8 million species have been identified and named to date, and thousands more are identified each year Estimates of the total number of species that actually exist range from 10 million to over 100 million

14 Grouping Species: The Basic Idea Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth Domains, followed by kingdoms, are the broadest units of classification

15 Figure 1.14 Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya

16 The Three Domains of Life Organisms are divided into three domains Domain Bacteria and domain Archaea compose the prokaryotes Most prokaryotes are single-celled and microscopic

17 2 m 2 m Figure 1.15 (a) Domain Bacteria (b) Domain Archaea (c) Domain Eukarya Kingdom Animalia 100 m Kingdom Plantae Protists Kingdom Fungi

18 Charles Darwin and the Theory of Natural Selection Fossils and other evidence document the evolution of life on Earth over billions of years

19 Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859 Darwin made two main points Species showed evidence of descent with modification from common ancestors Natural selection is the mechanism behind descent with modification Darwin s theory explained the duality of unity and diversity

20 Darwin observed that Individuals in a population vary in their traits, many of which are heritable More offspring are produced than survive, and competition is inevitable Species generally suit their environment

21 Darwin inferred that Individuals that are best suited to their environment are more likely to survive and reproduce Over time, more individuals in a population will have the advantageous traits Evolution occurs as the unequal reproductive success of individuals

22 In other words, the environment selects for the propagation of beneficial traits Darwin called this process natural selection

23 The Elements of Life About 20 25% of the 92 elements are essential to life Carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter Most of the remaining 4% consists of calcium, phosphorus, potassium, and sulfur Trace elements are those required by an organism in minute quantities

24 Table 2.1

25 Concept 2.2: An element s properties depend on the structure of its atoms Each element consists of unique atoms An atom is the smallest unit of matter that still retains the properties of an element Proton Neutron Electron Atomic number Atomic mass

26 Figure 2.9 First shell Second shell Third shell Hydrogen 1H Lithium 3Li Sodium 11Na Beryllium 4Be Magnesium 12Mg Boron 5B Aluminum 13Al Carbon 6C Silicon 14Si Nitrogen 7N Phosphorus 15P Oxygen 8O Sulfur 16S Fluorine 9F Chlorine 17Cl Neon 10Ne Argon 18Ar Helium 2He 2 He 4.00 Mass number Atomic number Element symbol Electron distribution diagram

27 Valence electrons are those in the outermost shell, or valence shell The chemical behavior of an atom is mostly determined by the valence electrons Elements with a full valence shell are chemically inert

28 Covalent Bonds A covalent bond is the sharing of a pair of valence electrons by two atoms In a covalent bond, the shared electrons count as part of each atom s valence shell

29 In a nonpolar covalent bond, the atoms share the electron equally In a polar covalent bond, one atom is more electronegative, and the atoms do not share the electron equally Unequal sharing of electrons causes a partial positive or negative charge for each atom or molecule

30 Figure 2.13 O H H + + H 2 O

31 Ionic Bonds Atoms sometimes strip electrons from their bonding partners An example is the transfer of an electron from sodium to chlorine After the transfer of an electron, both atoms have charges A charged atom (or molecule) is called an ion

32 Figure Na Sodium atom Cl Chlorine atom Na + Sodium ion (a cation) Cl Chloride ion (an anion) Sodium chloride (NaCl)

33 A cation is a positively charged ion An anion is a negatively charged ion An ionic bond is an attraction between an anion and a cation

34 Weak Chemical Bonds Most of the strongest bonds in organisms are covalent bonds that form a cell s molecules Weak chemical bonds, such as ionic bonds and hydrogen bonds, are also important Weak chemical bonds reinforce shapes of large molecules and help molecules adhere to each other

35 Hydrogen Bonds A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom In living cells, the electronegative partners are usually oxygen or nitrogen atoms

36 Figure Water (H 2 O) + Hydrogen bond Ammonia (NH 3 ) + + +

37 Molecular Shape and Function A molecule s shape is usually very important to its function A molecule s shape is determined by the positions of its atoms valence orbitals In a covalent bond, the s and p orbitals may hybridize, creating specific molecular shapes

38 Figure 2.17 s orbital z Three p orbitals Four hybrid orbitals x y (a) Hybridization of orbitals Tetrahedron Space-Filling Model Ball-and-Stick Model Unbonded Electron pair Hybrid-Orbital Model (with ball-and-stick model superimposed) Water (H 2 O) Methane (CH 4 ) (b) Molecular-shape models

39 Biological molecules recognize and interact with each other with a specificity based on molecular shape Molecules with similar shapes can have similar biological effects

40 Figure 2.18 Natural endorphin Carbon Hydrogen Nitrogen Sulfur Oxygen Morphine (a) Structures of endorphin and morphine Natural endorphin Morphine Brain cell Endorphin receptors (b) Binding to endorphin receptors

41 Figure 3.1

42 Concept 3.1: Polar covalent bonds in water molecules result in hydrogen bonding The water molecule is a polar molecule: the opposite ends have opposite charges Polarity allows water molecules to form hydrogen bonds with each other

43 Figure Hydrogen bond Polar covalent bonds

44 Concept 3.2: Four emergent properties of water contribute to Earth s suitability for life Four of water s properties that facilitate an environment for life are Cohesive behavior Ability to moderate temperature Expansion upon freezing Versatility as a solvent

45 Cohesion of Water Molecules Collectively, hydrogen bonds hold water molecules together, a phenomenon called cohesion Cohesion helps the transport of water against gravity in plants Adhesion is an attraction between different substances, for example, between water and plant cell walls

46 Animation: Water Transport Right-click slide/select Play

47 Figure 3.3 Adhesion Two types of water-conducting cells Direction of water movement 300 m Cohesion

48 Surface tension is a measure of how hard it is to break the surface of a liquid Surface tension is related to cohesion

49 Figure 3.4

50 Moderation of Temperature by Water Water absorbs heat from warmer air and releases stored heat to cooler air Water can absorb or release a large amount of heat with only a slight change in its own temperature

51 Water s High Specific Heat The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1ºC The specific heat of water is 1 cal/g/ºc Water resists changing its temperature because of its high specific heat

52 Water s high specific heat can be traced to hydrogen bonding Heat is absorbed when hydrogen bonds break Heat is released when hydrogen bonds form The high specific heat of water minimizes temperature fluctuations to within limits that permit life

53 Figure 3.5 Santa Barbara 73 70s ( F) 80s 90s 100s Los Angeles (Airport) 75 Pacific Ocean 68 Burbank 90 San Diego 72 Santa Ana 84 San Bernardino 100 Riverside 96 Palm Springs miles

54 Evaporative Cooling Evaporation is transformation of a substance from liquid to gas Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas As a liquid evaporates, its remaining surface cools, a process called evaporative cooling Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water

55 Floating of Ice on Liquid Water Ice floats in liquid water because hydrogen bonds in ice are more ordered, making ice less dense Water reaches its greatest density at 4 C If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth

56 Figure 3.6 Hydrogen bond Liquid water: Hydrogen bonds break and re-form Ice: Hydrogen bonds are stable

57 Hydrophilic and Hydrophobic Substances A hydrophilic substance is one that has an affinity for water A hydrophobic substance is one that does not have an affinity for water Oil molecules are hydrophobic because they have relatively nonpolar bonds

58 Concept 3.3: Acidic and basic conditions affect living organisms A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H + ) The molecule with the extra proton is now a hydronium ion (H 3 O + ), though it is often represented as H + The molecule that lost the proton is now a hydroxide ion (OH )

59 Water is in a state of dynamic equilibrium in which water molecules dissociate at the same rate at which they are being reformed

60 Figure 3.UN H 2 O Hydronium Hydroxide ion (H 3 O + ) ion (OH )

61 Acids and Bases An acid is any substance that increases the H + concentration of a solution A base is any substance that reduces the H + concentration of a solution

62 Increasingly Basic [H + ] < [OH ] Increasingly Acidic [H + ] > [OH ] Figure 3.10 ph Scale 0 1 Battery acid H + H + H + OH OH H + H + H + H + H + Acidic solution OH OH H + H + OH OH OH H + H + H + Neutral solution OH OH OH H + OH OH OH H + OH Basic solution Neutral [H + ] = [OH ] Gastric juice, lemon juice Vinegar, wine, cola Tomato juice Beer Black coffee Rainwater Urine Saliva Pure water Human blood, tears Seawater Inside of small intestine Milk of magnesia Household ammonia Household bleach Oven cleaner

63 Buffers The internal ph of most living cells must remain close to ph 7 Buffers are substances that minimize changes in concentrations of H + and OH in a solution Most buffers consist of an acid-base pair that reversibly combines with H +

64 The Carbonic-Acid-Bicarbonate Buffer in the Blood By far the most important buffer for maintaining acid-base balance in the blood is the carbonic-acid-bicarbonate buffer. The simultaneous equilibrium reactions of interest are (H 3 PO 4 ) in equilibrium with dihydrogen phosphate ion (H 2 PO 4- ) and H +.

65 The burning of fossil fuels is also a major source of sulfur oxides and nitrogen oxides These compounds react with water in the air to form strong acids that fall in rain or snow Acid precipitation is rain, fog, or snow with a ph lower than 5.2 Acid precipitation damages life in lakes and streams and changes soil chemistry on land

66 Figure 4.5 (a) Length (c) Double bond position Ethane Propane 1-Butene 2-Butene (b) Branching (d) Presence of rings Butane 2-Methylpropane (isobutane) Cyclohexane Benzene

67 Isomers Isomers are compounds with the same molecular formula but different structures and properties Structural isomers have different covalent arrangements of their atoms Cis-trans isomers have the same covalent bonds but differ in spatial arrangements Enantiomers are isomers that are mirror images of each other

68 Animation: Isomers Rightclick slide / select Play

69 Figure 4.7 (a) Structural isomers (b) Cis-trans isomers cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides. (c) Enantiomers CO 2 H CO 2 H H NH 2 NH 2 H CH 3 L isomer CH 3 D isomer

70 Figure 4.7a (a) Structural isomers

71 Figure 4.7b (b) Cis-trans isomers cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides.

72 Figure 4.7c (c) Enantiomers CO 2 H CO 2 H H NH 2 NH 2 H CH 3 L isomer CH 3 D isomer

73 Enantiomers are important in the pharmaceutical industry Two enantiomers of a drug may have different effects Usually only one isomer is biologically active Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules

74 Animation: L-Dopa Right-click slide / select Play

75 Figure 4.8 Drug Condition Effective Enantiomer Ineffective Enantiomer Ibuprofen Pain; inflammation S-Ibuprofen R-Ibuprofen Albuterol Asthma R-Albuterol S-Albuterol

76 The Chemical Groups Most Important in the Processes of Life Functional groups are the components of organic molecules that are most commonly involved in chemical reactions The number and arrangement of functional groups give each molecule its unique properties

77 Figure 4.UN02 Estradiol Testosterone

78 Figure 4.9a Hydroxyl STRUCTURE (may be written HO ) Alcohols (Their specific names usually end in -ol.) NAME OF COMPOUND EXAMPLE Is polar as a result of the electrons spending more time near the electronegative oxygen atom. FUNCTIONAL PROPERTIES Ethanol Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars.

79 Figure 4.9b Carbonyl STRUCTURE EXAMPLE Acetone Propanal Ketones if the carbonyl group is within a carbon skeleton Aldehydes if the carbonyl group is at the end of the carbon skeleton A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Ketone and aldehyde groups are also found in sugars, giving rise to two major groups of sugars: ketoses (containing ketone groups) and aldoses (containing aldehyde groups). NAME OF COMPOUND FUNCTIONAL PROPERTIES

80 Figure 4.9c Carboxyl STRUCTURE Carboxylic acids, or organic acids NAME OF COMPOUND EXAMPLE Acts as an acid; can donate an H + because the covalent bond between oxygen and hydrogen is so polar: FUNCTIONAL PROPERTIES Acetic acid Nonionized Ionized Found in cells in the ionized form with a charge of 1 and called a carboxylate ion.

81 Figure 4.9d Amino STRUCTURE Amines NAME OF COMPOUND EXAMPLE Acts as a base; can pick up an H + from the surrounding solution (water, in living organisms): FUNCTIONAL PROPERTIES Glycine Nonionized Ionized Found in cells in the ionized form with a charge of 1.

82 Figure 4.9e Sulfhydryl STRUCTURE Thiols NAME OF COMPOUND (may be written HS ) EXAMPLE Two sulfhydryl groups can react, forming a covalent bond. This cross-linking helps stabilize protein structure. FUNCTIONAL PROPERTIES Cysteine Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be permanently curled by shaping it around curlers and then breaking and re-forming the cross-linking bonds.

83 Figure 4.9f Phosphate STRUCTURE Organic phosphates NAME OF COMPOUND EXAMPLE Glycerol phosphate Contributes negative charge to the molecule of which it is a part (2 when at the end of a molecule, as at left; 1 when located internally in a chain of phosphates). Molecules containing phosphate groups have the potential to react with water, releasing energy. FUNCTIONAL PROPERTIES

84 Figure 4.9g Methyl STRUCTURE Methylated compounds NAME OF COMPOUND EXAMPLE Addition of a methyl group to DNA, or to molecules bound to DNA, affects the expression of genes. FUNCTIONAL PROPERTIES 5-Methyl cytidine Arrangement of methyl groups in male and female sex hormones affects their shape and function.

85 What functional group is commonly used in cells to transfer energy from one organic molecule to another? a) carboxyl b) sulfhydryl c) hydroxyl d) phosphate e) amino

86 Is this molecule soluble in water? yes no

87 The general structure of amino acids are shown in this figure. What functional groups are highlighted in salmon and yellow, respectively? a) Amino and carbonyl b) Hydroxyl and carbonyl c) Amino and carboxyl d) Methyl and carboxyl e) Methyl and hydroxyl

88 The chemical equilibrium between carbonic acid and bicarbonate acts as a ph regulator in our blood. If the blood ph begins to rise, what will happen? H 2 CO 3 HCO 3 + H + Carbonic acid Bicarbonate ion Hydrogen ion reaction proceeds to the right; more carbonic acid dissociates reaction proceeds to the right; more carbonic acid forms reaction proceeds to the left; more carbonic acid dissociates reaction proceeds to the left; more carbonic acid forms

89 Based on the periodic table shown here, which elements will most likely form an ionic bond? Na and Cl, and Li and F C and O N and O Si and Cl all of the above

90 Overview Which of the following properties or processes do we associate with living things? a) evolutionary adaptations b) energy processing c) responding to the environment d) growth and reproduction e) all of the above

91 What is the lowest level of biological organization that can perform all the activities required for life? a) organelle for example, a chloroplast b) cell for example, a skin cell c) tissue for example, nervous tissue d) organ system for example, the reproductive system e) organism for example, an amoeba, dog, human, or maple tree

92 Form and Function The idea that form and function are related would not be exemplified by which of the following examples? a) Cells in the intestinal lining of vertebrates have many small projections that increase the surface area for absorption of nutrients. b) Plants that live in dry areas have large roots for absorbing water. c) Seeds that are dispersed by wind are very light. d) Fish that swim rapidly have bodies that are streamlined. e) None of the above.

93 Negative Feedback Which of the following examples would represent negative feedback? a) As carbon dioxide levels rise in the blood of a mammal, the rate of breathing increases, leading to a decrease in blood levels of carbon dioxide. b) As global temperatures rise, more ice melts, leading to greater planetary absorption of sunlight and additional temperature increase. c) The speed of a racehorse decreases after running a mile. d) The metabolic rate and energy consumption of grizzly bears decrease during hibernation. e) Frog eggs hatch after 5 days of development at 28 C but after 10 days of development at 23 C.