1. BSC 2010 - Exam I Lectures and Text Pages I. Intro to Biology (2-29) II. Chemistry of Life – Chemistry review (30-46) – Water (47-57) – Carbon (58-67) – Macromolecules (68-91) III. Cells and Membranes – Cell structure (92-123) – Membranes (124-140) IV. Introductory Biochemistry – Energy and Metabolism (141-159) – Cellular Respiration (160-180) – Photosynthesis (181-200)

2. Evolution accounts for life’s unity and diversity The history of life – Is a saga of a changing Earth billions of years old Figure 1.17 Evolution and Adaptation: Properties of Life

3. 3 basic themes: 1) variation: in the genetic makeup of individuals 2) adaptation: of traits to the environment 3) natural selection: leads to differential reproduction: those organisms better adapted produce more offspring

4. The evolutionary view of life – Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection – He described the theory of natural selection. Prior to this, many scientists and scholars believed in evolution, but there was no solid idea about how it worked. Figure 1.18

5. The Origin of Species articulated two main points – Descent with modification – Natural selection Figure 1.19

6. Theory of Natural Selection: requires 3 basic conditions: 1. Individuals vary (all organisms are not equal) 2. There is a struggle for limited resources (i.e. competition) 3. Organisms have differential success at reproduction. Evolution and Adaptation are key features of life. Evolution provides evidence that life responds to changes in the environment.

7. He proposed “Natural Selection” As the mechanism for evolutionary adaptation of populations to their environments Population of organisms Hereditary variations Differences in reproductive success Evolution of adaptations in the population Overproduction and struggle for existence Figure 1.20

8. Natural selection is the evolutionary process that occurs – When a population’s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others 1 Populations with varied inherited traits 2 Elimination of individuals with certain traits. 3 Reproduction of survivors. 4 Increasing frequency of traits that enhance survival and reproductive success. Figure 1.21

9. The products of natural selection Are often exquisite adaptations of organisms to the special circumstances of their way of life and their environment Figure 1.22

10. Evolution is change over time within the original gene pool. It is possible to have change through random mutations, without natural selection, but usually it is beneficial mutations that are enhanced through natural selection: Some mutations confer adaptive value. Example: A mutation may have the effect of allowing a bacterium to survive or resist a bacterial spray or an antibiotic. That bacterium survives, and produces offspring, passing on the resistance mutation, so in the next generation more of the bacteria are resistant. Thus a resistant strain of bacteria evolves, and soon we find it more and more difficult to eliminate harmful bacteria. So, a mutation can create variation on which natural selection then acts. The environment itself does not create change. Natural selection leads to greater reproduction of well-adapted individuals, which leads to evolution (change in gene frequency over time).

11. The Tree of Life Many related organisms – Have very similar anatomical features, adapted for their specific ways of life Such examples of kinship – Connect life’s “unity in diversity” to Darwin’s concept of “descent with modification”

12. Darwin proposed that natural selection Could enable an ancestral species to “split” into two or more descendant species, resulting in a “tree of life ” Large ground finch Small ground finch Geospiza magnirostris Seed eater Sharp-beaked ground finch Camarhynchus psitacula Green warbler finch Large tree finch Large cactus ground finch Ground finches Tree finches Insect eaters Bud eater Warbler finches Common ancestor from South American mainland Gray warbler finch Certhidea olivacea Certhidea fusca Geospiza difficilis Cactus flower eater Geospiza scandens Seed eater Geospiza conirostris Geospiza fortis Medium ground finch Geospiza fuliginosa Mangrove finch Cactospiza heliobates Cactospiza pallida Woodpecker finch Medium tree finch Camarhynchus pauper Small tree finch Vegetarian finch Camarhynchus parvulus Platyspiza crassirostris Cactus ground finch Figure 1.23

13. Each species is a twig on a branching tree of life – Extending back in time through ancestral species more and more remote All of life – Is connected through its long evolutionary history

14. Evolution: is a change in gene frequency over time. It is the result of two main processes: 1. natural selection: “survival of the fittest”. Some organisms, due to the characteristics of their environment, will survive and reproduce more than others. e.g. Galapagos finches- some had larger beaks than others when a drought hit the islands, leaving only thick, hard seeds. Only the birds with large beaks were able to eat, the others starved. Therefore, the big-beaked birds had the energy to reproduce and the next generation all had large beaks. 2. adaptation: the process of becoming better suited to the environment. Can happen through natural selection or through genetic drift (random change due to mutation or circumstances). * The word “adaptation” can also be used to describe a trait of a particular organism that has arisen through natural selection. e.g. a giraffe’s long neck is an adaptation for eating leaves of tall trees.

15. Eleven themes that unify biology Table 1.1

16. BSC 2010 - Exam I Lectures and Text Pages I. Intro to Biology (2-29) II. Chemistry of Life – Chemistry review (30-46) – Water (47-57) – Carbon (58-67) – Macromolecules (68-91) III. Cells and Membranes – Cell structure (92-123) – Membranes (124-140) IV. Introductory Biochemistry – Energy and Metabolism (141-159) – Cellular Respiration (160-180) – Photosynthesis (181-200)

17. Chemical Foundations of Biology An understanding of the workings of the cell and the physiology of multicellular organisms requires an understanding of chemistry. Living organisms are chemical systems.

18. The bombardier beetle uses chemistry to defend itself Figure 2.1

19. Matter, Elements, Molecules, Compounds Matter consists of chemical elements in pure form and in combinations called compounds Organisms are composed of matter, which is anything that takes up space and has mass. Element: basic unit of matter, cannot be subdivided into simpler substances (by ordinary chemical means). The smallest unit of an element is a single atom. Molecule: a substance composed of more than one atom.

20. SodiumChloride Sodium Chloride + A compound – Is a substance consisting of two or more elements combined in a fixed ratio – Has characteristics different from those of its elements Figure 2.2

21. Matter All matter is made up from 92 naturally occurring elements. Living matter requires only 25 of these 92 elements. These are the “Essential Elements of Life”.

22. Essential Elements of Life Carbon, hydrogen, oxygen, and nitrogen (CHON) account for 96% of living matter. A few other elements make up the remaining 4%. Trace elements – Are required by an organism in only minute quantities

23. The effects of essential element deficiencies (a) Nitrogen deficiency(b) Iodine deficiency Figure 2.3

24. Element’s properties depend on structure of its atoms Each element – Consists of a certain kind of atom that is different from those of other elements An atom – Is the smallest unit of matter that still retains the properties of an element

25. Subatomic Particles Atoms of each element – Are composed of even smaller parts called subatomic particles Relevant subatomic particles include – Neutrons, which have no electrical charge – Protons, which are positively charged – Electrons, which are negatively charged

26. Nucleus (a) (b) In this even more simplified model, the electrons are shown as two small blue spheres on a circle around the nucleus. Cloud of negative charge (2 electrons) Electrons This model represents the electrons as a cloud of negative charge, as if we had taken many snapshots of the 2 electrons over time, with each dot representing an electron‘s position at one point in time. Figure 2.4 Protons and neutrons a re found in the atomic nucleus Electrons s urround the nucleus in a “cloud”

27. Atomic Number and Atomic Mass Atoms of the various elements – Differ in their number of subatomic particles The atomic number of an element – Is the number of protons – Is unique to each element Example: Carbon has an atomic number of 6. If you know the atomic number, you know the element. Usually, in naturally occurring elements, the number of protons = the number of electrons. Therefore the atom has a neutral charge. The properties of atoms are determined by the number and arrangement of their electrons.

28. The mass number of an element – Is the sum of protons plus neutrons in the nucleus of an atom – Is an approximation of the atomic mass of an atom – One mole of protons or neutrons has a mass of one gram.

29. Isotopes of a given element – Differ in the number of neutrons in the atomic nucleus – Have the same number of protons Isotopes – atoms of an element may occur in different forms

30. – Are unstable and spontaneously give off particles and energy – Radioactivity has negative effects, as when it causes cancer, but also has positive uses, as when it is used as a marker in biological molecules. Radioactive isotopes

31. – Can be used in biology Cancerous throat tissue Figure 2.6 Radioactive isotopes

32. Electron orbitals Electrons are located in specific energy levels around the nucleus. You will need to know the number of electrons in the outermost (reactive) energy level for the different elements. The total number of electrons = the total number of protons (atomic number) DO NOT ASSUME A CHARGE on any atom unless you see a charge symbol. Atomic structure of atoms determines how they interact.

33. Energy levels – Are represented by electron shells Third energy level (shell) Second energy level (shell) First energy level (shell) Energy absorbed Energy lost An electron can move from one level to another only if the energy it gains or loses is exactly equal to the difference in energy between the two levels. Arrows indicate some of the step-wise changes in potential energy that are possible. (b) Atomic nucleus Figure 2.7B

34. The periodic table of the elements – Shows the electron distribution for all the elements Second shell Helium 2 He First shell Third shell Hydrogen 1 H 2 He 4.00 Atomic mass Atomic number Element symbol Electron-shell diagram Lithium 3 Li Beryllium 4 Be Boron 3 B Carbon 6 C Nitrogen 7 N Oxygen 8 O Fluorine 9 F Neon 10 Ne Sodium 11 Na Magnesium 12 Mg Aluminum 13 Al Silicon 14 Si Phosphorus 15 P Sulfur 16 S Chlorine 17 Cl Argon 18 Ar Figure 2.8

35. Valence electrons – Are those in the outermost, or valence shell – Determine the chemical behavior of an atom Figure 4.4

36. Each electron shell – Consists of a specific number of orbitals Electron orbitals. Each orbital holds up to two electrons. 1s orbital2s orbitalThree 2p orbitals 1s, 2s, and 2p orbitals (a) First shell (maximum 2 electrons) (b) Second shell (maximum 8 electrons) (c) Neon, with two filled shells (10 electrons) Electron-shell diagrams. Each shell is shown with its maximum number of electrons, grouped in pairs. x Z Y Figure 2.9

37. Bonding Rules 1. Interactions are based on exchange or rearrangement of electrons in the outer shell (valence shell), also called valence electrons. (valence # is # of e- needed to fill outer shell). 2. Stable atoms have a full outer shell. 3. Atoms that have 1, 2, or 3 valence e- tend to lose them in reactions with atoms that have 5, 6, or 7, and thus form + ions. 4. Atoms that have 5, 6, or 7 valence e- tend to gain those lost by those with 1, 2, or 3, and thus form - ions. 5. Atoms with 4 valence e- tend to share = covalent bonds