Theme 6 : The continuity of life is based on heritable information in the form of DNA

1. Theme 6: The continuity of life is based on heritable information in the form of DNA Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid) DNA is the substance of genes Genes are the units of inheritance that transmit information from parents to offspring

2. Each chromosome has one long DNA molecule with hundreds or thousands of genes DNA is inherited by offspring from their parents DNA controls the development and maintenance of organisms

3. Inherited DNA directs the development of an organism Sperm cell DNA Nuclei containing DNA Embryo’s cells with copies of inherited DNA Fertilized egg with DNA from both parents Egg cell Offspring with traits inherited from both parents

4. Each DNA molecule is made up of two long chains arranged in a double helix Each link of a chain is one of four kinds of chemical building blocks called nucleotides

5. Nucleus DNA Nucleotide Cell (a) DNA double helix (b) Single strand of DNA

6. Genes control protein production indirectly Why are proteins important? Proteins are essential parts of organisms and participate in every process within cells Many proteins are enzymes that catalyze (speed up) biochemical reactions and are vital to metabolism

7. DNA controls protein production indirectly using RNA as an intermediary DNA is transcribed into RNA then translated into a protein

8. An organism’s genome is its entire set of genetic instructions The human genome and those of many other organisms have been sequenced using DNA-sequencing machines Knowledge of a cell’s genes and proteins can be integrated using a systems approach

9. Advances in systems biology at the cellular and molecular level depend on 1) “High-throughput” technology, which yields enormous amounts of data 2) Bioinformatics, which is the use of computational tools to process a large volume of data 3) Interdisciplinary research teams

10. Theme 7: Feedback mechanisms regulate biological systems Feedback mechanisms allow biological processes to self-regulate 1) Negative feedback a change in a physiological variable triggers a response that counteracts the initial fluctuation 2) Positive feedback a change in a physiological variable triggers mechanisms that amplify the change

11. Negative feedback: Like a thermostat in the home: as the temperature rises (above the ideal normal temperature), the thermostat detects the change and triggers the air-conditioning to turn on and cool the house. Once the temperature reaches its thermostat setting, the air conditioning turns off.

12. Positive feedback: The onset of contractions in childbirth: when a contraction occurs, the hormone oxytocin is released into the body, which stimulates further contractions. This results in contractions increasing in amplitude and frequency.

13. The Core Theme: Evolution accounts for the unity and diversity of life “Nothing in biology makes sense except in the light of evolution” Evolution unifies biology at different scales of size throughout the history of life on Earth

14. Organizing 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

15. 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

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

17. The Three Domains of Life The three-domain system is currently used, and replaces the old five-kingdom system Domain Bacteria and domain Archaea comprise the prokaryotes Domain Eukarya includes all eukaryotic organisms

18. (a) DOMAIN BACTERIA Prokaryotes (b) DOMAIN ARCHAEA (c) DOMAIN EUKARYA Eukaryotes Protists Kingdom Plantae Kingdom Fungi Kingdom Animalia

19. DOMAIN BACTERIA – the most diverse and widespread of the prokaryotes • e.g., Staphylococcus spp., Lactobacillus spp., Streptomyces spp. E. coli

20. (b) DOMAIN ARCHAEA - prokaryotes that live in extreme environments, such as salt lakes and boiling hot springs (sometimes called extremophiles); believed to be the oldest organisms on Earth

21. Domain Eukarya: includes three multicellular kingdoms: 1) Plantae 2) Fungi 3) Animalia Other eukaryotic organisms were formerly grouped into a kingdom called Protista, though these are now often grouped into many separate kingdoms

22. Protists Kingdom Plantae Kingdom Fungi (c) DOMAIN EUKARYA Kingdom Animalia

23. Protists – are in multiple kingdoms; unicellular eukaryotes and their relatively simple multicellular relatives e.g., Amoebas, Euglena (unicellular animal-like protists); Algae (multicellular plant-like protists)

24. Kindom Fungi – absorb nutrients after decomposing organic matter (leaf litter, animal feces)

25. Kingdom Plantae – consists of multicellular eukaryotes that carry out photosynthesis, the conversion of light energy to the chemical energy in food

26. Kingdom Animalia – consists of multicellular eukaryotes that ingest other organisms Basilisk

27. Unity in the Diversity of Life There is unity in the diversity of life; for example: - DNA is the universal genetic language common to all organisms - Unity is evident in many features of cell structure

28. Cilia of Paramecium Cilia of trachea cells Cross section of a cilium, as viewed with an electron microscope

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

31. 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

32. Darwin observed that: • Individuals in a population have traits that vary • Many of these traits are heritable (passed from parents to offspring) • More offspring are produced than survive • Competition is inevitable • Species generally suit their environment

34. 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 In other words, the natural environment “selects” for beneficial traits

35. Example: a population of beetles lives in an area that commonly experiences forest fires; these beetles vary in coloration, from light grey to black Reproduction of survivors. Increasing frequency of traits that enhance survival and reproductive success. Population with varied inherited traits. Elimination of individuals with certain traits. 1 2 3 4 Birds eat the beetles that they can see best (black beetles are more camouflaged) – as a result, black beetles live to reproduce, others do not. Black beetles are “selected for” and predominate in the population.

36. Natural selection is often evident in adaptations of organisms to their way of life and environment Bat wings are an example of adaptation

37. The Tree of Life “Unity in diversity” arises from “descent with modification” For example, the forelimb of the bat, human, horse and the whale flipper all share a common skeletal architecture Fossils provide additional evidence of anatomical unity from descent with modification

38. For example, the finch species of the Galápagos Islands Evolutionary relationships are often illustrated with tree-like diagrams that show ancestors and their descendents Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species

39. Green warbler finch Certhidea olivacea Warbler finches Insect-eaters Gray warbler finch Certhidea fusca COMMON ANCESTOR Sharp-beaked ground finch Geospiza difficilis Seed-eater Vegetarian finch Platyspiza crassirostris Bud-eater Mangrove finch Cactospiza heliobates Woodpecker finch Cactospiza pallida Tree finches Insect-eaters Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Large cactus ground finch Geospiza conirostris Cactus-flower-eaters Cactus ground finch Geospiza scandens Seed-eaters Ground finches Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris

40. Green warbler finch Certhidea olivacea Warbler finches Insect-eaters Gray warbler finch Certhidea fusca Sharp-beaked ground finch Geospiza difficilis Seed-eater Vegetarian finch Platyspiza crassirostris Bud-eater

41. Mangrove finch Cactospiza heliobates Woodpecker finch Cactospiza pallida Tree finches Insect-eaters Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus

42. Large cactus ground finch Geospiza conirostris Cactus-flower-eaters Cactus ground finch Geospiza scandens Seed-eaters Ground finches Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris

43. Scientists use two main forms of inquiry in their study of nature The word Science is derived from Latin and means “to know” Inquiry is the search for information and explanation There are two main types of scientific inquiry: discovery science and hypothesis-based science

44. Discovery Science (or Descriptive Science) – mainly involves describing nature Discovery science describes natural structures and processes - based on observation and the analysis of data European black caps

45. Types of Data Data are recorded observations or items of information Data fall into two categories 1) Qualitative: descriptions rather than measurements 2) Quantitative: recorded measurements, which are sometimes organized into tables and graphs FYI – the word “data” is plural, “datum” is singular! e.g., The data were collected from 120 nests.

48. Induction Inductive reasoning draws conclusions through the logical process of induction Repeat specific observations can lead to important generalizations For example, “the sun always rises in the east”

49. Hypothesis-based Science – involves explaining nature Observations can lead us to ask questions and propose hypothetical explanations called hypotheses

50. The Role of Hypotheses in Inquiry A hypothesis is a tentative answer to a well-framed question A scientific hypothesis leads to predictions that can be tested by observation or experimentation