Fundamentals of Biology Valencia College BSC1010C

Transcription

1 1 Fundamentals of Biology Valencia College BSC1010C

2 1 Studying Life Chapter objectives: What Is Biology? Is All Life on Earth Related? How Do Biologists Investigate Life? How Does Biology Influence Public Policy?

3 1.1 What is Biology? Biology: Bios (Greek) meaning life ology means a branch of learning or the study of the scientific study of living things i.e., structure, functioning, growth, origin, evolution, ecology & distribution of living organisms Living things: all the organisms descended from a single-celled ancestor.

4 1.1 What is Biology? Characteristics of living organisms: Consist of one or more cells Contain genetic information Use genetic information to reproduce themselves Are genetically related and have evolved Can convert molecules from their environment into new biological molecules Extract energy from the environment and use it to do biological work Regulate their internal environment

5 1.1 What is Biology? Evolution: a central theme of biology. Living systems evolve through differential survival and reproduction. The processes of evolution have generated the enormous diversity of life on Earth.

6 Levels of Organization Cellular Organization Cells Organelles Molecules Atoms The Cell is the basic unit of life. 6

7 1.1 What is Biology? Unicellular organisms: a single cell carries out all the functions of life. Multicellular organisms: made of many cells that are specialized for different functions. Viruses are acellular

8 Figure 1.1 The Many Faces of Life (Part 1) Sulfolobus E. Coli Coccolithophore Archea Domain - Prokaryotes - Bacteria Algae - Protist -

9 Figure 1.1 The Many Faces of Life (Part 2) (Fungi)

10 1.1 What is Biology? The study of cells was made possible by the invention of microscopes. Robert Hooke in the 1600s described repeating units of plant material as cells. Antony van Leeuwenhoek discovered single-celled organisms in pond water

11 Figure 1.2 Cells Are the Building Blocks of Life Cork Leaf Duckweed stem

12 1.1 What is Biology? Cell Theory: Cells are the basic structural and physiological units of all living organisms. Cells are both distinct entities and building blocks of more complex organisms. (Schleiden and Schwann 1838)

13 1.1 What is Biology? Cell Theory: All cells come from preexisting cells. All cells are similar in chemical composition. Most of the chemical reactions of life occur within cells. Complete sets of genetic information are replicated and passed on during cell division.

14 1.1 What is Biology? All of life shares a common evolutionary history Evolution: change in the genetic makeup of biological populations through time. Charles Darwin proposed that all living organisms are descended from a common ancestor by the mechanism of natural selection. Differential survival & reproduction Survival of the fittest

15 1.1 What is Biology? Darwin proposed that living organisms are descended from common ancestors and therefore related to one another Species: a group of organisms that can produce viable and fertile offspring with one another. Members of one species do not normally interbreed with members of other species in nature.

16 1.1 What is Biology? Humans can select for desired traits when breeding animals. Traits that increase the probability that the organism will survive and reproduce will become more common in the population. Natural selection and other evolutionary processes (e.g., sexual selection/mating choice and genetic drift) lead to adaptation that enhance an organism s chances of survival & reproduction in its environment. What is the source of information that is passed on parent to offspring?

17 1.1 What is Biology? Biological information is contained in a genetic language common to all organisms Genome: sum total of all the DNA in a cell. Contains the blue print for existence DNA: the information that is passed from parent to daughter cells. consists of repeating subunits called nucleotides. Gene: a specific segment of DNA that contains information for making a protein. Mutations are alterations in the nucleotide sequence. All cells in a multicellular organism have the same genome.

18 Figure 1.4 DNA Is Life s Blueprint Four nucleotides are the building blocks of DNA (C, G, A, T) DNA is made up of two strands of linked sequences of nucleotides A gene is a specific sequence of nucleotides The nucleotide sequence in a gene contains the information to build a specific protein

19 1.1 What is Biology? Organisms require nutrients from their environment. Nutrients are a source of energy and materials for biochemical reactions in cells. Some reactions break nutrient molecules down into smaller units, releasing energy for work. Examples of cellular work requiring energy: Movement of molecules, or the whole organism Synthesis - building new complex molecules from smaller chemical units Electrical work of information processing in nervous systems

20 Figure 1.5 Energy Can Be Used Immediately or Stored

21 1.1 What is Biology? Metabolism, or metabolic rate: the sum total of all chemical transformations and other work done in all the cells of an organism. The reactions are integrally linked the products of one are the raw materials of the next. Any break or intruption within these sequential reactions can result in disease

22 1.1 What is Biology? Multicellular organisms have an internal environment that is not cellular. Their cells are specialized or differentiated, and organized into tissues; tissues are organized into organs. Organ systems are groups of organs with interrelated functions.

23 Figure 1.6 Biology Is Studied at Many Levels of Organization (Part 1)

24 1.1 What is Biology? Living organisms also interact: Populations are groups of individuals of the same species that interact with one another. A community consists of populations of all the species that live in the same area and interact. Communities plus their abiotic environment constitute an ecosystem.

25 Figure 1.6 Biology Is Studied at Many Levels of Organization (Part 2)

26 1.1 What is Biology? Individuals may compete with each other for resources; Or they may cooperate, e.g., in a termite colony. Plants also compete for light and water, and many form complex partnerships with fungi, bacteria, and animals.

27 1.1 What is Biology? The interactions of plant and animal species are major evolutionary forces that produce specialized adaptations. Species interactions with one another and with their environment is the subject of ecology.

28 1.1 What is Biology? Model systems: using one type of organism to understand others. This is possible because all life is related by descent from a common ancestor, shares a genetic code, and consists of similar building blocks cells.

29 1.2 How Is All Life on Earth Related? All species on Earth share a common ancestry; they are genetically related. The fossil record allows study of evolutionary relationships based on anatomy. Modern molecular methods allow biologists to compare genomes to establish degrees of relationship. The greater the distance between genomes, the more distant the common ancestor.

30 Figure 1.7 Fossils Give Us a View of Past Life

31 1.2 How Is All Life on Earth Related? Life arose from non-life via chemical evolution Earth formed 4.6 to 4.5 billion years ago but it was 600 million years or more before life evolved. Life arose by chemical evolution. Molecules that could reproduce themselves were critical. Biological molecules were then enclosed in membranes, forming cells. The history of Earth can be pictured as a 30-day month

32 Figure 1.8 Life s Calendar Each day represents 150 million years Homo sapiens arose in the last 5 minutes of day 30 (~500,000 years ago)

33 1.2 How Is All Life on Earth Related? For 2 billion years, life consisted of single cells called prokaryotes. These cells were in the oceans, protected from UV radiation, little or no oxygen (O 2 ) in the atmosphere, no protective ozone (O 3 ) layer. Photosynthesis evolved about 2.5 billion years ago. This process transforms sunlight energy into biological energy. Early photosynthetic cells were probably similar to cyanobacteria.

34 1.2 How Is All Life on Earth Related? Consequences of photosynthesis: O 2 accumulated in the atmosphere Aerobic metabolism began Ozone layer formed, which allowed organisms to live on land. Eukaryotic cells evolved from prokaryotes. These cells have intracellular compartments called organelles with specialized cellular functions. The nucleus contains the genetic information.

35 1.2 How Is All Life on Earth Related? Some organelles probably originated by endosymbiosis: when cells ingested smaller cells. Mitochondria (generate cell s energy) and chloroplasts (conduct photosynthesis) could have originated when prokaryotes were ingested by larger eukaryotes. Multicellular organisms arose about 1 billion years ago. Cellular specialization: Cells became specialized to perform certain functions

36 1.2 How Is All Life on Earth Related? Classification & Phylogeny An evolutionary tree (phylogenetic tree) illustrates the order in which populations split and eventually evolved into new species. Systematists study the evolution and classification of organisms using the fossil record and molecular evidence.

37 Figure 1.10 The Tree of Life Evolutionary Classification

38 1.2 How Is All Life on Earth Related? The three domains of life are separated by molecular techniques: Achaea (prokaryotes) Bacteria (prokaryotes) Eukarya (eukaryotes)

39 Hierarchical Classification Taxonomic Categories Kingdom Phylum Class Order Family Genus Species King Phillip Came Over For Green Soup

40 1.2 How Is All Life on Earth Related? Each species has a distinct scientific name, a binomial: Genus noun, in Caps, underlined or italicized Species descriptive lower case, underlined or italicized Example: Homo sapiens Evolution results in speciation. Structural & functional changes can evolve within a population, but if the population is separated or isolated, differences can occur in their evolution resulting in divergence.

41 1.2 How Is All Life on Earth Related? The tree of life is predictive. Placement of a new species on the tree of life immediately informs us about its biology. Understanding relationships among species allows biologists to make predictions about species that have not yet been studied. Today Systematics use comparative sequencing DNA/RNA among organisms (rrna, Chloroplast & mitochondrial DNA) to determine relationships

42 Making Sense of Science What is science? Science is learning or study concerned with demonstrable truths or observable phenomena, and characterized by the systematic application of the scientific method. Science is a body of knowledge Science is a way of constructing knowledge Science asks questions Science looks for cause and effect Science is tentative Science relies on mathematics and technology

43 1.3 How Do Biologists Investigate Life? Biologists use many methods to expand our understanding of life how science works 1. Discovery Science / Observation: When scientists seek out and observe living things in nature i.e., Astronomy Development is based on new & improved technologies telescopes, microscopes, etc 2. Experimentation: Hypothesis-based science called the Scientific Method & experimental design 3. Comparative - ecosystems

44 Figure 1.11 Tuna Tracking

45 Figure 1.15 Bluefin Tuna Do Not Recognize Boundaries

46 1.3 How Do Biologists Investigate Life? 2. Experimentation Using the Scientific Method (hypothesis prediction (H P) method): is a methodical & systematic process necessary for scientific investigation, generally using the following principles: Observations asking questions Questions -the why or how do background research Hypotheses Predictions / design experiments Testing - the idea Results Analysis measurable using math & statistics Conclusions support/validation of the hypothesis Communicate your results

47 Figure 1.12 The Scientific Method

48 1.3 How Do Biologists Investigate Life? Inductive logic leads to tentative answers or explanations called hypotheses. Piece together clues to try and come up with most likely explanation / hypothesis Deductive logic is used to make predictions. If then statements Experiments are designed to test the predictions.

49 1.3 How Do Biologists Investigate Life? Controlled experiments manipulate the variable that is predicted to cause differences between groups. The variable is manipulated in an experimental group and the results compared with data from an unmanipulated control group.

50 Graphing Results: DRY = Dependent variable, Responding variable, y axis y axis X axis MIX = Manipulated variable, Independent variable, x axis

51 1.3 How Do Biologists Investigate Life? Independent variable: the variable being manipulated. Dependent variable: the response that is measured.

52 1.3 How Do Biologists Investigate Life? Statistical methods help scientists determine if differences between groups are significant. Statistical tests start with a null hypothesis: that no differences exists.

53 Figure 1.13 Controlled Experiments Manipulate a Variable (Part 1)

54 Figure 1.13 Controlled Experiments Manipulate a Variable (Part 2)

55 1.3 How Do Biologists Investigate Life? 3. Comparative experiments look for differences between samples or groups. The variables can not be controlled; data are gathered from different sample groups and compared.

56 Figure 1.14 Comparative Experiments Look for Differences among Groups

57 1.3 How Do Biologists Investigate Life? Statistical methods are applied to data to determine the probability of getting a particular result even if the null hypothesis is true. Statistical methods eliminate the possibility that results are due to random variation. A scientific theory therefore describes a higher level of understanding that ties "facts" together. A scientific theory stands until proven wrong -- it is never proven correct.

58 1.3 How Do Biologists Investigate Life? Distinguishing science and nonscience: Scientific hypotheses must be testable, and have the potential of being rejected. Science depends on evidence that comes from reproducible and quantifiable observations.

59 1.4 How Does Biology Influence Public Policy? Biological knowledge allows advances in human pursuits such as medicine and agriculture. These advancements can raise ethical and policy questions.

60 1.4 How Does Biology Influence Public Policy? Biological knowledge contributes to our understanding of human influences on our environment. Biologists are called on to advise governments making policy decisions.