Themes in the Study of Biology Ch 1.1 Course Overview

I. Biology is the scientific study of life A. Life is recognized by what living things do. B. All living things demonstrate the following characteristics: 1. Order 2. Adaptation 3. Response to the environment 4. Reproduction 5. Growth & Development 6. Energy processing 7. Regulation (Homeostasis)

Characteristics of life

II. Themes connect the concepts of Biology (sec 1.1) We use themes to organize and connect biological information. A. The overarching theme used today is biological evolution 1. Evolution is used to connect what we know about living and extinct organisms. 2. Living organisms are modified descendant’s of common ancestors. So, we look for common traits, chemistry, etc. to help us see how one area of info. relates to another or one organism is related to another.

Themes (cont.) B. Emergent properties – New properties emerge at each level in the biological hierarchy. 1. The study of life is divided into different levels of biological organization. These levels are a. Atomsj. Populations b. Moleculesk. Communities c. Organellesl. Ecosystems d. Cells(m. Biomes) f. Tissuesn. Biosphere g. Organs h. Organ systems i. Organisms

Emergent properties and Reductionism 2. Emergent properties result from the arrangement and interaction of the parts within a system. a. Emergent properties are seen in non-biologicial systems too. b. Reductionism- the study of a system by reducing it to smaller, more manageable parts (i.e. study the components of a system) oWe must balance reductionism with emergent properties to get the “big picture”

Emergent properties and Systems Biology c. Systems Biology- studies how the component parts of a system work together by making models An example would be to look at the parts of a DNA molecule to see how it is constructed, then to study how the construction of DNA makes it easier to use and to copy DNA. (Form follows Function)

Themes (cont.) C. Organisms interact with the environment & exchange matter and energy with it. 1. Organisms react with both biotic & abiotic factors in the environment. 2. Both the organism and the environment will be affected. 3. Ecosystem dynamics (how one part of an ecosystem affects another) include: a. the cycling of nutrients- plants take nutrients from the ecosystem that eventually return to it. b. Energy flow through the ecosystem- energy flows from sunlight to producers to consumers

Energy flow in ecosystems: 1) All organisms do work. Work requires energy. 2) Energy is stored in many forms. 3) Energy exchanges between organisms & the environment require energy transformations. 4) Energy “flows” through an environment entering as light & exiting as heat (usually) having taken many different forms.

Themes (cont.) D. Structure & function are closely related at all levels of biology. 1. “Form fits function” at all levels of biology a. Ex. Gulls wings are curved to provide lift. b. Ex. Mitochondria’s folded inner membranes provide more surface area so more reactions occur.

Themes (cont.) D. Cells are the basic unit of structure & function in an organism. 1. The cell is the lowest level of organization that can carry out the functions of life. 2. All cells are enclosed by a membrane and use DNA to hold (encode) their genetic info. 3. Because cells can divide, they can carry out growth, development, and the repair of multicellular organisms. 4. Two types of cells: 1)Eukaryotic- has membrane wrapped organelles including the nucleus. 2) Prokaryotic- no organelles & thus no nucleus

Cell types Eukaryotic Animal Cell Prokaryotic bacterial cell

Themes (cont.) E. The continuity of life is based on inheritable (heritable) information found in DNA 1. DNA is a double stranded molecule made of 4 different kinds of nucleotides. a. A nucleotide is made of sugar, phosphate and one of four different nitrogen bases b. Nucleotides are joined together in long strands. c. Two of these strands, linked to each other by hydrogen bonds and twisted into a spiral make a DNA molecule. 2. One long, double stranded DNA molecule makes a chromosome.

DNA Molecule & Genes DNA

3. Genes are sections of just 1 strand of a chromosome 4. So- Genes are made of DNA and 2 long chains of Genes, plus some extra DNA, make a chromosome. 5. Genes are “units of inheritance”; genes carry the genetic info. from parents to kids. 6. Gene expression- making a protein using the instructions found in the DNA of the gene. 7. Proteins give us our “traits.” 8. Genes are expressed indirectly through a two step process using RNA. 9. Genes control development & maintenance of organisms 10. A genome is the whole genes set of an organism.

Inheritance

Themes (cont.) F. Regulation of biological systems is through feedback mechanisms 1. Feedback systems let organisms self-regulate their processes. 2. Negative feedback occurs when the product of a process builds up and forces the system that makes it to slow down or stop making the product. (ex. 3. Positive feedback occurs when the build up of the product causes the system that makes it to speed up making the product.

Feedback mechanisms Negative feedback Positive feedback

Review Questions 1. What are the 7 characteristics of life? 2. Give an example of each. 3. Name all 7 themes used to connect the concepts of Biology. 4. Briefly define each theme. Acknowledgements: This presentation is drawn almost entirely from the materials provided by Reese Campbell 8 th ed. DVD materials & notes.