Biology The Study of Life

Course Description "Biology of organisms and cells concerns living things, their appearance, different types of life, the scope of their similarities and differences, where they live and how they live. Living things are made of the same components as all other matter, involve the same kinds of transformation of energy and move using the same basic kinds of forces as described in chemistry and physics. Through the study of the diversity of life, students learn how life has evolved. This great variety of life forms continues to change even today as genetic instructions within cells are passed from generation to generation, yet the amazing integrity of most species remain." source Pennsylvania Department of Education; Academic Standards for Science and Technology and Engineering Education ; pg 7 January 29, 2010

A student performing at the proficient level 1. Applies scientific thinking, processes, tools, and technologies in the study of biology. 2. Describes structural and functional similarities and differences between prokaryotes and eukaryotes. 3. Interprets relationships between structures and functions at various levels of biological organization. 4. Describes how the unique properties of water support life on Earth. 5. Describes and interprets relationships between structure and function at various levels of biochemical organization. 6. Explains the role of enzymes as a catalyst and the factors that influence their activity. 7. Describes cell structures and processes that transform energy in living systems. 8. Describes structures and processes involved in the movement of materials into, out of, and within a cell. 9. Explains mechanisms that permit organisms to maintain homeostasis. 10. Describes the three stages and the outcomes of the cell cycle. 11. Explains how genetic information is inherited, altered, and expressed. 12. Describes the processes associated with protein synthesis. 13. Explains the impacts of genetic engineering on medicine, forensics, and agriculture. 14. Distinguishes between the scientific terms: hypothesis, inference, law, theory, principle, fact, and observation. 15. Analyzes and explains the mechanisms and evidence related to the theory of evolution. 16. Describes ecological levels of organization in the biosphere. 17. Describes interactions and relationships in an ecosystem as they relate to energy flow, biotic components, biogeochemical cycles, and limiting factors. 18. Describes changes in an ecosystem in response to natural and human disturbances.

All Life is related All known life is related by several factors or “characteristics” All life is made of cells that contain DNA All cells are surrounded by a membrane made of lipids Living organisms have systems to maintain homeostasis Organisms that cannot maintain homeostasis are not well-adapted for the environment they live in Life gradually changes to suit an environment Poorly-adapted individuals cannot reproduce as much as well-adapted individuals All life requires energy to grow and reproduce Energy for all life is in carbohydrates produced using thermal, solar or chemical energy

Homeostasis is vital to all life Each organism has systems to maintain an internal balance. –The cell membrane is the first line of defense –Multicellular organisms have tissues, organs and organ systems that work together to maintain homeostasis –Single-celled organisms rely on organelles and chemical means to maintain homeostasis –Water is a critical component

Stem cells are the first cells Multicellular organisms begin as a large, unspecialized cell As the organism grows and develops, the individual’s cells become specialized into tissues and organs.

All life depends on certain types of macromolecules Proteins – regulate cell metabolism, regulate what comes into and out of the cell membranes Lipids – form the main portion of the cell membranes, store excess energy in animals Carbohydrates – store energy in plants, provide energy in animals, form the plant cell wall, giving it structure and support Nucleic Acids – stores the code for all the proteins a cell can make. Gets copied and passed on each time a cell divides.

Water is the most essential nutrient Chemical reactions depend on water –Dehydration synthesis –Hydrolysis –Dissolves ions and other polar molecules Important for transportation of nutrients, vitamins and minerals –Keeps cell temperature stable (high specific heat)

Carbon-based molecules are extremely diverse Carbon can make four bonds at once because it has four available electrons –Carbon will usually bond with H, C, N and O Carbon can make single bonds, double bonds and triple bonds Molecules can be rings, chains, branched chains as well as a combination of the three

Carbon molecules can be large or small Small carbon-based molecules can be combined to make larger molecules –Small carbon molecules are often called monomers –Large carbon molecules may be many monomers combined – called a polymer Glucose -> carbohydrates – like starch or cellulose Nucleotides -> Nucleic acids –DNA, RNA Amino acids -> proteins –Enzymes, transport proteins

Environmental conditions are important for cell functions Proteins run cellular reactions that life depends on –These types of proteins are called enzymes –Enzymes MUST maintain their structure to function properly High temperatures and incorrect pH levels can change the hydrogen bonds between amino acids If the hydrogen bonds change the structure of the enzyme changes, making it non-functional

All reactions require energy Enzymes reduce the amount of energy needed for chemical reactions However, there is a critical amount of energy needed for any reaction to occur. –If an organism becomes too cold its vital chemical reactions may become too slow or simply stop

Photosynthesis and Cellular Respiration Photosynthesis gathers energy (endothermic) and cellular respiration releases energy (exothermic) These are the two chemical reactions that are essential for life –They both occur in green plants –Only cellular respiration occurs in animals Animals cannot live without plants –Photosynthesis provides the energy from the sun in a usable form Products of photosynthesis provide the reactants for cellular respiration