Introduction to Biology

1. Introduction to Biology

2. Biology – The Study of Life • Life arose more than 3.5 billion years ago • Single-celled (unicellular) organisms (living things) 1st appeared floating alone in the seas • Only life on Earth for millions of years • Over 40 mil speciesexist, while only2 mil are identified • Many are unidentified & are still being discovered.

3. Biology –study of life & how organisms interact with each other & environment • Over time, species change, orevolved, so that new organisms arose from earlier kinds • They inhabit almost every region of Earth today, for example bacteria are found in thermal vents & parasites are found inside other organisms • Organisms MUST adapt to their environment to survive & reproduce

4. 6 Characteristics or Properties of Life—unify Biology • All living things: • Made up of 1 or more cells • Grow, develop, reproduce, & share a universal genetic code • Obtain material & use the energy from it • Maintain a fairly stable internal environment (homeostasis) • Respond to other organisms & changes within its environment (interdependence) • Change over time (evolve)

5. Life is characterized by the presence of ALL of these properties at some stage in an organism’s life, not just by one or two.

6. Learning Target We will be able to: differentiate the levels of organization among living organisms.

7. Cell Structure and Function • All living things are made of 1 or more cells. • A cell is the basic unit of structure & function • Cells are tiny, but organized & have coverings called membranes. • Cells contain structures that carry out jobs for the cell; they’re called organelles • A cell is the smallest unit capable of life • Unicellular organisms are made of 1 cell • Multicellularorganism that is composed of many cells

8. In multicellularorganisms, cells and groups of cells (tissues) are organized by their function Cells tissues Tissues organs Organs  systems Systems ORGANISM

9. Criteria for Success: I can list the levels of organization. Check for Understanding: Which of the following is ordered from simplest to most complex? • Tissue, cell, system, organ, organism • Cell, organ, system organism, tissue • Cell, tissue, organ, system, organism • Cell, tissue, organism, system, organ

10. Criteria for Success: I can define each level of organization. Check for Understanding: A group of similar cells that perform a common function is called— A. a molecule. B. an organ. C. a tissue. D. a compound.

11. Criteria for Success: I can relate the levels of organization to each other. Check for Understanding: The eye is considered an organ because it— • is made up of different tissues working together. • requires light energy to function correctly. • contains a fluid-filled central cavity. • is almost completely surrounded by bone.

12. Check for Understanding: Which of the following shows the correct order of arrangement from simplest to most complex level of organization? • Organ → Cell→ Tissue→ Organ system • Molecule → Cell→ Organ→ Organ system • Cell→ Organ→ Tissue→ Compound • Tissue→ Compound→ Molecule→ Cell

13. Reproduction and Inheritance • All organisms produce new organisms like themselves REPRODUCE • Organisms transmit hereditary information to their offspring INHERITANCE

14. Reproduction It is the process by which organisms make more of their own kind from one generation to the next. Reproduction is not essential for the survival of an individual organism. It is essential for the continuity of life because no organism lives forever. If members of a group of living things fail to reproduce, they become extinct.

15. Asexual Reproduction • Genetic information from single parent • Hereditary information from one organism that divides (usually unicellular) • Resulting cells contain identical hereditary information (clones) • Ex: budding, binary fission, spore formation, fragmentation

16. Sexual Reproduction • The joining of 2 specialized cells (from diff. parents) • Hereditary information from two different organisms of the same species are combined • Egg and sperm  zygote (fertilized egg) • Sexual reproduction may involve 2 diff. processes, internal fertilization & external fertilization.

17. Inheritance (DNA) • Heredity: the passing of traits from parents to offspring. • All living things are able to pass their characteristics (traits) to their offspring through genes. • Genesare short segments of DNA that contains the instructions for the development of a single trait. • These instructions, which are coded in a molecule called deoxyribonucleic acid (DNA), determine an organism’s traits.

18. Ex: Thyroid glands use a set of genes from your DNA to make the thyroid hormone. Other body cells ignore those genes. • Ex: Muscle cells have the genes to make thyroxine, but they don’t actually use these genes. The DNA of a cell is like a large library. It contains all of the books of instructions (genes) that the cell will ever need. The DNA (genome) in every body cell is identical; however, each cell only uses certain genes from the complete set to carry out its function.

19. Sometimes damages cause genes to change. A change in the DNA of a gene is called a mutation. Most mutations are harmful, but sometimes mutations can help an organism survive. • Example: In humans, a genetic mutation for the blood protein hemoglobin, which carries oxygen to the body’s cells, may cause sickle cell anemia. • Harmful effect—results in sickle cell anemia, which impairs the oxygen-carrying capability of the cell. • Positive effect—the mutation produces a resistance to malaria.

20. Energy • Metabolismis the sum of all chemical reactions carried out in an organism. • Living organisms perform many diff. chemical reactions in order to obtain & use energy to run & to process info. • All living things use energy to grow, to move, and to process information. Without energy life soon stops. • Organisms are highly organized, maintain internal order, and require a constant energy supply.

21. Autotrophs • Organisms that make their own food • Plants & unicellular organisms with chlorophyll capture sunlight through photosynthesis & store it in food to be used by other organisms.

22. Heterotrophs • Organisms that gain energy by eating other organisms • Consume autotrophs (herbivores), other heterotrophs (carnivores) or both (omnivores) for their energy needs • Some unicellular organisms, as well as ALL animals & fungi, are heterotrophic because they rely on other organisms as their energy source.

23. Chemotrophs (Chemoautotrophs) • Uses a diff chemical process to make energy. • Some unicellular organisms that thrive in extreme environments, called extremophiles, rely on chemicals for energy.

24. Stability and Homeostasis • ALL organisms must maintain stable internal conditions, such as body temp chemical content, & water content. • The maintenance of stable internal conditions in spite of changes in the external environment is called homeostasis.

25. Ex: In humans, breathing rate, heart rate, & blood pressure returning to “normal” after exercise keeps the body stable (@ homeostasis). • “Normal” homeostasis for human blood pressure is usually 120/80 mm of mercury • Ex: In dogs, panting helps to cool the body back down after rigorous activity.

26. Response to organisms & changes (Interdependence) • Interdependence of organisms: • Interdependence is when organisms in a biological community have evolved to live and interact with other organisms. • A biological community is a group of interacting organisms. • Ecology is the study of the interactions of organisms with each other and their environment. • Sunlight is the ultimate energy source for all organisms. • Energy from the sun is passed from one organism to another. • Ex: Producers (plants) to herbivores to carnivores to decomposers. • Abioticfactors, such as air, water, energy, soil, temperature, and minerals are also needed for survival. • Biotic factors include all living things on earth (plants, animals, fungi, & microorganisms) • Biosphere supports all life, including the biotic and abiotic factors on earth.

27. Responsiveness Organisms use special structures or behaviors to respond to conditions and changes in their environment. They live in a constant connection with the environment which includes the air, water, weather, temperature, and organisms in the area, and many other factors. These external environmental factors act as stimuli and can cause a response from living things. Organismsneed to respond to the changes in order to stay alive and healthy. Ex: A specialized leaf of the Venus flytrap senses the light footsteps of a soon-to-be-digested green bottle fly. The plant responded to this stimulus by rapidly folding the leaf together. Ex: While walking across the courtyard, a cool breeze blows. Students began getting chills and immediately reached for their jackets because their bodies responded to the stimulus (cool breeze). Organisms respond to their environment by: fleeing, adapting, & dying

28. Evolution • Populations of organisms change over time or evolve (Theory of Evolution). • Natural Selection or “survival of the fittest” is the process that drives evolution. • Charles Darwin has been credited for his work on Natural Selection in which species with favorable genes are better able to survive and reproduce than those without favorable traits. • A species is a group of genetically similar organisms that can produce fertile offspring. • The survival of organisms with favorable traits causes a gradual change in populations of organisms over many generations. • Evolution by natural selection is driven by competition for resources, such as food, water, habitat, mates, & sunlight (plants).