Biology Lesson 1 - Cell Theory PDF

Cell Theory Lesson 1 What do you think classifies something as being alive?  Characteristics of Living Things For something to be considered living (biotic), it must have all of the following characteristics. Anything that does not have these characteristics is...

Cell Theory Lesson 1 What do you think classifies something as being alive?  Characteristics of Living Things For something to be considered living (biotic), it must have all of the following characteristics. Anything that does not have these characteristics is considered non- living (abiotic). Living things: ○ are made up of one or more cells. ○ are highly organized and contain many complex chemical substances. ○ require energy. ( metabolic action) ○ produce waste. ○ have a definite form and limited size. ○ have a limited life span. ○ grow and develop. ○ respond to stimuli (homeostasis). ○ adapt to their environment ○ reproduce. ○ evolve or change over time. General Sherman" is the biggest tree in the world. The Cell Theory Biology is based on the cell theory. The cell theory is a broad explanation of what is “life.” It was developed by a number of scientists including Theodor Schwann (1810–1882), Matthias Schleiden (1804–1881), and Rudolph Virchow (1821–1902). The Cell Theory The Cell Theory states and explains: 1. All living organisms are composed of cells. ⛯ Organisms may be unicellular (one cell) or be multicellular (made up of many cells). 2. The cell is the basic unit of structure and function. 3. Cells arise from pre-existing cells. (RV) The modern cell theory also includes: 4. Energy flow occurs within cells. 5. Heredity information (DNA) is passed on from cell to cell. 6. All cells have the same basic chemical composition (organic chemicals such as proteins, fats, carbohydrates).  Early Scientific Theories About the Origin of Life Prior to the cell theory, Greek philosopher Aristotle (334 BC) came up with the theory of abiogenesis or spontaneous generation (a-bio means not- living). This theory suggested that living things spontaneously formed from non-living or inanimate matter. This was believed for a long time. People also Aristotle Aristotle did not conduct believed actual experiments that to test this sickness came from bad air or idea. He contributed to the cell curses theory with his basic placed upon you. classifications of living things. He classified different species and showed that there are connections between every organism. Which lead to the first principle of the cell theory. “All living things are made of cells and thus similar”  Early Scientific Theories About the Origin of Life contd Francesco Redi (1626-1697) was the first person to test spontaneous generation by also performing experiments on rotting meat. He successfully refuted the idea that life came from non-life. He successfully demonstrated that it was flies landing on the meat that caused the maggots. The maggots (larvae) hatched from fly eggs; they didn’t just appear. Early Scientific Theories About the Origin of Life There were several rebuttals to Redi’s experiment. There were many errors. However, In 1860, Louis Pasteur’s experiment finally laid the argument to rest by controlling all variables well and addressing concerns raised by the scientific community. He created the swan neck flask, which allowed air in, but would trap microorganisms equallying no contamination  Development of the Cell Theory In 1665, English scientist Robert Hooke made an improved microscope and viewed thin slices of cork. The shapes he saw reminded him of the plain small rooms that monks lived in. He called these structures cells, like the rooms. What he was seeing were dead plant cell walls. It soon became accepted that the basic building block of life was the cell. The development of this new technology enabled scientists to glimpse into the microscopic world and begin to collect new evidence about living things. Microscopic view of cork outline It enabled them to describe the of a cell 1838 ~ German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells 1839 ~ German zoologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells. 1855 ~ Rudolph Virchow stated that all cells come from preexisting cells Systems A system is a group of individual parts (components) that interact together to accomplish a task or perform in a certain way. Science is interested in systems and how they work. Systems include: ○ solar systems ○ ecosystems ○ circulatory systems ○ electrical systems Biological Systems The cell is both a system and a component of a system. ○ it is a system, like a factory, where the organelles are functioning components ○ When cells are specialized, they are components of larger systems such as the circulatory system, nervous system, or digestive system. components: components: cells organelles system: skin Cell Function Biologists are interested in the relationship between structure and function in living things. Cellular function - as a system each cell must be able to: 1. obtain food and energy 2. convert energy into a usable form -they use chemical reactions such as photosynthesis and cellular respiration to do this 3. make protein (the most common molecule in cells) 4. package and export these and other molecules (such as digestive enzymes and hormones) 5. eliminate metabolic wastes (such as water, salt, CO2) Cell Structure All cells are enclosed by a cell membrane that provides support, and controls what goes in and out of the system. ○ In plants, there is a also a cell wall surrounding the membrane (Why is this necessary?) It functions as support, it is rigid, made of cellulose, and creates the structure Inside the cell are the organelles (little organs) embedded in a watery, gel-like substance called cytoplasm. Cell Structure Each organelle has a specialized function. ○ the nucleus contains DNA and controls duplication of cells—cells come from cells. ○ vacuoles are spaces, sometimes membrane-bound, that store- waste material, water, or material being produced (like sugar/sap). ○ the mitochondria are where glucose (C6H12O6) is broken down to release energy in the form of ATP. ○ the Golgi apparatus packages and transports proteins and lipids where  The endoplasmic reticulum (ER) is a large structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. SMOOTH ThereERis SMOOTH ER and ROUGH ROUGH ER ER No Ribosomes Has Ribosomes Found near Cell Membrane Found near Nucleus Main Function - lipid Main function - protein metabolism synthesis Ribosomes convert genetic coding into amino acid sequences, so proteins can get made  Classification of Cells Prokaryotic Cells Eukaryotic Cells bacterial cells cells of fungi, plants, less evolved, primitive animals small cells 1 -10 µm more evolved; complex NO membrane-bound organelles 10-1000x larger than do not have a nucleus prokaryotic cells DNA found free in the cell more organelles contain a nucleus DNA enclosed in the PROKARYOTIC EUKARYOTIC nucleus plant cell CELLS animal cell CELL bacterium Prokaryotes vs. Eukaryotes Unicellular vs. Multicellular Unicellular Organisms Multicellular Organisms living things such as living things that are bacteria that are composed of two or composed of a single more cells that function cell. as a unit. green alga spirogyra multicellular bacterial colony colony human (multicellular) each cell is a unique high degree of specialized individual cells that combine to make  Cell Division Cells arise from pre-existing cells. This happens through the process of cell division. There are two types of cell division - meiosis and mitosis. During cell division hereditary information (DNA in the nucleus, in the form of chromosomes) is passed on to new generations. The new cells formed from cell division are called daughter cells. Each time a cell divides, small changes in the genetic material called mutations occur. ○ These mutations result in variation and genetic diversity. ○ Diversity is necessary for the health of populations. ○ Mutations allow organisms to adapt to their  The cell theory is a broad explanation of the diversity and continuity of life.  Practice Questions 1. Use scientific reasoning to explain why a planet such as Mars is not considered to be living. 2. List the three components of cell theory. 3. Explain the theory of spontaneous generation and the scientific evidence that refuted it. 4. Describe how new technology led to the understanding that the cell is the building block of life? 5. Why are cells called cells? 6. Define the term system and provide examples of sciences examined by scientists and engineers. Use examples that are not in your notes. 7. Why are cells considered to be a system and a component of a system? 8. Explain why the cell is considered to be a living system. 9. Scientists are interested in the relationship between structure and function. Provide three examples of a structure and its function in the cell. 10.Contrast cell membrane and cell wall. 11.Compare and contrast prokaryotic and eukaryotic cells.