Stem Cells • Stem cells differ from regular cells by two characteristics: • 1. Undifferentiated cells capable of cell division, can proliferate into the millions unlike other cells. • 2. Can be induced to become a specific type of cell • Why stem cells remain unspecialized for long periods of time is not understood.
Two Types of Stem Cells • 1. Embryonic Stem Cells • 2. Adult Stem Cells- aka somatic stem cells • Stem cell research began in 1981 when scientists were able to extract stem cells from mice. • 1998 human stem cells were discovered • 2006 adult cells were “reprogrammed” to become induced pluripotent stem cells
Stem Cell Differentiation • Stem cells while undifferentiated do not perform normal cellular tasks. • If some of these stem cells differentiate, it is caused by DNA and the extracellular environment. (chemicals) • Still do not understand the initiation of cell differentiation • Adult stem cells usually give rise to the cell type in which they are located. • Possibly can cause adult stem cells to differentiate into different cell types
Where do most embryonic stem cells come from? • In vitro fertilization- donated for research • Left over eggs at donation clinics • Embryos are typically 4-5 days old when used for cell culturing
Adult Stem Cells • These are undifferentiated cells that are found in tissues and organs. • Function: repair and maintenance • Small number of these cell types, and scientists have a hard time culturing these • Transdifferentiation- when adult cells differentiate into cell types other than their origin.
Induced Pluripotent Stem Cells • Adult stem cells that are genetically reprogrammed to be embryonic stem cell like. • Human iPSC discovered 2007, still a lot unknown • Used in drug development and disease modeling. • Trying to learn how to use them as transplant cells
How do embryonic stem cells become undifferentiated? • If embryonic stem cells are allowed to clump together they begin to spontaneously differentiate. • Scientists control cell differentiation by inserting genes, and controlling the environment.
Assignment • Explain the diagram on p. 15. Draw it out and explain under each box, use paragraph above to further the explanation. • PI- What are stem cells, how can they be used, why are they different than other cells. • P2- Describe heart disease, & why is it a national concern. • P3- What steps in stem cell research have been taken to address cardiovascular disease. What other factors could one do to prevent heart disease (think biomolecules) • P4- What is your position on SCR, do you think the government should fund it, do you think we should utilize this technology, when does life begin, what are some pros/cons to SCR, concluding statement
Graphing Tuesday • Create a line graph with 2 y axes. • These are fake numbers @ hunting in Summer Shade!
Stem Cell Review • 1. What is a stem cell? _____________ ________ • 2. List the 2 types of stem cell: ______ ________ • 3. Which stem cell is controversial? Why? • 4. Where do they get adult stem cells from?
Question of the Day Don’t write the questions today • 1. Name the yellow structure. • 2. Name the yellow area inside the cell. • 3.What do the little blue dots do? What re they called?
A scientist wants to measure the effects of running on the amount of sweat a person produces. He hypothesizes that “If a person runs they will produce more sweat than a person than a person that is not running.” • Control Group: • Experimental Group: • Independent Variable: • Dependent Variable:
Francesco hypothesizes that “If he covers raw meat on a table it will not grow maggots, versus meat on a table uncovered will grow maggots. • Control group: • Experimental group: • Independent variable: • Dependent variable:
Enzymes Sketch • Title the Page: Types of Metabolism, and divide sheet in 1/2 • Draw Anabolism and Catabolism • Be sure to include these terms on both drawings: • Substrate • Product • Active site • Enzyme • Enzyme-substrate complex
Cell Size • Cells have a large surface area: volume ratio. • Important for large SA:V ratio so that a cell can remain small, yet do its job. • Let’s practice calculating SA and Volume for a cube cell and a spherical cell.
Let’s Practice • Calculate the SA: V ratio for a cube cell with a length=2. • Calculate the SA: V ratio for a spherical cell with a r=6.
Surface Area: Volume Calculations SHOW WORK Cube Cell (Plant) Spherical Cell (Animal) • A. 2nm • B. 5nm • C. 17nm • D. 1.5nm • E. 3.2nm • A. r=2nm • B. r=6nm • C. r= 13nm • D. r=21nm • E. r=4nm
Cell Analogies • The nucleus is like a principal because the nucleus controls the cell like a principal controls the school. • The cytoplasm is like air because cytoplasm surrounds everything inside the cell like air surrounds everything in the school. • The cell wall is like the building walls because the cell wall protects the cell like building walls protect the people inside the building.
Anticipatory Set 10-10-12 • According to the temperatures in the graph, which property of water is responsible for the extreme temperature fluctuations in AZ, but less drastic fluctuations in FL? • A. high heat of vaporization • B. high specific heat • C. evaporative cooling • D. universal solvency
Vocabulary List # 4 • Prokayote- cell that has no nucleus. • Eukayote- cell that has a nucleus (plant and animal) • Selectively Permeable- some things can enter and exit • Nucleus- holds the DNA in a eukaryote • Mitochondria- makes energy for cell • Spontaneous generation- old theory that says life arose from nothing • Plasma membrane- aka cell membrane • Cell wall- surrounds plant and bacteria cells only- not animal cells
Microscopy • Light Microscope • Ocular lens- eyepiece (10X) • Objective Lens-varied magnification • Total magnification= ocular x objective • Stage • Light source • Course Adjustment • Fine Adjustment • Base
Letter “e” Observation • Draw letter “e” as it appears on low, medium, and high. • State three observations that you noticed during this lab.
Cell Discovery Robert Hooke Anton van Leeuwenhoek • Used a microscope to view cork. • Said what he saw reminded him of cells in a monastery. • Used a microscope to observe pond water. • Called his observations “animalcules”
Figure 1.2 All Life Consists of Cells The study of cells was made possible by the invention of the microscope.
Question of the Day • 1. What is the name of this microscope? • 2. Draw what letter “e” looked like yesterday for you.
Question of the Day • 1. True/False All living organisms are composed of cells. • 2. Based on the graph which is more powerful: Light microscope or electron microscope?
Question of the Day • A scientist notices that several birds in Summer Shade have only one wing. She also notices that the water in Summer Shade has a purplish tint. • 1. Propose a hypothesis. • 2. Set up an experiment with both control and experimental groups
What are Cells? What are Cellular Organelles • http://www.hippocampus.org/course_locator?course=AP%20Biology%20I&lesson=7&topic=2&width=600&height=454&topicTitle=What%20Are%20Cells?&skinPath=http://www.hippocampus.org/hippocampus.skins/default
SA:V Ratios • Calculate the SA:V Ratio for a cube cell with a side length of 4 nm. • Calculate the SA:V Ratio for a spherical cell with a radius of 2nm.
Two Types of CellsAll cells have a cell membrane, cytoplasm, ribosomes, and DNA Prokaryotes Eukaryotes • Do not have a nucleus. • Do not have organelles • Thought to have evolved before eukaryotes. • Have a nucleus • DNA is in the nucleus. • Have organelles.