IB Bio year 2 2.1 cell theory
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Created by:
mariahtjackson on October 3, 2011
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36 terms
Terms | Definitions |
|---|---|
 outline the cell theory | three main principles 1) all organisms are composed of one or more cells 2) cells are smallest unit of life 3) all cells come from pre-existing cells |
| evidence of cell theory | -hooke: observed cork with microscope -leeuwenhoek: observed first living cells..."animalcules"- little animals -schwann and schlieden: plants made of independent separate beings called cells -virchow: all cells come from pre-existing cells by cell division |
| state that unicellular organisms carry out all the functions of life (8) | -metabolism -growth -reproduction -response -homeostasis -nutrition -heredity of DNA -organized cells |
| compare the relative sizes of -molecules -cell membrane thickness -viruses -bacteria -organelles -cells using the appropriate SI unit | -molecules: 1 nanometer (nm) -cell membrane thickness: 10X molecules = 10 nm -viruses: 100X molecules = 100 nm -bacteria: 1 micrometer = 1,000 nm = 1,000X molecules -organelles: 10 micrometers = 10,000 nm = 10,000X molecules -eukaryotic cells: 100 micrometers = 100,000 nm = 100,000X molecules |
| explain the importance of the surface area to volume ratio as a factor limiting cell size | -when cell gets bigger, so does activity level -SA affects rate of particles entering and exiting cell -volume affects rate of heat and waste production, rate of resource consumption -more SA/unit V = can move more stuff in and out of cell -when cell gets bigger, SA to volume ratio gets smaller (SA increases but at slower rate than V) -large cell = less SA to bring in needed materials and get rid of waste ( less efficient than smaller cell) -cell size is limited so functions of life can still occur efficiently |
| state that multicellular organisms show emergent properties | -start as single cell and reproduce rapidly, allowing body to function -cells...tissues...organs...organ systems...multicellular organisms -ex. nerve and muscle cells, epithelial cells |
| explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others | -it depends on which cell are on and off, they are going to follow certain pathway -each cell becomes a specific type of cell dependent on which DNA segment becomes active -genes encode for proteins, proteins affect cell structure and function to specialize -differentiation depends on gene expression which depends on transcription |
| state that stem cells retain the capacity to divide and have the ability to differentiate along different pathways | -stem cells divide and reproduce themselves- replacing damaged/dead cells -differentiation allows reproduction of single cell at rapid rate for cells needed all over body |
| outline one therapeutic use of stem cells | -bone marrow transplants treat people w/ cancer -fixes problem of chemotherapy (kills normal cells in bone marrow and cant make blood cells) -harvest bone marrow from donor...stem cells find their way back to bone marrow and start making healthy blood cells |
| stem cells | cells that retain their ability to divide and differentiate into diff cells |
| viruses | -not considered living -dont carry out functions of life on their own -non cellular structures of DNA or RNA surrounded by a protein coat |
| metabolism | chemical reactions that occur within an organism |
| growth | may be limited but is always evident one way or another |
| reproduction | hereditary molecules that can be passed to offspring |
| response (to the environment) | imperative to survival of an organism |
| homeostasis | maintaining a constant internal environment |
| nutrition | providing source of compounds with chemical bonds which brake to provide energy and nutrients needed to maintain life |
| resolution | clarity of an object viewed |
| light microscopes | -use light (which passes through the living or dead specimen) to form an image |
| stains | used to improve viewing of parts |
| electron microscopes | -have greatest mag (over 100,000X) and resolution -use electrons passing through a specimen to form an image |
| decreasing order of size | organelles bacteria viruses membranes molecules |
| conversions | 1 mm = 1,000 micrometers = 1,000,000 nanometers |
| diff in cell sizes | mycoplasmas 0.1-1.0 micrometers (diameter) most bacteria 1.0-10.0 micrometers (diameter) most prokaryotes 10.0-100.0 micrometers (diameter) |
| 2 restrictions to cell size | 1) SA to V ratio 2) involves ability of nucleus to provide enough copies of chemicals required to control processes of the cell |
| calculate the linear magnification of drawings and the actual size of specimens in images of known magnification | -Take a measurement of the drawing (left to right) -Take this same measurement of the specimen (particular thing) -Remember to convert units if needed to 1 mm = 1,000 micrometers -magnification=size of image/size of specimen -size of specimen=size of image/magnification You can also calculate the length of the specimen if this is unknown: length of the drawing / magnification. |
| disadvantage of embryonic stem cell research | it will kill the embryo (ethical considerations) |
| advantages of embryonic stem cells | -unspecialized (can turn into a lot of things) -can adapt more easily/ less likely to cause an immune response |
| diff between adult and embryonic | adult usually only blood cells |
| researchers use ________ to deduce developmental pathways; less expensive and not ethical problems | mutations |
| transformation from a zygote into an organism results from 3 interrelated processes | -cell division (mitotic) -cell differentiation (specialization) -morphogenesis (causes cell to form shape) |
| stem cells of animals | -relatively unspecialized -can reproduce itself indefinetly |
| magnification | -how big -ratio of an object's image to its real size |
| transmission electron microscope | -use magnet to turn electron beam -wavelengths alot smaller -greater resolution -can see organelles |
| what limits the resolving power of a light microscope | shortest wavelength of light used to illuminate the specimen |
| scanning electron microscope | helps u see surface of specimen |
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