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01:119:115 (825)
A L L (20)
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GENERAL BIOLOGY Notes (Part 4) - 4.0ed the course!

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Department
Biological Sciences
Course
01:119:115
Professor
A L L
Semester
Fall

Description
Cells 10/04/2013 Cells are fundamental units of life Robert Hooke (1665) coined term “cell” Microscopes Looked at bark of tree – noticed little chambers where monks lived Antoni van Leeuwenhoek (1674) Discovered “animalcules” Microscopes facilitate the study of cell structure & function Light microscopes pass visible light through specimens and then through glass lenses Electron microscopes focuses beams of electrons through or on surface of specimen Transmission Electron Microscope Electrons go through cells Scanning Electron Microscope Reflect beam of electrons off surface Three key parameters Magnification – ratio of object’s real size to image size Resolution – clarity of image Minimum distance b/w two points in order to distinguish points Contrast – difference in brightness between dark & light areas of the image Other tools in study of cells include cell fractionation Centrifuge Figure 6.4 Two types Prokaryotic Bacteria & Archaea Figure 6.5 Eukaryotic Protozoa, Fungi, Animals, Plants) Figure 6.8 Similarities Chromosomes – carry DNA Plasma (cell) membrane Consist of double layer of phospholipids Figure 6.6 Cytosol Ribosomes – synthesize proteins Differences Prokaryotes DNA in nucleoid No membrane­bound organelles Smaller in size Eukaryotes DNA in nucleus Membrane­bound organelles Larger in size Limits on cell size Only limited amt of nutrients & other substance can cross membrane/sec Surface area to volume ratio of cell is critical SA increase by n^2 V increase by n^3 Smaller cells have greater SA relative to volume Fig 6.8 Nucleus Contain most of genes in cells Bound by nuclear envelope Inner & outer layer Phospholipid bilayer Materials can enter/exit through nuclear pores Chromatin: complex of DNA & protein Save space Discrete version of DNA Takes form of chromosomes during cell replication Nucleolus (can have multiple) rRNA produced here Ribosome subunit synthesis Shape of nucleus maintained by nuclear lamina Ribosomes can attach to outer portion of nuclear envelope Ribosomes Complex made of protein & rRNA Large & small subunit Carry out proteins synthesis in cell Can be free ribosomes Suspended in cytosol Function within cytosol Or bounded ribosomes Attached to the outside of the ER or nuclear envelope Generally make proteins for insertion into membranes Nucleus & ribosomes are important in gene expression Fig 5.23 DNA ▯ (
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