Biology Lecture 11 A - Exam 3
Biology Lecture 11 A - Exam 3 BIO 121 A
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This 2 page Class Notes was uploaded by Devin Mart on Friday March 25, 2016. The Class Notes belongs to BIO 121 A at Missouri State University taught by Dr. Durham in Spring 2016. Since its upload, it has received 9 views. For similar materials see General Biology in Biology at Missouri State University.
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Date Created: 03/25/16
Mart 1 Lecture 11A: Tour of the Cell ● Microscopes lead to the discovery and early study of cells 17th century. ○ The light microscope allows visible light to pass through the specimen and then through glass lenses, the lenses refract light making the image magnified. ○ Magnification is the ratio of an object’s image to its real size. ○ Resolving power is the ability of an electronic device to produce images that can be distinguished, the measure of image clarity. ■ The minimum distance two points can be separated and still viewed as two separate points. ■ Light microscopes can resolve individual cells, but not organelles. ○ The electron microscope allows a beam of electrons focused through specimen or onto the surface. ○ The transmission electron microscopes are used to study the ultrastructure of cells. ■ Images are focused and magnified by electromagnets. ○ The scanning electron microscopes are used to study the surface of structures. ■ A beam excites electrons found on the surface of a substance providing a great depth of field, 3D images. ■ Limitations: the study of dead cells and processing may introduce artifacts. ■ Cytology is the branch of biology concerned with the structure and function of plant and animal cells. ● Cell fractionation is the process of separating major organelles of the cells. ● General features of prokaryotic and eukaryotic cells include: ○ Surrounded by a plasma membrane. ○ Substance within a membrane cytosol, the aqueous component of the cytoplasm of a cell, within which various organelles and particles are suspended, and contains organelles. ○ Contains chromosomes, genes in the form of DNA. ○ Ribosomes , organelles that code for the production of protein. ● The major difference: ○ Eukaryotic cell chromosomes in the membrane bound nucleus. ■ Cytoplasm is what fills the region between nucleus and the plasma membrane, this contains membranebounded organelles. ■ Eukaryotic cells are bigger than prokaryotic cells. ○ Prokaryotic cell DNA is in nucleotides and not membranes. ● The plasma membrane is a selective barrier that allows the passage o, nutrients, and waste. Mart 2 ○ Internal membranes can be found in eukaryotic cells. ○ This participates in metabolism and facilitates specific metabolic functions. ○ The general structure of biological membranes includes: ■ A double layer of phospholipids, lipids, and proteins. ■ A unique combination of lipids and proteins for its specific functions (i.e. mitochondria). ● The nucleus contains a eukaryotic cell’s genetic library. ○ Some genes can even be found in the mitochondria and the chloroplasts. ○ Nuclear pores are large proteins that process the diffusion of small molecules. ○ Chromatin is the material of which the chromosomes of organisms other than bacteria are composed, consists of protein, RNA, and DNA. ○ Chromosomes are a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. ■ Humans contain a total of 46 chromosomes, 23 from each spouse. ○ The nucleolus is a small dense spherical structure in the nucleus of a cell during interphase. ■ Ribosomal RNA (rRNA) is synthesized and assembled with proteins to form ribosomal subunits. ○ The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA). ■ mRNA travels to cytoplasm and combines with ribosomes to translate genetic message into proteins. ● Ribosomes contain a strand of rRNA and protein. ○ Free ribosomes make proteins function in cytosol. ○ Bound ribosomes are attached to the endoplasmic reticulum and synthesize proteins, membranes or exported from the cell.