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Unformatted text preview: 1 Cellular Physiology Unit II Study Guide (Chapters 5-8) 1. Describe the structure and function of an animal cell nucleus. Know the structures like nuclear envelope, pore complex, various forms of chromatin and nucleolus. Discuss the role of the nucleus as the cell’s command center and how the genetic diseases are linked to the functions of nucleus. Define a genome. How many kinds of genomes are there in human cells? Ÿ structure -- surrounded by a double membrane layer Ÿ about 8 micrometers in diameter with 2 meters of DNA and 12 miles of chromatin threads -- tightly paced Ÿ nuclear envelope : supported by networks of protein filaments -- nuclear lamina Ÿ forms a thin layer supporting the inner nuclear membrane Ÿ the outer membrane contains ribosomes and is continuous with the ER Ÿ the gap between the 2 membranes is the perinuclear space Ÿ nuclear pore complex: octagonal orifices about 120 micrometers in diameter Ÿ shaped like a wheel Ÿ transporter -- hub of the wheel, the 8 subunits connect the 2 parallel rings here Ÿ can open or close to allow the passage of macromolecules thru it Ÿ mammalian nucleus may have 4000 pores -- number corresponds to transcriptional activity of the cell Ÿ function -- transport macromolecules from the nucleus to the cytoplasm and vice versa Ÿ RNA and ribosomal subunits Ÿ histone proteins Ÿ nucleoplasm : fluid part of the nucleus Ÿ contains the chromatin and one or more nucleoli Ÿ chromatin : chromosome material in the interphase nucleus Ÿ types: Ÿ Euchromatin -- scattered in interphase nucleus Ÿ Heterochromatin -- condensed in interphase of nucleus Ÿ Perinucleolar -- part of the nucleolus -- DNA protein Ÿ Intranucleolar -- part of the nucleolus -- DNA protein Ÿ nucleoli : non-membranous bodies Ÿ chemical composition -- RNA 10% of the cell’s RNA, 90% in cytoplasm Ÿ has its own DNA Ÿ proteins Ÿ functions -- Ÿ biogenesis of ribosomes -- different sub-units of RNA are arranged Ÿ indirect role in protein synthesis Ÿ nucleolar DNA responsible for resynthesis of daughter nucleoli at the end of cell division Ÿ functions of the nucleus: Ÿ command center Ÿ contains DNA -- contain genes Ÿ control reproduction Ÿ control heredity Ÿ control moment by moment functions of all cells Ÿ DNA à (transcription) à RNA à (translation) à proteins Ÿ 2 types of proteins: structural and dynamic Ÿ several disorders have been traced to errors in numbers and shapes of chromosomes in the nucleus Ÿ many diseases are caused by abnormal genes Ÿ gene -- segment of DNA that determines the sequence of amino acids in a protein Ÿ the biological unit of heredity...
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- Spring '08
- DNA, RNA molecules, tRNAs