Stores genes on chromosomes Organizes genes into chromosomes to allow cell

Stores genes on chromosomes organizes genes into

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•Stores genes on chromosomes. •Organizes genes into chromosomes to allow cell division. •Transports regulatory factors and gene products will be regulated by the pores. •Produces different types of RNA. •Produces ribosomes. •Organizes the set of DNA to replicate and decode genes. •DNA repair. DNA •DNA codes for polypeptides. •The types of proteins a cell produces determines what kind of cell it is and what it is able to do.
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•DNA replication must be carried out very carefully so as to minimize the introduction of genetic errors. What is chromatin? •DNA + Associated proteins (histones and non-histones) •The genes can be found to direct protein synthesis and to make sure the DNA strands do not get tangled or broken. From nucleus to cytoplasm •mRNA: Brings instruction for protein synthesis out to ribosomes. •Ribosomal subunits: The ribosomes are made in the nucleus but work in the cytoplasm. Once the ribosomes are assembled the cannot get back into the nucleus.
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•tRNA molecules: They are made in the nucleus, they bring the amino acids one by one in the cytoplasm while proteins are being synthesized. •Proteins for the construction of ribosomes: Composed of ribosomal RNAs and proteins. The proteins are made in the cytoplasm while the RNAs are made in the nucleus. The Nucleolus is the site of ribosome synthesis •The nucleolus contains a lot of the DNA, rRNAs and ribosomal proteins. •It forms as those areas of DNA that contain genes coding for rRNAs bundle together and become active rRNA synthesis. Histology •Study of tissues & their cellular organization. 4 main types of tissues 1. epithelium (Covers the body surface and lines its cavities) •Creates boundaries -Covering and lining epithelium -Glandular epithelium Functions of epithelia -Protection (skin: mechanical, chemical, infectious) -Absorption (GI tract) -Filtration (kidney) -Excretion (Kidney) -Secretion (Glands)
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-Sensory reception (Taste buds, olfactory membranes) 5 special structural characteristics of epithelial •Polarity: Apical and basal surface; apical surface often specialized such as having motile cilia or microvilli. •Specialized contacts: tight junctions prevent substances from leaking through spaces between cells and desmosomes keep cells from pulling apart. Supported by connective tissue: Basement membrane is composed of a basal lamina sitting on top of a reticular lamina. Innervated but avascular: Contains no blood vessels but they are supplied by nerve fibers. They are nourished by substances diffusing from blood vessels in the underlying connective tissue. Regeneration: High regenerative capacity for when a apical-basal or polarity and lateral contacts are destroyed, epithelial cells will began to reproduce themselves rapidly. 2 criteria used to classify epithelial cells Cell shape -Squamous cells: Are flattened and scale-like.
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  • Fall '08
  • CARNEGIE

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