1 / 10

The Nucleolus

The Nucleolus. Drew Blazewicz , Maia Dinsmore, and Megan Durning. Vocabulary. Mitosis – the division of a single nucleus into two daughter nuclei; part of cell reproduction Chromatin – a combination of DNA and proteins that constitutes eukaryotic chromosomes

yaphet
Download Presentation

The Nucleolus

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Nucleolus Drew Blazewicz, Maia Dinsmore, and Megan Durning

  2. Vocabulary • Mitosis – the division of a single nucleus into two daughter nuclei; part of cell reproduction • Chromatin – a combination of DNA and proteins that constitutes eukaryotic chromosomes • Chromosomes - a threadlike, gene carrying structure found in the nucleus of a eukaryotic cell • RNA – ribonucleic acid, a type of nucleic acid consisting of nucleotide monomers, formed from the transcription of DNA • Nucleotides – building blocks of nucleic acids • Monomer – a chemical subunit that serves as a building block of a polymer • Polymer – a large molecule consisting of many identical or similar molecular units (monomers), covalently joined together in a chain. An example of this is DNA • Filaments – a very fine threadlike structure (dictionary.com) All definitions taken from Biology: Concepts and Connections, unless otherwise stated.

  3. Location • The nucleolus is located in the nucleus • It can take up as much space as 25% of the nucleus • Animals can have more than one nucleolus, depending on the species • Humans only have one • It dissipates during mitosis when chromatin compacts into chromosomes http://micro.magnet.fsu.edu/cells/nucleus/nucleolus.html

  4. Nucleolus in a Cell • The nucleus (red) is filled with nucleoplasm (green), in the center of which rests the nucleolus (orange) • Surrounding the nucleus, filling the rest of the cell, is cytoplasm (blue). http://www.biologyreference.com/Mo-Nu/Nucleolus.html

  5. Composition/Formation • The nucleolus is a bundle of chromatin, RNA, and proteins • It has two distinct parts: Fibrillar and Granular • Nucleoli form at Nucleolus Organizer Regions (NORs), located at the ends of certain genes • The number of NORs determines how many nucleoli form; however, one nucleolus can form from several NORs • The human nucleolus forms from 5 different pairs of NORs • It is not held together by a membrane but stays roughly spherical

  6. Function of the Nucleolus: the Creation of Ribosomes • The first step in the process of creating ribosomes, which are organelles involved in protein synthesis, is the transcription of DNA into ribosomal RNA • This occurs at the nuclear organizer region of the nucleolus • The transcribed rRNA surrounds the NOR in a dense ring of filaments called pars fibrosa RNA transcription http://www.cytochemistry.net/cell-biology/nucleus3.htm

  7. Function • Proteins are then combined with the rRNA, which form ribonucleoproteins • These form the subunits of ribosomes • Ribonucleoproteins surround the pars fibrosain a layer called the pars granulosa http://www.cytochemistry.net/cell-biology/nucleus3.htm

  8. Ribosomes • Ribosomes are then formed from the two subunits - a large subunit and a small subunit, created in the nucleolus • They are involved in protein synthesis, the translation of RNA into proteins • The number of nulceoli an animal has is determined by the amount of proteins it needs • This is because an animal needs more ribosomes in order to create a larger number of proteins, and it therefore would need more nucleoli to produce these ribosomes. • A healthy cell can create up to 10,000 ribosomes per minute http://www.biologie.uni-hamburg.de/b-online/library/onlinebio/BioBookCELL2.html

  9. Protein Synthesis (to be explained in more detail later in class) • In the first step of protein synthesis, mRNA is transcribed (copied) from the DNA in the nucleus • Messenger RNA (mRNA), which forms in the nucleus, binds to the ribosomes • Transfer RNA (tRNA), carries amino acids to the ribosomes • The order of nucleotides in the mRNA determines the order of amino acids in the polypeptide that is created, this process is called translation • Therefore, the nucleolus has an indirect effect on protein synthesis Amino acid Polypeptide (result) http://www.absoluteastronomy.com/topics/Protein_biosynthesis

  10. Bibliograpy • http://micro.magnet.fsu.edu/cells/nucleus/nucleolus.html (images and information) • http://www.biologyreference.com/Mo-Nu/Nucleolus.html (images and information) • http://www.cytochemistry.net/cell-biology/nucleus3.htm (images and information) • http://www.absoluteastronomy.com/topics/Protein_biosynthesis (image) • Campbell, Neil A. Biology. 2nd ed. Redwood City, CA: Benjamin/Cummings, 1987. Print. (information) • http://www.biologie.uni-hamburg.de/b-online/library/onlinebio/BioBookCELL2.html (image) • http://books.google.com/books?id=LorrYj5pkKYC&pg=PA839&lpg=PA839&dq=pars+fibrosa&source=bl&ots=Kza6AjnZq2&sig=t2qEX8lndfVrBVO4sj0fDkAi8tY&hl=en&ei=QNLqTKmAKous8Ab1wrnUDA&sa=X&oi=book_result&ct=result&resnum=7&ved=0CD8Q6AEwBg#v=onepage&q=pars%20fibrosa&f=false (information) • Helena, Curtis. Biology. 4th ed. New York, NY: Worth, 1983. Print. (information)

More Related