The Nucleus By Meredith Derecho, Elizabeth Eyermann, and Hannah Woolf Source 3

Key Facts About Nuclei “The nucleus is the genetic control center of a eukaryotic cell” (Source 5) Only eukaryotic cells have a nucleus— prokaryotic cells do not The word “nucleus” comes from the Latin word “nucula” meaning “little nut” (Source 6) Some eukaryotic cells have multiple nuclei or none at all The nucleus is near the center of the cell, and it takes up about 10% of a cell’s mass Source 5

Structure of the Nucleus The nucleus has three main components: 1.The Nuclear Envelope 2.The Chromatin 3.The Nucleolus Source 4

The Nuclear Envelope Space between the layers is called the perinuclear space This space connects with the rough endoplasmic reticulum The inner layer of the double membrane, the nuclear lamina, is made of protein The entire nuclear envelope disintegrates during mitosis and reforms as the new cells are created Double membrane structure made of phospholipids Nuclear pores control the flow of materials They allow building blocks of RNA and DNA molecules and energy sources to enter the nucleus Source 2

Chromatin and Chromosomes Chromatin is made up of strings of DNA and histones The strands come together to form chromosomes during mitosis Heterochromatin and euchromatin are two classifications of chromatin Heterochromatin is more condensed while euchromatin is delicate and less tightly packed The six feet of DNA within the cell are stored as chromatin An artist’s depiction of chromatin! Source 7

The Nucleolus For more information about the nucleolus, see Josh, Callie, and Garrett’s project The nucleolus is spherical, dense, and located in the middle of the nucleus It produces ribosomal subunits, thus indirectly helping to synthesize proteins GEMs (gemini of coiled bodies) are made by the nucleolus Interchromatin granule clusters are also made by the nucleolus It is visible when the cell is not being divided The nucleolus may affect the senescence, or aging, of an organism Source 5

Major Functions of the Nucleus 1. Gene expression 2. Managing cellular reproduction Source 8

DNA, RNA, and Gene Expression The Nucleus: 1.Stores and regulates the DNA 2.Uses transcription DNA to make the mRNA 3.Processes the pre-mRNA through post-transcriptional modification 4.Exports the mRNA to the ribosomes, where the mRNA becomes protein DNARNA Consequently, controlling gene expression allows the nucleus to manage cellular activities such as: Intermediary metabolism Protein synthesis Growth Cell compartmentalization Mitosis Nuclear transport Source 12 Source 11

The Nucleus’s Role in Cellular Reproduction Mitosis is the process of cells dividing to create new cells The nucleus must replicate all the cell’s genomic DNA The DNA divides into two identical sets for mitosis to occur The nucleus splits and forms two nuclei around each new set of DNA That allows the cell to divide into two new identical cells The process of mitosis: Source 13

Works Cited: Thanks to all our sources! 1. functions.html 14. Our lovely textbook! Campbell, et al. Biology: Concepts and Connections html micro.magnet.fsu.edu/cells/nucleus/nucleus.html 9. ibiblio.org/virtualcell/textbook/chapter3/nucf.htm 8. glogster.com online/library/onlinebio/ Thanks for watching our slideshow about the nucleus!