““The Nucleus: Not Just a The Nucleus: Not Just a Sack of Chromosomes”Sack of Chromosomes”

Eunnie, Stephen, Shane and Eunnie, Stephen, Shane and MeaganMeagan

Electron MicrographElectron Micrograph

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Artist’s Rendition or “Nucleus Artist’s Rendition or “Nucleus Cartooneus”Cartooneus”

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Eunnie’s Nucleus ComparisonEunnie’s Nucleus Comparison

What is the Nucleus?What is the Nucleus?

From the latin word for “kernel” or “nut”From the latin word for “kernel” or “nut”Control centre of the cellControl centre of the cellContains most of the cell’s genetic Contains most of the cell’s genetic

materialmaterial It’s function is to maintain the integrity of It’s function is to maintain the integrity of

these genes and to control the activities of these genes and to control the activities of the cellthe cell

Found only in eukaryotic cellsFound only in eukaryotic cells

StructureStructure

Typically located in the centre of the cellTypically located in the centre of the cellMost eukaryotic cells possess one Most eukaryotic cells possess one

nucleus, although the cells of fungi and nucleus, although the cells of fungi and some other groups may have several some other groups may have several nuclei.nuclei.

Nuclear MembraneNuclear Membrane

Surrounded by a double membrane, Surrounded by a double membrane, similar to that of the cell, known as nuclear similar to that of the cell, known as nuclear membranemembrane

Nuclear pores allow movement of Nuclear pores allow movement of molecules such as mRNA across the molecules such as mRNA across the membranemembrane

Nuclear pores are filled with proteins that Nuclear pores are filled with proteins that act as gatekeepers.act as gatekeepers.

NucleoplasmNucleoplasm

The nucleoplasm or nuclear sap, a liquid The nucleoplasm or nuclear sap, a liquid filled with genetic material known as filled with genetic material known as chromatinchromatin

Chromatin contain the cell’s genetic Chromatin contain the cell’s genetic material, DNA, as well as proteinmaterial, DNA, as well as protein

When the cell is dividing, chromatin coils When the cell is dividing, chromatin coils into chromosomes which appear shorter into chromosomes which appear shorter and fatter. and fatter.

NucleolusNucleolus

Produces and assembles ribosomesProduces and assembles ribosomesThere can be more than one nucleolus in There can be more than one nucleolus in

one nucleusone nucleusThe nucleolus is a knot of chromatinThe nucleolus is a knot of chromatin

DiseasesDiseases

Chromosomal abnormalities occur when there is Chromosomal abnormalities occur when there is an error in cell division following meiosis or an error in cell division following meiosis or mitosismitosis

Down Syndrome (Trisomy 21)Down Syndrome (Trisomy 21) When an individual has three copies of chromosome When an individual has three copies of chromosome

2121

Turner SyndromeTurner Syndrome When an individual is born with only one sex When an individual is born with only one sex

chromosome, an Xchromosome, an X

Cancers, Cystic FibrosisCancers, Cystic Fibrosis

RibosomesRibosomes

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RibosomesRibosomes

Serve as the site of protein synthesisServe as the site of protein synthesis Assembles proteins by the process of translationAssembles proteins by the process of translation Two types of ribosomes:Two types of ribosomes:

Free ribosomes, move around freely in the cytoplasmFree ribosomes, move around freely in the cytoplasm Membrane-bound ribosomes, bound to the Membrane-bound ribosomes, bound to the

endoplasmic reticulumendoplasmic reticulum

Among the most complex molecular assemblies Among the most complex molecular assemblies found in cellsfound in cells

DiseasesDiseases

Alzheimer’s DiseaseAlzheimer’s DiseaseDecreased activity of ribosomal genesDecreased activity of ribosomal genes

Associated with psychosis and depressionAssociated with psychosis and depression

ReferencesReferences

Biology seventh edition, McGraw-HillBiology seventh edition, McGraw-HillWikipediaWikipediaBio 11 textbookBio 11 textbook