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

“The Nucleus: Not Just a
Sack of Chromosomes”
Eunnie, Stephen, Shane and
Meagan
Electron Micrograph
Image from answers.com
Artist’s Rendition or “Nucleus
Cartooneus”
Image from McGraw-Hill
Eunnie’s Nucleus Comparison
What is the Nucleus?
From the latin word for “kernel” or “nut”
 Control centre of the cell
 Contains most of the cell’s genetic
material
 It’s function is to maintain the integrity of
these genes and to control the activities of
the cell
 Found only in eukaryotic cells

Structure
Typically located in the centre of the cell
 Most eukaryotic cells possess one
nucleus, although the cells of fungi and
some other groups may have several
nuclei.

Nuclear Membrane
Surrounded by a double membrane,
similar to that of the cell, known as nuclear
membrane
 Nuclear pores allow movement of
molecules such as mRNA across the
membrane
 Nuclear pores are filled with proteins that
act as gatekeepers.

Nucleoplasm
The nucleoplasm or nuclear sap, a liquid
filled with genetic material known as
chromatin
 Chromatin contain the cell’s genetic
material, DNA, as well as protein
 When the cell is dividing, chromatin coils
into chromosomes which appear shorter
and fatter.

Nucleolus
Produces and assembles ribosomes
 There can be more than one nucleolus in
one nucleus
 The nucleolus is a knot of chromatin

Diseases


Chromosomal abnormalities occur when there is
an error in cell division following meiosis or
mitosis
Down Syndrome (Trisomy 21)


Turner Syndrome


When an individual has three copies of chromosome
21
When an individual is born with only one sex
chromosome, an X
Cancers, Cystic Fibrosis
Ribosomes
Image from answers.com
Ribosomes



Serve as the site of protein synthesis
Assembles proteins by the process of translation
Two types of ribosomes:



Free ribosomes, move around freely in the cytoplasm
Membrane-bound ribosomes, bound to the
endoplasmic reticulum
Among the most complex molecular assemblies
found in cells
Diseases

Alzheimer’s Disease


Decreased activity of ribosomal genes
Associated with psychosis and depression
References
Biology seventh edition, McGraw-Hill
 Wikipedia
 Bio 11 textbook
