2005-2006AP Biology

Chapter 7.

The Cell:Nucleus, Ribosomes

2005-2006AP Biology

Nucleus Function

contains eukaryoticcell’s genetic library most genes in nucleus some genes located in

mitochondria &chloroplasts

Size ~ 5 microns (µm)

in diameter

2005-2006AP Biology

Nucleus structure Structure

separated from cytoplasm by a doublemembrane, nuclear envelope

double membrane is fused in spotsforming pores allows large macromolecules

& particles to pass through

What kind of moleculesneed to pass through?

2005-2006AP Biology

2005-2006AP Biology

2005-2006AP Biology

Nucleus structure Within nucleus, DNA organized into

fibrous material, chromatin in normal cell appears as diffuse mass

When cell preparesto divide, chromatinfibers coil up asseparate structures,chromosomes

2005-2006AP Biology

Nucleus structure Densely stained region

= nucleolus Function

production ofribosomal subunitsfrom rRNA & proteins pass through

nuclear pores tocytoplasm &combine to formribosomes

2005-2006AP Biology

2005-2006AP Biology

2005-2006AP Biology

Ribosomes Function

protein production Structure

ribosomes contain rRNA & protein composed of 2 subunits that combine to carry

out protein synthesis

2005-2006AP Biology

Types of Ribosomes Free ribosomes

suspended in cytosol synthesize proteins that

function within cytosol Bound ribosomes

attached to outside ofendoplasmic reticulum

synthesize proteins forexport or for membranes

2005-2006AP Biology

Ribosomes Prokaryotes & eukaryotes have

different ribosomes different size subunits different proteins can this difference be useful?

2005-2006AP Biology

Prokaryote vs. eukaryote ribosomes

2005-2006AP Biology

Any Questions??