Eukaryotic Cell Structure, Study notes of Cell Biology

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Eukaryotic Cell Structure

Learning Targets

 Describe the function of major cell structures.  Compare and contrast plant and animal cells.

Eukaryotic Cells

 Eukaryotic cells are divided into two major parts: the nucleus and the cytoplasm.

Cytoplasm

 Cytoplasm is the clear, gelatin like substance that fills each cell and is enclosed by the cell membrane.  In eukaryotic cells, the cytoplasm contains all the cell material outside the nucleus.  The nucleus and cytoplasm work together to maintain life.

The Nucleus

 The control center of the cell.  Contains nearly all the cell’s DNA, the coded instructions for making proteins and other important molecules.  The nucleus is surrounded by a nuclear envelope composed of two membranes.

The Nucleus

 The nuclear membrane is dotted with thousands of nuclear pores, which allow materials such as proteins, RNA and other molecules, to move into and out of the nucleus.

Chromatin

 The nucleus contains a granular material called chromatin.  Chromatin consists of DNA bound to protein.  Chromatin is usually spread throughout the nucleus except during cell division when it condenses to form chromosomes.

Chromosomes

 Chromosomes are thread-like structures that contain the genetic information that is passed from one generation of cells to the next.

Nucleolus

 Most nuclei also contain a small, dense region known as the nucleolus where ribosome assembly begins.

Organelles in the Cytoplasm

Endoplasmic Reticulum

 An internal, interconnected network of flattened, membrane-enclosed sacs or tube-like structures, continuous with the nuclear envelope, where lipid components of the cell membrane and proteins are assembled and transported, along with other materials that are exported from the cell.

Endoplasmic Reticulum

 The endoplasmic reticulum is composed of the rough endoplasmic reticulum and the smooth endoplasmic reticulum.

Rough Endoplasmic Reticulum

 Rough ER is abundant in cells that produce large amounts of protein for export (pancreas, salivary glands).

Rough ER