Cells are the Structural and Functional Units of an Organism

Cells are Diverse in Size, Shape, and Length

Parts of a Cell: Nucleus, Cytoplasm, and Plasma Membrane

The Cytoplasm

The major functional area of the cell.

Consists of:

Cytosol

Organelles

Inclusions

Inclusions: Stored Nutrients

Glycogen

Lipid (brown fat)

Melanin Secretory Granules

Substantia Nigra Pancreas

Mitochondria - Structure

Mitochondria

The site of ATP production.

Metabolically active cells have more mitochondria.

Are self-replicating.

May have evolved from purple bacteria.

Ribosomes

Composed of protein and rRNA.

May be free in the cytoplasm or bound to endoplasmic reticulum.

Rough Endoplasmic Reticulum

Endoplasmic Reticulum

Smooth Endoplasmic Reticulum

The Golgi Apparatus

The Golgi Apparatus

Plasma Cells

Lysosomes

Sites of digestion.

Lysosomal enzymes are produced by the RER.

The lysosomal membrane has special adaptations.

Lysosomes function in:

1. Digestion of ingested particles2. Digestion of worn-out organelles3. Metabolism of stored glycogen

Lysosomal rupture results in autolysis.

Lysosomes Phagocytosis

Peroxisomes

Convert free radicals to H2O2

Required for detoxification

Self-replicate

Peroxisomes

The Cytoskeleton

Cytoskeletal Elements

Microtubules:

* Hollow tubes formed by proteins called tubulins

* Comprise the centrosome and other structures (e.g., cilia & flagella)

* Variable stability (mitotic spindle is labile)

* Maintain cell shape and rigidity

Structure of a Microtubule

Cilia

Basal bodies control the assembly of theaxoneme.

Structure of Cilia

Axoneme

Cytoskeletal Elements

Microfilaments:

consist of thin strands of actin

form the core of microvilli, allow amoeboid movement, produce the cleavage furrow

most highly developed in muscle cells

labile

are attached to the cytoplasmic side of the plasma membrane

Cytoskeletal Elements

Intermediate Filaments:

Intermediate in size

Have tensile strength

Most stable

Specific names in certain cell types (see table 2-4)

The Nucleus

The largest organelle and has 3 regions:

nuclear membrane

nucleolus – protein and rRNA

chromatin – DNA and histone proteins

euchromatin - active(vesiculate nucleus)

heterochromatin - inactive(pachychromatic nucleus)

The Nucleus

Nuclear Pores

200,000 X 48,000 X

Nucleosomes – the fundamental units of chromatin

Intracellular Pigments

* Endogenous or exogenous (environmental)

* Exogenous pigments include carbon and other dusts

* Endogenous pigments: lipofuscin, melanin, hemosiderin.

Apoferritin + iron = ferritin

hemosiderin = large amounts of ferritin

Endogenous Intracellualr Pigments - Hemosiderin

Exogenous Intracellular Pigments

Silicosis

Asbestosis

Endogenous Intracellular Pigments

Lipofucsin