Inside the Cell7.1 What’s Inside the Cell?

Prokaryotic CellsEukaryotic Cells– The Nucleus– Ribosomes– Rough Endoplasmic Reticulum– Golgi Apparatus– Smooth Endoplasmic Reticulum– Peroxisomes– Lysosomes– Mitochondria– Chloroplasts– Cytoskeleton– The Cell Wall

How Does Cell Structure Correlate with Function? The Dynamic Cell

7.2 The Nuclear Envelope: Transport Into and Out of the NucleusHow Are Molecules Imported into the Nucleus?How Are Molecules Exported from the Cell

7.3 The Endomembrane System: Manufacturing and Shipping ProteinsEntering the Endomembrane System: The Signal HypothesisGetting from the ER to the GolgiWhat Happens Inside the Golgi Apparatus? How are Products Shipped from the Golgi?

7.4 The Dynamic CytoskeletonActin FilamentsIntermediate FilamentsMicrotubules– Studying Vesicle Transport– Microtubules Act as “Railroad Tracks”– A Motor Protein Generates Motile Forces

Cilia and Flagella: Moving the Entire Cell– How Are Cilia and Flagella Constructed?– A Motor Protein in the Axoneme

KEY CONCEPTS• The structure of cell components is closely

correlated with their function.

• Inside cells, materials are transported to their destinations using molecular “zip codes.”

• Cells are complex, dynamic ever-changing factories, each with their own particular program that depends on their own genes, surroundings and developmental history.

KEY CONCEPTS

• Cells are dynamic. Thousands of chemical reactions occur each second within cells; molecules constantly enter and exit across the plasma membrane; cell products are shipped along protein fibers; and elements of the cell’s internal skeleton grow and shrink.

Prokaryotic CellsGram positive bacteria: single cell membrane with thick peptidoglycan (Staph; strep) Gram negative bacteria: double cell membrane with single layer of peptidoglycan between (E. coli; Pseudomonas; Vibrio cholera)

Archaea: third biological kingdom – adaptations to withstand major stresses of pH and temperature; more like eukaryotes in their informational machinery (ribosomes, RNA synthesis, etc.)

Eukaryotic Cells

The Nucleus

Mitochondria: cellular power plants

Chloroplasts, for photosynthesis in plants

Plant Cell Walls

Cell Structure-Function Relationships

The Dynamic CellTools for understanding cell components

and structure-function relationships:

Ultracentrifugation, fluorescent and dye labeling,

7.2 The Nuclear Envelope: Transport Into and Out

of the Nucleus

7.3 The Endomembrane System: Manufacturing and Shipping

Proteins

Entering the Endomembrane System:

What happens inside the Golgi apparatus?

Summary:

Ions, ATP, amino acids, and other small molecules diffuse randomly throughout the cell, but the transport of proteins and other large molecules is tightly regulated and takes energy. Proteins must have the appropriate molecular zip code to enter or leave the nucleus, enter the lumen of the rough ER, or become incorporated into vesicles destined for lysosomes or the plasma membrane.

Often, proteins and other types of cargo are shipped in vesicles that contain molecular zip codes on their surface.

The Dynamic Cytoskeleton

Microtubules

Microtubules Act as“Railroad Tracks” for vessicles

A protein “motor”, kinesin, generates the motion

Cilia and Flagella: Moving the Entire Cell

Dynein is a protein motor in the axoneme

CHECK YOUR UNDERSTANDINGEach component of the cytoskeleton has a unique structure and set of functions. In addition to providing structural support, actin filaments and microtubules work in conjunction with motor proteins to move the cell or materials inside the cell. Intermediate filaments provide structural support. Most elements of the cytoskeleton are dynamic—they grow and shrink over time. You should be able to predict what will happen when experimental cells are treated with drugs that inhibit formation of each type of cytoskeletal filament.