Biology 1406- Chapter 6 Objectives

Distinguish between free and bound ribosomes in terms of location and function.

Free ribosomes float around in the cytoplasm and synthesize proteins for use within the cell. Bound ribosomes are attached to the Rough ER and synthesize proteins for the plasma membrane and for outside the cell.

Explain how the structure of cilia and flagella relate to their functions.

*Cilia* work like oars , alternating between power and recovery strokes. This helps move liquid and particles across the surface. *Flagella* move like a fish and are primarily used for movement and swimming.

Compare the structure, monomers, and functions of microtubules, microfilaments, and intermediate filaments.

*Microtubules*: hollow tubes made of tubulin. Maintains the cell's shape and aids in motility, chromosome movement in cells, and movement of other organelles. *Microfilaments*: Two intertwined strands of actin. Maintains cell shape; changes the cell shape; muscle contraction;cell motility; division of the cell through formation of the cleavage furrow. *Intermediate filaments*: cable-like structure of fibrous proteins. Maintains cell shape; anchors nucleus and other organelles; forms the nuclear lamina.

Name the intercellular junctions found in plant and animal cells and list the function of each type of junction.

*Plasmodesmata* perforates a cell wall and joins the cytoplasm of two adjacent cells. *Tight Junctions* keep a cell bound together tightly to prevent the leakage of extracellular fluid. *Desmosomes* fasten cells together into strong sheets using intermediate filaments to anchor into the cytoplasm. *Gap Junctions* Provide a pathway of communication between the cytoplasm of two cells (similar to the plasmodesmata)

Compare the structure and functions of smooth and rough ER.

*Rough ER*: Studded with ribosomes. Connected to the nucleus. Make secretory proteins (proteins leaving the cell or becoming part of the plasma membrane). Sight of lipid synthesis. *Smooth ER*: Connected to the nucleus. Used for calcium storage and detoxification of the cell. Sight of lipid synthesis.

Distinguish differences between prokaryotic and eukaryotic cells.

Eukaryotic cells have a nucleus and Prokaryotic cells don't. Eukaryotic cells have membrane-bound organelles Prokaryotic cells don't. Eukaryotic cells are significantly bigger than Prokaryotic cells.

plasma membrane

Phospholipid bilayer surrounding the cell.

Describe the principles, advantages, and limitations of the Scanning Electron microscope (TEM)

Principles: Profiles a thin section of a specimen to see the inside of cells. Advantages: Can observe specimen down to 2 nanometers across, used to study the internal structure of cells Limitations: Doesn't see the outside of the cell. Methods to view cells kill the cell.

Describe the principles, advantages, and limitations of the Transmission Electron microscope (SEM)

Principles: Shows a 3D surface image of the specimen Advantages: Useful in the topographical study of cells, can view specimen down to 2 nanometers across. Limitations: Doesn't see the inside of the cell. Methods to view cells kill the cell.

Describe the principles, advantages, and limitations of the light microscope.

Principles: visible light is passed through a specimen and then through glass lenses. The lenses bend the light in a way that magnifies the image Advantages: Easily see groups of cells and general properties. Can view living cells. Limitations: Cannot view specimen less than 200 nanometers.

Golgi Apparatus

Process; storage; sending. consists of cis and trans faces. Cis is receiving and trans is sending.

Describe the functions of the cytoskeleton.

Reinforces the cell's shape. Functions in cell movement. Made of proteins. Includes Microfilaments, Intermediate Filaments, and Microtubules.

Explain the significance of the cis and trans sides of the Golgi apparatus.

The *Cis* side receives vesicles from the ER and the *Trans* side sends vesicles to other sights.

Explain how the extracellular matrix may act to integrate changes inside and outside the cell

The ECM communicates with the nucleus mechanically through through fibronectin, integrins, and microfilaments. It communicates chemically through changes in the cytoskeleton which signal to the nucleus to produce new proteins for outside the cell.

List the components of the endomembrane system, and briefly describe the structure and function of each component.

The Nuclear Envelope, The Endoplasmic Reticulum, the Golgi Apparatus, Lysosomes, Various vesicles and vacuoles, and the plasma membrane.

What is *Contrast* in respect to Microscopy?

The difference in brightness between the light and the dark areas of an image. You can enhance contrast through the use of the diaphragm and gram staining.

Explain the advantages of compartmentalization in eukaryotic cells.

The different compartmentalized organelles provide unique environments to support specific metabolic functions.

Explain the roles of peroxisomes in eukaryotic cells.

Various specialized functions. Produces hydrogen peroxide as a by-product then converts it to water.

The Endoplasmic Reticulum

network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes. Has smooth and rough sections

Distinguish common characteristics between prokaryotic and eukaryotic cells.

Both have cytoplasm, a membrane, ribosomes, and DNA.

Lysosomes

Digestive organelle where macromolecules are hydrolyzed.

Describe the structure and roles of the extracellular matrix in animal cells.

It is made up of collagen, proteoglycans, fibronectin, and integrins. Plays a role in regulating a cell's behavior and communication between cells

Explain why cell fractionation is a useful technique.

It is used to isolate cell components based on size and weight. This enables researchers to prepare specific cell components in bulk and identify their functions.

Describe the basic structure of a plant cell wall.

Layer outside of the plasma membrane that maintains the cell's shape and protects it from mechanical damage. Made of cellulose Microfibrils, other polysacharides, and proteins. Can expand to allow for the absorption of water without bursting in hypotonic solutions.

What are the three parameters in microscopy?

Magnification, Resolution, and Contrast

Briefly describe the energy conversions carried out by mitochondria and chloroplasts.

Mitochondria is the site of cellular respiration where it uses oxygen to drive the production of ATP by extracting energy form sugar, fats, and other fuels. Chloroplast converts light energy from the sun into chemical energy.

What is *Resolution* in respect to Microscopy?

The measure of clarity of an image. The minimum distance two points can be separated and still be distinguished as two separate points.

Describe the structure and function of the nuclear envelope, including the role of the pore complex.

The nuclear envelope encloses the nucleus with a lipid bilayer perforated with pores. It separates the nucleus and its contents from the cytoplasm. The pore complex lines each pore and plays a role in regulating the entry and exit of proteins and RNA.

Explain the role of the nucleolus in protein synthesis.

The nucleolus contains DNA which makes rRNA. rRNA is then used to syntheisze ribosomal sub-units.

Briefly explain how the nucleus controls protein synthesis in the cytoplasm

The nucleus is where ribosomal sub-units are made. In the cytoplasm, these ribosomal sub-units join together to make ribosomes which are the sight of protein synthesis.

What is *Magnification* in respect to Microscopy?

The ratio of an object's image size to it's actual size. Light microscopes have magnifications up to 1000 times the actual size.

Explain why there are both upper and lower limits to cell size.

The surface to volume ration needs to be high. For each square micrometer of membrane only a limited amount of a particular substance can cross per second. Bigger organisms doesn't mean *bigger* cells, it means *more* cells.

Describe the endosymbiont theory for the evolutionary origin of mitochondria and chloroplasts, including the evidence that supports this theory.

This theory states that an ancestor cell engulfed an oxygen-using non-photosynthetic prokaryotic and eventually merged into a single organism. At least one of these "ancestral" cells engulfed a photosynthetic prokaryote which then merged to form into a single organism.