BIO150 Chapter 6

What are the advantages of compartmentalization in eukaryotic cells? Include SA/V ratio in your answer.

Different cell organelles perform different functions, many of which require specialized components for specific targets. Compartmentalization creates appropriate microenvironments for these diverse processes, allows damage limitation, minimizes non-specific interactions and consequently increased cellular efficiency. Compartmentalization provides a large surface area that enhances the productivity of the mitochondrion, cellular respiration/ATP/ energy production and provides a unique internal environment for reactions.

What is the difference between the smooth and rough endoplasmic reticulum?

Both the smooth and rough endoplasmic reticulum help in the production and storage of proteins. The main difference is that the rough ER contains ribosomes on it and the other does not.

How many compartments do mitochondrion and chloroplasts have?

Chloroplasts contain three separate membranes that divide them into three distinct internal compartments. Mitochondria have a complex, dynamic internal structure. Comprised of at least six compartments: outer membrane, inner boundary membrane, intermembrane space, cristal membranes, intracristal space, and matrix,

How are free and bound ribosomes similar? How are they different?

Membrane bound ribosomes are attached to a structure known as the rough endoplasmic reticulum. Free ribosomes are suspended in cytosol. Free and membrane-bound ribosomes produce proteins that are exported from the cell to be used elsewhere. Free ribosomes synthesize proteins that are mostly used inside the cell. Membrane-bound ribosomes synthesize proteins for export (secretion) from the cell or for use in lysosomes.

What are the names of the microfilaments that make up the cytoskeleton? What are the functions of each?

Microfilaments are filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They function in cellular movement, have a diameter of about 7 nm, and are made of two intertwined strands of globular protein called actin. For this reason microfilaments are also known as actin filaments.

What is a lysosome? How do they work?

One of the key organelles involved in digestion and waste removal. Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. Lysosomes are like the stomachs of the cell.

How do Prokaryotic and Eukaryotic cells differ?

Organisms of the domains bacteria and archaea consist of prokaryotic cells. Protists, fungi, animals, and plants all consist of eukaryotic cells. Major difference between eukaryotic and prokaryotic cells is the location of their DNA. In a eukaryotic cell, most of the DNA is in an organelle called the nucleus which is bounded by a double membrane. In prokaryotic cell, the DNA is concentrated in a region that is not membrane-enclosed called the nucleoid. Prokaryotic cells appear much simpler in internal structure.

What are the names and functions of intercellular junctions found in plant and animal cells.

Plasmodesmata, gap junctions, tight junctions, and desmosomes

What are the role of preoxisomes in eukaryotic cells?

Preoxisomes are membrane bound organelles occurring in the cytoplasm of eukaryotic cells. Preoxisomes break down fatty acids to be used for forming membranes and as fuel for respiration. They also transfer hydrogen from compounds to oxygen to create hydrogen peroxide and then convert hydrogen peroxide into water.

What is the significance of the cis and trans sides of the Golgi apparatus?

Several vesicles move in and out of the Golgi apparatus. The receiving side of the Golgi apparatus is called the cis face. The opposite side is called the trans face.

What is the function of the central vacuole and where is it found?

The central vacuole is a cellular organelle found in plant cells. It is often the largest organelle in the cell. It is surrounded by a membrane and functions to hold materials and wastes. It also functions to maintain the proper pressure within the plant cells to provide structure and support for growing plants.

What are the components of the endomembrane system? What is the function of each component?

The endomembrane system includes the nuclear envelope, lysosomes, vesicles, the ER, and Golgi apparatus, as well as the plasma membrane. The nuclear envelope surrounds the nucleus with a double membrane with multiple pores. The pores regulate the passage of macromolecules. The lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. Lysosomes are like the stomach of the cell. The vesicles are small enclosed sacs that can transport and store substances within a cell from one cell to another. They have a lipid bilayer, which separates the contents of the vesicle from the rest of the cell. The ER (endoplasmic reticulum) serves many general functions including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus. The Golgi apparatus is considered the post office of the cell. Involved in the packaging, sorting, and modifying proteins for secretion. It is also involved in the transport of lipids around the cell and the creation of lysosomes. The sacs and folds of the Golgi apparatus are called cisternae. The plasma membrane protects the cell from its surroundings. Composed of a phospholipid bilayer with embedded proteins the plasma membrane is selectively permeable. These cellular components work together to modify, package, tag, and transport proteins and lipids from the membranes.

What evidence exists that suggest some organelles were once free living cells?

The endosymbiotic theory suggests that the origins of mitochondria and chloroplasts have their own DNA and were once free living cells. It has proven that the DNA in the mitochondria and chloroplasts resemble the DNA of bacteria.

What are the roles of the extracellular matrix in animal cells?

The extracellular matrix helps to bind and regulate a number of cellular functions such as adhesion, migration, proliferation, and differentiation. It is formed by macromolecules and ultimately it regulates a cell's dynamic behavior.

Why is it advantageous for prokaryotes to remain small?

The logistics of carrying out cellular metabolism sets limits on cell size. A large cell size means a greater requirement for food and other resources. A small cell size means requirement of food and resources is less. Prokaryotes have a smaller amount of DNA and do not have any organelles therefore it is advantageous for prokaryotes to remain small as there is no reason for them to be large.

How does the structure of the nuclear envelope relate to its function including the nuclear pore complex?

The nuclear envelope encloses the nucleus seperating its contents from the cytoplasm. The nuclear envelope is a double membrane: the two membranes, each a lipid bilayer with associated proteins. The envelope is perforated by pore structures and complex protein structures that span the double membrane serve as selective channels for the movement of macromolecules in and out of the nucleus.

What role does the nucleolus play in protein synthesis?

The nucleolus is a condensed region of chromatin where ribosome synthesis occurs. Ribosomes, large complexes of protein and ribonucleic acid (RNA) are the cellular organelles responsible for protein synthesis. During protein synthesis, ribosomes assemble amino acids into proteins.

How does DNA in the nucleus control protein synthesis in the cytoplasm?

The nucleus controls protein synthesis in the cytoplasm by 1. Messenger RNA (mRNA) is transcribed in the nucleus from DNA instructions. 2. It then passes through the nucleus pores into the cytoplasm. 3. Finally, it attaches to ribosomes where the genetic message is translated into primary protein structure.

How is energy conversion carried out by mitochondria and chloroplast?

They convert solar energy into chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from carbon dioxide and water.