Cell Bio Final_Exam 1 Essay_2019

Question 1

Please list 8 Basic Properties of Cells

Answer 1

1) Cells are alive
2) Cells Are Highly Complex and Organized
3) Cells Possess a Genetic Program and the Means to Use It
4) Cells Are Capable of Producing More of Themselves
5) Cells Acquire and Utilize Energy
6) Cells Carry Out a Variety of Chemical Reactions
7) Cells Engage in Mechanical Activities
8) Cells Are Able to Respond to Stimuli
9) Cells Are Capable of Self-Regulation
10) Cells Evolve

Question 2

Please list the structures which are involved in the cell-cell interaction and the core components of the two structures which are universally exist (not specifically for epithelial cells).

Answer 2

Cell-cell adhesive junctions

• Adherens junction
• Desmosomes
• Tight junctions
• Gap junctions

Focal adhesions 
- Extracellular ligands
oCollagen, Fibronectin
-Large clusters of integrins
-Intracellular adaptor proteins
oTalin, α-actinin, and vinculin
-Actin filaments

Hemidesmosomes
Contain a dense plaque with Keratin filaments on the inner surface of plasma membrane
-Thicker
-Intermediate filaments
-Play a supportive function
-Keratin filaments are linked to the ECM by membrane-spanning integrins

Question 3

List the major components of extra cellular matrix and their major functions individually.

Answer 3

Basement membrane
Provide mechanical support to cells attached
-Generate signals that maintain cell survival
-Serve as a substratum for cell migration
-Separate adjacent tissues within an organ
-Act as a barrier to the passage of macromolecules
o Proteins
o Cancer cells

Collagen
-Provide the insoluble framework that determines many of the mechanical properties of the ECM
oTendon: resist pulling forces
oCornea: plywood-like structure

Proteoglycans
-Provide resistance to crushing (compression) forcesfor cells

Fibronectin

• Provide binding sites for numerous components of the ECM, including collagens, proteoglycans and other fibronectin molecules
• Facilitating establishment of a stable, interconnected network of ECM
• Provide binding sites for receptors on the cell surface
• Holding the ECM in a stable attachment to the cell
• Influence cell’s potential for migration, growth and differentiation

Laminins

• Help cell migration, growth and differentiation during embryonic development
• Bind to cell membrane receptors and other ECM proteins

Question 4

Describe the procedure of how Na+/K+ pup functions across the plasma membrane

Answer 4

A form of primary active transport that “actively” moves materials across the barrier by using energy generated by the hydrolysis of ATP. ATPase causes a change in the pump conformation and ion affinity. The pump moves against the gradient.

Question 5

List the major steps for aerobic metabolism (cellular respiration) and the location of where the reactions take place.

Answer 5

Glycolysis
- Cytoplasm

Oxidative decarboxylation
- Mitochondria matrix

Tricarboxylic acid cycle
- Mitochondria matrix

Oxidative phosphorylation in the formation of ATP
- Mitochondria membrane

Question 6

Please describe the difference between prokaryotic cells and eukaryotic cells. You can use a table to help you organize your contents and try to provide at least 8 differences.

Answer 6

Differences:

• Pro: Simple Eu: Complex
• Cell wall chemical composition
• Eukaryotes have mitochondria
• Eukaryotes have golgi complex
• Eukaryotes have simple membrane-bound vesicles
• In eukaryotes it divides cytoplasm into compartments
• Eukaryotes have a more complex system of interconnecting channels and vesicles
• Eukaryotes have more complex cytoskeletal proteins to form tubules and filaments
• Prokaryotes have: nucleoid region
• Eukaryotes have membrane bound nucleus
• Eukaryotes have more genetic information
• Eukaryotes have linear DNA, a number of seperated chromosomes
• Eukaryotes have chromatin
• Prokaryotes have circular DNA, no chromatin
• Eukaryotes divide by mitosis
• Prokaryotes divide by binary fission
• Eukaryotes are a sexual organism; meiosis
• Prokaryotes are a nonsexual organism
• Prokaryotes have multiple flagella
• Eukaryotes have single flagellum

Question 7

In the intercellular junctional complex, why is the tight junction closer to the surface of the epithelium (the apical end of the cell) than the belt desmosome?

Answer 7

Prevent exposure and diffusion of external materials into the body.

• Some are permeable to specific ions or solutes
• Serve as barrier to free diffusion of water and solutes from the extracellular compartment

Question 8

In the middle of the winter, the membranes from a tissue sample from an organism dwelling in a pond are the analyzed for their phospholipid content. In the middle of the summer, another tissue sample is taken from the same type of organism and the membrane lipid content determine. The lipid content has changed. How has it changed and why?

Answer 8

Lipid content changes based on temperature which determines fluidity. Temperature is the determinant for fluidity of lipid molecules. During the winter it was colder so there was more lipid content available versus during in the summer