Biology Memorization

Question 1

Structural Proteins: Collagen

Answer 1

• trihelical fiber (three left-handed helices woven together to form secondary right-handed helix)
• makes up most of ECM of connective tissues
• found throughout body, provides strength and flexibility

Question 2

Structual Proteins: Elastin

Answer 2

• component of ECM of connective tissue
• stretches and recoils like a spring to restore original shape of the tissue

Question 3

Structural Proteins: Keratin

Answer 3

• intermediate filament proteins found in epithelial cells
• contribute to mechanical integrity of the cell and function as regulatory proteins
• primary protein in hair/nails

Question 4

Structural Proteins: Actin

Answer 4

• makes up microfilaments and thin filaments in myofibrils
• most abundant protein in eukaryotic cells
• polar: positive and negative sides
  
  • polarity allows motor proteins to travel unidirectionally along actin filaments

Question 5

Structual Proteins: Tubulin

Answer 5

• makes up microtubules
• polar: negative end usually adjacent to nucleus, positive end in periphery of the cell

Question 6

Motor Proteins: Myosin

Answer 6

• primary motor protein that interacts with actin
• thick filament in myofibrils
• can be involved in cellular transport
• each myosin subunit has a single head and neck; movement of the neck is responsible for the power stroke in sarcomere contractions

Question 7

Motor Proteins: Kinesins and Dyneins

Answer 7

• motor proteins associated with microtubules
• have two heads, at least one of which remains attached to tubulin at all times
• Kinesins:
  
  • play key role in aligning chromosomes during metaphase and depolymerizing microtubules during anaphase of mitosis
  • bring vesicles toward the positive end of cell during vesicular transport
• Dyneins:
  
  • involved sliding movement of cilia and flagella
  • bring vesicles toward negative end of cell during vesicular transport

Question 8

CAMs: Cadherins

Answer 8

• glycoproteins that mediate calcium-dependent cell adhesion
• hold similar cell types together

Question 9

CAMs: Integrins

Answer 9

• group of proteins with 2 membrane-spanning chains called alpha and beta
• chains are important for binding to and communication with ECM
• play role in cell signaling
• impact cell function by promoting cell division, apoptosis, etc.
• part of clotting
• WBC migration

Question 10

CAMs: Selectins

Answer 10

• bind to carbohydrate molecules that project from other cell surfaces
  
  • weakest bonds of CAMs
• expressed on WBCs and endothelial cells
• play an important role in host defense: inflammation and WBC migration

Question 11

Cytoskeletal Components: Microtubules

Answer 11

• hollow polymers of tubulin
• radiate throughout cell, providing primary pathways along which motor proteins carry vesicles
• cilia and flagella are composed of microtubules
• microtubules are organized by centrioles in the centrosome; during mitosis, centrioles mirgrate to opposite poles of the dividing cell and organize the mitotic spindle; microtubules emanating from centrioles attach to the chromosomes via kinetochores and pull the sister chromatids apart

Question 12

Cytoskeletal Components: Microfilaments

Answer 12

• made up of actin polymers organized into bundles and networks
• resistant to compression and fracture = protection for cell
• actin filaments can use ATP to generate force for movement by interaction with myosin (muscle contraction)
• Cytokinesis: microfilaments organize as a ringe at the site of division in cytokinesis

Question 13

Cytoskeletal Components: Intermediate Filaments

Answer 13

• diverse group; includes: keratin, desmin, vimentin, and lamins
• involved in cell-cell adhesion or maintenance of integrity of cytoskeleton
• can withstand great tension, increasing structural rigidity of the cell
• intermediate filaments help anchor organelles, including the nucleus