Chapter 2: Cell Physiology

Question 1

Major Cell Divisions

Answer 1

• Plasma Membrane: bounds the cell
• Nucleus: contains DNA
  Important concepts: roles of RNA, Human genome and proteome, epigenetics, and lipidome
• Cytoplasm: consists of various organelles, the cytoskeleton, and the cytosol
  Cytoplasm is the portion of the cell interior not occupied by the nucleus

Question 2

Endoplasmic Reticulum (ER)

Answer 2

• elaborate fluid-filled membranous system
• distributed extensively throughout the cytosol
• Primary Function: produce proteins and lipids
• Rough-ER synthesizes proteins for secretion and membrane construction
• Smooth-ER packages new proteins in transport vesicles

Question 3

ER and Segregated Synthesis

Answer 3

• misfolded proteins are destroyed by the ubiquitin-proteasome pathway
• tagged with ubiquitin, “doom tag”
• labels the flawed proteins for degradation
• labels undamaged or unneeded intracellular proteins for degradation in proteasomes

Question 4

Golgi Apparatus

Answer 4

• consists of a stack of flattened, slightly curved, membrane-enclosed sacs
• they do not come in contact with each other
• Vesicular transport from one Golgi sac to the next: accomplished through action of membrane-curving coat protein 1 (COP1)
• In secretory cells, the Golgi complex packages proteins for export by exocytosis

Question 5

Exocytosis

Answer 5

• a secretory vesicle fuses with the plasma membrane, releasing the vesicle contents to the cell exterior. The vesicle membrane becomes part of the plasma membrane

Question 6

Endocytosis

Answer 6

• materials from the cell exterior are enclosed in a segment of the plasma membrane that pockets inward and pinches off as an endocytic vesicle
• internalization of extracellular material within a cell
  Processes:
  Pinocytosis
  Receptor-Mediated Endocytosis
  Phagocytosis

Question 7

Lysosomes

Answer 7

• small, membrane-enclosed degradative organelles

- digest extracellular material brought into the cell by phagocytosis and remove worn-out organelles

Question 8

Pinocytosis

Answer 8

• solute molecules and water molecules are outside the plasma membrane
• membrane pockets inward, enclosing solute molecules and water molecules
• pocket pinches off as endocytic vesicle containing sample of ECF.

Question 9

Receptor-Mediated Endocytosis

Answer 9

• substances attached to membrane receptors
• membrane pockets inward
• pocket pinches off as endocytic vesicle containing target molecule

Question 11

Phagocytosis

Answer 11

• white blood cell engulfs a worn out red blood cell and breaks it apart

Question 12

Peroxisomes

Answer 12

• membranous organelles
• produce and decompose hydrogen peroxide (H2O2) while degrading potentially toxic molecules
• house oxidative enzymes that detoxify various wastes
  Oxidative enzymes use oxygen (O2) to strip hydrogen from certain organic molecules

Question 13

Mitochondria

Answer 13

• energy organelles of the cell
• extract energy from food nutrients and transform it into a usable form for activities
• enclosed by tow membranes that form the cristae
• form a mitochondrial reticulum in some cell types
• play a major role in generating ATP
  Processes:
  Glycolysis
  Citric Acid Cycle
  Oxidative Phosphorylation

Question 14

Glycolysis

Answer 14

• conducted in cytosol of cell

- pyruvate-> citric acid cycle

Question 15

Mitochondria and ATP Productions

Answer 15

Aerobic Conditions
- more energy is generated in these conditions than in anaerobic conditions
Energy Stored within ATP
- used for synthesis, transport, and mechanical work
Programmed Cell Death
- mitochondria plays a role

Question 16

Vaults

Answer 16

• non-membranous organelles
• shaped like octagonal barrels and have a hollow interior
• may serve as cellular transport vehicles
• believed to pick up nucleus molecules and transport elsewhere in the cell
• may transport mRNA from nucleus to ribosomal sites for protein synthesis
• may play an undesirable role in bringing about multi-drug resistance displayed by cancer cells

Question 17

Cytosol

Answer 17

• semiliquid portion of cytoplasm that surrounds organelles
• categories of activities associated with cytosol
• enzymatic regulation of intermediary metabolism
• ribosomal protein synthesis
• storage of fat, carbohydrate, and secretory vesicles

Question 18

Cytoskeleton

Answer 18

• complex protein network that acts as “bone and muscle” of cell
• links cell together
• responsible for the shape, rigidity, and spatial geometry of each different cell type
• serves as a lattice to organize groups of enzymes for many cellular activities
• may serve as a mechanical communications system
• responsible for directing intracellular transport and for regulating numerous cellular movements
  Distinct elements
• Microtubules: help maintain asymmetric cell shapes and play a role in complex cell movements
• Microfilaments: important to cellular contractile systems and as mechanical stiffeners
• Intermediate Filaments: important in cell regions subject to mechanical stress

Question 19

What basic cellular functions are essential to a cell’s survival?

Answer 19

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Question 20

What are some examples of specialized cellular tasks that promote homeostasis?

Answer 20

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Question 21

What are the stages of cellular respiration and where is each accomplished?

Answer 21

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