Chapters 3-4: Cell Structure and Function, Cell Injury

Question 1

What is the plasma membrane structure made of?

Answer 1

Phosolipid bilayer

Question 2

What is the function of the plasma membrane?

Answer 2

• Transportation of nutrients and waste products
• Generation of membrane potentials
• Recognition and communication of cells

Question 3

What does amphiphilic mean?

Answer 3

Hydrophilic charged or polar head

Hydrophobic non-polar end

Question 4

What are the three major membrane proteins?

Answer 4

• Cholesterol
• Phospholipid
• Glycolipid

Question 5

Why are membrane proteins so important?

Answer 5

Membrane proteins execute most of the membrane’s functions

Including transport and signal transduction

Question 6

What is the purpose of the cytoskeleton?

Answer 6

Maintains the cell’s shape

Question 7

What is the cell cytoskeleton made of?

Answer 7

• Actin filaments (movement)
• Microtubules (organize cytoplasm and organelles)
• Intermediate filaments (mechanically support the cell)

Question 8

What is the difference between the nucleus and the nucleolus?

Answer 8

Nucleus: Contains DNA
Nucleolus: Assembles ribosomes, synthesizes rRNA, forms spindles

Question 9

What is the function of the endoplasmic reticulum?

Answer 9

“Conveyor belt”

Question 10

What is the difference between rough and smooth endoplasmic reticulum?

Answer 10

Rough: coated with ribosomes
Smooth: no ribosomes, involved in lipid metabolism

Question 11

What is the function of the Golgi apparatus?

Answer 11

“Packages proteins”

Question 12

What are the three components of the Golgi apparatus?

Answer 12

• Cis-face: receives newly synthesized proteins and lipids
• Medial: middle component
• Trans-face: proteins and lipids leave for final destination

Question 13

What is the difference between lysosomes and peroxisomes?

Answer 13

Lysosomes: Breaks down cellular waste
Peroxisome: Degrades free radicals

Question 14

What is the function of the mitochondria?

Answer 14

Converts energy to forms that can be used to drive cellular reactions

Also plays a role in apoptosis

Question 15

What is the difference between anabolism and catabolism?

Answer 15

Anabolic: energy-using metabolic process; synthesis

Catabolic: energy-releasing metabolic process; breakdown

Question 16

Describe glycolysis

Answer 16

Anaerobic process

Glucose -> G6P -> 2x G3P -> 2x pyruvate + 2 NADH + 2 ATP

Net 2 ATP and 2 NADH

Question 17

What happens to pyruvate in the citric acid cycle?

Answer 17

Pyruvate -> acetyl CoA -> 2x ATP, 2x FADH, 6x NADH

Question 18

What is the conversion of FADH and NADH to ATP in oxydative phosphorylation?

Answer 18

1 FADH: 1.5 ATP

1 NADH: 3 ATP

Question 19

What is the total amount of ATP produced from one glucose in cellular respiration?

Glycolysis + Krebs + Oxydative phosphorylation

Answer 19

37 ATP

Question 20

What are the three types of endocytosis?

Answer 20

• Pinocytosis: ingestion of fluids and small molecules
• Phagocytosis: ingestion of large molecules
• Receptor-mediated endocytosis: uptake of a specific substance regulated by receptors on the external surface of the membrane

Question 21

Explain electrochemical gradients

Answer 21

There is a slight excess of negative ions along the inner aspect of the membrane

Membrane is permeable only to K+ ions
Fixed intracellular anions hold onto K+ within the cell

The slight excess of negative ions in the cell attracts K+ into it, the concentration gradient favors movement out of the cell

Question 22

Discuss hypopolarization vs hyperpolarization in terms of K+ ions

Answer 22

If extracellular K+ is greater, K+ remains in the cell due to a decreased concentration gradient (Hypopolarized)

If extracellular K+ is less than inside, K+ shifts out of the cell, cell interior will become more negative (Hyperpolarized)

Question 23

What are the three types of carrier proteins?

Answer 23

• Uniporter: carries one molecule or ion
• Symporter: carries two different molecules or ions in the same direction
• Antiporter: carriers two different molecules or ions in the opposite direction

Question 24

Discuss action potential

Answer 24

Electrical excitations of the membrane

Depolarization: Influx of Na in the cell from voltage gated Na+ channel

Repolarization: Resetting membrane potential via voltage-gated K+ channel

Question 25

Glycolysis is the metabolic process of breaking down a glucose molecule to form: 1. 30 ATP 2. 2 ATP and 2 pyruvate 3. CO2 and H2O 4. Oxygen

Answer 25

2 ATP and 2 pyruvate

Question 26

Which of the following correctly match intracellular organelles to their functions? 1. Lysosomes: Digests organic waste materials 2. Mitochondria: Produce proteins 3. Phospholipid bilayer: Holds the cell's genetic material and directs cell activity 4. Golgi apparatus: Arranges the lipid bilayer according to polarity

Answer 26

Lysosomes: Digests organic waste materials

Question 27

What structure prevents water-soluble molecules from entering cells across the plasma membrane? 1. Carbohydrate chains 2. Glycoprotein channels 3. Membrane channel proteins 4. Lipid bilayer

Answer 27

Lipid bilayer

Question 28

Gap junctions

Answer 28

Connecting channels found in most tissues ## Footnote Found in the majority of cardiac cells; "hole in the wall for communication"

Question 29

What are the different types of cell signaling that utilize ligands?

Answer 29

* Synaptic: nervous system * Paracrine: localized areas * Endocrine: hormones traveling through the bloodstream * Autocrine: feedback to secreting cell

Question 30

Interphase

Answer 30

G1, S, and G2 phases of cell proliferation Growing of the cell, preparing for mitosis

Question 31

What are the phases of mitosis?

Answer 31

Prophase Metaphase Anaphase Telophase

Question 32

What is the difference between mitosis and meiosis?

Answer 32

Mitosis: Proliferation of body cells in which little genetic variation is needed; each daughter cell receives 46 chromosomes Meiosis: Division of germ cells (sperm, oocytes); significant chromosomal rearrangement occurs * one cell -> four daughter cells

Question 33

What is cellular atrophy and what are some of the causes?

Answer 33

Cells shrink and reduce their differentiated functions * Disuse * Denervation * Ischemia * Nutrient starvation * Interruption of endocrine signals * Persistent cell injury

Question 34

What is cellular hypertrophy and what are some of the causes?

Answer 34

Increase in cell mass with an augmented functional capacity * Response to increased physiologic or pathophysiologic demands ## Footnote Ex: cardiomegaly

Question 35

What is cellular hyperplasia and what are some of the causes?

Answer 35

Increasing functional capacity by increasing the number of cells * Increased physiologic demands * Hormonal stimulation * Persistent cell injury ## Footnote Ex: menstruation

Question 36

What is cellular metaplasia and what are some of the causes?

Answer 36

Replacement of one differentiated cell type with another; fully reversible when injurious stimulation is removed * Adaptation to persistent injury

Question 37

What is cellular dysplasia and what are some of the causes?

Answer 37

Disorganized appearance of cells due to abnormal variations in size, shape, and arrangement * Adaptive effort gone astray ## Footnote Significant potential to transform into cancerous cells (preneoplastic lesions)

Question 38

What are the different types of necrosis and in which situations do they typically occur?

Answer 38

* Coagulative: Denaturation of proteins (kidneys) * Liquefactive: Cells digested by their own hydrolases (neurons/glial cells in the brain) * Caseous: Cells disintegrate but debris is walled off; combination of coagulative and liquefactive (TB) * Fat: Caused by lipases; creates saponification (breast, pancreas, abdominal structures * Gangrenous: Extremities due to physical injury and trauma

Question 39

How does tissue ischemia lead to lactic acidosis?

Answer 39

Ischemia -> decreased O2 delivery to mitochondria -> decreased ATP production -> increased pyruvate accumulation which then converts to lactate -> increased lactate leads to cellular acidification

Question 40

What is ischemia-reperfusion injury and what causes it?

Answer 40

Occurs when blood supply returns to tissue after a period of ischemia Caused by calcium overload, free radicals, and subsequent inflammation