NU 545 Unit 1 Questions and Answers|Graded A+
Where is the genetic info contained in the cell? - ANSWER -The nucleus contains
the Nucleolus, a small dense structure composed of RNA, DNA, DNA protein. Pg
3.
Cell membranes contain which major chemical components? - ANSWER -"The
main components of cell membranes are lipids and proteins. The basic structure of
cell membranes is the lipid bilayer..." pg 12
What allows potassium to diffuse in and out of cells? - ANSWER -Diffusion is
the movement of a solute molecule from and area of greater solute concentration to
an area of lesser solute concentration. (pg. 29). Active transport of K+ and Na+
requires a Sodium-Potassium Pump (pg. 31).
How is the cell protected from injury? - ANSWER -Plasma membrane pg 12 table
1.1 (functions of membrane).
In cirrhosis, what does cholesterol have to do with the erythrocytes? - ANSWER -
causes a decrease in membrane fluidity and affects the cells' ability to transport
oxygen
What is platelet-derived growth factor? - ANSWER -PDGF stimulates
proliferation of connective tissue cells and neuroglial cells. Can help with creating
blood clots. Pg 38.
What is cell communication? How does it occur? - ANSWER -Cells need to
communicate w/ each other to maintain a stable internal environment, or
homeostasis; to regulate growth and division... it is done by 3 main ways. 1) they
display plasma membrane-bound signaling molecules (receptors) that affect the
cell itself and other cells in direct physical contact. 2) they affect receptor proteins
inside the target cell and the signal molecule has to enter the cell to bind w/ them.
3) they form protein channels that directly coordinate the activities of the adjacent
cells. Pg 19.
, What is chemical signaling? - ANSWER -Primary means of cell-to-cell
communication. 5 forms of signaling mediated by secreted molecules: (1) Contact-
dependent signaling requires cells to be in close membrane-membrane contact; (2)
Paracrine signaling- cells secrete local chemical mediators that are quickly
absorbed, destroyed, or immobilized; (3) Autocrine signaling- cells produce signals
that they, themselves, respond to (cancer cells); (4) Hormonal signaling involves
specialized endocrine cells that secrete chemicals called hormones (TSH).
Hormones are released by one set of cells and travel through the tissue and through
the bloodstream to produce a response in other sets of cells; (5) Neurohormonal
signaling- hormones are released into the blood by neurosecretory neurons. (p.19)
How is glucose transported from the blood to the cell? - ANSWER -Pancreatic
cells secrete and release insulin to signal muscle cells to absorb sugar from the
blood for energy. (p.3)
Understand the transportation of potassium and sodium across plasma membranes
- ANSWER -The Na+ -K+ antiport system (Na+ moving out of the cell and K+
moving into the cell) uses the direct energy of ATP to move these cations. The
transporter protein is the enzyme adenosine triphosphatase (ATPase).
Approximately 60% to 70% of the ATP synthesized by cells is used to maintain
the Na+-K+ transport system. 1, three Na+ ions bind to sodium- binding sites on
the carrier's interface. 2, at the same time, an energy- containing adenosine
triphosphate molecule produced by the cell's mitochondria bind to the carrier. The
ATP disassociates, transferring its stored energy to the carrier. 3 and 4, the carrier
then changes shape, releases the three Na+ ions to the outside of the cell, and
attracts two potassium ions to its potassium- binding site. 5, the carrier then returns
to its original shape, releasing the two K+ ions and the remnant of the ATP
molecule to the inside of the cell. The carrier is now ready for another pumping
cycle (p.31)
What is active transport? - ANSWER -requires life, biologic activity, and the
cell's expenditure of metabolic energy. Unlike passive transport, active transport
occurs across only living membranes that have to drive the flow "uphill" by
coupling it to an energy source (p. 28)
, What are cytokines? - ANSWER -Growth factor, also called cytokines, stimulate
an increase in cell mass or cell growth by promoting the synthesis of proteins and
other macromolecules and inhibiting their degradation (p. 38)
Cytokines constitute a large family of small-molecular-weight soluble
intracellular-signaling molecules that are secreted, bind to a specific cell membrane
receptors, and regulate innate or adaptive immunity; either proinflammatory or
anti-inflammatory. Majority of important cytokines are classified as interleukins or
interferons (p. 201)
Do all cells continue to replicate and divide? - ANSWER -No. For example, most
of the neurons and skeletal muscle cells are in a terminally differentiated G0 state;
with their cell cycle control system disassembled, the molecular regulatory
switches become permanently turned off and cell division rarely occurs (p. 37)
When normal columnar ciliated epithelial cells of the bronchial lining are replaced
by stratified squamous epithelial cells, the process is called? - ANSWER -
Bronchial metaplasia (p. 49)
What is the relation between ischemia and ATP? - ANSWER -An anaerobic
(without oxygen) metabolic pathway can synthesize ATP. This process called
substrate phosphorylation, or anaerobic glycolysis, is linked to the breakdown
(glycolysis) of carbohydrates.... The reactions in anaerobic glycolysis involve the
conversion of glucose to pyruvic acid (pyruvate) with the simultaneous production
of ATP. If oxygen is absent, pyruvate is converted to lactic acid, which is released
into the extracellular fluid. Elevated lactate level is indicative of tissue hypoxia or
low oxygen concentration (pp.26 & 27)....As lactic acid increases, oxygen
decreases (hypoxia), cell tissues...this is reversible if oxygen is reintroduced...
When does sodium enter the cell and cause swelling? - ANSWER -A reduction in
ATP levels causes the plasma membrane's sodium-potassium pump (Na+-K+) and
sodium-calcium exchange to fail, which leads to an intracellular accumulation of
sodium and calcium, resulting in cellular swelling and diffusion of potassium out
of the cell (p. 51)
Where is the genetic info contained in the cell? - ANSWER -The nucleus contains
the Nucleolus, a small dense structure composed of RNA, DNA, DNA protein. Pg
3.
Cell membranes contain which major chemical components? - ANSWER -"The
main components of cell membranes are lipids and proteins. The basic structure of
cell membranes is the lipid bilayer..." pg 12
What allows potassium to diffuse in and out of cells? - ANSWER -Diffusion is
the movement of a solute molecule from and area of greater solute concentration to
an area of lesser solute concentration. (pg. 29). Active transport of K+ and Na+
requires a Sodium-Potassium Pump (pg. 31).
How is the cell protected from injury? - ANSWER -Plasma membrane pg 12 table
1.1 (functions of membrane).
In cirrhosis, what does cholesterol have to do with the erythrocytes? - ANSWER -
causes a decrease in membrane fluidity and affects the cells' ability to transport
oxygen
What is platelet-derived growth factor? - ANSWER -PDGF stimulates
proliferation of connective tissue cells and neuroglial cells. Can help with creating
blood clots. Pg 38.
What is cell communication? How does it occur? - ANSWER -Cells need to
communicate w/ each other to maintain a stable internal environment, or
homeostasis; to regulate growth and division... it is done by 3 main ways. 1) they
display plasma membrane-bound signaling molecules (receptors) that affect the
cell itself and other cells in direct physical contact. 2) they affect receptor proteins
inside the target cell and the signal molecule has to enter the cell to bind w/ them.
3) they form protein channels that directly coordinate the activities of the adjacent
cells. Pg 19.
, What is chemical signaling? - ANSWER -Primary means of cell-to-cell
communication. 5 forms of signaling mediated by secreted molecules: (1) Contact-
dependent signaling requires cells to be in close membrane-membrane contact; (2)
Paracrine signaling- cells secrete local chemical mediators that are quickly
absorbed, destroyed, or immobilized; (3) Autocrine signaling- cells produce signals
that they, themselves, respond to (cancer cells); (4) Hormonal signaling involves
specialized endocrine cells that secrete chemicals called hormones (TSH).
Hormones are released by one set of cells and travel through the tissue and through
the bloodstream to produce a response in other sets of cells; (5) Neurohormonal
signaling- hormones are released into the blood by neurosecretory neurons. (p.19)
How is glucose transported from the blood to the cell? - ANSWER -Pancreatic
cells secrete and release insulin to signal muscle cells to absorb sugar from the
blood for energy. (p.3)
Understand the transportation of potassium and sodium across plasma membranes
- ANSWER -The Na+ -K+ antiport system (Na+ moving out of the cell and K+
moving into the cell) uses the direct energy of ATP to move these cations. The
transporter protein is the enzyme adenosine triphosphatase (ATPase).
Approximately 60% to 70% of the ATP synthesized by cells is used to maintain
the Na+-K+ transport system. 1, three Na+ ions bind to sodium- binding sites on
the carrier's interface. 2, at the same time, an energy- containing adenosine
triphosphate molecule produced by the cell's mitochondria bind to the carrier. The
ATP disassociates, transferring its stored energy to the carrier. 3 and 4, the carrier
then changes shape, releases the three Na+ ions to the outside of the cell, and
attracts two potassium ions to its potassium- binding site. 5, the carrier then returns
to its original shape, releasing the two K+ ions and the remnant of the ATP
molecule to the inside of the cell. The carrier is now ready for another pumping
cycle (p.31)
What is active transport? - ANSWER -requires life, biologic activity, and the
cell's expenditure of metabolic energy. Unlike passive transport, active transport
occurs across only living membranes that have to drive the flow "uphill" by
coupling it to an energy source (p. 28)
, What are cytokines? - ANSWER -Growth factor, also called cytokines, stimulate
an increase in cell mass or cell growth by promoting the synthesis of proteins and
other macromolecules and inhibiting their degradation (p. 38)
Cytokines constitute a large family of small-molecular-weight soluble
intracellular-signaling molecules that are secreted, bind to a specific cell membrane
receptors, and regulate innate or adaptive immunity; either proinflammatory or
anti-inflammatory. Majority of important cytokines are classified as interleukins or
interferons (p. 201)
Do all cells continue to replicate and divide? - ANSWER -No. For example, most
of the neurons and skeletal muscle cells are in a terminally differentiated G0 state;
with their cell cycle control system disassembled, the molecular regulatory
switches become permanently turned off and cell division rarely occurs (p. 37)
When normal columnar ciliated epithelial cells of the bronchial lining are replaced
by stratified squamous epithelial cells, the process is called? - ANSWER -
Bronchial metaplasia (p. 49)
What is the relation between ischemia and ATP? - ANSWER -An anaerobic
(without oxygen) metabolic pathway can synthesize ATP. This process called
substrate phosphorylation, or anaerobic glycolysis, is linked to the breakdown
(glycolysis) of carbohydrates.... The reactions in anaerobic glycolysis involve the
conversion of glucose to pyruvic acid (pyruvate) with the simultaneous production
of ATP. If oxygen is absent, pyruvate is converted to lactic acid, which is released
into the extracellular fluid. Elevated lactate level is indicative of tissue hypoxia or
low oxygen concentration (pp.26 & 27)....As lactic acid increases, oxygen
decreases (hypoxia), cell tissues...this is reversible if oxygen is reintroduced...
When does sodium enter the cell and cause swelling? - ANSWER -A reduction in
ATP levels causes the plasma membrane's sodium-potassium pump (Na+-K+) and
sodium-calcium exchange to fail, which leads to an intracellular accumulation of
sodium and calcium, resulting in cellular swelling and diffusion of potassium out
of the cell (p. 51)
