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Marieb Hoehn 8e Chapter 3


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Name the 3 Basic parts of a cell and describe the function of each
1) Plasma Membrane (outer boundary of cell) 2) Nucleus (control center of cell) 3) Cytoplasm (fluid material between the nucleus and plasma)
How would you explain the meaning of a "generalized cell" to a classmate?
It is the cell concept that includes structures and functions common to all cells.
what basic structure do all cellular membranes share?
Double layer of phospholipids in which proteins are embedded.
Why do phospholipids, which form the greater part of cell membranes, organize into a bilayer - tail-to-tail - in a watery environment?
Hydrophobic regions (tails of phospholipid molecules) orient toward each other while the hydrophilic regions (phospholipid heads) orient to the aqueous fluid inside and outside the cell
What is the importance of the glycocalyx in cell interactions?
Sugar residues of the glycocalyx provide recognizable biological markers for cells to recognize each other.
What two types of membrane junctions would you expect to find between muscle cells of the heart?
The heart has desmosomes (anchoring junctions) that secure cardiac cells together as the heart works and gap junctions (communicating junctions) that allow ions to flow from cardiac cell to cardiac cell.
What is the energy source for all type of diffusion?
Kinetic Energy
What determines the direction of any diffusion process?
Relative concentration of the substance in different areas determines the direction of diffusion. Diffusion occurs from regions of high concentration to regions of low concentration
What are the two types of facilitated diffusion and how do they differ?
Channel-mediated: substance moves THROUGH a membrane channel. Carrier-mediated: substance ATTACHES to a membrance (protein) which moves it across the membrane.
What happens when the Na+ -K+ pump is phosphorylated?
Causes the pump protein to change shape so that it "pumps"
Na+ across the membrane. K+ binding to the pump protein triggers the release of phosphate and the pump protein returns to its original shape.
As a cell grows, its plasma membrane expands. Does this membrane expansion involve endocytosis or exocytosis?
What vesicular transport process allows a cell to take in cholesterol from the extracellular fluid?
Receptor -mediated endocytosis.
What event or process of the glycocalyx when cells interact with their environment
Diffusion of ions, mainly the diffusion of K+ from the cell through leakage channels, establishes the resting membrane potential.
Is the inside of the plasma membrane negative or positive relative to its outside in a polarized membrane?
1) What term is used to indicate signaling chemicals that bind to membrane receptors? 2) Which type of membrane receptor is most important in directing intracellular events by promoting formation of second messengers?
1) Signaling chemicals: ligands. 2) G protein-linked receptors
What organelle is the major site of ATP synthesis?
What are three organelles involved in protein synthesis and how do these organelles interact in that process?
1) Ribosomes are the sites of protein synthesis. 2) Rough ER provides a site for ribosome attachment for the transport to the Golgi apparatus. 3) Golgi apparatus modifies and packages the proteins it receives for various destinations within or outside the cell
How does the function of lysosomes compare to that of peroxisomes?
Lysosomal enzymes digest foreign substances engulfed by the cell, nonuseful or deteriorating organelles, or even the cell itself to prevent the buildup of cellular debris. Enzymes in peroxisomes detoxify harmful chemicals and neutralize free radicals.
How are microtubules and microfilaments related functionally?
Both are involved in organelle movements within the cell and/or movements of the cell as a whole
Of microfilaments, microtubules, or intermediate filaments, which is MOST important in maintaining cell shape?
Intermediate filaments.
If a cell ejects or loses its nucleus, what is its fate and why?
It is doomed to DIE! - because it will be unable to make proteins which include the enzymes needed for all metabolic reactions
What is the role of nucleoli?
They are the site of synthesis of ribosomal subunits.
What is the importance of the histone proteins present in the nucleus?
Provide the means to pack DNA in a compact, orderly way and play a role in gene regulation.
If one of the DNA strands being replicated "reads" CGAATG what will be the base sequence of the corresponding DNA strand?
During what phase of the cell cycle is DNA synthesized?
S phase
What are three events occurring in prophase that are undone in telophase?
Nuclear envelope breaks up, spindle forms, nucleoli disappear and the chromosomes coil and condense.
Codons and anticodons are both three-base sequences. How do they differ?
Codons=mRNA each of which specifies an amino acid, anticodons=tRNA that are complementary to the codons specifying the amino acid they transport to the ribosome during protein synthesis
How do A, P and E ribosomal sites differ functionally during protein synthesis?
A site=entry site for tRNA at the ribosome. P site=site where peptide bonds form between delivered amino acids, E site=the tRNA exit site from the ribosome
What is the role of DNA in transcription?
Provides the coded instructions (is the template) for protein synthesis via the mRNA synthesized on it.
What is the importance of ubiquitin in the life of a cell?
Attaches to misfolded, damaged, or unneeded proteins, tagging them for destruction by proteasomes
What are two body fluids that inhabit the extracellular space and what role does each play in the body?
1) Blood plasma: extracellular fluid that transports nutrients, gases, hormones, and other substances throughout the body. 2) Interstitial Fluid: important transport and dissolving medium.
What is apoptosis and what is its importance in the body?
A process of programmed cell death which rids the body of cells that are stressed, damaged, old or no longer needed.
What is the wear-and-tear theory of aging?
Attributes aging to little chemical insults and free radicals which have cumulative detrimental effects
Which of the following names the three main parts of a human cell? (homework)
Plasma membrane, cytoplasm, and nucleus.
What is the diffusion of a solvent, such as water, across a selectively permeable membrane.

Diffusion is a form of active transport. (T or F) (homework)
Solutions with a higher concentration of solutes than the concentration inside the cell are:
True or False? During exocytosis, substances from the inside of the cell are moved outside. (homework)
Phagocytosis is a form of exocytosis. (t or f) (homework)
The plasma membrane is made primarily of what? (homework)
What is the primary function of the mitochondria? (homework)
They are the main sites of ATP production.
Which organelle is responsible for building proteins? (homework)
Lysosomes perform digestive functions within a cell. (t or f) (homework)
What is exocytosis? (lecture)
moves substance from cell interior to extracellular space
What it endocytosis? (lecture)
enables large particles and macromolecules to enter the cell.
What is transcytosis? (lecture)
moving substances into, across, and then out of a cell.
Vesicular Trafficking is what? (lecture)
moving substances from one area in the cell to another

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