4.1-which type of microscope would you use to study the changes in shape of a living human white blood cell?
4.1-which microscope would you use to study a surface structure of hair
scanning electron microscope
4.1-which microscope would you use to study the detailed structure of an organelle in a human liver cell?
transmission electron microscope
4.2-using a light microscope to examine a thin section of a spherical cell, you find the diameter is .3mm in diameter. the nucleus is about one-fourth as wide. what is the diameter of the nucleus in micrometers
about 75 um
4.3-red blood cells take up O2 in the lungs and then give up the O2 as they pass through the blood vessels of other organs. These cells are among the smallest on human cells. Explain one functional advantage of their small size.
They have more surface area and therefore are more effective
4.4-How is the nucleoid region of a prokaryotic cell unlike the nucleus of a eukaryotic cell?
There is no membrane enclosing the DNA of the nucleoid region.
4.5-Which of the following organelles does not belong in the list: mitochondrion, chloroplast, ribisome, lysosome, peroxisome. Why?
Ribosome, because it is the only organelle in the list not bound by a membrane
4.7-Which structure includes all others in the list: rough ER, smooth ER, endomembrane system, or nuclear envolope.
4.9-What are three functions of smooth ER?
Lipid synthesis, detoxification, regulation of muscle contraction
4.10-What is the relationship of the Golgi apparatus to the ER in a protein secreting cell?
The golgi receives transport vesicles that bud from the ER, and finishes processing the proteins inside of them.
4.11-When lysosomes were first discovered they were sometimes called suicide capsules. In what way does that nickname fit.
If a cell's lysosomes break open, the hydrolytic enzymes released kill the cell.
4.12-How can defective lysosomes result in excess accumulation of a particular compound in a cell?
If the lysosomes lack an enzyme needed to hydrolyze the compound, the cell will accumulate an excess of the compound.
4.13-The Paramecium cell in the picture is about 0.08mm long. Estimate the diameter in micrometers of the larger contractile vacuole?
4.14-How do transport vesicles integrate the endomembrane system?
Transport vesicles move membranes and substances they enclose between other components of the endomembrane system.
4.15-What does photosynthesis accomplish?
The conversion of light energy to chemical energy stored in sugar molecules.
4.17-Which component of the cytoskeleton is most important in holding the nucleus in place within the cell?
4.17-Which component of the cytoskeleton is most important in guiding transport vesicles from the golgi to the plasma membrane
4.17-Which component of the cytoskeleton is most important in contracting muscle cells
4.18-How do cilia and flagella bend?
Dyneim arms, powered by ATP move neighboring doublets of microtubules relative to one another.
4.19-How is a plant or animal tissue different from just an aggregate of similar cells?
cell junctions integrate the cells of a tissue, the cells are different and they make up the tissue
4.20-How do mitochondria, smooth ER, and the cytoskeleton cooperate in contraction with a muscle cell.
Mitochondria supply energy in the form of ATP. The smooth ER helps regulate contraction by the uptake and release of calcium. Microfilaments function as the actual contractile apparatus.
4.21-What three major characteristics are shared by eukaryotic cells and prokaryotic cells?
A plasma membrane, DNA as the genetic material, ability to carry out metabolism
5.2-Describe the energy transformations that occur when you climb to the top of a stair case?
You convert the chemical energy of food to the kinetic energy of your upward climb. At the top of the stairs, some of the energy has been stored as potential energy due to higher elevation. The rest has been converted to heat.
5.3-Cellular respiration is an exergonic process. Remembering that energy must be conserved, what becomes of the energy extracted from food during cellular respiration?
Some of it is stored in ATP molecules, the rest is released as heat
5.4-Explain how ATP transfers energy from exergonic to endergonic processes in the cell.
ADP to ATP is an exergonic reaction, the adding of a phosphate group, ATP to ADP is an endergonic reaction, the releasing of a phosphate group
5.5-Explain why an enzyme cannot change an endergonic reaction into an exergonic one.
Enzymes speeds a reaction up by lowering the activation energy, it has no effect on the energy contents of products and reactants
5.6-What is meant by induced fit?
Induced fit is the slight change in shape of the active site of an enzyme as it embraces its substrate. In this new shape, the active site catalyzes the reaction.
5.7-A few human enzymes work best at very low pH, about 2. Where in he body do you think these enzymes are located?
In the stomach
5.8-A competitive inhibitor of the enzyme sucrase slows the production of glucose and fructose in a test-tube reaction. How could you overcome the effect of the inhibitor?
Add a lot more sucrose
5.9-How does the antibiotic penicillin work?
It inhibits a bacterial enzyme that functions in cell wall production
5.10-How do membranes organize the chemical activities of cells?
form organelles that contain enzymes in a solution
5.11-Why do phospholipids tend to organize into a bilayer in an aqueous environment?
This structure shields the hydrophobic tails of the phospholipids from water, while exposing the hydrophilic heads to water
5.12-Why are cellular membranes described as a fluid mosaic?
diverse proteins float in a fluid phospholipid bilayer
5.13-The hormone epinephrine can cause a liver cell to hydrolyze its stored glycogen and release sugar without the hormone even entering the cell. Explain.
Epinephrine binds to a receptor on the liver cell surface, activating a signal transduction pathway inside the cell that leads to sugar release.
5.14-Explain how the second law of thermodynamics helps explain diffusion to a substance across a membrane.
Diffusion of a substance to a region where it is initially less concentrated increases entropy, as mandated by the second law.
5.15-Explain why it is not enough just to say that a solution is hypertonic.
It must be compared with something.
5.16-Explain the function of the contractile vacuoles in the Paramecium cell in the picture in terms of what you have learned about water balance in cells.
the contractile vacuole pumps out excess water
5.17-How do transport proteins contribute to a membrane's selective permeability?
transport proteins are specific to what they transport
5.19-Explain how a protein-secreting cell can synthesize and secrete its product without the protein ever having to cross a membrane.
From the time the protein is made by rough ER it is outside the cell, first in the ER interior, then within the Golgi and transport vesicles, and finally outside the plasma membrane as the vesicles release their contents by exocytosis
5.20-Explain how a person can have an excessive cholesterol level in the blood even without producing more cholesterol than other people.
They have a shortage of LDL receptors so they can't get rid of cholesterol