Chapter 5
What makes one amino acid different from another?
The different side chains (R groups) attached to an alpha carbon.
A mycoplasma is an organism with a diameter between 1.0 and 10.0 μm. What does the organism's size tell you about how it might be classified?
It is probably a bacteria
Chemical substances diffuse down their own ______ ______, which is the region along which the density of a chemical substance increases or decreases
concentration gradient
Prokaryotes are classified as belonging to two different domains. What are the domains?
Bacteria and Archaea
What cellular structure is common to all three domains of life?
A cell membrane with phospholipid bilayer
The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking 5 glucose molecules together by dehydration reactions?
C30H52O26
When a sodium ion (Na+) moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures. Which of the following correctly describes the order in which these structures will be encountered by the ion?
primary cell wall → secondary cell wall → plasma membrane → cytoplasm → vacuole
How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. This allows the membrane to remain fluid and flexible even when the temperature drops, stopping the membrane from solidifying.
Water diffuses across a membrane from a region of _____ solute concentration to a region of ____ solute concentration until the solute concentration is equal on both sides of the membrane in a process called _____
lower; higher; osmosis
If one strand of a DNA molecule has the sequence of bases 5'GGCTAATC3', the other complementary strand would have which of the following sequences?
5'GATTAGCC3'
Compared to arctic fish, tropical fish oils have what feature? Why?
Lower levels of unsaturated omega-3 fatty acids and higher amounts of saturated fatty acids. This is because artic fish need fats that don't freeze at lower temperatures, and unsaturated fatty acids remain liquid at lower temperatures, while tropical salmon need fats that are more stable at higher temperatures, and saturated fatty acids need higher temperatures to boil/become unstable.
What organelles are present in animal cells but not plant cells? What organelles are present in plant cells but not animal cells?
Animal cells additionally have Lysosomes, centrosomes, and flagella. Plant cells additionally have Chloroplasts, cell wall, central vacuole, and plasmodesmata.
What are the major functions of membrane proteins?
(1) Transport
(2) Enzymatic activity
(3) Signal transduction
(4) Cell-cell recognition
(5) Intercellular joining
(6) Attachment to the cytoskeleton and extracellular matrix
What is an endosymbiont?
An endosymbiont is a cell that lives within a host cell
If a DNA sample were composed of 29% thymine, what would be the percentage of guanine?
21%
What maintains the secondary structure of a protein? what about tertiary? what about quaternary? what about primary?
Primary - peptide bonds
Secondary - hydrogen bonds between repeating constituents of the polypeptide backbone
Tertiary - hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bridges, and van der Waals interactions between R groups.
Quaternary - hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bridges, and van der Waals interactions between different polypeptides.
A cell with a predominance of free ribosomes is most likely doing what? Explain why.
It is producing primarily cytoplasmic proteins because proteins are generally made by free ribosomes, remain within the cell, and perform functions in the cytosol.
What is the net movement of solutes if:
Inside a cell:
.4M glucose
.2M sucrose
.8M fructose
Outside:
.6M glucose
.1M sucrose
.6M fructose
Glucose would move into the cell, sucrose and fructose would move outside the cell.
What is the difference between an ester linkage and a glycosidic linkage?
An ester linkage is made between three fatty acids and a glycerol to make a fat. A glycosidic linkage is a covalent bond linking each glucose molecule together to make carbohydrates.
Mitochondria have two membranes, a smooth outer membrane and a convoluted inner membrane with infoldings called cristae. In eukaryotic cells, the most important product of cellular respiration (energy production) is ATP, which is synthesized by special enzymes located primarily on the cristae of the mitochondrial inner membrane. What advantage do the cristae of the inner membrane impart on the process of cellular respiration?
The formation of cristae greatly increases the surface area of the inner membrane, which in turn increases the number of ATP synthesizing enzymes that can be used during cellular respiration, ultimately increasing the rate of ATP production
Why can humans not digest cellulose but can digest starch?
Humans do not have enzymes that can hydrolyze beta-glycosidic linkages of cellulose but they do have enzymes that can hydrolyze the alpha-glycosidic linkages of starch.
What is an explanation of how the compartmental organization of a eukaryotic cell contributes to its biochemical functioning?
Reactants and enzymes can be concentrated in one area instead of spread throughout the cell, increasing efficiency of metabolism.
Reactions that require specific conditions, such as a lower pH, can be compartmentalized.
Enzymes required for specific reactions are often embedded in the membranes that enclose or partition an organelle.
Hydrolytic enzymes that destroy cellular molecules, such as those used in the lysosome, can be kept separate from the rest of the cell
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly found where?
Embedded in a phospholipid bilayer
What is a dehydration reaction? What is a hydrolysis reaction?
A dehydration reaction is a reaction that occurs when two monomers form a covalent bond together and release a water molecule in the process. A hydrolysis reaction is a reaction that occurs when a polymer is disassembled into monomers by the use of a water molecule to break the covalent bond between monomers.
Of the eukaryotic organelles derived from endosymbionts, which one was most likely the first endosymbiont and why was it most likely the first endosymbiont?
The mitochondria resulted from the first endosymbiotic event because all present-day eukaryotes have mitochondria, while only a subset of present-day eukaryotes have chloroplasts