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56 terms

Ch 3 Mastering a&p

STUDY
PLAY
Which of the following statements correctly describes the plasma membrane?
a. It is a flexible protein barrier supported by cholesterol rods
b. It is a dynamic fluid structure that is in constant flux
c. It is a solid structure formed by phospholipids and cholesterol designed to be stable against pressure.
d. It is a unique, solid barrier custom designed for each type of cell.
b. It is a dynamic fluid structure that is in constant flux
Which of the following is a function of a plasma membrane protein?
a. circulating antibody
b. oxygen transport
c. molecular transport through the membrane
d. forms a lipid bilayer
c. molecular transport through the membrane
The cell (plasma) membrane normally contains 15-25% of cholesteral.
True
Other than the nucleus, which organelle has its own DNA?
Mitochondria
Which structures are fingerlike projections that greatly increase the absorbing surface of cells?
microvilli
Only one cell type in the human body has a flagellum
False
Which cell organelle provides the majority of the ATP needed by the cell to carry out its metabolic reactions?
mitochondrion
Which cell component helps to maintain the structural integrity of the cell?
cytoskeleton
Interstitial fluid represents one type of extracellular material.
True
During interphase of the cell life cycle, the cell divides into two daughter cells.
False - Interphase consists of preparing the cell for division, including obtaining nutrients (also considered the last living stage of a cell)
Passive membrane transport processes include
a. movement of a substance down its concentration gradient
b. movement of water from an area of low concentration to an area of high concentration
c. consumption of ATP
d. the use of transport proteins when moving substances from areas of low to high concentrations
a. movement of a substance down its concentration gradient
Once solid material is phagocytized and taken into a vacuole, which of the following statements best describes what happens?
a. Nitrogen enters the vacuole and "burns" the enclosed solid material.
b. The vacuole remains separated from the cytoplasm and the solid material persists unchanged
c. A lysosome combines with the vacuole and digests the enclosed solid material.
d. A ribosome enters the vacuole and uses amino acids in the "invader" to form new protein
c. A lysosome combines with the vacuole and digests the enclosed solid material
Which of the following is the main component of the cell membrane?
phospholipids
Although phospholipids have a polar head, the long fatty acid tails are nonpolar, making the membrane mostly nonpolar.
Which of the following is not a major function of proteins in the cell membrane?
forming the entire glycocalyx
The glycocalyx is composed mostly of carbohydrates.
What part of a cell membrane is usually in contact with the interstitial fluid?
phosphate heads of phospholipids
The phosphate heads of the phospholipids are polar, so they are attracted to the polar water molecules.
Which of the following would not be a constituent of a plasma membrane?
a. phospholipids
b. glycolipids
c. glycoproteins
d. messenger RNA
d. messenger RNA
Which of the following is not required for osmosis to occur?
Energy
Osmosis is a special type of diffusion, which is always a passive process.
Which of the following solutions contains the most solute?
a. hypertonic
b. hypotonic
c. isotonic
d. equilibrium
Hypertonic
"Hyper" means "high," so a hypertonic solution has a higher solute concentration than the solution to which it is being compared.
In general, to maintain homeostasis the relationship between our intracellular and extracellular fluids should be which of the following?
Isotonic to each other
In order to prevent the cells from either swelling or shrinking, the body fluids should be isotonic, meaning that they are at equilibrium.
If a person is severely dehydrated, their extracellular fluids will become hypertonic to the intracellular fluid. What do you predict will happen to the person's cells?
The cells will lose water and shrink
The hypertonic extracellular fluid will draw water out of the hypotonic intracellular fluid, so the cells will shrink. This is called crenulation.
A primary active transport process is one in which _____.
Molecules move through transport proteins that have been activated by ATP
Primary active transporters, such as the sodium-potassium pump, are activated when ATP is hydrolyzed. This activation allows for the transport of solutes across the plasma membrane against concentration gradients.
Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as ____.
Facilitated diffusion
Facilitated diffusion is a passive transport during which molecules move down their concentration gradient through transport proteins.
A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____.
Exocytosis
The term exocytosis literally means "out of the cell."
Why are protein channels and carriers required for the movement of glucose into or out of the cell?
Glucose is a hydrophilic molecule. Glucose and other monosaccharides are polar hydrophilic molecules that are not able to traverse the hydrophobic region of the phospholipid bilayer.
By which mechanism would a steroid molecule diffuse into the cell?
Diffusion
Steroid molecules are nonpolar fat-soluble molecules, which would be expected to diffuse directly across the phospholipid bilayer. Such solutes do not require a membrane protein to facilitate transport.
Which of the following is a difference between primary and secondary active transport?
In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated.
In primary active transport, energy comes directly from the hydrolysis of ATP and the subsequent phosphorylation of primary active transporter. In secondary active transport, the solute ( usually Na+) concentration gradient produced by primary active transport provides kinetic energy to move other solutes, such as ions and glucose, against their concentration gradient. For example, glucose can be transported against its concentration gradient through a Na+ glucose symporter as Na+ moves down its concentration gradient ( a gradient produced by the Na+K+ pump).
Mitosis ________.
is the division of the nucleus.
The RNA responsible for bringing the amino acids to the ribosome for protein formation is ________.
tRNA
Ribosomal RNA
Forms part of the protein synthesis site in the cytoplasm; may be attached to the ER or scattered in the cytoplasm
Transfer RNA
Act as "interpreter" molecules that recognize specific amino acids and nucleotide base sequences.
During translation, each new amino acid is carried to the ribosome by a tRNA molecule. Each tRNA molecule carries a particular amino acid. This amino acid is dictated by the particular anticodon that the tRNA molecule contains. For a particular mRNA codon, only one tRNA molecule contains the complementary anticodon necessary to bind. Once bound, the amino acid is transferred from the tRNa molecule to the growing polypeptide.
Synthetase enzymes
attaches the correct amino acid to its transfer RNA
ATP
provides the energy needed for synthesis reactions
Messenger RNA
Produced in the nucleus, this molecule specifies the exact sequence of amino acids of the protein to be made
G1
Description:
1. cellular growth and biosynthesis of organelles and proteins for various functions
2. centrioles begin to replicate
S
DNA replication
G2
Description
1. Growth and biosynthesis of products to be used in mitosis
2. Centrioles finish replicating
These structures act as the focal points for the appearance of the mitotic spindles
centrosomes
These RNA structures disappear when chromosomes appear
nucleoli
Structures containing DNA only visible during mitosis and first seen in prophase
chromosomes
DNA containing structures which condense during prophase
chromatin
Microtuble arrays around centrosomes
asters
Which is representative of early prophase?
Chromosomes condense as sister chromatid pairs.
Which is representative of late prophase?
Attachment of chromatid pairs to spindle microtubules.
Select the correct activity occurring during anaphase.
Chromosomes move towards oposite poles of the cell.
Which is true regarding cytokinesis?
Cytokinesis usually beings in anaphase.
What is the function of mRNA during translation?
mRNA carries the code for a polypeptide's sequence of amino acids. The code for each amino acid is a 3-base sequence called a codon.
After DNA replication is completed, each DNA double helix strand consists of _____.
One old parent strand and one new daughter strand.
This mechanism is called semiconservative replication and is based on the ability of each strand of the DNA double helix to function as a template for the synthesis of the opposite strand.
What must happen before a body cell can begin mitotic cell division?
Its DNA must be replicated exactly so that identical copies of the cell's genes can be passed on to each of its offspring.
What are the 2 basic steps of polypeptide synthesis?
transcription and translation
1) transcription, in which DNA's information is encoded into mRNA
2) translation, in which the information carried by the mRNA is decoded and used to assemble polypeptides
Chromosomes uncoil to form chromatin
Telophase
Chromosomal centromeres split and chromosomes migrate to opposite ends of the cell
Anaphase
Nuclear membrane and nucleolus disintegrate
Late prophase
Chromosomes align on the spindle equator
Metaphase
Centrioles move to opposite ends of the cell
Early prophase
Which of the following is the most correct statement regarding transcription/translation?
The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.
Which of the following is a function of a plasma membrane protein?
molecular transport through the membrane