cellular level organization set 4 Flashcards
Most of the surface area of the cell membrane consists of
lipids
Because of its chemical-structural composition, the cell membrane is called a
phospholipid bilayer
The primary components of the cytoskeleton, which gives the cell strength and rigidity and anchors the position of major organelles, are
microtubules
Most of the energy a cell needs to live is generated by the
mitochondria
The major factor that allows the nucleus to control cellular operations is its
regulation of protein synthesis
Ribosomal proteins and RNA are produced primarily in the
nucleolus
Along the length of the DNA strand, information is stored in the sequence of
nitrogen bases
A sequence of three nitrogen bases can specify the identity of
a single amino acid
The process in which RNA polymerase uses the genetic information to assemble a strand of mRNA is
transcription
If the DNA triplet is TAG, the corresponding codon on the mRNA strand will be
AUC
Passive or leakage channels within the cell membrane permit
water and ion movement at all times
Ions and other small water-soluble materials cross the cell membrane only by passing through
a receptor protein
All transport through the cell membrane can be classified as either
active or passive
The major difference between diffusion and bulk flow is that when molecules move by bulk flow they move
as a unit in one direction
The rate that solute molecules are filtered depends on
their size, the force of hydrostatic pressure, rate of water passing through membrane
The transmembrane potential is important in maintaining cell integrity because
it increases cell environment sensitivity.
The factor(s) that interact(s) to create and maintain the transmembrane potential is (are) the
membrane permeability for sodium and potassium, presence of Na-K exchange pump
The correct sequence of the cell cycle beginning with interphase is
G0, G1, S, G2, Gm
As the cell life cycle proceeds, cyclin levels climb, causing the maturation promoting factor (MPG) to appear in the cytoplasm, initiating the process of
mitosis
The spreading process of a primary tumor is called _____, and the dispersion of malignant cells to establish a secondary tumor is called _____.
invasion; metastasis
The process of differentiation resulting in the appearance of characteristic cell specializations involves
gene repression (switching off)
Homeostasis at the tissue, organ, system, and individual levels reflects
the combined and coordinated actions of many cells
Structurally, the cell membrane is best described as a
phospholipid bilayer interspersed with proteins
Isolating the cytoplasm from the surrounding fluid environment by the cell membrane is important because
cytoplasm’s composition differs from extracellular fluid and differences must be maintained
Regulation of exchange with the environment is an important function of the cell membrane because it controls
the entry of ions and nutrients, and waste elimination
Which type of vesicular transport uses pseudopodia to surround a solid object
phagocytosis
Membranous organelles differ from nonmembranous organelles in that membranous organelles are ________.
surrounded by lipid membranes that isolate them from the cytosol
The major functional difference between flagella and cilia is that flagella
move a cell through the surrounding fluid
The smooth ER (SER) has a variety of functions that center around the synthesis of
lipids and carbohydrates
The reason lysosomes are sometimes called “cellular suicide packets” is
the breakdown of lysosomal membranes can destroy a cell
The energy-producing process in the mitochondria involves a series of reactions in which __________ is consumed and __________ is generated
oxygen; carbon dioxide
The most notable characteristic of the G0 phase of an interphase cell is that
it is not preparing for mitosis
The replication of DNA occurs primarily during the
S phase
The process of cytokinesis refers to
the physical separation of the daughter cells
The passive factor which helps to maintain the transmembrane potential is
K+ diffuse out of the cell faster than Na+ can enter and the interior of the cell develops an excess of negative charges
The reason that dead skin cells are usually shed in thick sheets rather than individually is because of
the strength of the links of the desmosomes
The reason that water-soluble ions and molecules cannot enter certain regions of the cell membrane is because of
the presence of hydrophobic tails on the interior of the membrane
The effect of diffusion in body fluids is that it
tends to eliminate local concentration gradients
During osmosis water will always flow across a membrane toward the solution that has the
highest concentration of solutes
A solution that is hypotonic to cytoplasm has
a solute concentration lower than that of the cytoplasm
Red blood cells are hemolyzed when the cells are placed in contact with
a hypotonic solution
An injection of a concentrated salt solution into the circulatory system would result in
crenation of the red blood cells
Facilitated diffusion differs from ordinary diffusion in that
carrier proteins are involved
One of the great advantages of moving materials by active transport is
the process is not dependent on a concentration gradient
In the human body, the process of phagocytosis is illustrated by
a white blood cell engulfing a bacterium
Epsom salts exert a laxative effect due to the process of
osmosis
The formation of a malignant tumor indicates that
mitotic rates of cells are no longer responding to normal control mechanisms
Which organelle absorbs and breaks down fatty acids and other organic compounds?
peroxisome
Protein channels within the cell membrane
permit water and ion movement at all times
A sequence of three nucleotide bases in the mRNA is called a(n) ________.
codon
What is the functional unit of heredity?
gene
Which of the following is an important characteristic of the transmembrane potential?
The ions held on either side of the cell membrane have potential energy.
In which phase does a cell make enough organelles for two functional cells?
G1
In which phase does centriole replication complete?
G2
The cell membrane isolates the cytoplasm from the surrounding fluid environment. Why is this important?
Cytoplasm has a composition different from that of the extracellular fluid, and the differences must be maintained.
Cilia function to ________.
move fluids or secretions across the cell surface
Which of the following influences diffusion rates?
distance, temperature, and molecular size
Water-soluble ions and molecules CANNOT enter certain regions of the cell membrane because of ________.
the presence of hydrophobic tails on the interior of the membrane
The difference between an area of high concentration and an area of low concentration is known as ________.
a concentration gradient
