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Bio203 Final Study Guide
Terms in this set (100)
What would be the most likely outcome of repeated cell cycles consisting of S phase and M phase only?
The cells produced would get smaller and smaller
Which of the following events does NOT usually occur during interphase?
The nuclear envelope breaks down
Which of the following statements about the cell cycle is FALSE?
once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells.
The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by
inhibiting cyclin transcription
The G1 DNA damage checkpoint
involves the inhibition of cyclin-Cdk complexes by p21.
How does S-Cdk help guarantee that replication occurs only once during each cell cycle?
it phosphorylates and inactivates Cdc6
Which of the following statements is TRUE?
The mitotic spindle helps segregate the chromosomes to the two daughter cells
Sister chromatid separation occurs because _________ are destroyed by the APC/C.
Cytokinesis in animal cells
Which of the statements about apoptosis is TRUE?
Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria
During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in __________ signaling.
Which of the following statements is TRUE?
Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
Survival factors promote the expression of which anti-apoptotic protein(s)?
A cell with nuclear lamins that cannot be phosphorylated during M phase will be unable to
disassemble its nuclear lamina during prometaphase
Which of the following will slightly precede the re-formation of the nuclear envelope during M phase in animal cells?
assembly of the contractile ring
Kinetochores assemble onto chromosomes during late prophase. True or False
Kinetochores contain DNA-binding proteins that recognize sequences at the telomere of the chromosome. True or False
Kinetochore proteins bind to the tubulin molecules at the minus end of microtubules. True or False
Kinetochores assemble on chromosomes that lack centromeres. True or False.
Major category of living cells distinguished by the absence of a nucleus; includes the archaea and the eubacteria (commonly called bacteria)
an organism whose cells have a distinct nucleus and cytoplasm
are present in essentially all eukaryotic cells, and they are among the most conspicuous organelles in cytoplasm
are large, green organelles that are found in the cells of plants and algae, but not in the cells of animals or fungi
the process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water
is the site where most cell-membrane components, as well as materials destined for export from the cell, are made. Enlarged in cells that are specialized for the secretion of proteins
endoplasmic reticulum (ER)
modifies and packages molecules made in the ER that are destined to be either secreted from the cell or transported to another cell compartment
are small, irregularly shaped organelles in which intracellular digestion occurs, releasing nutrients from ingested food particles into the cytosol and breaking down unwanted molecules for either recycling within the cell or excretion from the cell.
are small, membrane-enclosed vesicles that provide a sequestered environment for a variety of reactions in which hydrogen peroxide is used to inactivate toxic molecules
portions of the plasma membrane tuck inward and pinch off to form vesicles that carry material captured from the external medium into the cell
vesicles from inside the cell fuse with the plasma membrane and release their contents into the external medium
abundant in all eukaryotic cells but occur in especially large numbers inside muscle cells, where they serve as a central part of the machinery responsible for muscle contraction
the thickest filaments in the cytosol, they come reorganized into a spectacular array that helps pull the duplicated chromosomes apart and distribute them equally to the two daughter cells
serve to strengthen most animal cells
use the energy stored in molecules of ATP to trundle along these tracks and cables, carrying organelles and proteins throughout the cytoplasm, and racing across the width of the cell in seconds
describes the top or the tip of a cell, structure, or organ; in an epithelial cell, for example, this surface is opposite the base, or basal surface
situated near the base; opposite of apical. Attached to a sheet of connective tissue called the basal lamina
thin mat of extracellular matrix, secreted by epithelial cells, upon which these cells sit.
provides adhesive sites for integrin molecules in the basal plasma membranes of epithelial cells, serves a linking role like that of fibronectin in other connective tissues.
seal neighboring cells together so that water-soluble molecules cannot easily leak between them
types of proteins that form tight junctions and are arranged in strands along the lines of the junction to create the seal
claudins and occludins
bind one epithelial cell to another
adherens junctions and desmosomes
bind epithelial cells to the basal lamina
A member of a family of Ca2+ dependent proteins that mediates the attachment of one cell to another in animal tissues
cell junction that helps hold together epithelial cells in a sheet of epithelium, actin filaments inside the cell attach to its cytoplasmic face
specialized cell-cell junction, usually formed between two epithelial cells, that serves to connect the ropelike kertain filaments of the adjoining cells, providing tensile strentgth
structure that anchors epithelial cells to the basal lamina beneath them
in animal tissues, specialized connection between juxtaposed cells through which ions and small molecules can pass from one cell to another
cell-cell junction, that connects one plant cell to the next; consists of a channel of cytoplasm lined by membrane
What is the purpose of the extracellular matrix?
helps cells bind together and regulates a number of cellular functions, such as adhesion, migration, proliferation, and differentation
proteins found within the cell interact with extracellular matrix proteins
are cells that have the capacity to self-renew by dividing and to develop into the three primary germ cell layers of the early embryo and into extra-embryonic tissues such as the placenta
totipotent stem cells
capable of giving rise to any type of cell or tissue
pluripotent stem cells
can differentiate into the various cell types in a family of related cells, such as blood cells.
multipotent stem cells
those that occur in individual somatic cells of the body
a gene that, when activated, can potentially make a cell cancerous. Typically a mutant form of a normal gene involved in the control of cell growth or division
gene that when mutated or overexpressed can transform a normal cell into a cancerous one
a gene that in a normal tissue cell inhibits cancerous behavior. Loss or inactivation of both copies of such a gene from a diploid cell can cause it to behave as a cancer cell.
tumor supressor gene
Serves as an important time of decision-making for the cell.
How does a cell upheaval of M phase to the relative tranquility of G1?
The cell-cycle control machinery must inactivate its inventory of S-Cdk and M-Cdk
is abundant in the nuclei of all vertebrate cells, where it binds to particular transcription regulators and prevents them from turning on the genes required for cell proliferation
Retinoblastoma (Rb) protein
release the Rb brake by triggering the activation of G1-Cdks and G1/S-Cdks
phosphorylate the Rb protein, altering its conformation so that it releases its bound transcription regulators, which are then free to activate the genes required for entry into S phase.
G1-Cdks and G1/S-Cdks
Transcription regulator that controls the cell
s response to DNA damage, preventing the cell from entering S phase until the damage has been repaired or inducing the cell to commit suicide if the damage is too extensive; mutations in the gene encoding this protein are found in many human cancers
protein binds to G1/S-Cdk and S-Cdk, preventing them from driving the cell into S phase
resting phase is a period in the cell cycle in which cells exist in a quiescent state
How do cells reproduce?
by duplicating their contents and dividing in two
How do cells coordinate all the steps and the machinery involved in the cell cycle?
control system and checkpoints
complex system of regulatory proteins, switch machinery on and off at correct times
pause the system at certain transition points, "molecular breaks"
What ensures that key processes occur in proper sequence>
cell-cycle control system
What is the decision point for the cell?
G1(start) to S phase transition
regulatory proteins that bind to cyclin-dependent kinases, concentrations "cycle" during cell cycle
kinase, when bound to cyclin can trigger cell cycle events, cyclin binding required for activity but not sufficient, concentrations remain relatively constant throughout cell cycle
cyclin-dependent kinases (Cdks)
What controls entry into mitosis?
What regulates S-Cdk and M-Cdk
anaphase promoting complex/cyclosome
What can be blocked by binding to Cdk Inhibitor Proteins (CKIs)?
Cells grow, decide and prepare for S phase
What happens if M-Cdks and S-Cdks are not disabled at the end of M phase?
cell will immediately replicate and divide
What are the mechanisms to disable S-Cdks and M-Cdks ?
Eliminate all cyclins (degradation), block synthesis of new cyclins, and utilize Cdk inhibitors
promote the production of cyclins that stimulate cell division
repetitive nucleotide sequence that caps the ends of linear chromsomes. Counteracts the tendency of the chromosome to otherwise shorten with each round of replication
nucleotide sequence at which DNA replication is initiated
specialized DNA sequences that allow duplicate chromosomes to be separated during M phase; can be seen as a constricted region of mitotic chromsome
copy of chromosome, produced by DNA replication, that remains bound to the other copy
is the process whereby one type of signal is converted into another
What do extracellular signal molecules bind to?
either to cell-surface receptors or to intracellular receptors
A limited set of what can produce a huge variety of cell behaviors?
A cell's response to a signal can be __________________?
fast or slow
Cell-surface receptors relay extracellular signals via what?
intracellular signaling pathways
What can intracellular signaling proteins do?
relay, amplify, integrate, distribute, and modulate via feedback an incoming signal
What can adjust the response to an extracellular signal?
feedback regulation within an intracellular signaling pathway
What do many intracellular signaling proteins act as?
What two types of regulatory proteins control the activity of monomeric GTPases?
Guanosine exchange factors (GEF) and GTPase activatin (GAP)
What are the three main classes that cell-surface receptors fall into?
ion-channel-coupled receptors, G-protein-coupled receptors, and enzyme-coupled receptors
What do ion-channel-coupled receptors do?
convert chemical signals into electrical ones
What directly regulate ion channels?
An activated GPCR activates G proteins by doing what?
encouraging the a subunit to expel its GDP and pick up GTP
The G protein a subunit switches itself off by doing what?
by hydrolyzing its bound to GTP to GDP
Some bacterial toxins cause disease by?
altering the activity of G proteins
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