BIO 323 final (assignments 3-6)

Rank the following types of cell signaling from 1 to 4, with 1 representing the type of signaling in which the signal molecule travels the least distance and 4 the type of signaling in which the signal molecule travels the largest distance. ______ paracrine signaling ______ contact-dependent signaling ______ neuronal signaling ______ endocrine signaling

3124

Cells in the G0 state ________________. A) do not divide. B) cannot re-enter the cell cycle. C) have entered this arrest state from either G1 or G2. D) have duplicated their DNA.

A

Consider two mammalian cells, one in G1 and the other in G0 (stationary) phase. If they are stimulated to pass the restriction point by the addition of an extracellular proliferation signal, but the signal is then immediately removed, what would you expect to happen? A) Both cells will replicate their DNA. B) Only the G1 cell will replicate its DNA. C) Only the G0 cell will replicate its DNA. D) Only the G1 cell will start to replicate its DNA, but will stop halfway through the replication and will not reach G2. E) Neither of the cells will replicate their DNA.

A

Each milliliter of blood normally contains about _______ red blood cells and _______ white blood cells [A] 5 billion; 7 million [B] 5 million; 7 billion [C] 5 thousand; 7 thousand [D] 5 million; 7 thousand [E] 5 million; 7 million

A

Mitogens are _____. A) extracellular signals that stimulate cell division. B) transcription factors important for cyclin production. C) kinases that cause cells to grow in size. D) produced by mitotic cells to keep nearby neighboring cells from dividing.

A

Phagocytes kill pathogenic bacteria by [A] endocytosis [B] producing antibodies [C] complement fixation [D] stimulating T cells [E] causing inflammation

A

Which of the following is more directly driven by active M-Cdk? A) Maturation of mitosis specific proteins B) Chromosome duplication C) Nuclear envelope reassembly D) Inactivation of APC/C E) Cell cleavage

A

Which of the following statements about the cell cycle is false? A) Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells. B) An unfavorable environment can cause cells to arrest in G1. C) A cell has more DNA during G2 than it did in G1. D) The cleavage divisions that occur in an early embryo have short G1 and G2 phases

A

Which of the following statements is true? A) Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior. B) To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol. C) A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response. D) Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type.

A

One of a large group of enzymes that catalyze hydrolysis of ATP to yield ADP and inorganic phosphate with release of free energy

ATPase

Class of prokaryotes that constitutes one of the three distinct evolutionary lineages of modern-day organisms. These prokaryotes are in some respects more similar to eukaryotes than to the so-called true bacteria.

Archaea

Acetylcholine is a signaling molecule that elicits responses from heart muscle cells, salivary gland cells, and skeletal muscle cells. Which of the following statements is false? A) Heart muscle cells decrease their rate and force of contraction when they receive acetylcholine, whereas skeletal muscle cells contract. B) Heart muscle cells, salivary gland cells, and skeletal muscle cells all express an acetylcholine receptor that belongs to the transmitter-gated ion channel family. C) Active acetylcholine receptors on salivary gland cells and heart muscle cells activate different intracellular signaling pathways. D) Heart muscle cells, salivary gland cells, and skeletal muscle cells all respond to acetylcholine within minutes of receiving the signal.

B

Select the feature that is characteristic of both the humoral and cellular immune responses [A] Specificity [B] Cell-cell communication via interleukin [C] Component of immunological memory [D] Recognition of diverse antigenic determinants [E] Recognition of self from nonself

B

Signal transduction is regulated in which of the following ways A) The amount of signal present can be regulated. B) Enzymes in the pathway convert active forms of proteins to inactive forms. C) Signals are denatured. D) None of the above

B

When a signal needs to be sent to most cells throughout a multicellular organism, the signal most suited for this is a ___________. A) neurotransmitter. B) hormone. C) dissolved gas. D) scaffold.

B

Which of the following is an inhibitory extracellular signal for cell proliferation? A) EGF B) TGFβ C) Erythropoietin D) IGF E) PDGF

B

Which of the following statements is true? A) Because endocrine signals are broadcast throughout the body, all cells will respond to the hormonal signal. B) The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling. C) Paracrine signaling involves the secretion of signals into the bloodstream for distribution throughout the organism. D) The axons of neurons typically signal target cells using membrane-bound signaling molecules that act on receptors in the target cells.

B

. How does S-Cdk help guarantee that replication occurs only once during each cell cycle? A) It blocks the rise of Cdc6 concentrations early in G1. B) It phosphorylates and inactivates DNA helicase. C) It phosphorylates the Cdc6 protein, marking it for destruction. D) It promotes the assembly of a prereplicative complex.

C

In wound healing and regeneration, the affected tissue produces growth factors that A) increase the rate of cell division of individual cells B) shorten G1 and G2 of the cell cycle C) recruit quiescent cells to rejoin the cell cycle D) stop cells from dividing E) make you squeal in pain like a french person reading a history book on France

C

One explanation for the absence of antiself B cells in the bloodstream is [A] the presence of memory cells [B] immunological memory [C] clonal deletion [D] interferon production [E] their destruction by natural killer cells

C

The concentration of mitotic cyclin (M cyclin) ________________. A) rises markedly during M phase. B) is activated by phosphorylation. C) falls toward the end of M phase as a result of ubiquitylation and degradation. D) is highest in G1 phase.

C

The major difference between a cell that responds to a signal and one that does not is the presence of a A) DNA sequence that binds to the signal. B) nearby blood vessel. C) receptor. D) second messenger. E) transduction pathway.

C

The region of the antibody that binds to the antigen is the [A] constant region of the heavy chain [B] constant region of the light chain [C] variable region [D] Both a and b [E] Both b and c

C

The retrovirus HIV specifically destroys T-helper cells and thus disrupts [A] the humoral immune response [B] the cellular immune response [C] both the humoral and cellular immune responses [D] the inflammatory response [E] the complement cascade

C

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? A) The cell would be unable to enter M phase. B) The cell would be unable to enter G2. C) The cell would enter M phase under conditions when normal cells would not. D) The cell would pass through M phase more slowly than normal cells

C

Which of the following events normally activates a GTP-binding protein? A) GTP hydrolysis by the protein B) Activation of an upstream GTPase-activating protein C) Activation of an upstream guanine nucleotide exchange factor D) Phosphorylation of a bound GDP molecule by an upstream phosphorylase E) Pi release after GTP hydrolysis

C

Which of the following is not associated with a nonspecific defense mechanism [A] Inflammation [B] Mucous membranes [C] Cytokines [D] Phagocytes [E] Interferons

C

Which of the following proteins is the product of an immediate early gene expressed following mitogenic stimulation of cell-cycle entry? A) E2F B) Rb C) Myc D) G1-cyclins E) All of the above

C

A cell has been subjected to ultraviolet irradiation, causing a significant number of mutations in the genome. Which of the following would you NOT expect to occur as a result? A) Activation of the protein kinase ATR B) Activation of the protein kinase Chk1 C) Inactivation of the protein phosphatase Cdc25 D) Binding of p53 to Mdm2 E) Stabilization of p53

D

According to the clonal selection theory [A] antibodies are not produced until the animal encounters a specific antigen [B] antigens determine the three-dimensional structure of antibodies [C] all B cells have identical genotypes [D] an antigen stimulates the proliferation of a specific group of B cells [E] B cells give rise to specific T cells

D

All members of the steroid hormone receptor family __________________. A) are cell-surface receptors. B) do not undergo conformational changes. C) are found only in the cytoplasm. D) interact with signal molecules that diffuse through the plasma membrane.

D

Cell surface receptors that bind dimeric growth factors are often referred to as A) G-proteins B) G-protein linked receptors C) Ras proteins D) receptor tyrosine kinases E) G-Remlins

D

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? A) at the transition between G1 and S B) when cells enter G0 C) during M D) at the end of G2

D

Levels of Cdk activity change during the cell cycle, in part because ________________. A) the Cdks phosphorylate each other. B) the Cdks activate the cyclins. C) Cdk degradation precedes entry into the next phase of the cell cycle. D) cyclin levels change during the cycle.

D

Protein kinase cascades are significant because A) amplification can occur at each step in the path. B) information at the plasma membrane is communicated to the nucleus. C) the multiple steps allow for specificity of the process. D) All of the above

D

Select the order that is correct for signal transduction A) Binding of a signal, secondary messenger released, receptor conformation altered, cellular function altered B) Binding of a signal, secondary messenger released, receptor conformation altered, transcription of gene C) Binding of a signal, responder activates target protein, receptor conformation altered, secondary messenger released transcription of gene D) Binding of a signal, receptor conformation altered, responder activates target protein, cellular function altered

D

The G1 DNA damage checkpoint ________________. A) causes cells to proceed through S phase more quickly. B) involves the degradation of p53. C) is activated by errors caused during DNA replication. D) involves the inhibition of cyclin-Cdk complexes by p21.

D

What is the correct order for the following events in the interaction of a cell with a signal? (1) alteration of cell function; (2) signal binds to receptor; (3) signal released from source; (4) signal transduction A) 1234 B) 2314 C) 3214 D) 3241 E) none of the above

D

Which of the following cell populations in our body has the highest mitotic index? A) Neurons B) Hepatocytes C) Red blood cells D) Fibroblasts E) Skeletal myocytes

D

Which of the following statements about G-protein-coupled receptors (GPCRs) is false? A) GPCRs are the largest family of cell-surface receptors in humans. B) GPCRs are used in endocrine, paracrine, and neuronal signaling. C) GPCRs are found in yeast, mice, and humans. D) The different classes of GPCR ligands (proteins, amino acid derivatives, or fatty acids) bind to receptors with different numbers of transmembrane domains.

D

Why do some signals ( "first messengers" ) trigger a "second messenger" to activate a target cell A) The first messenger requires activation by ATP. B) The first messenger is not water soluble. C) The first messenger binds to many types of cells. D) The first messenger cannot cross the plasma membrane. E) There are no receptors for the first messenger.

D

. T cells [A] have immunoglobulin receptors [B] have antibodies as effector molecules [C] develop from activated B cells [D] are secreted by plasma cells [E] release perforin

E

Allergies involve [A] IgE [B] mast cells [C] basophils [D] histamine release [E] All of the above

E

Hay fever is an allergic response to pollen. Which type of antibody molecule is being produced [A] IgG [B] IgM [C] IgD [D] IgA [E] IgE

E

Which of the following events contributes to driving the mammalian cell past the restriction point of the cell cycle? A) Phosphorylation of Cdh1-APC/C by G1/S-Cdk B) Destruction of CKIs that target S-Cdks C) Phosphorylation of Rb by G1-Cdk, G1/S-Cdk, and S-Cdk D) Activation of E2F gene expression by active E2F protein E) All of the above

E

Which of the following is a nonspecific defense mechanism that protects animals against pathogenic microorganisms [A] Sealing off the damaged tissue [B] Production of phytoalexins [C] Production of antibodies [D] Humoral immune response [E] Inflammation

E

Indicate by writing "Y" or "N" whether amplification of a signal could occur at the particular steps described below.(answer in the form e.g. YYNN) A. An extracellular signaling molecule binds and activates a GPCR. B. The activated GPCRs cause Ga to separate from Gb and Gg. C. Adenylyl cyclase produces cyclic AMP. D. cAMP activates protein kinase A. E. Protein kinase A phosphorylates target proteins.

NNYYY

Russian dude. Formulated the ________ hypothesis regarding prebiois

Oparin

Indicate whether each of the following descriptions better applies to a Wee1 protein (W) or a Cdc25 protein (C). Your answer would be a four-letter string composed of letters W and C only, e.g. WWCW. ( ) It is a protein kinase. ( ) It activates M-Cdk complexes. ( ) It is activated by M-Cdk complexes. ( ) Its loss in fission yeast results in small cell size.

WCCW

The _____________ layer is one site of skin stem cells

basal

A thin sheetlike network of extracellular-matrix components that underlies most animal epi-thelial layers and other organized groups of cells (e.g., muscle), separating them from connective tissue

basal lamina

Type of molecule that acts like velcro in adhesion belts

cadherin

Fill in the blank in the following paragraph. "Cytosolic Ca2+ can be sensed by ..., a small, conserved, dumbbell-shaped protein with four Ca2+-binding sites. Upon Ca2+ binding, it binds and activates dozens of proteins by changing its conformation in different ways."

calmodulin

Molecule that binds calcium intracellulary, responsible for maintaining signal transduction pathways after the signal is turned off

calmodulin

Ordered sequence of events in which a cell duplicates its chromosomes and divides into two

cell cycle

Specialized regions on the cell surface through which cells are joined to each other or to the extracellular matrix.

cell junctions

Any of several points in the eukaryotic cell cycle at which progression of a cell to the next stage can be halted until conditions are suitable

checkpoint

Fibrous protein of the ECM

collagen

Any of several related proteins whose concentrations rise and fall during the course of the eukaryotic cell cycle.

cyclin

Type of enzyme that is active during checkpoints in the cell cycle

cyclin dependent kinase

Signaling molecule, usually in reference to the immune system

cytokine

The (2words) system is responsible for many cellular interactions that result in selective inhibition of neighbors during differentiation

delta notch

Intracellular signaling molecule produced by cleavage of phosphoinositides in response to stimulation of certain cell-surface receptors; functions as a membrane-bound second messenger in inositol-lipid signaling pathways

diacylglycerol

general growth factor associated with differentiation of skin cells

epidermal growth factor

A usually insoluble network consisting of polysaccharides, fibrous proteins, and adhesive proteins that are secreted by animal cells. It provides structural support in tissues and can affect the development and biochemical functions of cells

extracellular matrix

A common type of connective-tissue cell that secretes collagen and other components of the extracellular matrix. It migrates and proliferates during wound healing and in tissue culture

fibroblast

Dimeric adhesive protein, commonly found in the ECM of connective tissues

fibronectin

Any of numerous heterotrimeric GTP-binding proteins that function in intracellular signaling pathways; usually activated by ligand binding to a coupled seven-spanning receptor on the cell surface.

g protein

Overall process by which the information encoded in a gene is converted into an observable phenotype (most commonly production of a protein)

gene expression

A long, linear, highly charged polymer of a repeating disaccharide in which one member of the pair usually is a sugar acid (uronic acid) and the other is an amino sugar and many residues are sulfated. Generally are covalently bound to core proteins forming proteoglycans, which are major components of the extracellular matrix.

glycosaminoglycan

An extracellular polypeptide molecule that binds to a cell-surface receptor triggering an intracellular signaling pathway leading to proliferation, differentiation, or other cellular response

growth factor

Energy supply for the first cells, theoretically

hydrothermalvent

Where the mammalian embryo proper is derived from

inner cell mass

___________ triphosphate is a second messenger

inositol

A large family of heterodimeric transmembrane proteins that promote adhesion of cells to the extracellular matrix or to the surface of other cells

integrins

Part of a primary transcript (or the DNA encoding it) that is removed by splicing during RNA processing and is not included in the mature, functional mRNA, rRNA, or tRNA

intron

An enzyme that transfers the terminal (γ) phosphate group from ATP to a substrate

kinase

Three chain molecule of the ECM, a main constituent of basal laminae

laminin

Protein kinase that is activated in response to cell stimulation by many different growth factors and that mediates cellular responses by phosphorylating specific target proteins

map kinase

Atmospheric source of carbon - 3.8 billion years ago

methane

Small, membrane-covered projection on the surface of an animal cell containing a core of actin filaments. Many found on the absorptive surface of intestinal epithelial cells, increasing the surface area for transport of nutrients

microvillus

Any extracellular substance, such as a growth factor, that promotes cell proliferation

mitogen

An enzyme that removes a phosphate group from a substrate by hydrolysis

phosphatase

Kinase enzymes pass on the message in cascade systems by __________

phosphorylation

Term used to describe a cell that has the ability to give rise to more than one cell type, but does not have unlimited potential

pluripotent

The _________ is cleaved from collagen molecules after secretion to allow self-assembly of fibrils

propeptide

Type of cytosolic enzyme that is activated by cAMP and functions to regulate the activity of numerous cellular proteins. Generally is activated in response to a rise in cAMP level resulting from stimulation of G protein- coupled receptors.

protein kinase A

. Referring to a cell that has exited the cell cycle and is in the G0 state.

quiescent

A monomeric GTP-binding protein that functions in intracellular signaling pathways and is activated by ligand binding to receptor tyrosine kinases and other cellsurface receptors

ras protein

Member of an important class of cell-surface receptors whose cytosolic domain has tyrosine-specific protein kinase activity. Ligand binding activates this kinase activity and initiates intracellular signaling pathways

receptor tyrosine kinase

the point in late g1 of the cell cycle at which mammalian cells become committed to entering the s phase and completing the cell cycle even in the absence of growth factors

restriction point

Term referring to a molecule that assists in signal transduction, enabling a specific sequence of transduction events

scaffold protein

An intracellular signaling molecule whose concentration increases (or decreases) in response to binding of an extracellular ligand to a cell-surface receptor. Examples include cAMP, Ca2, diacylglycerol (DAG), and inositol 1,4,5-trisphosphate (IP3

second messanger

What collagen (and other ECM molecules) does when secreted by cells

self assembly

Conveying the message from outside the cell to the inside, often involves conformational changes in the receptor

signal transduction

Type of endoplasmic reticulum that generates the plasma membrane and stores calcium

smooth

Type of cell that commonly gives rise to transit amplifications in tissue formation

stem cell

Term related to the potential fate of a zygotic cell

totipotent

A region in DNA, bounded by an initiation (start) site and termination site, that is transcribed into a single primary transcript.

transcription unit