Test 3 Flashcards
In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the organism, changing the target cells’ functioning.
Hormone
A series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response.
Signal transduction pathway
A molecule that binds specifically to another molecule, usually a larger one.
Ligand
An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.
Protein kinase
A series of chemical reactions during cell signaling mediated by enzymes (kinases), in which each kinase in turn phosphorylates and activates another, ultimately leading to phosphorylation of many proteins.
Phosphorylation cascade
An enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effect of a protein kinase.
Protein phosphatase
Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells.
Cyclic amp (cAMP)
An enzyme that converts ATP to cyclic AMP in response to an extracellular signal.
Adenylyl Cyclase
A second messenger that functions as an intermediate between certain signaling molecules and a subsequent second messenger, Ca2+, by causing a rise in cytoplasmic Ca2+ concentration.
Inositol triphosphate
A second messenger produced by the cleavage of the phospholipid PIP 2 in the plasma membrane.
Diacylglycerol
A type of large relay protein to which several other relay proteins are simultaneously attached, increasing the efficiency of signal transduction.
Scaffolding protein
A type of programmed cell death, which is brought about by activation of enzymes that break down many chemical components in the cell.
Apoptosis
The genetic material of an organism or virus; the complete complement of an organism’s or virus’s genes along with its noncoding nucleic acid sequences.
Genome
A cellular structure consisting of one DNA molecule and associated protein molecules.
Chromosome
The complex of DNA and proteins that makes up eukaryotic chromosomes.
Chromatin
Any cell in a multicellular organism except a sperm or egg or their precursors.
Somatic cell
A haploid reproductive cell, such as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis.
Gamete
Two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms.
Sister chromatids
In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid by proteins that bind to the centromeric DNA.
Centromere
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase
Mitosis
The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.
Cytokinesis
The phase of the cell cycle that includes mitosis and cytokinesis.
Mitotic phase (M phase)
The period in the cell cycle when the cell is not dividing.
Interphase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
G1 phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
S phase
The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
G2 phase
The first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact.
Prophase
The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.
Prometaphase
The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.
Metaphase
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.
Anaphase
The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.
Telophase
An assemblage of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis.
Mitotic spindle
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division.
Centrosome
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle.
Kinetochore
An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.
Metaphase plate
The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane.
Cleavage
The first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.
Cleavage furrow
A membrane-bounded, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis.
Cell plate
A method of asexual reproduction in single-celled organisms in which the cell grows to roughly double its size and then divides into two cells.
Binary fission
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
Origin of replication
A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle.
Cell cycle control system
A control point in the cell cycle where stop and go-ahead signals can regulate the cycle.
Checkpoint
A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle.
Cyclin
A protein kinase that is active only when attached to a particular cyclin.
Cyclin-dependent kinases
Maturation-promoting factor
MPF
A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.
G0 phase
A protein that must be present in the extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells.
Growth factor
The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
Density dependent inhibition
The requirement that a cell must be attached to a substratum in order to initiate cell division.
Anchorage dependence
The process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells.
Transformation
A mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor’s origin.
Benign tumor
A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites.
Malignant tumor
The spread of cancer cells to locations distant from their original site.
Metastasis
The transmission of traits from one generation to the next.
Heredity
Differences between members of the same species.
Variation
The scientific study of heredity and hereditary variation.
Genetics