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
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA
Gene
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
A specific place along the length of a chromosome where a given gene is located.
Locus
The generation of offspring from a single parent that occurs without the fusion of gametes.
Asexual reproduction
A lineage of genetically identical individuals or cells.
Clone
Reproduction arising from fusion of two gametes.
Sexual reproduction
The generation-to-generation sequence of stages in the reproductive history of an organism.
Life cycle
A display of the chromosome pairs of a cell arranged by size and shape.
Karyotype
A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.
Homologous chromosomes
A chromosome responsible for determining the sex of an individual.
Sex chromosomes
A chromosome that is not directly involved in determining sex; not a sex chromosome.
Autosomes
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
Diploid cell
A cell containing only one set of chromosomes
Haploid cell
The union of haploid gametes to produce a diploid zygote.
Fertilization
The diploid cell produced by the union of haploid gametes during fertilization;
Zygote
A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte
Alteration of generations
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.
Meiosis 1
The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.
Meiosis 2
complex A zipper-like structure composed of proteins, which connects a chromosome to its homolog tightly along their lengths during part of prophase I of meiosis.
Synaptonemal complex
The pairing and physical connection of one duplicated chromosome to its homolog during prophase I of meiosis.
Synopsis
A chromosome created when crossing over combines DNA from two parents into a single chromosome.
Recombinant chromosome
An observable heritable feature that may vary among individuals.
Character
One of two or more detectable variants in a genetic character.
Trait
Referring to organisms that produce offspring of the same variety over many generations of self-pollination.
True breeding
In genetics, the mating, or crossing, of two true-breeding varieties.
Hybridization
The true-breeding (homozygous) parent individuals from which F 1 hybrid offspring are derived in studies of inheritance
P generation
The first filial, hybrid (heterozygous) offspring arising from a parental (P generation) cross.
F1 generation
The offspring resulting from interbreeding (or self-pollination) of the hybrid F 1 generation.
F2 generation
Any of the alternative versions of a gene that may produce distinguishable phenotypic effects.
Allele
An allele that is fully expressed in the phenotype of a heterozygote.
Dominant allele
An allele whose phenotypic effect is not observed in a heterozygote.
Recessive allele
Mendel’s first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation.
Law of segregation
A diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses between individuals of known genotype.
Punnet square
An organism that has a pair of identical alleles for a gene (encoding a character).
Homozygote
Having two identical alleles for a given gene.
Homozygous
An organism that has two different alleles for a gene (encoding a character).
Heterozygote
Having two different alleles for a given gene.
Heterozygous
The observable physical and physiological traits of an organism, which are determined by its genetic makeup.
Phenotype
The genetic makeup, or set of alleles, of an organism.
Genotype
Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype.
Testcross
An organism that is heterozygous with respect to a single gene of interest.
Monohybrid
A cross between two organisms that are heterozygous for the character being followed
Monohybrid cross
An organism that is heterozygous with respect to two genes of interest
Dihybrid
A cross between two organisms that are each heterozygous for both of the characters being followed
Dihybrid cross
Mendel’s second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation
Law of independent assortment
A rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities.
Multiplication rule
A rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities.
Addition rule
The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
Complete dominance
The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.
Incomplete dominance
The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways.
Codominance
A human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain.
Tay-Sachs disease
The ability of a single gene to have multiple effects.
Pleiotropy
A type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene.
Epistasis
A heritable feature that varies continuously over a range rather than in an either-or fashion.
Quantitative character
An additive effect of two or more genes on a single phenotypic character.
Polygenic inheritance
Referring to a phenotypic character that is influenced by multiple genes and environmental factors.
Multifactorial
A diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations.
Pedigree
In genetics, an individual who is heterozygous at a given genetic locus for a recessively inherited disorder.
Carriers
A human genetic disorder caused by a recessive allele for a chloride channel protein
Cystic fibrosis
A recessively inherited human blood disorder in which a single nucleotide change in the a-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals.
Sickle-cell disease
A human genetic disease caused by a dominant allele
Huntington’s disease
A basic principle in biology stating that genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
Chromosome theory of inheritance
The phenotype most commonly observed in natural populations
Wild type
A gene located on either sex chromosome. Most sex-linked genes are on the X chromosome and show distinctive patterns of inheritance
Sex-linked gene
A gene located on the X chromosome
X-linked gene
A human genetic disease caused by a sex-linked recessive allele
Dechenne muscular distrophy
A human genetic disease caused by a sex-linked recessive allele resulting in the absence of one or more blood-clotting proteins
Hemophilia
A dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome.
Barr body
Genes located close enough together on a chromosome that they tend to be inherited together.
Linked genes
General term for the production of offspring with combinations of traits that differ from those found in either parent.
Genetic recombination
An offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes
Parental type
An offspring whose phenotype differs from that of the true-breeding P generation parents
Recombinant types/recombinant
The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.
Crossing over
An ordered list of genetic loci (genes or other genetic markers) along a chromosome.
Genetic map
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.
Nondisjunction
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
Aneuploidy
Referring to a diploid cell that has only one copy of a particular chromosome instead of the normal two.
Monosomic
Referring to a diploid cell that has three copies of a particular chromosome instead of the normal two.
Trisomic
A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
Polyploidy
A deficiency in a chromosome resulting from the loss of a fragment through breakage.
Deletion
An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated.
Duplication
An aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated.
Imversion
An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome.
Translocation
A human genetic disease usually caused by the presence of an extra chromosome 21
Down syndrome
A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.
Genomic imprinting
