Heredity and Genetics (C652)(WGU)

gene - answer-a string of nucleotides within a DNA molecule that is the basic structural and functional unit of genetics allele - answer-this is the term for one of a number of different forms of a gene phenotype - answer-physical characteristics of an organism genotype - answer-genetic makeup of an organism heterozygous - answer-this term describes an organism that has two different alleles for a trait homozygous - answer-this term describes an organism that has two identical alleles for a trait dominant - answer-describes a trait that covers over, or dominates, another form of that trait recessive - answer-an allele that is masked when a dominant allele is present meiosis - answer-cell division that produces reproductive cells in sexually reproducing organisms; one diploid cell containing forty six chromosomes undergoes one round of chromosome replication and two rounds of division to produce four haploid cells each of which contains one copy of each chromosome Interphase - answer-this is the phase during which the chromosomes replicate Prophase I - answer-during this phase chromosomes condense and become visible under a microscope, the nuclear envelope disappears, and the spindle becomes organized Metaphase I - answer-during this phase paired homologous chromosomes line up at the equator of the cell with each chromosome attached to spindle fibers from opposite poles of the cell Anaphase I - answer-during this phase the paired chromatids are separated from each other and move towards opposite sides of the cell Telophase I - answer-during this phase the cytoplasm begins to divide resulting in two haploid cells Prophase II - answer-during this phase the unpaired chromosomes consist of two sister chromatids joined by a centromere Metaphase II - answer-during this phase the twenty three unpaired chromosomes are at the equator of the cell with spindle fibers from opposite poles of the cell attached to their centromeres Anaphase II - answer-during this phase spindle fibers pull the chromatids apart in both cells Telophase II - answer-during this phase the chromosomes uncoil and the nuclear envelope reforms and the cytoplasm begins to split resulting in four haploid cells crossing over - answer-this is the process in which homologous chromosomes exchange portions of their chromatids during the first prophase and metaphase in meiosis and this allows for genetic codes to be swapped between homologous pairs of chromosomes Principle of Segregation (Mendel's First Law) - answer-this principle states that members of a gene pair must separate or segregate from each other during gamete formation and each gamete receives only one of the two genes that control a particular trait Principle of Independent Assortment - answer-this principle states that genes for different traits can segregate independently during the formation of gametes incomplete dominance - answer-this describes a situation in which one allele is not completely dominant over another allele such as a red flower crossing with a white flower and producing a pink flower codominance - answer-this describes a situation in which both alleles of a gene are fully expressed such as with blood types autosomal recessive - answer-this inheritance pattern is characterized by affected individuals having unaffected parents, all the children of two affected individuals being affected, and male and female children being affected in roughly equal numbers autosomal dominant - answer-this inheritance pattern is characterized by every affected individual having at least one affected parent and males and females being affected in roughly equal amounts x-linked dominant - answer-this pattern of inheritance is characterized by affected males having affected daughters and more females are affected than males x-linked recessive - answer-this pattern of inheritance is characterized by mostly males being affected y-linked - answer-this pattern of inheritance is characterized by all affected males having all affected male offspring polygenic traits - answer-these are traits controlled by two or more genes and result in a variation of certain traits discontinuous variation - answer-a variation in a characteristic in which individuals show two, or a few, traits with large differences between them continuous variation - answer-this variation is characterized by the appearance of many different phenotypes polyploidy - answer-this is the term for an increase in the number of chromosome sets in a cell triploidy - answer-this is a type of polyploidy in which there are three sets of chromosomes tetraploidy - answer-this is a type of polyploidy in which there are four sets of chromosomes aneuploidy - answer-this term is the gain or loss of a single chromosome monosomy - answer-the term for the loss of a single chromosome trisomy - answer-term for the gain of a single chromosome nondisjunction in meiosis I - answer-this occurs when one pair of chromosomes fails to separate properly at anaphase I of meiosis and results in two gametes carrying both members of a chromosome pair and two missing one chromosome nondisjunction in meiosis II - answer-this occurs in one cell and produces two cells with the normal haploid number of chromosomes and one cell with an extra chromosome and one cell with a missing chromosome missense - answer-this type of mutation occurs due to a change in the nucleotide sequence and results in a changed amino acid nonsense - answer-this type of mutation occurs due to a change in the nucleotide sequence and results in an amino acid being changed to a stop codon sense - answer-this type of mutation occurs due to a change in the nucleotide sequence and changes a stop codon to code for a different amino acid silent - answer-this type of mutation occurs due to a change in the nucleotide sequence and changes a single nucleotide but it does not change the amino acid that is coded for frameshift mutation - answer-this type of mutation involves the insertion or deletion of a nucleotide and changes the reading frame resulting in different amino acids deletion - answer-this is a frameshift mutation in which one or more nucleotides are removed from the sequence insertion - answer-this is a frameshift mutation in which one or more nucleotides is inserted into a DNA sequence point (single nucleotide replacement) - answer-this is a mutation in which a single base pair in DNA has been changed tautomeric shift - answer-this is a mutation caused by small atomic changes to the purine and pyrimidine bases in nucleotides that change the hydrogen bonding properties of bases and allow bonding with noncomplementary bases radiation - answer-this is an environmental factor that can cause mutations if it interacts with DNA by splitting hydrogen ions into hydroxyl radicals chemical modification of nucleotides - answer-this is used to describe the mutations that occur in DNA due to different chemicals in the environment and all chemicals can cause different mutations and changes base analogs - answer-this term describes a purine or pyrimidine that differs in chemical structure from those normally found in DNA or RNA and these differently structure bases can result in mutations senescence - answer-this is a cell's response to damaged DNA in which the cell becomes dormant apoptosis - answer-this is a cell's response to damaged DNA in which the cell induces suicide and destroys itself cancer - answer-this can occur when the DNA in a cell becomes so damaged that it escapes the normal control of the cell cycle DNA polymerase proofreading - answer-this process occurs during replication and allows DNA polymerase to reverse and remove an incorrectly placed nucleotide and place the correct one DNA repair enzymes - answer-these enzymes monitor DNA for distortions and if they detect one they can cut the distorted portion of the strand and allow DNA polymerase to repair it PCR (polymerase chain reaction) - answer-this is a laboratory technique for amplifying specific sequences of DNA DNA microarray - answer-this is a laboratory technique in which there is immobilized single-stranded DNA fragments of a known nucleotide sequence that is used especially in the identification and sequencing of DNA samples and in the analysis of gene expression DNA sequencing - answer-this laboratory technique is the process of determining the precise order of nucleotides within a DNA molecule