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| What are genetics? | the branch of biology concerned with the ways in which hereditary information is transmitted from parents to offspring |
| A hybrid is... | an individual that is heterozygous for a particular trait; an individual produced by a cross between members of two closely related species |
| F1 generation = | parents |
| F2 generation = | offspring |
| If a trait is dominant it means that... | it appears in the offspring of a cross between two pure individuals showing contrasting forms of the trait |
| What is a recessive trait? | a trait that is masked in the offspring of a cross between two pure individuals showing contrasting forms of the trait |
| What is the law of dominance? | the principle of genetics stating that when organisms pure for contrasting traits are crossed, all their offspring show the dominant trait |
| The law of segregation is... | the genetic principle stating that the alleles of a gene occur in pairs and are separated from each other during meiosis and are recombined at fertilization |
| A gene is... | a distinct unit of hereditary material found in chromosomes; a sequence of nucleotides in DNA that codes for a particular tRNA, r RNA or polypeptide |
| What is an allele? | one of the two or more forms of the gene for a specific trait |
| Having two identical alleles for a trait means that an organism is... | homoozygous |
| A heterozygous organism is one that... | has two different alleles for a trait |
| What is the genotype? | the genetic make up of an individual |
| What is phenotype? | the physical traits that appear in an individual as a result of its genetic makeup |
| A punnett square is used in genetics to... | show the result of a cross |
| A monohybrid cross is... | a genetic cross in which only one pair of contrasting traits is studied |
| A dyhybrid cross is... | a genetic cross in which two pairs of contrasting traits are studied |
| What is a test cross? | a genetic cross in which a test organism showing the dominant trait that is crossed with one showing the recessive trait |
| Incomplete dominance is... | a type of inheritance in which neither pair of contrasting alleles is dominant over the other and the heterozygous individual is immediate in phenotype; blending inheritance |
| What is codominance? | a type of inheritance in which two dominant alleles are expressed at the same time without blending of traits |
| Multiple alleles are... | three or more different forms of a gene each producing a different phenotype |
| What are sex chromosomes? | one of two unmatched chromosomes that determine the sex of an individual; represented as X and Y |
| What is an autosome? | a chromosome other than a sex chromosome |
| A sex linked trait is... | a trait that is controlled by a gene found on one of the six chromosomes |
| Color blindness is... | a sex linked trait in which an individual cannot perceive certain colors |
| Gene linkage is... | genes located on the same chromosome; they are not independently assorted but are distributed together during meiosis |
| In crossing over... | pieces of homologous chromosomes are exchanged during synapsis in the first meiotic division |
| What is a mutation? | the appearance of a new allele on a chromosome |
| What is gene mutation? | a change in the sequence of the bases in a gene which changes the structure of the polypeptide that the gene codes for |
| Chromosomal mutations are | changes in chromosome structure resulting in new gene combinations |
| Translocation is... | the transfer of a chromosome segement to a nonhomologous chromosome |
| An inversion is .. | a type of chromosomal alteration in which a portion of a chromosome is rotated resulting in the reversal of the order of genes in that segment |
| An addition is... | the breaking off of a chromosome segment and its attachment to the homologous chromosome |
| A deletion is... | a type of chromosomal alteration in which a portion of a chromosome and the genes it contains is lost |
| Nondisjunction is... | the failure of homologous chromosomes to separate normally during meiosis producing gametes or spores with one more or one less chromosome than normal |
| What is polyploidy? | a condition in which the cells have the some multiple or the normal chromosome number |
| What is sickle cell anemia? | a disease in which the red blood cells have an abnormal hemoglobin moleculre which gives the cells an abnormal shape which causes them to clump and block small blood vessels |
| What is PKU? | a disease in which an enzyme necessary for the normal breakdown of the amino acid phenylalanine is missing; products of phenylalaning metabolism accumulate in the body damaging the brain and causing mental retardation |
| Tay-Sachs disease is the result from... | the lack of an enzymen necessary for the breakdown of lipids in the brain. |
| Amniocentesis is... | a technique in which amniotic fluid which contains fetal cells is withdrwn from the amniotic sac of a pregnant woman so the cells can be examined for the presence of genetic abnormalities |
| Four breeding methods are... | selection, inbreeding, outbreeding, hybrid vigor/heterosis |
| Selection is... | a technique in which only those animals and plants with the most desireable traits are chosen for breeding |
| Inbreeding is... | when closely related individuals are mated to retain or strengthen certain desireable traits |
| Outbreeding is... | when individuals not closely related are mated to introduce new beneficial alleles into the population |
| Hybrid vigor/heterosis is... | superior characteristics that are often found in hybrids |
| DNA is made of of what chemical groups? | 5 carbon sugar(deoxyribose), phosphate group, 4 kinds of nitrogenous(nitrogen containing) bases |
| The composition and structure of RNA is... | 5 carbon sugar (ribose), and 4 bases are adenine, guanine, cytosine and uracil |
| What is the one gene, one enzyme hypothesis? | Each gene produces its effects by controlling the synthesis of a particular enzyme |
| What is the function of mRNA? | to carry the message for a single polypeptide in complementary form |
| What is transcription? | the copying of a genetic message into a molecule of mRNA |
| What is a codon? | each group of three bases that specifies an amino acid |
| What is transfer RNA (tRNA)? | has only about 80 nucleotides--will pick up only one type of amino acid |
| What is an anticodon? | the sequence of 3 bases that are complements of an mRNA codon |
| What is ribosomal RNA (rRNA)? | RNA that is formed by DNA in the nucleoli of the cell |
| What is a gene mutation? | a change in the sequence of the bases in a gene, which changes the structure of the polypeptide that the gene codes for |
| What is a natural mutation? | all causes are not known--each type of mutation seems to occur at definite low rates in populations |
| What are mutagenic agents? | factors in the environment that cause mutations (ex: x-rays, chloroform, mustard gas) |
| Name two types of gene mutations. | When an entire nucleotide may be added or removed (ex: alkaptonuria, PKU) or when one base could be substituted |
| What is transformation? | the transfer of DNA from dead, ruptured bacteria to living bacterial cells |
| What is transduction? | the process in which pieces of DNA are transferred from one bacterial cell to another by viruses |
| What is recombinant DNA? | DNA that has been altered by genetic engineering |
| Genetic engineering (gene splicing) is | the process of producing altered DNA usually by breaking a DNA molecule and inserting new genes |
| What is a plasmid? | a small circular segment of DNA that is found in bacteria that stays separate from the bacterial chromosome; used in genetic engineering |
| What is a clone? | a group of individual organisms that have identical genetic makeup |
| What is somaclonal variation? | spontaneous genetic changes in cloning that results in many unexpected and useful genetic variations |
