Hula's Pre-Ap Biology Ch. 9 Vocabulary

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-centesis

Back 1

a puncture

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co-

Back 2

together

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di-

Back 3

two

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gen-

Back 4

produce

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hetero-

Back 5

different

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homo-

Back 6

alike

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mono-

Back 7

one

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pheno-

Back 8

appear

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pleio-

Back 9

more

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poly-

Back 10

many

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gene-

Back 11

produce

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re-

Back 12

again

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com-

Back 13

together

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bin-

Back 14

two at a time

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ABO blood groups

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genetically determined classes of human blood that are based on the presence or absence of carbohydrates ! and B on the surface of red blood cells. These phenotypes, also called blood types, are A, B, AB, and O.

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alleles

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an alternative version of a gene

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amniocentesis

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a technique for diagnosing genetic defects while a fetus is in the uterus. A sample of amniotic fluid, obtained by a needled inserted into a uterus, is analyzed for telltale chemicals and defective fetal cells.

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carriers

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an individual who is heterozygous for a recessively inherited disorder and who therefor does not show symptoms of that disorder but who may pass on the recessive allele to offspring

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character

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a heritable feature that varies among individuals within a population, such as flower color in pea plants or eye color in humans

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chorionic villus sampling (CVS)

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a technique for diagnosing genetic defects while the fetus is in an early development stage within the uterus. a small sample of the fetal portion of the placenta is removed and analyzed

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chromosome theory of inheritance

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a basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns

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codominant

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inheritance pattern in which a heterozygote expresses the distinct trait of both alleles

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complete dominance

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a type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable

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cross

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a mating of two sexually reproducing individuals; often used to describe a genetics experiment involving controlled mating.

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dihybrid cross

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an experimental mating of individuals that are each heterozygous for both of two characters (of the self-pollination of a plant that is like that)

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dominant allele

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the allele that determines the phenotype of a gene when the individual is heterozygous for that gene

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F1 generation

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the offspring of two parental (P generation) individuals; stands for first filial

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f2 generation

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the offspring of the F1 generation; stands for second filial

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genetics

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the scientific study of heredity; the modern version of this began with the work of Gregor Mendel in the 19th century

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genotype

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the genetic makeup of an organism

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heredity

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the transmission of traits (inherited features) from one generation to the next

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heterozygous

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having two different alleles for a given gene

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homozygous

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having two identical alleles for a given gene

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Huntington's disease

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a human genetic disease cased by a single dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after onset symptoms

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hybrids

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an offspring of parents of two different species or of two different varieties of one species; an offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes

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incomplete dominance

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a type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa)

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law of independent assortment

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a general rule of inheritance (originally formed by Mendel) that when gametes form during meiosis, each pair of alleles for a particular character segregates independently of other pairs; also known as Mendel's second law of inheritance.

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law of segregation

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a general rule of inheritance (originally formed by Mendel) that individuals have two alleles for each gene and that when gametes form by meiosis, the two alleles separate, each resulting gamete ending up with one one allele of each gene; also known as Mendel's first law of inheritance

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linkage map

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a listing of the relative locations of genes along a chromosome, as determined by recombination frequencies

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linked genes

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genes located near each other on the same chromosome that tend to be inherited together

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locus

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the particular site where a gene is found on a chromosome. homologous chromosomes have corresponding gene ones.

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monohybrid cross

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an experimental mating of individuals that are heterozygous for the character being followed

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pedigree

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a family genetic tree representing the occurrence of heritable traits in parents and offspring across a number of generations. one can be used to determine genotypes of matings that have already occurred.

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P generation

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the parent individuals from which offspring are derived in studies of inheritance; P stands for parental

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phenotype

Back 45

the expressed traits of an organism

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pleiotropy

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the control of more than phenotypic character by a single gene

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polygenic inheritance

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the additive effects of two or more gene loci on a single phenotypic character

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Punnett square

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a diagram used in the study of inheritance to show the results of random fertilization

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recessive allele

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an allele that has no noticeable effect on the phenotype of a gene when the individual is heterozygous for that gene

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recombination frequency

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with respect to two given genes, the number of recombinant progency from a mating divided by the total number of progency. recombinant progency carry combinations of alleles different from those in either of the parents as a result of crossing over during meiosis

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rule of addition

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a rule stating that the probability of an event can occur in two or more alternative ways is the sum of separate probablities of the differen ways

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rule of multiplication

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a rule stating that the probability of a compound event is the product of separate probabilities of the independent events

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sex chromosomes

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a chromosome that determines whether an individual is male or female

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sex-linked gene

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a gene located on a sex chromosome. in humans, the cast majority of these are located on the x chromosome

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sickle-cell disease

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a genetic condition caused by a mutation in the gene for hemoglobin. the mutation causes the protein to crystallize, which deforms red blood cells into a curved shape. such blood cells can produce a cascade of symptoms that can be life-threatening.

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testcross

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the mating between an individual of unknown genotype for a particular character and an individual that is homozygous recessive for that same character. this can be used to determine the unknown genotype. (homozygous dominant versus heterozygous)

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trait

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a variant of a character found within a population, such as purple or white flowers in pea plants

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true-breeding

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referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents. the organisms are homozygous for the characters under consideration

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ultrasound imaging

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a technique for examining a fetus in the uterus. high-frequency sound waves echoing off the fetus are used to produce an image of the fetus.