Bio Test 2

Front 1

Karyotype

Back 1

A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position.

Front 2

Nondisjunction

Back 2

An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to seperate ay anaphase.

Front 3

Deletion

Back 3

The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosomes.

Front 4

Duplication

Back 4

Repetition of part of a chromosome resulting from fusion with a fragment from a homologous chromosome; can result from an error in meiosis or from mutagenesis.

Front 5

Inversion

Back 5

A change in a chromosome resulting from reattachment of a chromosome fragment to the original chromosome, but in a reverse direction. Mutagens and errors during meiosis can cause inversions.

Front 6

Translocation

Back 6

1) During protein synthesis, the movement of a tRNA molecule carrying a growing polypeptide chain from the A site to the P site on a ribosome. 2)A change in a chromosome resulting from a chromosomal fragment attaching to a nonhomologous chromosome; can occur as a result of an error in meiosis or from mutagenesis.

Front 7

Carrier

Back 7

An individual who is heterozygous for a recessively inherited disorder and who therefore doesn't show symptoms of that disorder but who may pass on the recessive allele to offspring.

Front 8

Cystic Fibrosis

Back 8

A genetic disease that occurs in people with two copies of a certain recessive allele; characterized by an excessive secretion of mucus and vulnerability to infection; fatal if untreated.

Front 9

Achondroplasia

Back 9

A form of human dwarfism caused by a single dominant allele; the homozygous condition is lethal.

Front 10

Huntington's Disease

Back 10

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10-20 years after the onset of symptoms.

Front 11

Alzheimer's Disease

Back 11

An age-related dementia charazterized by confusion, memory loss, and other symptoms.

Front 12

Aminocentesis

Back 12

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

Front 13

Chorionic villus sampling
(CVS)

Back 13

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

Front 14

Ultrasound Imaging

Back 14

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.

Front 15

Self-fertilize

Back 15

The fusion of sperm and egg produced by the same individual organism.

Front 16

Cross-fertilization

Back 16

The fusion of sperm and egg derived from two different individuals.

Front 17

Pure-breeding strain

Back 17

Crosses between identical homozygotes.

Front 18

Hybrid

Back 18

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

Front 19

Allele

Back 19

An alternative version of a gene.

Front 20

Gene

Back 20

A discrete unit of heredity information consisting of a specific necleotide sequence in DNA (of RNA in some viruses). Most of the genes of a eukaryote are located in its chromosomal DNA; a few are carried by the DNA of mitochondria and chloroplasts.

Front 21

Locus

Back 21

The particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci.

Front 22

Dominant allele

Back 22

The allele that determines the phenotypeof a gene when the individual is heterozygous for that gene

Front 23

Recessive allele

Back 23

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

Front 24

Homozygous

Back 24

Having two identical alleles for a given gene.

Front 25

Heterozygous

Back 25

Having two different alleles for a given gene.

Front 26

Punnett square

Back 26

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

Front 27

Genotype

Back 27

The genetic makeup of an organism.

Front 28

Phenotype

Back 28

The expressed traits of an organism.

Front 29

Monohybrid cross

Back 29

An experimental mating of individuals differing at one genetic locus.

Front 30

Dihybrid cross

Back 30

An experimental mating of individuals differing at two genetic locations.

Front 31

testcross

Back 31

The mating between an individual of unknown genotype for a particular characteristic and an individual that is homozygous recessive for that same characteristic.

Front 32

Incomplete dominance

Back 32

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

Front 33

Codominant

Back 33

Inheritance patter in which a heterozygote expresses the distinct trait of both alleles.

Front 34

Pleiotropy

Back 34

The control of more than one phenotypic characteristic by a single gene.

Front 35

Polygenetic Inheritance

Back 35

The additive effect of two or more gene loci on a single phenotypic characteristic.

Front 36

Epistasis

Back 36

One gene suppresses or "dominates" a different gene, rather than an allele.

Front 37

Mosaicism

Back 37

A trait of female mammals due to inactivation of one X chromosome in every cell.

Front 38

Dosage compensation

Back 38

A trick for equalizing the "dose" of X genes in XX vs.XYindiv's.

Front 39

Crossing over

Back 39

The exchange of segments between chromotids of homologous chromosomes during synapsis in prophase 1 of meiosis; also, the exchange of segments between DNA molecules in prokaryotes.