Genetics Exam I Vocab

Front 1

alternative form of a gene found at the same locus on homologous chromosomes

Back 1

alleles

Front 2

different mutations in the same gene cause the same disease

Back 2

allelic heterogeneity

Front 3

the tendency for some autosomal dominant diseases to manifest at an earlier age and or to increase in severity with each suceeding generation

Back 3

anticipation

Front 4

choice of mate because of a particular triat (which is typically genetic in nature)

Back 4

assortative mating

Front 5

unequal distribution of mutant mitochondria to offspring. One sibling may have higher mutant load and be more severly affected while another may have a low mutant load and be mildly affected

Back 5

bottleneck effect

Front 6

two alleles at a locus are responsible for different phenotypes and both alleles affect the phenotype of a heterozygote. For example, in the ABO blood group botht he A and B alleles contribute to the phenotype of the blood type AB. Thus alleles A and B are said to be codominant

Back 6

co dominant alleles

Front 7

an individual that is heterozygous for a recessive disease allel so that they are not afflicted by the disease but could pass a disease allele on to their offspring

Back 7

carrier

Front 8

a unit of measure of linkage between two loci. Loci that are 1 CM apart will be recombined in 1% of meiosis

Back 8

centimorgan

Front 9

mating of related individuals

Back 9

consanguinity

Front 10

the process by which homologous chromosomes exchange segments of DNA immediately prior to the first meiotic division

Back 10

crossing over (or meitotic recombination)

Front 11

a nucleoside containing 2 deoxyribose in place of ribose

Back 11

deoxynucleoside

Front 12

a deoxynucleoside with one or more phosphate groups attached at the 5' 3' or the 2' oxygen of ribose

Back 12

deoxynucleotide

Front 13

an enzyme that hydrolyzes an internal phophoester linkage in a dNA and or RNA chain producing two chains from one and typically creating 3'OH and 5' phosphate termini

Back 13

endonuclease (be sure to compare to exonuclease)

Front 14

a CNA sequence that increases the activity of a promoter that is more than aobut a thousand base pairs away. Enhancers are generally considered not to be part of the promoter since they are so far from the transcription start site

Back 14

enhancer

Front 15

an allele of one gene can block the phentypic expression of alleles of another gene

Back 15

epistasis

Front 16

a contiguous poriton of a premRNA that is retained in the mRNA. The 5'most exon includes the cap and some 5' untranslated region and the 3'most exon contains at least some of the 3' UTR including eh polyA signal and polyA site

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exon

Front 17

the measure of offsping of persons with a mutant allele who survive to reproductive age

Back 17

fitness

Front 18

a deletion or insertion of one or more nucleotides within a protein coding region that alters the reading frame of the mrna downstream 3' of the mutation. deletions or insertions that are a mutliple of three nucleotides do not cause a frameshift.

Back 18

frameshift mutation

Front 19

collection of cells that give rise to the haploid gametes, eggs and sperm

Back 19

germ line

Front 20

the presence in the germline or gonadal tissue of two or more genetically different types of cells, resulting from mutation during hte proliferatio nand differentitation of the germline

Back 20

germline mosaicism

Front 21

mutations in the heterozygous state that result in half of the normal levels of the gene product leading to phenotypic effect (ie sensistive to gene dosage)

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haploinsufficiency

Front 22

a group of alleles in coupling at closely linked loci usually inherited as a unit

Back 22

haplotype

Front 23

two or more populations (wild tyep and mutant) of mitochondria existing in a cell

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heteroplasmy

Front 24

the normal state of the mitochondra. All mtDNA is the same

Back 24

homoplasmy

Front 25

an internal portion of a primary transcript for exampel a premRNA that is removed ruing formation of the mature RNA

Back 25

intron

Front 26

the chromosomal complement of an individual or a photomicrograph thereof from a metaphase cell

Back 26

karyotype

Front 27

The exctent to which alleles at two different loci tend to cosegregate during meiosis

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linkage

Front 28

a position on a chromosome that is occupied by a particular gene

Back 28

locus

Front 29

the phenomeon of a disorder being due to mutations in more than one gene or locus

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locus heterogeneity

Front 30

mothers can transmit mtDNA mutations to both sons and daughters equally

Back 30

maternal inheritance

Front 31

a nucleotide substition in a protein coding region that canges the amino aci specified y a codon

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missense mutation

Front 32

the unequal istribution of mitochondria following division of heteroplasmic cells

Back 32

mitotic segregation

Front 33

genes at other loci that modify expression of disease genes resulting in phenotypic variability

Back 33

modifier genes

Front 34

two cell lines in an individual are genetically distinct but derived from a single zygot

Back 34

mosaicism

Front 35

the transcript of a protein coding gene that carries the information for production of that protein to the cytoplasm where it is read by the ribosome

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mRNA

Front 36

a nucleotide substition in a protein coding region that changes a codon that specifies an amino acid into a stop codon

Back 36

nonsense mutation

Front 37

the strand of double stranded DNA in a gene that does not act as a template for RNA polymerase

Back 37

non template strand

Front 38

ribose in cyclic hemiacetal form attached to a purine or pyrimidine base through a bond between the anomeric C1 carbon of ribose and a nitrogen atom of the base

Back 38

nucleoside

Front 39

a nucleoside with one or more phophate groups attached at the 5' 3' or 2' oxygen of ribose

Back 39

nucleotide

Front 40

the probability that a gene will have ANY phenotypic expression (all or one effect)

Back 40

penetrance