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34 terms

Std. 7 Vocab.

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allele
one of two alternate forms of a gene that can have the same locus on homologous chromosomes and are responsible for alternative traits
chromosomes
threadlike structures made of DNA molecules that contain the genes
codominance
situation in which both alleles of a gene contribute to the phenotype of the organism
color blindness
a variety of disorders marked by inability to distinguish some or all colors
cystic fibrosis
the most common congenital disease
dihybrid cross
hybridization using two traits with two alleles each
down syndrome
a condition of retardation and associated physical disorders caused by an extra chromosome in one's genetic makeup
dominant allele
an allele whose trait always shows up in the organism when the allele is present
genes
the biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein
genetic code
the ordering of nucleotides in DNA molecules that carries the genetic information in living cells
genetic variation
the number and frequency of alleles that are present in a particular population
genotype
the particular alleles at specified loci present in an organism
genetics
the branch of biology that studies heredity and variation in organisms
genotypic ratio
the ratio of the genotypes that appear in offspring
heterozygous
an organism that has two different alleles for a trait
homologous
corresponding or similar in position or structure or function or characteristics
homozygous
having identical alleles at corresponding chromosomal loci
incomplete dominance
one allele is not completely dominant over the other allele
karyotype
A picture of all the chromosomes in a cell arranged in pairs
Mendel's laws
laws of dominance,segregation,and independent assortment
monohybrid cross
hybridization using a single trait with two alleles `
multiple alleles
three or more forms of a gene that code for a single trait
offspring
something that comes into existence as a result
pedigree
ancestry of a purebred animal
phenotype
what an organism looks like as a consequence of its genotype
phenotypic ratio
a ratio that shows the varied outcomes that results from a genetic cross and is based on physical appearance alone
PKU
phenylketonuria (disease due to lack of an enzyme in infants)
polygenetic trait
trait controlled by two or more genes
Punnet square
A chart that shows all the possible combinations of alleles that can result from a genetic cross
recessive alleles
An allele that is masked when a dominant allele is present.
recombinant DNA
genetically engineered DNA made by recombining fragments of DNA from different organisms
sex-linked trait
Characteristic such as red-green color blindness, controlled by genes on the X chromosome also called an X linked trait.
sickle cell anemia
a genetic disorder in which erythroctyes take on an abnormal curved or "sickle" shape
Tay-Sachs disease
recessive disorder that is of the nervous system and the child usually dies by the age of 4