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chapter 5

Terms in this set (32)

*heredity
the passing of genetic traits from parent to offspring
*dominant trait
the trait observed in the first generation when parents that have different traits are bred.
*recessive trait
A trait that reappears in the second generation after disappearing in the first generation when parents with different traits are bred
*gene
one set of instructions for an inherited trait
*allele
one of the alternative forms of a gene that governs a characteristic, such as hair color
*phenotype
an organism's physical appearance, or other detectable characteristics; visible traits
*genotype
the entire genetic makeup of an organism; also the combination of genes for one or more specific traits. Represented by capital and/or lower-case letters.
*probability
the likelihood that a possible future event will occur in any given instance of the event
*homologous chromosomes
chromosomes that have the same sequence of genes and the same structure
*meiosis
a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells
*sex chromosomes
One of the pair of chromosomes that determine the sex of an individual. 23 in humans
*pedigree
a diagram that shows the occurrence of a genetic trait in several generations of a family
*punnet square
a chart that shows all the possible combinations of alleles that can result from a genetic cross
herterozygous
having different genes on a pair of chromosomes
homozygous
an organism that has two identical alleles for a trait
selective breeding
the human practice of breeding animals or plants that have certain desired traits
hybridization
crossing dissimilar individuals to bring together the best of both organisms
Gregor Mendel
discoved the principles of heredity while studying pea plants
self pollination
when a plant has both male and female reproductive structures
true-breed
plant self pollinated so all of its offspring look the same
cross-pollination
pollen from one plant is transferred to the ovule of another plant which isdone by means of animals or the wind
characteristic
a feature that has different forms in a population
Mendel's first experiments
He figured out that after a cross breed the dominant trait will always appear in the first generation
first generation
the offspring from a cross breed
Mendel's second experiments
the first generation flower self pollinates and creates 4 second generation flowers. One of the four flowers has the recessive trait
Ratio
there was a 3:1 ratio of dominant to recessive genes in the second generation
Second generation
the offspring from the first generation self pollinates and creates offspring which are the second generation
Each parent gives one set of these to the offspring
Alleles
trait
specific characteristic that varies from one individual to another
Dominant alleles are shown in ______________.
upper case letters
Recessive alleles are shown in______________.
lower case letters
Albinism
An inherited trait that prevents normal hair color, eye color and skin color.
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