Chapter two test one Flashcards
what is a gene
basic unit of biological info
what is heredity
the way genes transmit physiological, anatomical and behavioral traits from parents to offspring
what is genetics
the science of heredity
what is artificial selection
the purposeful control of mating by choice of parents for the next generation
what were the ideas of heredity before mendel
one parent (male) contributes most to an offsprings inherited features blended inheritance: parental traits become mixed and forever changed
why did mendel choose the pea plant
female and male organs in same plant (self-fertilizing)
easy to breed
large numbers, short period of time
what are discrete traits
an inherited trait that clearly exhibits an either/or status
what are continuous traits
an inherited trait that exhibits many intermediate forms
such as skin color or height
what are hybrids
offspring of genetically dissimilar parents
what are reciprocal crosses
crosses performed in two directions, with the traits in the males and females reversed relative to each other, thereby controlling whether a particular trait is transmitted by the male or female gamete
what crosses reveal the law of segregation
monohybrid crosses
what do F1 generations look like in a monohybrid cross
all one phenotype
what are monohybrid crosses
crosses between parents that differ in only one trait
what is the ratio for a F2 monohybrid cross
3:1
what was evidence in monohybrid crosses that showed blending did not occur
green reappeared in the F2 generation
what is an allele
alternative forms of a single gene
what are gametes
eggs or sperms that carry genes between generations
what is a zygote
fertilized egg
what is mendels law of segregation
two alleles for each trait segregate during gamete formation, and then unite at random, one from each parent, at fertilization
purpose of punnett square
visualize the fertilization events possible in a give cross
what is the product rule
the probability of two or more independent events occurring together is the product of the probabilities that each event will occur by itself
what is the key word to look for in product rule
AND
what is the sum rule
the probability that any of two or more mutually exclusive events will occur is the sum of their individual probabilities
what is the key word to look for in the sum rule
OR
what is the ratio of a specific yellow genotype for a monohybrid
1 YY ; 2 Yy
purpose of a testcross
determine phenotype
if phenotype shows one color in testcross what is the genotype
YY
if phenotype shows two colors in testcross what is the genotype
Yy
what kind of crosses shows the law of independent assortment
dihybrid crosses
what is a dihybrid
an individual that is heterozygous at different genes
how many phenotypes produced in F1 generation for a dihybrid cross
1
what is a parental type
phenotypes that reflect a previously existing parental combination of alleles that is retained during gamete formation
what is a recombinant type
phenotypes reflecting a new combination of genes that occurs during gamete formation
what is the phenotypic ratio of a f2 generation for a dihybrid cross
9:3:3:1
each individual trait in a dihybrid f2 generation has what phenotypic ratio
3:1
what is the law of independent assortment
alleles of different genes segregate into gametes independently of each other
what is the possible allele combination ratio in gametes for dihybrid cross
1:1:1:1
what is a pedigree
an orderly diagram of a family’s relevant genetic features, extending through as many generations as possible
what is a late onset genetic trait
symptoms not present at birth and manifest later in life
what disease is an example of a late onset genetic trait
huntingtons disease
what is a vertical pattern in pedigrees
at least one person is affected in each generation
what genotype is the diseased huntington
Hd HD+, HD HD
a vertical pattern of inheritance indicates what
a rare dominant trait
a horizontal pattern of inheritance indicates what
rare recessive trait
what is a common rare recessive disease
cystic fibrosis
what is a trait of horizontal pattern in pedigrees
unaffected parents can have affected children
