Test one Flashcards
what is genetics
the study of heredity or the study of biological information
what do we use as our experimental model organism
Drosophila melanogaster
what is the life cycle of a drosophila
embryo first instar larva second instar larva third instar larva pupa adult
what on a virgin will you find on their abdomen
meconium
what principles of genetic did Mendel discover
law of segregation
law of independent assortment
what was the first scientist to combine data collection, analysis, and theory to discover the basic principles of genetics
gregor mendel
why did mendel use peas in his experiment
breeding could be done by cross fertilization or selfing
large # of progeny in short period of time
traits remained constant in crosses within a line
what determines traits
genes
one from mother
one from father
each gene comes in alternative forms which are called
alleles
what is a phenotype
an observable characteristic
what is a genotype
a pair of alleles in an individual
what is an homozygote
two identical alleles
what is a heterozygote
two different alleles
what are the parent phenotypes of a hybrid cross
one is homo dom and homo recess
what is the F1 phenotype of a hybrid cross
all one phenotype
hetero dom
what is a simple way to visualize the segregation and random union of alleles
punnett square
what can reveal an unknown genotype
a testcross
in a monohybrid what is the ratio of phenotypes for the F1 progeny
3:1
when a true breeding dihybrid crosses, what is the F1 of this cross
heterozygote
RrYy
what is the phenotypic ratio of the F2 generation in a dihybrid
9:3:3:1
in the F1 dihybrid produces four possible gametes in what kind of ratio
1:1:1:1 YR Yr yR yr
what is the product rule
probability of two independent events occurring together is the product of their individual probabilities
if both parents are true bred in dihybrid testcross what is the possible F1
one possible outcome
heterozygote dom
if one parent is true bred and one parent is heterozygous for one trait, what does the F1 generation look like
two types of F1 phenotypes
if one parent is true bred and one parent is heterozygous for both traits what does the F1 looks like
4 products of F1 generation
shows all four phenotypes
what does a chi square test measure
how well the observed results conform the expected results
what is a null hypothesis
observed values are no different from expected values
what is needed to do a chi square
total number of progeny
how many classes of progeny
number of offspring observed in each class
how to find degrees of freedom
df= n- 1 n= number of classes
where is DNA packed
into highly condensed chromosomes
how many chromosomes are present in a drosophila
4
what are the steps in mapping a mutant allele
determine chromosome
determine the region on the chromosome
determine the actual gene locus
how can you tell if mutant allele is on x chromosome
all males show the mutant phenotype
males inherit mutant fro mom
when are two genes linked
when the parental type is greater than the recombinant type
when are two genes not linked
ratio is 1:1:1:1
parental type is equal in number to recombinant type
when does unlinked genes occur
either when two genes are on different chromosomes or when they are sufficiently far apart on the same chromosome that at least one crossover occurs between them in every meiosis
what is recombination frequency
percentage of total recombinant progeny
where does crossover occurs
chiasmata
what else can recombination frequencies be used for
a measure of physical distance between two linked genes
in a three point cross, what does the most frequent class represent
parental configuration of alleles
in a three point cross, what does the least frequent class represent
double cross overs
what is the first step in mapping the genes in relation to each other in a three point cross
identify the middle gene
double cross over
deviation from the 1:1:1:1 ratio always mean
linkage
what is special about drosophila salivary glands
contain giant chromosomes
what are giant chromosomes called
polytene
