chp 1 mendels principles of heredity

what is a gene

specific segment of DNA that specify protein or RNA molecules which will determine traits

define heredity

transmission of traits from parents to offspring

what is a genome

the sum of all an organisms genes / genetic information

what is artificial selection

the purposeful control of mating by choice of parents to achieve a certain outcome or test a hypothesis

what were two misconceptions about inheritence

parental traits become mixed and permanently changed in offspring, traits contributed by one parent

what made peas a great experimental organism

bisexual, so they could self mate while still being able to cross fertilize. large progeny, short breeding times and discrete traits

what is an antagonistic pair

two alternate forms of a discrete trait

what would define a pure bred pea and how did Mendel achieve pure bred lines ( also called inbreds)

a set of homozygous alleles that always express a certain trait when bred with itself. achieved through repeated self fertilization

what is a hybrid

offspring of genetically dissimilar parents aka heterozygotes

what are reciprocal crosses and what did it prove

during cross breeding, alternating which parents had which trait, controls which parents is transmitting trait. proved each parent contributes equally

what is a monohybrid cross

mating two homozygous (true-breeding) parents that differ in traits

explain why during a monohybrid cross recessive traits reappear in F2. what did this prove ?

recessive allele is carried via dominant allele to F1 even though it is not expressed. Expressed in F2 since 2 heterozygous peas can cross and create a recessive homozygous pea. disproved blended inheritance

what is an allele give an example and explanation

( Xx vs xx) same gene but different version. (hair is hair but it can be straight or curly)

what is a monohybrid

an individual with two different alleles of the same gene

explain the law of segregation

the two alleles for a certain trait separate during gamete formation and unite at random (one from each parent) during fertilization

what does the product rule find and state it

the probability of two independent events occurring together. what is the probability that event 1 AND event 2 will occur? (prob of event 1) x (prob of event 2) = prob of event 1 and 2

what does the sum rule find and state it

the probability of either two exclusive evets occurring. what is the prob that event 1 OR event 2 will occur? (prob of event 1) + (prob of event 2) = prob of event 1 or 2

what does the product rule predict

chance of a certain fertilization event

what does the sum rule predict

teh proportion of progeny with an allele combo or form of trait

define phenotype

observable form of trait

what is a genotype

pair of alleles that express a phenotype

what is a testcross

a way to establish a dominant individuals genotype via crossing with recessive phenotype and examining progeny.

what would an all dominant result of a test cross reveal about the dominant unknown genotype

homozygote

what woulda 1:1 dominant to recessive result of a test cross reveal about the dominant unknown genotype

heterozygous

what is a dihybrid

heterozygous for two genes

what is a dihybrid cross

a cross of true-breeding two gene parents to yield two heterozygous dominant individuals (F1). F1 self fertilizes to produce F2 which yields array of trait expression either parental or recombinant

what is a parental type in a dihybrid cross

phenotype seen in one of 4 parents

what is a recombinant type in a dihybrid cross

phenotype combination not seen in any parent

describe a multi hybrid cross

mating F1 progeny of true breeding parents that differ in three or more traits

what is the easiest way to predict genotypes of multi hybrid crosses

break down into independent monohybrid crosses

what is a functional allele

alleles that carries a DNA sequence which allows for full realization of the gene product. Normal biochemical function

what is a non functioning allele

an allele which has mutated DNA that does not allow for full transcription or translating resulting in an unstable, inactive or misfolded protein.

what makes an allele dominant

encodes a functional protein

what makes an allele recessive

encodes no protein or a non functional one

what is a pedigree

an ordered diagram of families relevant genetic features

explain what makes the Huntington allele dominant

the allele produces an abnormal protein that damages nerve cells

what does a vertical pattern in a pedigree indicate about generations affected , what does it indicate about the disease allele (if trait is rare)

affected people have at least one affected parent , suggests disease allele is dominant

what does a horizontal pattern in a pedigree indicate about generations affected, what does it indicate about the disease allele (if trait is rare )

parents or grandparents typically not affected but siblings may be, suggests parents are heterozygous carriers of recessive disease allele

what is consanguineous mating

mating between two genetic relatives sharing a recent ancestor

explain why the CF allele is recessive

describe what dominant traits look like in pedigrees

affected children always have an affected parent, shows vertical pattern of inheritance showing u in every generation, two affected parents can produce an unaffected child if both parents are heterozygous

describe what recessive traits look like in pedigrees

affected individuals can be the children of two unaffected carriers, all offspring of two affected parents are also affected, rare will show horizontal pattern of inheritance