beyond mendel

Question 1

what is a wild type allele

Answer 1

allele that occurs most frequently in the population, usually dominant but not always, responsible for most common phenotype

Question 2

what is a mutant allele

Answer 2

contain modified genetic information compated to the wile type allele, responsible for mutant phenotypes

Question 3

complete dominance

Answer 3

phenotypes of heterozygote and dominant homozygote are identical

Question 4

incomplete dominance

Answer 4

heterozygote phenotype is intermediate between those of homozyotes (1:2:1 ratio)

Question 5

codominance

Answer 5

two dominant alleles affect phenotype in seperate, distinguishable ways

Question 6

what does it mean when a gene has multiple alleles

Answer 6

most genes have two alleles, they are the alternative forms of the same gene so they influnece the same trait; many variations of the gene present

ie blood groups in humans is determined by three alleles

Question 7

what is polygenetic inheritance

Answer 7

results from the additive effect of multiple genes on one phenotype; many genes + enviornmental factors –> 1 characteristic

ie skin color

Question 8

what is multifactoral inheritance

Answer 8

influenced by multiple genetic and enviornmental factors; ie. intelligence, cancer, diabetes, height, skin color

Question 9

pedigree

Answer 9

family tree with genotypes and phenotypes used to trace inheritance patterns of particular traits; also used to make predicitions about the future

Question 10

what are carriers

recessiviley inherited traits

Answer 10

individuals with normal phenotype but heterozygous geneotype for a reccessive disorder

Question 11

phenotypes of autosomal recessive conditions

Answer 11

AA - wildtype
Aa - wildtype, carrier
aa - mutant
A=wildtype; a=mutant

Question 12

phenotypes of autosomal dominant condition

Answer 12

AA - mutant (rare)
Aa - mutant (common)
aa- wildtype
A=mutant; a=wildtype

Question 13

what are multifactorial disorders

Answer 13

many human diseases have both genetic and envionrmental factors; no clear cut pattern of inheritance; ie heart disease, diabetes, and cancer

Question 14

what is the chromosome theory of inheritance

Answer 14

specific genes are located at specific loci on chromosomes which undergo segregation and independant assortment; the behavior of chomosomes during meiosis accounts for Mendels Law of segregation and independant assortment

chromosomes are vehicles of genetic hereditary

Question 15

how was thomas hunt morgan able to show genes are on chromosomes

Answer 15

observed and noted wild-type allelesphenotypes in fruit fly populations; discovered a mutation that affected fruit fly color to provide evidence that genes are on chromosomes

Question 16

linked genes

Answer 16

genes that are inherited together with other genes as they are located on the same chromosome, do not undergo homologous recombination and are inherited together; chance of inheriting is more than 50% (dihybrid cross 3:1)

Question 17

unlinked genes

Answer 17

genes located father apart from each other, occur either in the same chromosome or in different chromosomes, undergoing homologous recombination, less likely to be inherited together; chance of inheriting is less than 50% (dihybrid cross 9:3:3:1

Question 18

what are parental-type offspring

Answer 18

exhibit the same allele combination as their parents; chromosomes are similar to that of their parents

Question 19

what are recombiant offspring

Answer 19

exhibit different allele combination from their parents; happens when crossing over occurs

Question 20

how can you use recombination
frequencies to determine how close two linked genes are to each other on the
chromosome?

Answer 20

if genes are far apart on a chromosome the recombination frequenct is 50%, the inheritance of the alleles are independant; is the frequency is less than 50% the two loci are linked

Question 21

what is x inactivation

Answer 21

mammalian XX individuals have one of two chromosomes in each cell randomly inactivated during embryonic development; XX individual heterozygous for x-linked gene will be mosiac