Chapter 12, Patterns of Inheritance Flashcards
Before the 20th century, what were the two concepts that were the basis for ideas about heredity?
- Heredity occurs within species
- Traits are transmitted directly from parent to offspring
___________-1760- crossed tobacco strains to produce hybrids
Josef Kolreuter
What two observations did Josef Kolreuter make about the hybrids?
- hybrid offspring differed from both parents
- additional variation observed in 2nd generation offspring contradicts direct transmission
__________ -1823- crossed two varieties of garden pea, Pisum sativa
T.A Knight
T.A knight crossed two _____-______ strains
true-breeding
What does it mean if a species is true-breeding?
with self-fertilization it produces one type
In T.A knight’s experiment’s 1st generation resembled only 1 ______ strain
parent
In T.A Knight’s experiment’s the 2nd generation resembled ______ strains
both parent
Why did Gregor Mendel use pea plants?
- other research showed that pea bybrids could be produced
- many pea varieties were available
- peas are small plants an easy to grow
- Peas can self-fertilize or be cross-fertilized
What was Mendel’s experimental method?
- Produce true-breeding strains for each trait he was studying
- cross-fertilize true-breeding strains having alternate forms of a trait
- Allow the hybrid offspring to self-fertilize for several generations and count the number of offspring showing each form of the trait
How did Mendel conduct his experiments?
- The anthers are cut away on the purple flower
- pollen is obtained from the white flower
- Pollen is transferred to the purple flower
- All progeny result in purple flowers
________ cross used to study only two variations of single trait
monohybrid
Mendel produced true-breeding pea strains for _____ different traits
seven
What are the seven traits of plants?
flower color, seed color, seed texture, pod color, pod shape, flower position, plant height, plant
F1 generation is also called ____________
first filial generation
For every trait Mendel studied, all F1 plants resembled the same _____
parent
The visible trait is referred to as _____
dominant
In Mendel’s experiments, no ________ inheritance was found
blending
F2 is the second ______ generation
filial
_____ ______ generation was produced from the self-fertilization of F1 plants
second filial
What is the F2 phenotypic ratio?
3:1
What is the genotypic ratio of F2 generation?
1 true-breeding dominant
2 not-true breeding dominant plants
1 true-breeeding recessive plant
What is Mendel’s five-element model?
- parents transmit discrete factors (genes)
- each individual receives one copy of a gene from each parent
- Not all copies of a gene are identical
- alleles remain discrete-no blending
- presence of allele does not guarantee expression
_____ is an alternatve form of a gene
allele
_______- two of the same allele
homozygous
________-different alleles
heterozygous
What is the principle that two alleles for a gene segregate during gamete formation and are rejoined at random during fertilization?
principle of segregation
The physical basis for allele segregation is the movement of ______ during meiosis
chromosomes
In Punnett squares the top right section contains the _____ DNA
male’s
In the punnett square the side left contains the _____ DNA
female’s
Each true-breeding parent makes only one type of ______
gamete
________ cross used to study two variations of two traits in a single cross
Dihbrid
In the F2 dihybrid cross what is the phenotypic ration produced?
9:3:3:1
In a dihybrid cross, the alleles of each gene assort ________
independently
The segregation of different allele pairs is ______
independent
Independent alignment of different homologous chromosomes pairs during _______ I leads to the independent segregation of the different allele pairs
metaphase
______ is used to determine the genotype of an individual with unknown phenotype
testcross
In a testcross the unknown genotype is crossed with a homozygous _____
recessive
______ allows the prediction of liklihoods of random events
probability
Rule of ______ is the probability of either of two mutually exclusive events occurring is the sum of their individual probabilities
addition
rule of ________ is the probability two independent events both occurring is the product of their individual probabilities
multiplication
_____ probabilities are based on monohybrid probabilities
dihybrid
Principle of _______ _____ means one dihybrid cross is equivalent to two independent monohybridcrosses
independent assortment
What does Mendel’s model of inheritance assume?
- Each trait is controlled by a single gene
- each gene has only two alleles
- there is a clear dominant-recessive relationship between the alleles
______ _____ is where more than one gene can affect a single trait
polygenic inheritance
_______ is when a single gene can affect more than one trait
pleiotrophy
________ _______ for one gene is where genes have more than two alleles in a populations
multiple alleles
________ dominance shows an intermediate phenotype for the heterzygote
incomplete
________, the heterozygote shows some aspect of the phenotypes of both homozygotes
codominance
_________ factors is where genes may be affected by the environment
environmental
_____ _____ is the products of genes can interact to alter genetic ratios
gene interactions
T or F: environment does effect phenotype
True
______ ______ refers to different phenotypes from same genotype due to environmental conditions
phenotypic plasticiity
________ _______ refers to a range of possible phenotypes across genotypes, the phenotype is the result of an accumulation of contributions by multiple genes
continuous variation
_______ ______ is a trait that is determined by the effect of more than one gene
quantitative traits
______ ______ heritability is the fraction of phenotypic variation due to underlying genetic variation
broad sense
______ _____ heritability is the fraction of phenotypic variation due to additive genetic variance, that is the genetic variance for a specific trait
narrow sense
Height is a ______ varying trait
continuously
_______ refers to an allele which has more than one effect on the phenotype
pleiotropy
Blood type A codes for what sugar?
galactosamine
Blood type B codes for what sugar?
galactose
Blood type AB codes for what type of sugar?
Galactose and galactosamine
Blood type O codes for sugar?
none
What blood types are codominant?
A and B
_______ is when the action of one gene obscures the effects of another gene
epistasis
In labradors what are the two genes that control coat color?
Brown and extension
