Chapter 5 Flashcards
Define true breeding organism
An organism that produces offspring identical in appearance to itself, generation after generation
Define trait
A specific characteristic or feature exhibited by an organism
Define cross-fertilization
The fertilization of a female gamete from one organism with the male gamete of another
Define parent generation (p generation)
Organisms that are initially crossed and are usually true breeding
Define first filial generation (f1 generation)
The offspring of a cross of P generation
Define second filial generation (f2 generation)
The offspring of a cross between the F1 generation
Define hybrid
Offspring that result from crossing two true breeding varieties of the same species
Define mono hybrid
The offspring produced from parents that differ in just one trait
Define mono hybrid cross
The cross of two individuals that differ by one trait
Define allele
A specific form of a gene
Define dominant
The form of a trait that always appears when an individual has an allele for it
Define recessive
The form of a trait that only appears when an individual has two alleles for it
Define homozygous
Having two identical alleles for a trait
Define heterozygous
Having two different alleles for a trait
Define genotype
The combination of alleles for any given trait or the genetic make up for an organism
Define phenotype
The physical traits of an organism
Define Punnett square
A grid used to illustrate all possible genotypes and phenotypes of offspring from genetic crosses
Define test cross must edit
A cross between a parent of unknown genotype and a homozygous recessive parent
Define dihybrid
Offspring produced from parents that differ in two traits
Define dihybrid cross
A cross of two individuals that differ in two traits due to two different genes
Who is Gregor Mendel?
He was an Austrian monk in the 1850s that begin experiments that help explain inheritance patterns. He worked with pea plants in the monastery garden. He hypothesized that parents passed down distinct factors to their offspring & were responsible for hereditary traits.
Describe Mendels true breeding cross
He chose 7 traits that were expressed in 2 forms. These plans were called the P generation. When crossed, the offspring was called F1 generation. This type of cross is called mono hybrid cross.
What is the Mendelian ratio?
The F2 generation produces a 3:1 ratio
What is Mendel called because of his work?
The Father of Genetics
What does the law of segregation state?
It states that traits are determined by pairs of alleles that segregate during meiosis so that each gamete receives one allele.
What does the law of independent assortment state?
It states that is genes are located on separate chromosomes, they will be inherited independently of one another.
What is a pedigree?
It is a type of flowchart that uses symbols to show inheritance patterns of traits in the family over many generations. Geneticist can use a pedigree to show how traits, controlled by a single gene or multiple genes, run through a family. This is useful for predicting diseases within a family line.
Define incomplete dominance
A situation where neither allele dominates the other & results in partial expression of both traits (blending).
Define codominance
A situation where both alleles are expressed fully to produce offspring with a third phenotype
What is an example of incomplete dominance?
Snapdragons. C^RC^R x C^WC^W crossed to make C^RC^W (pink).
What is an example of codominance?
Shorthorn cattle: red bull + white cow = roan cow
What are the three alleles for human blood?
I^A, I^B, i
What are the four different types of human blood?
A, B, AB, O
What are the alleles possible for each different blood type?
A - I^AI^A or I^Ai
B - I^BI^B or I^Bi
AB - I^AI^B
O - ii
Define linked genes
Some traits don’t follow Mendel’s law of independent assortment and are often inherited together. They are found on the same chromosome and do not sort independently. The unlinking of these genes can only happen if crossing over occurs during gamete formation.
What is a sex-linked gene?
Any gene located on the X or Y chromosome. For humans, most sex linked genes are found on the X chromosome since it is much larger than the Y chromosome.
What are sex-linked traits?
Traits controlled by X-linked or Y-linked genes. Many are genetic disorders (ie, red-green colour blindness & hemophilia).
