M1: Mendelian Genetics Flashcards
- Unit of inheritance
- Mendel’s unit factors
Gene
Alternative forms of a single gene
Allele
Allele Phenotypes
Dominant and Recessive trait
Symbolizes the character in question
First letter of the recessive trait
Physical expression
- Trait
- Information contained in the gene
Phenotype
Designates the genetic makeup of an individual for the trait it describes (whether diploid and haploid)
Genotype
Individual with identical alleles at one or more loci
Homozygote/Homozygous
Individual with different alleles at one or more loci
Heterozygote/Heterozygous
Plant used in Mendel’s Model Experimental Approach
Pisum sativum (Garden Pea)
Reason for using Garden Pea
- Easy to grow
- Grows to maturity in a single season
- Reproduces well
- Self-fertilizing in nature
- Easy to cross-breed experimentally
- Easy to hybridize artificially
One pair of contrasting traits
(1 character)
Monohybrid cross
In Monohybrid Cross, it expresses the same trait exhibited by one of the parents
F1 Offspring
In Monohybrid Cross, it shows a ratio of 3:1
F2 Offspring
In Monohybrid Cross, results are not
Results are not sex dependent
Mendel’s Principle of Inheritance
- The Principle of Unit Factors in Pairs
- The Principle of Segregation
- The Principle of Dominance
- The Principle of Independent Assortment
Genetic characters are controlled by unit factors existing in pairs in individual organisms
Principle of Unit Factors in Pairs
When two unlike unit factors responsible for a single character are present in a single individual, one unit factor is dominant to the other, which is said to be recessive
Principle of Dominance
During the formation of gametes, the paired unit factors separate, or segregate, randomly so that each gamete receives one or the other with equal likelihood
Principle of Segregation
He developed the Punnet Squares
Reginald C. Punnett
A diagram used to easily visualize the genotypes and phenotypes resulting from the recombination of gametes during fertilization
Punnet Square
He devised the Test Cross
Mendel
A test devised by Mendel to distinguish the genotypes of F2 offspring showing the dominant phenotype
Test Cross
During gamete formation, segregating pairs of unit factors (alleles) assort independently of each other
Principle of Independent Assortment
Examination of two characters simultaneously (Two-factor cross)
Dihybrid Cross
- Unit Factors in Pairs - Prophase I
- Segregation of Unit Factors during gamete formation - Anaphase I
- Independent Assortment of Segregating Unit Factors - M2
Chromosomal Theory of Inheritance
Inheritance of Multiple Traits and Three-factor cross
Trihybrid cross
An event is certain not to occur
0
The probability of obtaining any single outcome, where that outcome can be achieved by two or more events, is equal to the sum of the individual probabilities of all such events
Sum Law
An event is certain to occur
1
The probability of two or more independent events occurring simultaneously is equal to the product of their individual probabilities
Product Law
Evaluates the influence of chance on genetic data and assessment of the null hypothesis (H0)
Chi-square Analysis
No real difference exists between measured values and predicted values. Any apparent difference can be attributed purely to chance
Null Hypothesis
Observed deviation from the expected result cannot be attributable to chance alone
(Null Hypothesis) is Rejected
Any observed deviations are attributed to chance
(Null Hypothesis) Fails to be Rejected
p < 0.05
Rejected, Predicted is not equal to Observed
p > 0.05 or p = 0.05
Fails to be Rejected, Predicted is equal to Observed
Dominant Human Genetic Condition
Achondroplasia and Brachydactyly
Abnormal bone growth and dwarfism
Achondroplasia
Shortening of fingers and Toes
Brachydactyly
Recessive Human Genetic Conditions
Albinism and Alkaptonuria
Lack of pigment
Albinism
Black urine disease
Alkaptonuria
Used to determine the mode of inheritance if designed crosses are not possible and relatively few offsprings are available for study
Pedigree Analysis
A family tree indicating the presence or absence of the trait in question for each member of each generation
Pedigree
i. Either 1-3 or 1-4 are heterozygous
ii. Traits skips generations
iii. Traits appear equally in both sexes
Inheritance of Autosomal Recessive Traits
i. i-1 is heterozygous for a dominant allele
ii. Traits almost appear in each generation
iii. Affected individuals have affected parents
iv. Traits appear equally in both sexes
Inheritance of Autosomal Dominant Traits
