Lecutre 1(Basic Mendelian Genetics Flashcards
What does mendellian genetics deal with?
They deal with basic principles of heredity and also deal with arrangement of chromosomes, and genes.
what is heredity?
It deals with how traits are passed from generation to generation
What are alleles
Alleles are different versions of genes
genotype:
Gentoype is exact very of genes that an organism has.
what did people believe in before Mendel?
Inheritance of acquired characteristics, and Blending Inheritance
Inheritance of acquired characteristics:
They are traits that parents have that can be given to children
Blending Inheritance:
offspring are a mixture of potential traits/ genetic material blends
What type of plant did Mendel use?
He chose a plant that is annual, naturally self ferttilize, and could also have sexual rpdocuts removed so it could manually be fertilized
What is an annual plant
It grows from see in spring, makes flowers, is fertilized, sets seed and then parent dies.
What does naturally self fertilizing mean?
The pollen falls on the stigma of the flower before the flower even opens, ensuring that the seeds (peas) have the parent plant as both mother and father.
What is cross fertilization
Manually fertilizing a plant that can be done by transferring polled with a paint brush and therefor can run experiments doing this.
How do plants fertilize?
Plants could self fertilize because they had anthers, but anthers could be removed and cross fertilization (manual feritlization)
What is parent generation called?
PO
What are the first offsprings called?
F1 generation
What were critical methods employed by Mendel
He used pure breeding strain, selected dichotomous traits, quantified results, and also use of replicate, reciprocal, and test crosses
what does pure bred mean?
Which mean a pure lineage and no mixing of other traits
What does true breeding mean?
It is a genetic term used for organism that when self fertilized or bred with another of the same type, produce offspring with the same trait over generations
Dichotomous traits:
This means that the trait had only two alternative phenotypes
Continuous variability:
It means a range of phenotypes with gradual variation.
What were Mendel’s observation after the first cross:
Traits were determined by factors that are intwo forms, Traits that appeared F1 are dominant and the disappeared traits were recessive
What type of traits did he study
monogeneic traits, and traits that did not show linkage in crosses.
What does monogenic mean
Traits controlled by only a single gene
What was the F2 experiment?
It was the result of crossing the F1 with smooth sees
What were the results of the F2 experiment?
the results were that the F2 show cases dominant traits however but some showed recessive phenotype, and therefor the recessive gene never actually disappeared. The quantification for the F2 results were (3:1)(dominant: recessive)
What was Mendel’s experiment result from self fertilizing? F2
From the 4 results he obtained 1/4 plants with pods containing round F3 seeds, 3/4 gave plants with both round and wrinkled peas and 1/4 gave only wrinkled.
What was Mendel’s first law?
Mendel’s first law was the law of segregation
What does the law of segregation state?
It states that two alleles for each trait will separate from one another during gamete formation and each allele will have an equal probability of inclusion in a gamete, Random union of gametes at fertilization will unite one gamete from each parent to produce progeny in ratios that are determined by chance/
are true breeding parents homozygous or heterozygous
homozygousm and they only make one type of gamete
What does Mendel’s first law allow us to do?
It allows us to predict that F1 progeny from the true breeding-parents would all have a heterozygous genotype and dominant phenotype.
What did Mendel’s model consist of?
Each organism gets one copy of the gene from its mother, and one from its father, Dipoloid parents produce haploid gamete(reproductive cells: sperm, eggs, pollen, etc) that have only one copy of gene, The chance that a gamete will contain one allele or the other is random, Two gametes join together to make a new organism with two copies of the gene again (diploid), and Blending of the factors does not accur, they stay the same across generations.
What is a test cross?
crossing a strain with the dominant phenotype(but unknown genotype) with a control that is homozygous for the recessive allele.
what is a dihybrid cross
two traits crosses
how did Mendel perform a dihybrid cross?
he cross fertilized the parents and got F1 with both dominant traits, then self-fertilized the F1, he found the four classes F2 progeny.
What results did he get from dihybrid crosses
Each trait gave a ration of 3:1 ratio of domiant to recessive in the F2 and each trait still behaved normally would, independent of the other.
What is Mendel’s second law:
Law of independent assortment
What are the rule of probability theory?
The rule of independent events, The sum rule, and the product rule
law of independent assortment
It stemmed from the dihbrid cross result that gave 9:3:3:1 ratio, and the law stated that during gamete formation, the segregation of two alleles of one gene is independent of the segregation of alleles of another gene. The bheavior of the two traits in dihybird corsses was perfectly explained by treating the as two independently segregating traits present in the same offspring.
The sum rule:
The change of an event occuring when that event occurs two or more different ways is equal to the sum of probabilities of each event
rule of independent events
Past event have no influence on future events.
The product rule:
The chance that two or more independent events will occur together is equal to the product of the probabilities of each event.
What is chi square analysis?
It is a test used to determine if chance alone acccounts for observed differences, or is something else might be going on.
The Null hypotheesis is:
there is no difference between the observed results and the expected results, Any variation is due to chance
What si the equation for chi squre
x^2= ((observed - expected) ^2) / expected
What is degree of freedom?
It is the calculated as the one less than the number of possible results in your experiment.
The probability value
indicate the variance between observed results and expected results would occur from random chance alone about X*100% of the time, and the P value is less than 5% as the cutoff for accepting or rejecting a hypothesis.
When do you reject the null hypthoesis and when do you accept?
If the percentage is less than 5% you reject the null hypothesis, and if the percentage is greater you accept the null hypothesis
