Lec 4. Basic principles of Heredity Flashcards Preview

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Who is Mendel?

Set out mathematically description how some genes are passed down from one generation to the next.


What was the model organism Mendel used?

Pea plant


What does homozygous mean?

True breeding. The alleles are identical


Define a Monohybrid cross

Cross between two parents that differ in a single characteristic


What four conclusion can be made from the Monohybrid cross?

Each characteristic is encoded by two genetic factors, these two characteristics somehow separate during reproduction, the concept of dominant and recessive traits, two alleles separate with equal probability into the gametes.


What is Mendel's first law?

Principle of segregation


Define principle of segregation

For every characteristic we have a pair of genes and they segregate INDEPENDENT from on another and only one is passed from each parent.


What is independent assortment?

Alleles segregate independently when gametes are formed.


Define the concept of dominance

When two different alleles are present in a genotype, only the trait encoded by one of them-the dominant allele- is observed in the phenotype. The other is called recessive.


How do monohybrid crosses explain the principle of segregation?

Capital=dominant. Lower case= recessive trait. The symbols in the crosses correspond to alleles on chromosomes.


What is the Chromosomal Theory of Heredity (1902)?

identified chromosomes as the genetic material responsible for Mendelian inheritance. (sutton)


How is cystic fibrosis caused?

Mutations in the CFTR gene. Mutations are usually recessive


Define probablility

likelihood of the occurrence of an event


What is probability used for in genetics?

predict the outcome of a genetic cross


How is probability quantified as a number?

Between 0 and 1. 0 is impossible. 1 is certain.


What are probabilities numerically described as?

As the number of desired outcomes divided by the total number of all outcomes


What is the multiplication rule?

Multiply the probability of independent events happening simultaneously.


What is the addition rule?

When two events are mutually exclusive, the probability that either A OR B will occur is the sum of the probability of each event. Big word here is OR.


What is conditional probability?

probability of an event A, given that another B has already occurred.


What is the binomial equation used for?

Used to calc simple and complicated crosses with multiple genes


What is the binomial equation?



What do the variables in the binomial equation stand for?

p= frequency of one outcome. q= frequency of the other outcome. n= number of events. Know that p+q equal 1.


What is a Dihybrid Cross?

a cross that deals with 2 traits, with differing alleles.


How did Mendel reveal the principle of independent assortment?

By examining the behavior two traits simultaneously. Dihybrid cross.


Where does the principle of independent assortment result from?

From the independent separation of chromosomes in Anaphase I of meiosis.


What is a branch diagram and what can it be used to determine?

Another way to show a punit square, determines the phenotypes and expected proportions of offspring from a dihybrid cross.


What do Dihybrid crosses show?

Relate the principle of independent assortment to meiosis. Genes located on different chromosomes will sort independently.


Define Chi-square Goodness of Fit

A statistical test that indicated the probability that the difference between the observed and expected values is due to chance


What are some assumptions of a chi-square goodness of fit?

Random sample, sample size, independence


Define random sample

the sample data is a random sample of a larger population