Genetic Lecture 2 Flashcards
Charles Darwin
Published the origin of species around the time Mendel started his work. He went on a 5 year journey on a boat and is famous for his observations for how birds of the same species have different beaks when they live on different islands, because of food availability. Thought there was natural selection to survive and for it to be possible you need variation.
When was natural selection become popular?
At the end of the 19 century, biology was dominated by the theory of evolution by natural selection (origin of modern biology).
Natural Selection
Population could change (or evolve) only if variation in traits existed among its members. Variants that enhanced survival and reproduction
would increase in frequency with each generation. Variants that did not would decrease in frequency and
might eventually be eliminated from the population.
Blending Hypothesis
Widely accepted in the 1800s. The parent’s traits were mixed. ie. A short and tall parent, will make average height kids. However, people realized that traits disappeared and came back.
Particulate Hypothesis
Demonstrated by Mendel. Different alleys are handed out but still kept in the same gnome.
Gregor Mendel
He breed peas in his garden. He succeed because he used math. Developed many theories on how genes are pasted on. He didn’t care about crossing over and traits on sex chromosomes.
Dopler
Studied with Mendel, after Mendel failed to be come a teacher. He taught Mendel the experimental method, like asking questions and making hypothesis. He created the Dopler Effect where frequency increase the closer it gets to you.
Why did Mendel use garden peas?
Easy to Grow. Some characters had easily distinguishable traits. True-breeding varieties. Possible to cross-fertilize or self-fertilize different varieties of pea. Needed to use a characteristic that had an obvious answer.
True-Breeding Varieties
A particular trait is consistently inherited from one generation to the next.
How did he perform the cross?
Cut off the sex organ that he didn’t need in the pea then took the pollen of the stamen of one plant and put it on the carpel of the other. This is the parental generation (P).
F1
First filial generation offspring
What was Mendel’s question?
When F1 hybrid plants self- pollinate, which traits appear in the F2 generation?
What’s a heritable factor?
A Gene
How do recessive traits move from one generation to the next?
Not destroyed, deleted, or blended in the F 1 generation but was merely
masked.
Hybridization
Crossing of two true-breeding
varieties
Alleles
Alternative versions of the same gene
What do genes do?
Encode proteins, these protein determines the phenotype.
How do different alleles impact the genetic sequence?
They create a change in genetic sequences.
Who do dominant and recessive alleles work?
The dominant and recessive gene encodes different things. Eg. The dominant genes results in an enzyme that helps synthesize purple pigment, while the recessive gene encodes for a nonfunctional gene.
Does it matter if you have one or two dominant alleles.
No, they produce the same thing in this case.
Punnet Square
Shows the probability of getting a genotype and phenotype from two parents.
Dominant allele
Masks the recessive allele
What were Mendel’s observations?
Alternative versions of genes account for variations in inherited characters.
For each character, an organism inherits two copies (that is, two alleles) of a gene, one from each parent. If the two alleles at a locus differ: dominant allele determines the organism’s appearance recessive allele has no noticeable effect
Mendel’s First Law?
Segregation of Alleles. Two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes. It’s during gamete formation and is a random process.
