chapter 14 Flashcards
Who was Gregor Mendol?
A geneticist who primarily worked with pea plants.
Because there was a wide variety of pea plants available with easily identifiable traits.
- seed shape, seed color, height, etc.
- variety of plants that had slight variances but could be breed together.
What does a perfect flower mean?
male and female parts in the flower.
What are the male parts of the flower?
What are the female parts of the flower?
Stamen: anther and filament- produces the pollen.
Carpel: stigma, style, ovary- receives the pollen
What are the means in which a flower can reproduce?
Selfing: the pollen from one flower to fertilize eggs of that flower or different flower within that same plant.
- over many generations results in a true breeding line.
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Cross feralization: occurs when you take pollen from one plant and use that to fertilize the eggs of an entirely different plant.
What is a true breeding line?
line that allows exhibits a particularly interesting trait.
via selfing.
How did Mendel have his pea plants reproduce.
- Dude did it manually.
- Manual outcross: pick up pollen on plant with a fine tip brush and manually insert that on anther plant’s carpel structure.
What experiment did Mendel use reciprocal crosses for and what was he trying to prove?
- What is a reciporcal cross?
- talk about the experiment he used, don’t waste time mastering it just understand what the point it.
Reciprocal cross: when do crosses between…idk like sativa and Indica ( strands).
1st: dad is sativa and mom is Indica, then
2nd: dad is indica and mom is sative.
- Both must be of true breeding lines.
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For example:
1.) trait of interest is seed shape: round vs wrinkled.
2.) initially, he took pollen from a true breeding male plant who always generated round seed.
3.) He used that male plants pollen to fertilize the carpels of female true breeding plant, who always produced wrinkled seeds.
4.) Then he ran the bitch in reverse, and took pollen from a true breeding male who only generated winkled seeds.
5.) then used that pollen to fertilize the carpels of anther true breeding plant who only produced round seeds.
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- Findings: results of both reciprocal crosses were identical.
- no matter which parent gave the round seed trait it was always what their offspring contained.
- Round seed always appeared.
What does reciporcal crossing suggest?
- it doesn’t matter where the genetic determinant originates from (pollen or egg), each gamete had equal drive in the offspring genotype.
What was Medel’s second experiment and what did it test?
- What did it prove?
- Tested the blending hypothesis of inheritance: ( not wrinkled slightly wrinkled seeds like the reciporcal crossing predicts.)
- Null: one dominant trait.
- we are crossing two breeding lines of plants: round vs. wrinkled seeds.
- cross the plants again and watch for the results after the next two generations.
- takes male pollen of a round seed generator and pollenates a female plant generates wrinkled seeds.
- off spring, or F1 generation is all round seeds.
- The F1 generation is breed amongst itself, or heterozygote x heterozygote…
- generating 25% - wrinkled and 75% - round of the next gen: F2
- )
- round seed was dominant
- and the genotype of F1 was predominantly heterozygous.
What was the hypothesis of reciporcal crossing, what was the null?
- one of the two traits present would dominate over the over.
Null (blending hypothesis): the product of the reciporcal crossing led to a heterogenous individual. i.e. slightly wrinkled seed shape.
What does true breeding lines result in?
- homozygous, two identical alleles for the gene that encodes a specific trait.
What is progeny?
- context clues makes me think offspring.
What is heterozygous progeny?
Offspring have two different alleles encoding for different traits
What is a monohybrid cross?
- essentially make a punnet sqaure for two individuals that are heterozygous for the same trait.
- Which results in 25% homozygous dominant.
- 25% homozygous recessive
- 50% heterozygous .
What were Mendel’s claims?
What were the modern day responses?
- pea plants must have two copies of each gene making it possible to for any one pea plant to have two different alleles.
- This is true for many other organisms
- Genes are discrete particles of inheritance, they don’t get modified from one generation to the next.
- genes do not change when being transmitted between generations.
- Each gamete contains one copy of each gene.
- This is due to principle of segregation- the members of each pair segregate during the formation of gametes.
- males and females equally contribute to the inheritance of their offspring.
- When gametes fuse, offspring acquire a total of two of each gene- one from each parent.
- some alleles are dominant to others.
- When a dominant and recessive allele for a gene are paired in a heterozygote, that individual has the dominant phenotype.
