AP Bio Chapter 14 Part 1 Flashcards
Describe the 1800s conceptions of inheritance
The “blending” hypothesis: every offspring has a blend of traits from its parents
What was Gregor Mendels occupation
Monk
Why is the blending hypothesis incorrect
If blending were actually the way things worked, then all variations produced would be diluted over the generations
Why were peas chosen in the experiment
Easy to grow, maintain, and control mating
Lots of babies
Conspicuous traits
Quick generation time
What was mendels experimental method
- Establish “true breeding” lines for particular traits
- Start crossing the lines
- Count the offspring that show particular traits
What does P describe
The parental generation (true breeding plants)
What does F1 generation mean
First filial generation
What does mendel’s data show for any trait
When 2 different lines are crossed, the first generation offspring (F1) only shows one of the traits
When the F1 generation is crossed, both traits are shown in the F2, always in a 3:1 ratio
What did Mendel conclude
There are 2 alleles. Sexually reproducing organisms have 2 versions (alleles) of any gene. One from mom, one from dad.
Allele
Different versions of the same gene.
What’s the relationship if dominant and recessive
When an organism has 2 alleles, one (dominant) will be expressed over the other (recessive)
Phenotype
The physical characteristic that actually shows up(tall, short, etc)
Genotype
The combination of alleles (homozygous dominant, heterozygous)
What is different about his experiment now?
This is a “modern” restatement of Mendel’s conclusion. We are now aware of many exceptions which do not invalidate the conclusion
Law of segregation
Only one allele for a trait goes into a gamete
Law of independent assortment
Seoerate alleles for separate traits are passed independently of each other—as long as the alleles are “unlinked” (on separate chromosomes)
Who created the Punnett square
Reginald punnett
What does a dihybrid cross look like
YYRRxyyrr
What does it mean if the F2 is 3:1
Located on the same chromosome (linked)
Independent assortment only works on
Genes on different chromosomes
What is blending between
The blending of traits between 2 parent traits
How is the law of independent assortment explained
The behavior of chromosomes during metaphases and anaphases of meiosis
Recombinant offspring
Independent assortment can lead to combinations of traits in offspring that are different from the traits of their parents
What did Mendel as his main findings
Every version of a trait has 1 dominant and 1 recessive
How many boxes in a trihybrid cross
246
How are test crosses used to determine genotype of parents
Breeding an organism of an unknown genotype with a recessive homozygote, recording phenotype of offspring
Homozygous
Organism with a pair of identical alleles for the gene controlling a character
Heterozygous
Organism with a pair of different alleles for the gene controlling a character
Mono hybrid cross
Crosses parents of different traits with one factor
Dihybrid cross
Crosses parents of different traits
2 factors
