Theme 4A Flashcards
what is the problematic theories from mid 1800s…
what is blending inheritance?
offspring have traits that are intermediate to their parents
ex. child and parents you can see parts of both parents in the children
what is the problematic theories from mid 1800s…
what is the theory from lamarck?
” inheritance of acquired traits” in other words, favourable traits acquired by parents are passed on to offspring
-directed evolution
if blending inheritance is the mechanism what do we tend to see?
if blending inheritance was the mechanism variation will be reduced over time
- does not reflect the constant presence of variation observed in populations
-looks at individual as a whole doesn’t look at individual traits
who is gregor mendel and what did he test?
- how did offspring pick up traits of inheritance
tested hypothesis of blending vs.particulate inheritance - used true-breeding varieties of peas
what are the certain traits mendel looked for in the peas?
seed colour
seed shape
pod colour
pod shape
flower colour
flower position
plant type
what was mendel trying to achieve?
determine whether statistical patterns in the occurrence of the contrasting traits persisted by means of crossing
1) true breeding strains (“good” phenotypes) make sure when breeding same type came out
2) focusing on single trait at a time
3) Quantitative: counted the progeny
what are two generations called in reciprocal F1 crosses?
Parent generation
(P1)
(F1) First Filial generation
What are some key aspects that determine the difference between dominant versus recessive?
Often the dominant allele codes for a functional protein whereas the recessive allele does not.
-pea colour is determined by the presence of a functional enzyme that breaks down chlorophyll
parental generation always start with true breeding? TRUE OR FALSE
TRUE
what is considered a good symbol?
mutation a mutant allele/phenotype or recessive phenotype (usually rare phenotype)
ex. Gg
what is segregation of alleles, and explain the single character (monohybird) cross?
There is a parental generation: cross two true-breeding varieties with a different phenotype
F1 generation seeds (Filial) : F1 “self-fertilize”
F2 generation seeds: the parental generation appeared again.
goes against blending inheritance. Mendel saw green plants come back.
- clear ratio to 3:1
what did mendel propose from segregation experiment?
Principle of segregation tested by predicting the outcome of crosses
- the expected ratio of dominant to recessive phenotype is 3:1 phenotype ratio
- Expected genotypic ratio.
A/A:A/a/aa
1:2:1 - 1 homozygous dominant
- 2 heterozygotes
- 1 homozygous recessive
the punnet square makes two strong predictions what are they?
-seeds in the F2 generation showing the recessive green phenotype should be homozygous recessive a/a.
- the A/A and A/a genotypes: distinguished by seeds produced when F1 is self-fertilized
What was mendels hypothesis of particulate inheritance?
- all adult plants replicate through sexual reproduction carry two factors that contribute to the phenotype or inheritance character (ex. wrinkled vs smooth)
- if individual pair of genes consists of different alleles, one dominant over the other.
- Mendel ideas to meiosis:
pair of alleles that separate in formation of gametes.
so in case of mendel we have these 2 copies of these factors, and for every sperm or egg that is produced from these plants gonna get one of these 2 factors: - half gametes (haploids) have big A half have little a
what is mendels principle of segregation?
idea that in a deployed organism each gammy is going to get one allele from each parent
