Lesson 5: Mendelian Genetics Flashcards
what is a trait
a particular version of an inherited characteristic
examples of traits
features like a persons eye colour, the shape of the leaf, colour of a flower, colour of a pea, etc.
what was the past belief of how traits were inherited?
it was assumed that traits were a blend from the two parents (ex: black bird and white bird makes grey bird)
who is gregory mendel and what did he discover/do
he was a monk and a biologist, and he was one of the first successful scientists to answer the question of how traits are inherited
- he conducted a series of experiments with garden peas
what type of experiments did mendel conduct + whyd he pick that specific species
experiments with garden peas- chosen because it reproduces quickly and it was easy to control which parents produce offspring
the pea plants have both male and female reproductive organs, so, the peas can either..
- self fertilize (self-pollinate)
- cross-fertilize (mate with others)
what are true breeding plants, what happens when they reproduce by self pollination/sexual reproduction, and give an example
plants in which their offspring will have the same traits
- when these plants reproduce by self pollination or sexual reproduction with ANOTHER true breeding plant, the offspring produced will have the same traits
EX: purple flower true breeding plant will produce only purple flower offspring
what are hybrid plants
the offspring of two different true-breeding plants
what are crosses, and why did mendel do these processes?
crosses are controlled experiments- he did them to test how these traits were inherited through the use of true breeding and hybrid pea plants
in mendels experiements, what had to happen in order for plants not to self pollinate?
the male reproductive organs (the anther) was removed to prevent self-pollination
what is the generation of two true breeding plants called
parental (P) generation
what is the generation of hybrid offspring called?
filial (F1) generation
a new generation created from the F1 generation (with mixed traits) is called what + what is it a result of?
called the F2 generation- its a result of a MONOHYBRID CROSS
what are some information we can determine about traits based off mendel’s experiments?
- the F1 generation always resulted in purple flowers even though they had one white and one purple flower parent
- this didnt fit the “blending” hypothesis from the past
- this showed that one trait was masking the other (purple masked white)
what happened with the traits in the F2 generation? what ratio did it have and based off these results, what did mendel come up with?
the white flower trait reappeared
- the F2 generation consistently had a 3:1 purple to white flower ratio
- from these results, mendel came up with the first law of mendelian inheritance + the law of segregation
first law of mendelian inheritance (what did mendel conclude of how traits were passed on)
mendel concluded that traits must be passed on by discrete heredity units which he called factors
- he hypothesized that even if factors are not expressed in an individual, they may still be passed on
what are the different factors (in F1 generation)
- dominant factor (factor that is expressed)
- recessive factor (factor that remained, but was hidden)
what are alleles and what role does it play in homozygous and heterozygous
alternate version of genes
- if both of your alleles are identical you are homozygous
- if your two alleles are different you are heterozygous
what are the types of alleles
- dominant alleles
- recessive alleles
how are dominant alleles and recessive alleles represented with (letter wise)
dominant= uppercase letter
recessive= lowercase letter
what exactly does dominance mean in alleles
refers to which gene is EXPRESSED if two different alleles are present
- it doesnt have anything to do with a gene being better, more common, or stronger
mendel’s law of segregation (what did the law of segregation hypothesize and what does it state)
the law of segregation was used to hypothesize why the 3:1 ratio was present in the F2 generation
this law states:
- each organism carries two factors (genes) one from each parent for each characteristic
- parent organisms donate only one copy of each gene in their gametes
(^this was long before we had any knowledge of the chromosome)
genotype vs phenotype (what are both and how do they differ + provide examples of each)
the phenotype is the trait of an individual which is expressed
EX: a pea plant may have a purple flower or tall stem phenotype
the genotype is the individual genes an individual presents
- you cant determine this in all cases by what it looks like
EX: if you have purple flowers you are not certain if the genotype is Pp or PP
how do we predict inheritance of alleles
we can study and predict the possible genotypes of offspring by the use of punnett squares
- it is a grid system where parent 1 and 2 alleles are shown and it shows the possible genotypes of offspring
practice lots of scenarios and questions
