Chapter 14 - Mendelian Genetics Flashcards
What did Mendel’s particulate hypothesis theorize?
That some trait is being passed from parent to child
What are alleles?
The physical expression of a gene located on a chromosome (aka active trait)
Why did Mendel choose pea plants as his model study subject?
Because pea plants are easily accessible, can easily be pollinate with various other pea plants and they produce offsprings quickly
What are the parental generation in the pea plants?
The very first two plants that are cross pollinated
What’s the concept of true breeding?
True breeding involves in offsprings that have homozygous traits, the same as their parents did (TT)
What’s F1 generation in context of the pea plant experiment?
The offsprings of P generation plants, they are a hybrid between two true breeding generations.
Only one physical characteristic is expressed
What are F2 generations in context of the pea plant experiment?
F2 generations are the offsprings of the hybrid generation F1. In these generations, we can see variability in traits in a orderly ratio. (3:1)
Did the F1 generation ever produce white flowers in Mendel’s experiment?
No, they never produced white flowers because the hybrid generation only expressed either one characteristic every single time they were crossed over.
What laws did Mendel come up with from the experiment?
- Alleles exist that cause some characteristic to be passed on to offsprings
- There is only one allele for each characteristic that’s passed on from each parent (aka TT and Tt)
- One allele is more dominant/prevalent than the other in an offspring
- During meiosis, alleles from each parents seperate causing only one allele to be passed on
Are alleles just genes?
Yes, they are the genes on chromosomes but alleles refer to specific traits such as eye color on the chromosome.
What are homozygous traits and what are heterozygous traits?
Homozygous traits contain two alleles that are the same (PP)
Heterozygous traits contain two different alleles (Pp)
How exactly are the alleles of the same trait different?
one can be more recessive and one can be more dominant than the other
F1 generations alleles are reffered as being completely
Homozygous
F2 alleles can be both
Heterozygous and homozygous
What is the sequence of DNA that’s been written for a particular allele called?
Genotype
What’s the physical manifestation of an allele called?
Phenotype
What did mendel figure out by crossing the green and wrinkled and yellow and smooth pea plants together?
That when alleles of two different traits are indepdent, they provide more variation in the offsprings.
However if the alleles of traits were on the same chromosome, the result would have been something more simpler.
Why do the probability laws apply to genetics?
Because the alleles and their dominance/reccessiveness governs the likeliness of allele distribution in offsprings
What probability laws apply specifically?
Multiplication rule = applies to independent events (when alleles on different chromosomes)
Addition rule = applies to mutually exclusive events
How does the multiplication rule apply to the genotypes?
The multiplication rule applies to the genotypes because we multiple the alleles of two parents against each other
How does the addition rule apply to the phenotypes?
To calculate the ratios, all the similar offspring’s alleles are added up.
What’s the concept of incomplete dominance?
When F1 hybrids’s parents alleles are neither dominant or reccesive over one another, it results into a mixed result
What is codominance?
Codominance is when there no allele can mask the other allele’s appeareance. So black and white alleles aren’t blocking or masking each other and when an offspring has both, both of them show up.
AB Blood type is an example - when both blood types show up because neither blood type is actually blocking the other.
What does epistasis do?
When there’s a gene for a particular characteristic whose expression is being controlled by another gene.
So in allele GgKk, the allele Gg is controlling whether Kk is shown or not
What’s the difference between polygenetic inheritance and epistasis?
The difference between them is that polygenetic inheritance causes a range of different results but epistasis causes 3 major seperate results
What is polygenetic inheritance?
When a characteristic is controlled by more than one gene such as color being determined by multiple different genes. This causes a wide range of phenotypes to occur.
Does environment change genetics?
It can influence them
How exactly does the environment change the genetic expression in organisms?
The environment’s different elements’ presence can change the gene expression. So two exactly same genotypes can actually have very different results depending on what exists in environment.
Why are pedigrees helpful?
They help analyze what the offsprings’ phenotypic expression can be like