Mendelian Genetics 1 Flashcards
Why are fungal genetics a better representation of human genetics?
Eukaryotes, so more similar to humans as they have a nucleus
What is the budding yeast? Why is it used to study genetics?
Saccharomyces cerevidae
- Small compact genome-means that most of the genome actually codes for proteins
- Very short regions of non-coding sequence between each gene (open reading frame)
What plant is used in majority of genetic study?(in contrast to Mendel’s pea plant)gy
Arabidopsis
- Importance in basic research
- Importance in plant biology
How is the fruit fly been used in genetics(Drosophilia)?
- Among other things, has emerged as an important model for development
- Many of the most important genes that control development in humans were first identified in the fruit fly
Describe the worm (C. elegans; Caenorhabditis) as genetic model
-fate of each cell (about 1,000) has been mapped out during its development
Why has the zebra fish emerged as an important model for genetics?
Has a transparent embryo, and development can be directly observed(model for developmental genetics)
Why is the mouse used as a genetic tool?
-It’s a mammal
- long history of inbred strains;
- Backcrossed 1000s of times
- Reduced genetic heterogeneity in lab strains
- Allows controlled experiments(allows for homozygous/heterozygous test)
- Huge repertoire of genetic tools for manipulation
- Able to make gene knock-out mouse models (also helps when studying a single gene/disorder)
How are humans used as a genetic models?
We have the ability to self-report
- we are interested in ourselves
- we have extensive medical care and record keeping
Why did Mendel use pea plants to study genetics?
- easy to grow
- allowed for studying of true breeding strains (homozygous for an allele)
- Controlled mating: self-fertilization of cross-fertilization
- Grow to maturity in one season
- Many observable characteristics with two distinct forms(alleles)
- He made a lot of gardens and counted everything
Give a brief history of Mendel’s recognition
- Studied in the mid-19th century; published in a scientific journal, and then forgotten. Rediscovered in early 20th century
- One of the first examples of a study using “quantitative biology”
What is the wild type?
- Defined as the most frequently observed allele in a population (functional allele)
- we typically do not use wild type when describing humans
What are genotypes?
- Genetic make up of an indivual
- Alleles written in pairs( DD, Dd or dd)
When are wild types typical used?
Used in the lab to identify the control allele that is found in the starting strain
What does the wild type indicate?
The functional allele
Are genes are good or bad?
A gene may be functional (and good) under one environmental condition AND non-functional or deleterious (bad) under another environmental condition
Genes are neither good nor bad
Most plants are _________ our gametes are ________
Diploid
Haploid
What is a test cross?
Determines if individual displaying dominant phenotype is homozygous or heterozygous for that trait
Cross between gamete derived from an organism with dominant phenotype and gamete derived from homozygous recessive organisms
What are Mendel’s postulates?
- unit factors(gene) exist in pairs
- Dominance/recessiveness
- Segregation(pared unit factors(alleles) separate independently, randomly during gamete formation)
-independent assortment for discrete traits, one doesn’t affect the other
Example. Yellow vs green seeds doesn’t affect wrinkled vs smooth seeds
What is the MIM?
Started as a library project at Johns Hopkins University to catalogue all human disorders/traits that are controlled by single genes
What is the MIM?
The MIM is called OMIM and is a website based source
What is the chromosomal theory of inheritance?
The genetic material in living organisms is contained in chromosomes
- recognized in the late 19th century
- At the time, not known (of course) that this was as alleles of genes that consist of a “code” in the sequence of DNA
Most of our cells are in a “diploid” state
-That is we have one set of chromosomes from our father (paternal) and one set from our mother(maternal)
-meiosis allows creation of haploid germ/gamete cells
Meiosis allows for…
Germ/gamete cells
What is meiosis?
Reduction cell division where chromosomes go from diploid 2n to haploid 1n
State the law of independent assortment
All possible genetic combinations are formed with equal probability
After meiosis 2 the sister chromatids separate, so 4 gametes are formed from each gamete progenitor cell
What are the criteria for classifying as homologous pairs
-both have the same chromosome number
- Both are size and exhibit identical centromere locations
- X and Y chromosomes in mammals follow their own rules
- X and Y have a pseudo autosomal region, so during mitosis, meiosis they can pair up
When do homology form synapse/ pairs?
During stages of mitosis
-recall during meiosis, crossing over occurs so that the gamete chromosomes are different than the somatic cell chromosomes
Homologous contain…
Identical linear order of gene loci
One member of each pair is…
derived from the maternal parent and paternal
What are the two main drivers of genetic variation?
- independent assortment of chromosomes
- Crossing over during meiosis
What is the function of independent assortment?
Allows an individual to produce genetically dissimilar gametes
2^23= 8 x 10^6
But to gametes come together so the amount of genetic variation becomes doubled for each conceived becomes:
(8x10^6)*2= 64x10^12
The law do probability…
Help to explain genetic events and offer predictions of when something might recur
What is product law?
Calculates probability outcomes occurring together (all have to occur for the final outcome to occur)
Coin toss of penny and nickel, probabilities of heads or tails of each at the same time
Ex. 0.5 x 0.5 = 25% chance(find probs for each combo it can happen)
Summary : this must happen AND that must happen
What is sums law?
Calculates probability of outcomes independent of each other.
Probability of tossing our penny and nickel and obtaining one head and one tail?
Used For counting up all independent events that can occur irrespective of each other. In other words: this could happen or that could happen
Explain the genius behind Mendel
It was supposition that something unseeable (the gene, the genotype) was controlling “traits” (the phenotype) that he could see.
-results hold true for reciprocal crosses-not sec dependent
- F1 and F2 patterns of inheritance similar regardless of P1 source
- dwarf plant pollinates tall plant
- results for F1 and F2 are the same.
- dwarf plant pollinates tall plant
What are reciprocal crosses?
Crosses made in both directions
Yellow, round x yellow and wrinkled x green round
BOTH yield yellow, round so those are the two dominant traits
