Mendelian Genetics 1

Question 1

Why are fungal genetics a better representation of human genetics?

Answer 1

Eukaryotes, so more similar to humans as they have a nucleus

Question 2

What is the budding yeast? Why is it used to study genetics?

Answer 2

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)

Question 3

What plant is used in majority of genetic study?(in contrast to Mendel’s pea plant)gy

Answer 3

Arabidopsis

• Importance in basic research
• Importance in plant biology

Question 4

How is the fruit fly been used in genetics(Drosophilia)?

Answer 4

• 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

Question 5

Describe the worm (C. elegans; Caenorhabditis) as genetic model

Answer 5

-fate of each cell (about 1,000) has been mapped out during its development

Question 6

Why has the zebra fish emerged as an important model for genetics?

Answer 6

Has a transparent embryo, and development can be directly observed(model for developmental genetics)

Question 7

Why is the mouse used as a genetic tool?

Answer 7

-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)

Question 8

How are humans used as a genetic models?

Answer 8

We have the ability to self-report

• we are interested in ourselves
• we have extensive medical care and record keeping

Question 9

Why did Mendel use pea plants to study genetics?

Answer 9

• 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

Question 10

Give a brief history of Mendel’s recognition

Answer 10

• 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”

Question 11

What is the wild type?

Answer 11

• Defined as the most frequently observed allele in a population (functional allele)
• we typically do not use wild type when describing humans

Question 12

What are genotypes?

Answer 12

• Genetic make up of an indivual

- Alleles written in pairs( DD, Dd or dd)

Question 13

When are wild types typical used?

Answer 13

Used in the lab to identify the control allele that is found in the starting strain

Question 14

What does the wild type indicate?

Answer 14

The functional allele

Question 15

Are genes are good or bad?

Answer 15

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

Question 16

Most plants are _________ our gametes are ________

Answer 16

Diploid

Haploid

Question 17

What is a test cross?

Answer 17

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

Question 18

What are Mendel’s postulates?

Answer 18

• 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

Question 19

What is the MIM?

Answer 19

Started as a library project at Johns Hopkins University to catalogue all human disorders/traits that are controlled by single genes

Question 20

What is the MIM?

Answer 20

The MIM is called OMIM and is a website based source

Question 21

What is the chromosomal theory of inheritance?

Answer 21

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

Question 22

Meiosis allows for…

Answer 22

Germ/gamete cells

Question 23

What is meiosis?

Answer 23

Reduction cell division where chromosomes go from diploid 2n to haploid 1n

Question 24

State the law of independent assortment

Answer 24

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

Question 25

What are the criteria for classifying as homologous pairs

Answer 25

-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

Question 26

When do homology form synapse/ pairs?

Answer 26

During stages of mitosis

-recall during meiosis, crossing over occurs so that the gamete chromosomes are different than the somatic cell chromosomes

Question 27

Homologous contain…

Answer 27

Identical linear order of gene loci

Question 28

One member of each pair is…

Answer 28

derived from the maternal parent and paternal

Question 29

What are the two main drivers of genetic variation?

Answer 29

• independent assortment of chromosomes

- Crossing over during meiosis

Question 30

What is the function of independent assortment?

Answer 30

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

Question 31

The law do probability…

Answer 31

Help to explain genetic events and offer predictions of when something might recur

Question 32

What is product law?

Answer 32

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

Question 33

What is sums law?

Answer 33

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

Question 34

Explain the genius behind Mendel

Answer 34

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.

Question 35

What are reciprocal crosses?

Answer 35

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