Lecture 1 - genetics alter how you live

Intro to Genetics, Mendel vs Molecular Bio (causation), Genomics

What is the Central Dogma?

central idea of the process of DNA: DNA →(transcription) RNA →(translation) Protein

• how info is stored

What does Central Dogma NOT explain? (2)

1. inheritance; process of how genes are passed down from parent to offspring (eg. meiosis, mitosis)

   • can be measured either quantitavely or qualitatively

2. Trait/Phenotype: types of characteristics/what the characteristic is

Connection of Genotype, Allele, Gene?

Gene has a lot of alleles which when bred together creates a myriad of genotypes

What are the 3 mechanisms for how proteins are created?

1. Transcription

2. Translation

3. Replication

What is a Gene?

a UNIT of function that is expressed/coded

• whether that be traits or phenotypes

(ie. Promoter → RNA → Protein)

trait vs. phenotype

trait: quantitative (eg. height)

phenotype: qualitative (eg. brown eyes)

What were the 2 models of inheritance before Mendel?

1. Particulate: Particles that combine and separate (eg. yellow + blue = green → green + green = y/b)

2. Blending: combination of particles that do NOT separate (eg. yellow + blue = green)

   • can’t skip generations

Characteristics of Mendel Model when it came to Pea Plants? (3)

1. Fast Generation Time

2. Lots of Progeny; Mating could be selective

3. Peas had Bimodal Traits → allowed to test the 2 inheritance models (will offspring show separate or combined traits)

4. genes were diploid (simpler when testing for inheritance)

What does Genomics tell that Mendel doesn’t?

able to recognize genes that are not expressed as a phenotype

What is true-breeding?

idea that if only one trait is present or recessive, only that trait will be passed down or shown when parent with same trait is bred together 

What is test-cross?

Mendel’s hypothesis that the dominant gene is 2 different alleles whereby when crossed with another breed → the progeny phenotype will all be dominant

What are the postulates in genetics?

Parents genes are diploid (each have 2 alleles)

• each allele separate to determine a new genotype independently (ie. Mendel’s Model of Inheritance)

How many Genomes in our bodies?

2 genomes; the nucleus & mitochondria

in plants; (3) nucleus, mito, plastids 

bacteria >1

Conditionality?

Ability to respond to different levels based on conditions met

(eg. sensitivity to adrenaline in different situations)

Dimorphic vs. Discrete traits

1. Dimorphic: traits that are distinctly different like sex in a population or wingspan; X-linked trait

   • can involve discrete traits

2. Discrete: traits that is inherited continuously from distinguishable alleles (eg. pea plants)

Explain Meiosis & Mitosis Process:

Quick rules (how I decide)

• Meiosis I anaphase: homologous chromosomes (each still made of two sister chromatids) separate. So the things moving to opposite poles are double-armed chromosomes (drawn as V’s made of two closely-spaced lines) and the two members of a homologous pair will carry different alleles (e.g. one double-V labeled A and its homolog labeled a).

• Meiosis II anaphase: sister chromatids separate. You see single chromatids (single V lines) moving apart; each resulting chromatid carries one allele (A or a), and the starting cell was haploid for that chromosome (so both chromatids of a homolog have the same allele).

• Mitosis anaphase: sister chromatids separate (like meiosis II), but because the parent cell was diploid, each pole receives one chromatid of each homolog, so after separation each daughter will have the same set of alleles as the mother (heterozygosity preserved).

• Impossible: any drawing that shows contradictory allele patterns on a single chromatid (for example a single chromatid labeled with two different alleles for the same locus) or a pattern that cannot arise from normal replication/segregation.