Interested in Being a Preceptor? Reinforce your understanding of Bio182 topics Help peers navigate...

Interested in Being a Preceptor?

• Reinforce your understanding of Bio182 topics

• Help peers navigate 182L

• Help make the course better

• Learn teaching techniques while earning 3 credits

Interested in Being a Preceptor?

• Work with TAs to teach and develop labs

• Travel to exotic locations (okay, not that)

• Contact Kevin Baker (kbaker2@email.arizona.edu) for more info (link on Bio182L homepage)

Lab 9: In a Family Way

Goals for Today:

• Understand properties of light and molecules

• Dark side of recombination

• Develop skill at deducing genotype by observation of phenotype and inheritance patterns

What is “color”?

And how do we ‘see’ it?

Higherenergy

Wavelengths (nm)

Gamma rays

X-rays Ultra-violet

Infrared

Micro-waves

Radiowaves

Shorterwavelength Visible light

Longerwavelength

Lowerenergy

nm

Looking in at looking out

http://www.bio.miami.edu/dana/pix/retina.jpg

Looking Deeper

Where are we?

The difference between 2 and 3 receptors…

Or, the beautiful colors of fall

Can ~10 million American males be wrong?

http://www.rgblind.com/

http://www.rgblind.com/

http://www.rgblind.com/

What IS ‘color’?

The brain’s interpretation of the eye’s report of (three) samplings of a narrow bit of the electromagnetic spectrum

Higherenergy

Wavelengths (nm)

Gamma rays

X-rays Ultra-violet

Infrared

Micro-waves

Radiowaves

Shorterwavelength Visible light

Longerwavelength

Lowerenergy

nm

Higherenergy

Wavelengths (nm)

Gamma rays

X-rays Ultra-violet

Infrared Micro-waves

Radiowaves

Shorterwavelength Visible light

Longerwavelength

Lowerenergy

nm

If the light is red (680 nm), which receptor do you expect to ‘hear’ it more loudly?

‘gre

en

’ recep

tor

‘red

’ recep

tor

How do you get a ‘new’ receptor?

What’s in an Opsin

• Week 9 calendar: click on ‘Go_Opsin’ link

• Retinal eats the photon -> changes shape– Change is directly transmitted to change in

opsin (which is holding retinal)

• Work through the handout

Launch ‘Opsinize’• Starting with “red-tuned” opsin (559

nm)

• Your objective: make a ‘green-tuned’ (as close to 531) nm

• Your tool: mutating codon sequences

• From each menu you can mutate the codon (which reflects changes in DNA)

3-Letter Code• Ala: Alanine

• Arg: Arginine

• Asn: Asparagine

• Asp: Aspartic Acid

• Cys: Cysteine

• Gln: Glutamine

• Glu: Glutamic Acid

• Gly: Glycine

• His: Histidine

• Ile: Isoleucine

• Leu: Leucine

• Lys: Lysine

• Met: Methionine

• Phe: Phenylalanine

• Pro: Proline

• Ser: Serine

• Thr: Threonine

• Trp: Tryptophan

• Tyr: Tyrosine

• Val: Valine

Thinking it through…

• Shown: the only amino acid differences between red and green opsins

• DNA sequences would be… how similar?

• What happens in meiosis when the maternal and paternal chromosomes pair?

• Think anything might ever go wrong?

How do you get a ‘new’ receptor?

• What’s the ‘easiest’ way to get a slightly different protein?

– Make a new segment of DNA that happens to be similar

– Start with a random stretch of existing DNA and randomly mutate until…

– Copy the original gene and ‘tweek’

Remember Recombination?

Things don’t always go smoothly

Where to Recombine?

Oooooops

2

G G

How do the restriction enzymes ‘know’ whereto cut and recombine?

G G

But….

G

G

So…..• Is it easier to make a gene, or tinker

with an existing one?

G

G

So what if this gamete

‘fertilized’ with...G

This one

G G

G

How many colors?

But what if you alteredthe protein to make it

sensitive to a different wavelengthR

NOW what do you have?

Red and green 98% similar.Why?

“New” Genes – Sound Familiar?

“New” Genes – Sound Familiar?

• Green -> “Red” Opsin

• Myoglobin -> Hemoglobin

• Adult vs. Fetal Hemoglobin

What’s seX got to do with it?

• The “X” is big

• The “Y” not so much

• What does this mean?

What’s seX got to do with it?• Autosomal: chromosome NOT X or Y• Sex chromosome: X or Y (b/c of where each is

joined together during meiosis)• Symbolism: normally, we don’t care what

chromosome given allele is on; in sex, it matters

– On the X, we designate : XA, Xa

– On the Y, generally designate: Y How come no A or a?

• Hemizygous

What’s seX got to do with it?• Consider A and a

• How many genotypes for females? Males?

• How many possible crosses?– How to distribute

What’s seX got to do with it?• Consider A and a• How many genotypes for females? Males?• How many possible crosses?

– How to distribute

• Do the cross– How can you tell it’s sex-linked?– Compare sex-linked crosses to corresponding

autosomal• What is the equivalent of Y?

It sucks to be XY• R/G Colorblind

• Hemophilia

• Different anemias

How is this useful?

Pedigrees!

PTC and parentage• WASH HANDS

• Who can taste this?

• Separate into haves, have-nots

• Each: if trait is dominant, what can you deduce about your parents?

• If trait is recessive?

Boys Girlsvs

Makin’ BabiesPair up, decide who’s the adult consenting male & who the similarly conscientious female

You’re both heterozygotes (recall: ‘different-pairing’)

Make the babies--hold an allele in each hand, partner picks

How to determine the sex of the baby?

Pediducer

Deductions from Pedigrees

Two Phases• Phase I: Assign genotypes and justify

• Phase II: Rule model “plausible” or “out”

PediducerRules and Conventions

• What assumption about randomly selected, ‘healthy’ individual?

• Justification is “Outsider”

• REASON must be sufficient & necessary

PediducerRules and Conventions

• What does affected indiv. look like?

• You are TESTING models– How many right for model to be right?– How many wrong...

• Justification

• “Check me”

Explore• Menu progression: left to right

• If not logged in, first menu tells you what the ‘answer’ is

• Third menu specifies the model you are currently considering

• You are seeking to prove (how much data?) or disprove model (how many internal contradictions?)

NO POINTS!!!!!

If you don’t rule models in/out

Preparing for next week

Let me intreduce myself

• RHC=O + H2O => RCOOH + 2H+ + 2e-

• 2CU2+ + 2e- => 2Cu+

• 2Cu+ + 2OH- => Cu2O (red ppt.) + H2O

Who is oxidized (loses electron ownership--often to oxygen)?

Who is reduced?

Reagents for glucose (do all three)

• 1% glucose

• 0.2% glucose

• water

Capturing CO2

H2O + CO2 -> H2CO3

H2CO3 -> HCO3– -> CO3

2–

CO32– + Ba2+ ->BaCO3 (white ppt.)

53

Do it!• Appendix C--the supplies are on your benches• Do the Benedict’s test on C-1 (substituting 0.1% glucose for the 1%

starch indicated)

• Candidate solution = glucose

• Do the CO2 test on C-2– Place dry ice in flasks with appropriate tubes/stopper– Why dry ice?

If you don’t rule models in/out

Homework Pediducer: Three complete pedigrees solved to the plausible/ruled out for each of three hypotheses