Updates: Quiz average: 76% Project proposal grades/edits on d2l, attached to COMMENTS in DROPBOX. You will turn in a final draft, your final grade will be the average grade of the first and second drafts Genetic Diseases will be graded by next week (out of 60 points) 1

Groups Silvia, Nikko, Samantha, Breanna Ryan, Marissa, Sowmiya, Brian Keith, Cameron, Kaitlyn, Pam Iris, Kevin, Courtney, Ben Siddesh, Jessica, Thelma, Vick Christie, Mayzia, Danielle

3 Dividing & Delivering Distributing genetic information How?Why?

Goals for today Scaling: Nucleotide, Gene, Chromosome--and how many of each Concept: Chromosomes are hugely long threads of DNA; some regions are genes PURPOSES of ‘mitosis’ & ‘meiosis’ & how these dictate the events Mixing and matching parental DNA made you. It provides hope that you’re “better” than them! 4

The birthday cake gene metaphor You are a birthday cake-making company! A call comes in to order a cake for delivery. What information must you take? You’re an old fashioned mom-and-pop place; no photos 5

6 Scaling A gene is ~1, ,000 basepairs* A chromosome is tens or hundreds of thousands of genes A genome is 1-100s of chromosomes A genotype refers to the alleles present in a given genome Human genome is ~3,000,000,000 basepairs Human genome is (currently guesstimated at) ~20-30,000 genes** Human genome is ~1 meter of DNA *Includes control regions & stuff that won’t make it into the final product **We keep finding stuff that matters

Mitosis and Cell division Gene: A stretch of DNA that represents all the information for a product as well as when and where to make the product (What product? Cake metaphor) Allele: A version (or flavor) of a gene; two alleles of the same gene my differ by a nucleotide or dozens of them-- generally a small number Dominant/recessive: Two alleles enter; one allele leaves (which version manifests in the organism) NOT which version is more common! More in the lab manual & Vocab exercises! 7

Windows on the gene: eyes Find a brown- and a blue-eyed person. Look deep into their eyes & try to figure out the difference What does it mean genetically when we say ‘brown eyes are dominant’? One gene, two alleles Why should that be so? What do brown alleles got that blue do not? 8

Ripped from the headlines Blue eyes arise from a DNA change that prevents creation of melanin in the eye specifically Mutation appears identical in all blue-eyed folks, suggesting…? Headline: Blue eyes result of ancient genetic ‘mutation’ Headline It’s not a ‘mutation’; it’s a mutation 9

Mitosis and Cell Division How many cells When you were “0”? Now? What do cells DO? 10

What happens in each “Stage?”

What if a cell isn’t “listening”? Malignant Tumor – grows aggressively, invades surrounding tissue, metastasizes Benign Tumor – lacks malignant tumor’s properties Benign tumors CAN cause “mass effects” 13

It’s all in a name Chromosome Gene Chromatid Allele Homologous Dominant Recessive Spindle Fiber Centromere

1 “Chromatid” can also be a chromosome; it has all the genes on it.

1 “Chromatid” can also be a chromosome; it has all the genes on it.

1 “Chromatid” can also be a chromosome; it has all the genes on it. This

1 “Chromatid” can also be a chromosome; it has all the genes on it. This Is just a copy of this

So, in this scenario…

From Mother Chromosome 1 Chrm 2

From Mother Chromosome 1 Chrm 2 From Father Chromosome 1 Chrm 2

This is a DIPLOID Nucleus/Cell

Chromosome 1 (from mother) Chromosome 1 (from father)

Chromosome 1 (from mother) Chromosome 1 (from father) Copied during Interphase Copied during Interphase

Chromosome 1 (from mother) Chromosome 1 (from father) Copied during Interphase Copied during Interphase

So after replication…

Chromosome 1 (from mother) Chromosome 1 (from father) Condensed versions during mitosis/meiosis Chrm 2

This is ALSO a diploid nucleus/cell

This is a DIPLOID Nucleus/Cell

Mitosis and Cell Division Why are chromosomes usually shown like this?

Touching mitosis & meiosis 32

Meet the Chromosomes Compare our bead models with image What corresponds? 33

Genotype, phenotype Pick two traits Pick a dominant & recessive outcome arising from different alleles You all start off heterozygous 34

35 Symbolism String of beads = chromosome = double-stranded DNA bead = gene Pay close attention to the nipples!

Mitosis Manually Point at some of your cells that ‘do’ mitosis? What’s the goal/purpose of this thing called ‘mitosis’? So what must the first step be? Do it. Now what must be achieved? Any half? If not, how pick the appropriate half? How do your final results compare with starting? 36

Your brain: A lousy place to do your thinking You can do a lot of fuzzy math (and fuzzy biology and fuzzy chemistry and fuzzy...) up there Drawing/speaking/writing forces precision; reveals missing links 37

Mitosis and Cell Division What are homologous chromosomes? Show me a chromosome and it’s homolog How does cell know they go together? Show mitosis! Put an * next to any diploid cell! 38

What comes after mitosis? 39

Clear your mind Go outside & take a lap around the floor (Come back in 5 minutes!) Yeah. Go 40

Meiosis: the other cell division 41

Why have sex? Suppose I’m Jack Sprat; you’re my wife. I have the mutant form of the fat-eating gene; you of the lean-eating gene If we reproduce asexually (mitotically), how long until some descendant can eat a whole pig? If sexually, i.e. by taking parts of our holdings & throwing them together in an offspring? 42

Meiosis Why have sex? What do you want the cells to look like at the end of meiosis? How much are you ‘like’ your mom and dad? Do ‘mother’ chromosomes have to stay together? 43

44 Show Me How it’s Done!

Dances with Genes First, make a copy--b/c that’s the way it happens Pair the pairs: duplicated mom’s & dad’s contributions pair 45

Meiosis - Recombination Where should the circled site on Chromo1 recombine with Chromo2? 1 2 3

47 Show Me How it’s Done!

Now we’ve recombined; how to separate? When you’re a gamete, go fuse with a classmate Stop by and show me the genotype 48 Meiosis - Recombination

Clean up 49

Blinding you with Science (jargon) II Linked/Linkage: Referring to whether genes are tethered to one another by virtue of being ‘close’ on a chromosome Linked: referring to the resulting behavior of traits encoded by such genes 50

Get in your group around a Computer! Load Gameter don’t log in, just play with the program Load Gameter Interface walk-through: designing the parentals A & B close together on Chromosome II, A further to the right than B, A/A and b/B 51

Gameter Explore One meiosis 200 meioses Move ‘em around and try again Observe Hypothesize Test Evaluate 52

53 Homework