Transcript Chromosome 1

Updates:
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Quiz average: 76%
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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
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Genetic Diseases will be graded by next week (out
of 60 points)
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Groups
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Silvia, Nikko, Samantha, Breanna
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Ryan, Marissa, Sowmiya, Brian
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Keith, Cameron, Kaitlyn, Pam
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Iris, Kevin, Courtney, Ben
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Siddesh, Jessica, Thelma, Vick
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Christie, Mayzia, Danielle
How?
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Why?
Dividing & Delivering
Distributing genetic information
Goals for today
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Scaling: Nucleotide, Gene, Chromosome--and how
many of each
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Concept: Chromosomes are hugely long threads of
DNA; some regions are genes
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PURPOSES of ‘mitosis’ & ‘meiosis’ & how these
dictate the events
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Mixing and matching parental DNA made you. It
provides hope that you’re “better” than them!
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
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Scaling
•A gene is ~1,000-100,000 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
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Mitosis and Cell division
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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)
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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
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Dominant/recessive: Two alleles enter; one allele leaves
(which version manifests in the organism)
• NOT which version is more common!
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More in the lab manual & Vocab exercises!
Windows on the gene: eyes
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Find a brown- and a blue-eyed person. Look deep into their
eyes & try to figure out the difference
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What does it mean genetically when we say ‘brown eyes are
dominant’?
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One gene, two alleles
Why should that be so? What do brown alleles got that blue do
not?
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Ripped from the headlines
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Blue eyes arise from a DNA change that prevents creation of
melanin in the eye specifically
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Mutation appears identical in all blue-eyed folks, suggesting…?
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Headline: Blue eyes result of ancient genetic ‘mutation’
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It’s not a ‘mutation’; it’s a mutation
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Mitosis and Cell Division
• How many cells
• When you were “0”?
• Now?
• What do cells DO?
https://eapbiofield.wikispaces.com/file/view/12_05CellCycle-L.jpg
What happens in each
“Stage?”
What if a cell isn’t
“listening”?
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Malignant Tumor – grows aggressively, invades
surrounding tissue, metastasizes
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Benign Tumor – lacks malignant tumor’s properties
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Benign tumors CAN cause “mass effects”
It’s all in a name
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Chromosome
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Gene
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Chromatid
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Allele
• Homologous
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Dominant
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Recessive
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Spindle Fiber
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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)
Copied during
Interphase
Chromosome 1
(from father)
Copied during
Interphase
So after replication…
So after replication…
Chromosome 1
(from mother)
Chromosome 1
(from father)
Chrm 2
Chrm 2
Condensed versions during mitosis/meiosis
This is ALSO a diploid
nucleus/cell
This is a DIPLOID
Nucleus/Cell
Mitosis and Cell Division
Why are
chromosomes
usually shown
like this?
http://kmarsh2.umwblogs.org/2008/10/24/cartoon-mitosis/
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Touching mitosis &
meiosis
Meet the
Chromosomes
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Compare our bead
models with image
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What corresponds?
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Genotype, phenotype
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Pick two traits
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Pick a dominant & recessive outcome arising from
different alleles
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You all start off heterozygous
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bead = gene
Symbolism
Room 450
Room 460
Pay close attention
to the nipples!
String of beads = chromosome = double-stranded DNA
Room 430
Room 420
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Mitosis Manually
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Point at some of your cells that ‘do’ mitosis?
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What’s the goal/purpose of this thing called ‘mitosis’?
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So what must the first step be? Do it.
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Now what must be achieved?
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Any half? If not, how pick the appropriate half?
How do your final results compare with starting?
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Your brain: A lousy place
to do your thinking
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You can do a lot of fuzzy math (and fuzzy biology
and fuzzy chemistry and fuzzy...) up there
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Drawing/speaking/writing forces precision; reveals
missing links
Mitosis and Cell Division
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What are homologous chromosomes? Show me a chromosome
and it’s homolog
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How does cell know they go together?
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Show mitosis! Put an * next to any diploid cell!
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What comes after
mitosis?
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Clear your mind
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Go outside & take a lap around
the floor (Come back in 5
minutes!)
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Yeah. Go
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Meiosis: the other cell
division
Why have sex?
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Suppose I’m Jack Sprat; you’re my wife.
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I have the mutant form of the fat-eating gene; you of the
lean-eating gene
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If we reproduce asexually (mitotically), how long until some
descendant can eat a whole pig?
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If sexually, i.e. by taking parts of our holdings & throwing
them together in an offspring?
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Meiosis
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• 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?
Show Me How it’s Done!
Room 430
Room 420
Room 450
Room 460
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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
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Meiosis - Recombination
Where should the circled site on
Chromo1 recombine with Chromo2?
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2
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Show Me How it’s Done!
Room 430
Room 420
Room 450
Room 460
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Meiosis - Recombination
• Now we’ve recombined; how to
separate?
• When you’re a gamete, go fuse with a
classmate
• Stop by and show me the genotype
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Clean up
Room 430
Room 420
Room 450
Room 460
Blinding you with Science
(jargon) II
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Linked/Linkage: Referring to whether genes are
tethered to one another by virtue of being ‘close’
on a chromosome
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Linked: referring to the resulting behavior of traits
encoded by such genes
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Get in your group
around a Computer!
• Load Gameter don’t log in, just play with the program
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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
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Gameter
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Explore
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One meiosis
200 meioses
Move ‘em around and try again
Observe
Hypothesize
Test
Evaluate
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Homework
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