monday, april 23, 2012
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Monday, April 23, 2012Homework: none
Plan:1) Mitosis/Meiosis/Karyotype Checkup2) Review MendelSim data from Friday3) MendelSim Questions4) Heredity/genetics Notes
CheckupBe sure to write your VERSION A or B on your answer sheet.
Record all answers #1-18 on the answer sheet.
MendelSim Data ReviewGoes in entry from Friday-Entry 39: MendelSim Simulation- 4/20/12
Parent 1 Parent 2 Offspring (after 50 crosses)
Red Blue
Data Table 1: Pure Red X Pure Blue
Parent 1 Parent 2 Offspring (after 50 crosses)
Red Blue
Data Table 2: Cross of Two Red Offspring
Data Table 3: Cross of Two Blue OffspringParent 1 Parent 2 Offspring (after 50 crosses)
Red Blue
Red Blue
Red Red
Blue Blue
50 0
38 12
This one varied
0 50
PARENT 2BLUE
X 50 (ALL) RED OFFSPRING
=
PARENT 1RED
PARENT 2RED
X =
38 RED 12 BLUE
X = 50 (ALL) BLUEOFFSPRING
PARENT 1RED
PARENT 1BLUE
PARENT 1BLUE
TAPE in these questions and answer them in your logbook
1. What is the trait we observed?2. What are the results of crossing the red
flowers with the blue flowers?3. Based on the results, what do we know about
the flower color gene?4. What are the results for the second crossing
—red crossed with red?5. The flowers in the second crossing look red—
but what do we know about their genetics?6. What happened to the blue trait and how did
it show up again in the third generation?
Make an entry- Heredity and Genetics 1- 4/23/12This is a “see attached” entry-
First, some information we already know…
Chromosome structure- DNA
• Chromosomes = long pieces of DNA
Chromosomes come in pairs (one from mom and one from dad)
Cut out from picture and match each in pairs
Chromosomes have genetic information and are passed to offspring
chromosomes
Dividing onion cells
chromosomes
nucelus
cell wall
Chromosome structure - genes
Human chromosome # 7
• Contains about 1,800 genes
• Contains over 150 million nucleotides
Link to view genes and DNA sequence
• Parts of chromosomes that code for proteins are called genes
• Genes, and specifically the proteins made from them, help determine your characteristics RGene for
RED flowers
How does your DNA determine your traits?
DNA mRNA protein Observed trait
transcr
iption
transla
tion
Example1: A person has DNA that has instructions to make LACTASE (a protein) which allows them to digest milk
Example 2: The Labrador Retriever has DNA that has the instructions to make TRP-1 which converts brown pigment to black—so they have black fur.
Trait – a characteristic of an organism– Example: “flower color”
Gene – part of a chromosome that helps determine a specific trait– Example: “flower color gene”
Allele – a form of a gene – Example:• One allele is the “blue” form of the gene• One allele is the “red” form of the gene
• Humans = 23 chromosome pairs, or 46 total. We have about 24,000 genes.
Some other examples: (do not need to memorize)
• Pea flower = 7 chromosome pairs (14 total)• Fruit fly = 4 chromosome pairs (8 total) 13,601
genes identified so far!• Potato = 24 pairs (total 48)• Horse = 32 pairs (total 64)
How many chromosomes?
Chromosomes come in pairs (one from Mom and one from Dad)
• This pair of chromosomes is called a “homologous pair” because they have the same genes on them -
Flower chromosome 3
(from computer simulation)From Dad
From Mom
flower color gene
IMPORTANT: homologous pairs are NOT IDENTICAL, but they have the same genes, – Alleles can be different
flower color gene
From Dad
From Mom
“Blue” alleleof flower colorgene
“Red” alleleof flower colorgene
The combination of alleles determines the observed characteristics
Chromosomecombination
Allelecombination
Observedcharacteristic
REDallele
RED allele
REDallele
BLUE allele
BLUEallele
BLUE allele
red, red red, blue(or blue, red)
blue, blue
RED RED BLUE
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