plan for the day seating chart & group cards notes: introduction genetics activity: class...
TRANSCRIPT
Plan for the Day
Seating Chart & Group Cards
Notes: Introduction Genetics
Activity: Class Trait Variation
Exit Ticket: In class assessment
Homework = Bring Your Text book.
Learning Targets
• I can describe where an organism gets its unique characteristics.
• I can describe how the different forms of a gene are distributed to offspring.
Section 11- 1 How it all began
Gregor Mendel (1822-1884)• Known as the father of
genetics• Worked with pea plants
Mendel’s Pea Plants
He came up with the concept of alleles.He noticed that alleles are hereditary, and that you can predict the probability of the offspring having certain alleles.
Mendel’s Pea PlantsHe observed that some traits dominated over others
For instance, if you “crossed” a round seed-pod plant with a wrinkled seed-pod plant you generally get a round seed-pod plant.
Mendel Video
Mendel’s Pea PlantsWhat does “crossing” the pea plants mean?It means to mate a plant with another plant by pollination.
Garden peas are both self-fertilizing and cross-fertilizing.self-fertilizing – a plant’s pollen grains fertilize its own egg cells in the ovary.cross-fertilizing – a plant’s pollen grains fertilize another plant’s egg cells in the ovary.
Genes and Dominance• The offspring of crosses between
parents with different traits are called Hybrids
• When Mendel crossed plants with different traits he expected them to blend, but that’s not what happened at all.
• All of the offspring had the character of only one of the parents
Mendel drew two conclusions
1. Inheritance is determined by factors that are passed from generation to generation – today we call these factors genes
Alleles (uh LEELZ)
• Different forms of a gene• Plant Height
–One form produced tall plants–Another form produced short plants.
Mendel’s 2nd conclusion
2. The Principal of Dominance• Some alleles are dominant and
some are recessive
Quick Lab Period 6
Trait Survey
FeatureDominant
TraitNumber
Recessive Trait
Number Total
AFree ear
lobes29 Attached
ear lobes5 34
BHair on fingers
22No hair on
fingers12 34
CWidow’s
peak7
No widow’s peak
27 34
D Curly hair 17Straight
hair16 34
E Cleft chin 2Smooth
chin32 34
1. Copy the data table into your notebook.
2. Write a prediction.
3. We will collect our data together starting with Trait A.
4. Those with free ear lobes move to the left side and those with attached to the right.
5. Count the number in each group and record.
6. Repeat for B to E.
Quick LabPeriod 4
Trait Survey
FeatureDominant
TraitNumber
Recessive Trait
Number Total
AFree ear
lobes32
100%Attached ear lobes
0 32
BHair on fingers
2681%
No hair on fingers
619%
32
CWidow’s
peak10
31%No widow’s
peak22
69%
D Curly hair16
50%Straight
hair16
50%32
E Cleft chin4
13%Smooth
chin28
87%32
1. Copy the data table into your notebook.
2. Write a prediction.
3. We will collect our data together starting with Trait A.
4. Those with free ear lobes move to the left side and those with attached to the right.
5. Count the number in each group and record.
6. Repeat for B to E.
Segregation• Mendel wanted to answer another
question
Q: Had the recessive alleles disappeared? Or where they still present in the F1 plants?
• To answer this he allowed the F1 plants to produce an F2 generation by self pollination
The F1 Cross• The recessive traits reappeared!• Roughly 1/4 of the F2 plants
showed a recessive trait
Explanation of the F1 Cross• The reappearance indicated that at some point
the allele for shortness had been separated from the allele for tallness
• Mendel suggested that the alleles for tallness and shortness in the F1 plants were segregated from each other during the formation of sex cells or gametes
• When each F1 plant flowers, the two alleles segregate from each other so that each gamete carries only a single copy of each gene. Therefore, each F1 plant produces two types of gametes – those with the allele for tallness and those with the allele for shortness
Segregation• Segregation is the process of
alleles separating from one another during gamete formation.
In Your Notebooks:1a. What did Mendel conclude determines biological inheritance?
1b. What are dominant and recessive alleles?
1c. Why were true-breeding pea plants important for Mendel’s experiment?
2a. What is segregation?
2b. What happens to alleles between the P generation and the F2 generation?
2c. What evidence did Mendel use to explain how segregation occurs?