1. Which organic base pairs with each other?
1. Please have these
Items on your desk.
Agenda
Science Starters
Sheet
Strawberry
Lab
Packet
Which organic base pairs with each other?
What do you think the word genetics means?
Friday February 3, Day 1

2. Table of Contents Page 21 2/3 Punnett Square & Genes Notes
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3. Whose got Genes? Genes, Heredity, & DNA www.sciencequeen.net
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4. What are genes?
Genes are a segment of DNA on a chromosome that controls a particular trait.
Genes are located on the chromosomes in the nuclei. Each organims has a fixed number of chromosomes.
Humans have 23 pairs (46) chromosomes.
Genetics is the study of how traits are passed on from one generation to another
                                  
Baker 2003/2004

5. What is GENETICS?
The study of how traits are inherited through the interactions of genes.
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6. Define TRAIT Ways of looking, thinking, or being
Traits that are genetic are passed down through the genes from parents to offspring
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7. Describe RECESSIVE
A trait that is covered over, or dominated, by another form of that trait and seems to disappear
Hidden when the other copy of the gene contains the dominant allele.
A recessive allele shows up only when there is no dominant allele present
Shown with a lower-case letter
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8. Describe DOMINANT
A trait that covers over, or dominates, another form of that trait
Trait that always shows up, even when only one of the two alleles is in the dominant form
Shown by a capital letter
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9. Define GENOTYPE
An organism's genetic makeup
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10. Outward physical appearance and behavior of an organism
Define PHENOTYPE
Outward physical appearance and behavior of an organism
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11. What is a PUNNETT SQUARE?
Used to determine the likely hood that the offspring receives a certain trait.
An uppercase letter stands for a dominant allele
Lowercase letters stand for recessive alleles
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12. Who is the scientist?
Reginald Punnett and William Bateson were among the first English geneticists.
Punnett created the Punnett square in 1905.
He devised the Punnett square to depict the number and variety of genetic combinations.
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13. Punnett Squares
Sample Problem 1.   In roses, red flowers are dominant over white flowers. What are the possible offspring when a homozygous red rose is crossed with a homozygous white rose.
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14. Generation 1 (I Do) R R Red rose = RR white rose = rr R r R r r
Genotype
4 Rr
Phenotype
100% Red Rose R r r R r
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15. Generation 2 (We do) R r r r R r r Red rose = Rr white rose = rr R r r
Genotype
2 Rr 2 rr
Phenotype
50% Red 50% White R r r r r
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16. Generation 3 (You do) R r Red rose = Rr R r R R R Genotype
Phenotype
75% Red 25% White R r r r r
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17. References
Slideshow adapted from
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