1. Whose got Genes?
Genes, Heredity, & DNA
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2. Write underlined!
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
                                  
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3. So what is DNA?
DNA is a complex molecule (polymer) found in all living things.
The primary function of DNA is to store and transmit genetic information that tells cells which proteins to make and when to make them.
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4. DNA TRIVIA An idea about size:
An average cell nucleus is about 6 micrometers in diameter.
The total length of the DNA in the human genome is 1.8 meters.
There must be several levels of coiling and super coiling in DNA
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5. What is GENETICS?
Genetics is the study of how traits are inherited through the interactions of genes.
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6. What is a GENE?
The material that controls which traits are expressed in an organism
Genes come in pairs and offspring inherit one copy of each gene from each parent
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7. Define the following terms:
Heredity
Allele
Trait
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8. Define HEREDITY The passing of traits from parent to offspring
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9. Define ALLELE The different forms of a trait that a gene may have
One form of a gene
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10. 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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11. 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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12. What is HOMOZYGOUS? Both alleles [forms of the gene] are the same
When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant
When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive
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13. What is HETEROZYGOUS? When alleles occur in different forms
When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous
Since the dominant gene will be expressed, they are said to be heterozygous dominant
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14. 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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15. Define GENOTYPE
An organism's genetic makeup
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16. Outward physical appearance and behavior of an organism
Define PHENOTYPE
Outward physical appearance and behavior of an organism
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17. What is a PUNNETT SQUARE?
A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine
A way to show phenotype & genotype
A chart that shows all the possible combinations of alleles that can result when genes are crossed
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18. What is a PUNNETT SQUARE?
Letters stand for dominant and recessive alleles
An uppercase letter stands for a dominant allele
Lowercase letters stand for recessive alleles
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19. 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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20. Generation 1 homozygous red rose = RR homozygous white rose = rr
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21. Generation 2 homozygous red rose = RR heterozygous red rose = Rr
homozygous white rose = rr
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22. Generation 3 homozygous red rose = RR heterozygous red rose = Rr
homozygous white rose = rr
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23. List the 3 Principles of Heredity
Traits are controlled by alleles on chromosomes
An allele’s effect is dominant or recessive
When a pair of chromosomes separate during meiosis the different alleles for a trait move into separate sex cells
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24. References
Slideshow adapted from
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