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Genetics.

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Presentation on theme: "Genetics."— Presentation transcript:

1 Genetics

2 BTEOC, SWBAT: predict possible outcomes of various genetic combinations using notes and monohybrid practice problems

3 What is Genetics? Genetics is the study of heredity and variation
Heredity is how genes and traits are passed from one generation to the next, and is the reason why offspring tend to look like their parents and siblings Variations are differences in the physical traits of individuals Traits are physical characteristics

4 Who is Gregor Mendel? Father of genetics
Austrian monk of the mid 1800’s HIS WORK: Studied heredity in the garden pea plant

5 What is the Law of Segregation?
Parents only pass one copy of each gene that they carry to each of their offspring Random chance determines which copy of the gene is passed each time a sperm or egg is made by meiosis

6 What is the Law of Independent Assortment?
Genes for different traits assort independently during gamete formation (because chromosomes line up randomly in Meiosis I)

7 What is the Principle of Dominance?
When Mendel crossed plants with different traits, only one of the traits showed up in the offspring He concluded that some traits are dominant over other traits

8 What are Dominant and Recessive Traits?
Dominant traits are always expressed if the allele (copy of a gene) for that trait is present Recessive traits are only expressed when the dominant allele for that trait is NOT present

9 BTEOC, SWBAT: predict possible outcomes of various genetic combinations using notes and monohybrid practice problems

10 What are genes? A gene is a section of DNA that codes for a specific protein or trait

11 Where are genes located?
Genes are located on chromosomes, which are found in the nucleus of the cell Each chromosome is made of a very long molecule and PROTEINS that help to condense the DNA

12 Where are genes located?
Each gene has a specific location, called a locus, where it is found on a specific chromosome

13 Map of genes on the human chromosomes
If we all have the same genes on the same chromosomes, then why are we all so different?

14 What are Alleles? Alleles are alternate forms of a gene Each individual has two copies of each gene, or two alleles for each gene One allele is on a chromosome inherited from mom One allele is on a chromosome inherited from dad The two alleles may be identical or different

15 What is a Phenotype? The phenotype is the physical traits of an individual Phenotypes are determined by genes and environment Yellow Seeds Curly Hair Red Flowers Free Earlobes

16 What is a Genotype? gg Hh RR Ee
The genotype is the genetic make-up of an individual, or the alleles that an individual carries for a gene or genes gg Hh RR Ee

17 How do you write Genotypes?
Genotypes are written as two letters per gene Bb hh AA Dd Each letter represents one of the two copies of a gene that the individual carries Dominant alleles are written in capital letters Recessive alleles are written in lowercase letters

18 What is homozygous and heterozygous?
Homozygous genotype – when an individual has two identical alleles for a trait BB hh aa DD Heterozygous genotype – when an individual has two different alleles for a trait Bb Hh Aa Dd

19 BTEOC, SWBAT: predict possible outcomes of various genetic combinations using notes and monohybrid practice problems


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