Introduction to Genetics.ppt

Introduction to Genetics.ppt

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  Genetics and Heredity
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  TERMINOLOGY 1. Genetics isthe study of genes and heredity 2. Gene: The fundamental physical and functional unit of heredity. an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product (i.e., a protein or RNA molecule). 3. Heredity: The handing down of certain traits from parents to their offspring. The process of heredity occurs through the genes. 4. Allele: Alternative form of a (gene) genetic locus; a single allele for each locus is inherited separately from each parent (e.g., at a locus for eye color the allele might result in blue or brown eyes).
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  5. Allele Frequency:The proportion of a particular allele among the chromosomes carried by individuals in a population. 6. Genetic profile: A collection of information about a person's genes. 7. Genome: All the genetic material in the chromosomes of a particular organism; its size is generally given as its total number of base pairs 8. Chromosome: The self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes
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  9. Autosome: Achromosome not involved in sex determination. The diploid human genome consists of 46 chromosomes, 22 pairs of autosomes, and 1 pair of sex chromosomes (the X and Y Y chromosomes). 10. Sex Chromosome: The X or Y chromosome in human beings that determines the sex of an individual. Females have two X chromosomes in diploid cells; males have an X and a Y chromosome. 11. Locus (pl. loci): The position on a chromosome of a gene The specific physical location of a gene on a chromosome. 12. Inheritance is how traits, or characteristics, are passed on from generation to generation.
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  Mendelian Genetics  GregorMendel is considered “The Father of Genetics"  Dominant traits- traits that are expressed.  Recessive traits- traits that are covered up.  Alleles- the different forms of a characteristic.  Punnett Squares- show how crosses are made.  Probability- the chances/ percentages that something will occur.  Genotype- the types of genes (Alleles) present.  Phenotype- what it looks like.  Homozygous- two of the same alleles.  Heterozygous- two different alleles.
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  Gregor Mendel  AustrianMonk.  Experimented with “pea plants”.  Used pea plants because:  They were available  They reproduced quickly  They showed obvious differences in the traits Understood that there was something that carried traits from one generation to the next- “FACTOR”.
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  Mendel's Plant BreedingExperiments Gregor Mendel was one of the first to apply an experimental approach to the question of inheritance. For seven years, Mendel bred pea plants and recorded inheritance patterns in the offspring. Particulate Hypothesis of Inheritance Parents pass on to their offspring separate and distinct factors (today called genes) that are responsible for inherited traits.
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  Mendel was fortunatehe chose the Garden Pea •Mendel probably chose to work with peas because they are available in many varieties. •The use of peas also gave Mendel strict control over which plants mated. •Fortunately, the pea traits are distinct and were clearly contrasting.
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  Mendel studies sevencharacteristics in the garden pea
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  For each monohybridcross, Mendel cross-fertilized true-breeding plants that were different in just one character—in this case, flower color. He then allowed the hybrids (the F1 generation) to self-fertilize.
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  Typical breeding experiment Pgeneration (parental generation) F1 generation (first filial generation, the word filial from the Latin word for "son") are the hybrid offspring. Allowing these F1 hybrids to self-pollinate produces: F2 generation (second filial generation). It is the analysis of this that lead to an understanding of genetic crosses.
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  Law of Dominance Inthe monohybrid cross (mating of two organisms that differ in only one character), one version disappeared. What happens when the F1’s are crossed?
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  The F1 crossedproduced the F2 generation and the lost trait appeared with predictable ratios. This led to the formulation of the current model of inheritance.
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  Genotype versus phenotype. Howdoes a genotype ratio differ from the phenotype ratio?
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  Testcross A testcross isdesigned to reveal whether an organism that displays the dominant phenotype is homozygous or heterozygous.