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the study of patterns of inheritance and variations in organisms.
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GENES: control each trait of living thing by controlling the FORMATION of an organisms PROTEINS.
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Chromosomes are DIPLOID (A PAIR OF CHROMOSOMES) therefore, each cell contains TWO GENES for each TRAIT. ▪ One from MOM ▪ One from DAD
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Genes may be the SAME or they could be DIFFERENT ▪ Produce DIFFERENT CHARACTERISTICS of each TRAIT ▪ EXAMPLE: gene for plant height might occur in TALL or SHORT form.
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▪ Different forms of a gene are called ALLELES ▪ The TWO ALLELES are SEGREGATED during GAMETE FORMATION (MEIOSIS II)
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▪ Dominant allele: allele that is EXPRESSED ▪ Recessive allele: allele that is ONLY EXPRESSED when there is no dominant allele present.
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Modern Genetics: Based on GREGOR MENDEL’S explanations for the patterns of HEREDITY in garden PEA PLANTS.
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▪ CROSSING different PEA PLANTS ▪ Crossing: to mate or BREED two INDIVIDUALS Pea plant with PURPLE FLOWERS with a type that has WHITE FLOWERS. ALL OFFSPRING HAD PURPLE FLOWERS
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Mendel CROSSED those OFFSPRING and produced some WHITE FLOWERS and some PURPLE FLOWERS. ( THE WHITE FLOWERS CAME BACK!)
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1. Every trait (like flower color, or seed shape, or seed color) is controlled by two "heritable factors". [We know now that these are genes - we each have two copies of every gene].
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2. If the two alleles differ, one is dominant and one is recessive. Dominant traits mask the appearance of recessive traits.
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3. Alleles are randomly donated from parents to offspring - the factors (alleles) separate when the gametes are formed by meiosis, allowing all possible combinations of factors to occur in the gametes.
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3. Gene Composition is known as GENOTYPE The expression of the genes is PHENOTYPE EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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▪ It’s was you SEE a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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b. two paired ALLELES in an organism’s genotype may be IDENTICAL, HOMOZYGOUS. a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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c. The two paired ALLELES in an organism can also be DIFFERENT, HETEROZYGOUS. ▪ DOMINANT trait is EXPRESSED a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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Mendel’s Law of DOMINANCE: When an organism has TWO DIFFERENT ALLELES for a trait, ONE ALLELE IS DOMINANT. a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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Mendel’s Law of SEGREGATION: During GAMETE formation by a DIPLOID organism, the pair of ALLELES for a trait SEPARATE, during MEIOSIS. a.EXAMPLE: if a person has attached earlobes, the phenotype is “ attached earlobes ” if a person has free earlobes, the persons PHENOTYPE IS FREE EARLOBES
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Mendel’s Law of INDEPENDENT ASSORTMENT: The members of a GENE PAIR SEPARATE from one another INDEPENDENTLY from the members of the other GENE PAIRs.
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NAME MENDELS 3 LAWS OF GENETICS 1. 2. 3.
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5. Using a PUNNETT SQUARE: to PREDICT the PROBABLE GENETIC COMBINATIONS in the OFFSPRING that result from different PARENTAL ALLELE COBINATIONS that are INDEPENDENTLY assorted.
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MONOHYBRID CROSS examines the inheritance of ONE TRAIT. ▪ HOMOZYGOUS-HOMOZYGOUS
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▪ HETEROZYGOUS-HETEROZYGOUS
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▪ HETEROZYGOUS-HOMOZYGOUS
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EXAMPLE: trait for height ▪ T= DOMINANT TALL ▪ t= RECESSIVE SHORT The suare shows the following GENOTYPES: PARENTS ARE THE F1 GENERATION resulting in offspring as F2 GENERATION
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The square shows the following GENOTYPES: 1:4 RATIO of__________________ ____% 2:4 RATIO of__________________ ____%
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The square shows the following PHENOTYPES: 3:4 RATIO of__________________ ____% 1:4 RATIO of__________________ ____%
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a PEDIGREE is a family history that shows HOW A TRAIT is INHERITED over several GENERATIONS.
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a. can help answer questions about THREE aspects of inheritance 1. SEX LINKAGE 2. DOMINANCE 3. HETEROZYGOSITY
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b. males have ONE X AND ONE Y CHROMOSOME.
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PROCESS OF REPLACING SPECIFIC GENES IN AN ORGANISM IN ORDER TO ENSURE THAT THE ORGANISM EXPRESSES A DESIRED TRAIT.
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a. Take specific genes from ONE ORGANISM and place them INTO ANOTHER ORGANISM. 1. CLONING: an IDENTICAL copy of a gene or an entire organism is produced.
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scientists INSERT a normal gene into an ABSENT OR ABNORMAL GENE. Once inserted the normal gene begins to produce CORRECT proteins or enzymes. This ELIMINATES the cause of the disorder
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3. Results of genetic engineering may include: a. the development of PLANTS that make their own INSECTICIDES. b. the development of ANIMALS that are BIGGER, FASTER, RESISTANT TO DISEASE.
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9. SELECTIVE BREEDING: method of artificially SELECTING and BREEDING only organisms with a DESIRED TRAIT to produce the next generation.
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a. inbreeding: CROSSING INDIVIDUALS THAT ARE CLOSELY RELATED. 1. NOT THE BEST OPTION: DISEASE DEVELOPS EASILY.
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b. HYBRIDIZATION: choosing and breeding organisms that show STRONG EXPRESSION for TWO DIFFERENT TRAITS in order to produce their offspring that express the desired traits.
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