* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Gregor Mendel - HCC Learning Web
Therapeutic gene modulation wikipedia , lookup
Human genetic variation wikipedia , lookup
Gene nomenclature wikipedia , lookup
Gene therapy wikipedia , lookup
History of genetic engineering wikipedia , lookup
Behavioural genetics wikipedia , lookup
Gene expression profiling wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Neocentromere wikipedia , lookup
Medical genetics wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Gene therapy of the human retina wikipedia , lookup
Y chromosome wikipedia , lookup
Gene expression programming wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Genomic imprinting wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Population genetics wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Genome (book) wikipedia , lookup
Genetic drift wikipedia , lookup
Human leukocyte antigen wikipedia , lookup
X-inactivation wikipedia , lookup
Designer baby wikipedia , lookup
Microevolution wikipedia , lookup
Quantitative trait locus wikipedia , lookup
2/10/2016 o x x xo x x x 1. Source of variation x o o 3. Differential Survival 2. Selective Pressure o xo o o o oo The Next Generation but...HOW are traits passed on to offspring? Gregor Mendel - - Observed that the inheritance of traits from one generation to the next followed certain patterns Ideas changed biology but went unnoticed for 40 years 3 2/10/2016 Mendel’s Genetics Before Mendel -People had interbred animals and plants for nearly 10,000 years -People also knew where babies came from -However, it was assumed that “information” mixed during reproduction Evolution of corn + 4 2/10/2016 Mendel’s first experiment (color) What he EXPECTS (1st generation [p]) (1st generation [p]) (2nd generation [F1]) + = What he GETS (1st generation) (2nd generation) (1st generation) + = Mendel’s second experiment (3rd generation [F2]) (2nd generation [F1]) (2nd generation [F1]) = + Some traits skip generations.... Mendel’s theories *trait / gene 1. There is a factor* for pea color 2. Each parent contributes one determining factor to the offspring 3. Factors remain separate; they do not blend 4. Factors are either dominant or recessive 5 2/10/2016 Alleles & Loci LOCUS (pl. loci) - Each determinant (gene) has a specific location inside reproductive cells (chromosomes) ALLELE - Alternate forms of each determinant (gene) that occurs at a given locus. Loci may have only one allele - fingernail growth rate Loci may have two alleles - boys and girls Loci may have multiple alleles - A,B,O blood types (but any individual organism can only have two) Genotypes Genotypes - the genetic endowment of an individual example - Mendel’s pea plants PEA COLOR Allele 1 Allele 2 YELLOW green Phenotypes Phenotypes - the physical manifestation of the genotype (e.g. - the actual observable trait) ...but what about that green allele? Why does it get no love? 6 2/10/2016 Law of Segregation The genetic basis of any trait is determined by an allele from each parent. Mendel’s Law of Segregation states that within body cells, alleles occur in pairs. When sex cells are formed, only one of each pair is passes on. stuff A corrected reading calendar will be uploaded to the course website by the end of the day Quiz #1 - point adjustment Homework #1 – come talk to me if you have questions about how your point total was determined Dominant and Recessive Alleles There is a reason why crossing yellow and green peas can result in only yellow peas Dominant and Recessive Alleles Dominant Alleles - Manifest themselves even if there is only one of them present at a loci. Represented by a Capital letter (R - dominant allele for tongue rolling) Recessive Alleles - Can be MASKED by dominant genes. The only way for recessive alleles to be manifested is if the locus has TWO recessive alleles Represented by a lowercase letter (r – recessive allele for tongue rolling) 7 2/10/2016 Homozygous vs Heterozygous A homozygous factor (gene) is one where both alleles are the same (either dominant or recessive) A heterozygous factor (gene) is one where the alleles from each parent are different. In a heterozygous gene, the recessive allele will be masked by the dominant allele So for tongue rolling.... Homozygous Dominant = RR (tongues will roll) Homozygous Recessive = rr (no tongue rolling) Heterozygous = Rr (tongues will roll) Tongue rolling (dominant trait) Father - RR Mother - rr Female r r R Rr Rr R Rr Rr 100 % of children will roll tongues Tongue rolling (dominant trait) Second generation Father - Rr (child of the first couple) Female r r R Rr Rr r rr rr Mother - rr 50 % of children will roll tongues 8 2/10/2016 Tongue rolling (dominant trait) - your turn Father - Rr Female Mother - Rr R r R ? ? r ? ? Tongue rolling (dominant trait) - your turn Father - Rr Female Mother - Rr R r R RR Rr r Rr rr 75 % of children will roll tongues Factors vs. Alleles Alleles may be dominant or recessive R for dominant tongue rolling r for recessive NO tongue rolling Factors (genes) may ALSO be dominant or recessive That is, they may only express themselves in certain combinations of alleles What? 9 2/10/2016 Tongue folding (inverse trait) Father - Ff Female Mother - Ff F f F FF Ff f Ff ff 25 % of children will fold their tongues Imagine a car with 2 gas tanks Tank 1 Tank 2 Result Genotype No gas No gas No go homozygous recessive Some gas No gas Car is go! heterozygous Some gas Some gas Car is go! homozygous dominant Now a biological example Tank 1 Tank 2 Result Genotype No melanin No melanin Blue eye homozygous recessive Some melanin No melanin Brown eye heterozygous Some melanin Some melanin homozygous dominant Brown eye 10 2/10/2016 Rolling and Folding!!! RF Father - Rr Ff (roller / non folder) Mother - Rr Ff (roller / non folder) RF Rf rF rf RR FF RR Ff Rr FF Rr Ff Rf rF rf Rolling and Folding!!! Father - Rr Ff (roller / no folder) Mother - Rr Ff (roller / no folder) RF Rf rF rf RF RR FF RR Ff Rr FF Rr Ff Rf RR Ff RR ff Rr Ff Rr ff rF Rr FF Rr Ff rr FF rr Ff rf Rr Ff Rr ff rr Ff rr ff Genotypes RRFF = 1 RRFf = 2 RrFF = 2 RrFf = 4 RR ff = 1 Rr ff = 2 rr FF = 1 rr Ff = 2 rr ff = 1 Phenotypes Rollers / Non-folders 9/16 (56.25%) Rollers / Folders 3/16 (18.75%) Non-rollers / Non-folders (3/16) Non-rollers / Folders (1/16 or 6.25%) 11 2/10/2016 Law of Independent Assortment The distribution of one pair of genes does not influence the distribution of other pairs of genes So....the presence tongue rolling will not affect the presence of tongue folding Codominant Alleles Alleles are codominant when they both affect the phenotype of a heterozygous genotype. Neither is dominant over the other. In complex genetic systems with more than two alleles, some alleles may be dominant and some may be codominant. Example - blood types (A,B,O) A and B are codominant Pleiotropy a gene pair that influences the physical expression of a number of different characteristics and traits example - Phenylketonuria PKU is determined by a single gene and can lead to: mental retardation, reduced hair and skin pigmentation, and brain seizures Antagonistic pleiotropy a type of pleiotropy in which some gene expressions are positive and some are negative 12 2/10/2016 Antagonistic Pleiotropy Gene p53 Pros Regulates cell cycles Suppresses the development of tumors Cons Suppresses the production of stem cells - in adults, stem cells replace worn out cells So, the p53 gene prevents cancer and “causes” you to get old Sex linked traits Henry VIII King of England (15091547) Had six wives...whom he got rid of through various means because he wanted a son Thing is....it was his fault (sort of) Sex chromosomes There are two sex chromosomes: X and Y There are (generally) two genotypes and two phenotypes XX woman XY man X Y X XX XY X XX XY 13 2/10/2016 Sex-linked traits The X chromosome is much larger than the Y chromosome That means that there is more information contained in X chromosomes Some evidence for the idea that “men” are a mutation!! There are many traits that are carried along the X chromosome (carried by mother) Sex linked traits Traits carried on X chromosome Females need two affected chromosomes to manifest a trait Females with one affected chromosome is a carrier but is not affected Males only get one X, so if they have the affected X chromosome, then they manifest the trait This is why men manifest MORE sex-linked traits than women. Example - hemophilia Hemophilia is a disorder that prevents blood from clotting When creating Punnett squares for sex traits, we place a superscript letter next to the sex chromosome So... XHXH female with hemophilia XHX female carrier of hemophilia XHY male with hemophilia 14 2/10/2016 Mendelian Genetics is concerned with patterns and processes of inheritance Law of Segregation Law of Independent Assortment Homozygous dominant Homozygous recessive 15