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General Biology Unit 1 believe that sperm cells bear a Lesson 1: Mendelian Laws of Inheritance homunculus or little man Genetics: Genetics is the study of how -​ Blending theory: inheritance states traits are passed from parents to offspri...

General Biology Unit 1 believe that sperm cells bear a Lesson 1: Mendelian Laws of Inheritance homunculus or little man Genetics: Genetics is the study of how -​ Blending theory: inheritance states traits are passed from parents to offspring. that traits of parents blend every generation of offspring. 2 types of genetics -​ Heredity: process by which traits ​ Genetic terminologies are passed from parents to offspring. -​ Chromosomes: consists of DNA -​ Variation: differences between molecule which serves as the individuals within a species. repository of genetic information -​ Homologous chromosomes: Pair ​ Branches of Genetics of chromosomes -​ Molecular genetics: deals with DNA and gene expression (Gene expression is the process by which the information in a gene is used to create a functional product, such as a protein) and regulation. -​ Cytogenetics: deals with chromosomes structure and behavior during cell division -​ Transmission genetics(classical genetics): deals with different patterns of inheritance -​ oldest sub discipline of genetics -​ attempts to predict outcomes of reproduction Reminder: Genes occur in pairs (controls a -​ Population genetics: deals with particular characteristic how the process of evolution influences genes in a population. ​ Gregor Mendel -​ Father of Genetics -​ Farm Tender -​ Beekeeper -​ Academian ​ Alleles: Alternative forms of genes( -​ Augustinian monk variant form of gene) took the path of priesthood in Augustinian eg. The gene for eye color has different monastery of st. thomas and became a alleles. One allele might code for blue eyes, monk (performed the study of pea plants) while another might code for brown eyes.You inherit one allele from each ​ Pea plant hybridization parent, so your eye color is determined by -​ legumes garden peas or pisum the combination of alleles you inherit. sativum -​ they exhibit vigorous growth -​ dominant allele is always -​ self fertilize expressed -​ cross fertilize -​ recessive allele is only expressed if you inherit two copies of it ​ Previous notions of inheritance -​ Pangenesis: belief that seeds are ​ Genotype: set of alleles possessed produced in different organs and will by an organism (cannot be seen by later on gather to form the offspring. the naked eye) -​ Homozygous: alleles are identical -​ Homunculus theory: The invention -​ Heterozygous: alleles are different of the microscope made people  ​ Phenotype: actual manifestation of genotypes into observable traits eg. if the phenotype of the seed shape is round Round Pea: Dominant alleles Wrinkled Pea: Recessive alleles ​ Pea plant characteristics ​ Monohybrid cross -​ mating between two individuals involving one characteristic or one pair of contrasting traits. Example: P generation( Parental generation)- true breeding initial parents segregate= separate F1 generation (First filial generation) - ​ Punnett square offspring of the P generation F2 generation (Second filial generation)- offspring of the m F1 generation Reminder: Principle of Dominance In a heterozygous individual, one allele (dominant) masks the expression of the other allele (recessive) ​ Dihybrid cross: mating between two individuals involving two characteristics or two pairs of contrasting traits. Remember: -​ Mendel's monohybrid cross reveals the law of segregation. According to this law, the alleles segregate during gametogenesis. This explains the characteristic 3:1 phenotypic ratio of F, in monohybrid crosses. -​ Mendel's dihybrid cross reveals the law of independent assortment. According to this law, allele pairs from different genes separate independently during gamete formation. This explains the characteristics ratio of 9:3:3:1 of F, of dihybrid crosses. Lesson 3: Pedigree Analysis ​ Inheritance in peas -​ mating of individuals can be controlled -​ generation time is shorter -​ number of offspring is large -​ handling the organism is convenient ​ Inheritance in humans -​ mating can never be done in controlled conditions -​ generation time is longer -​ number of offspring is small -​ collection of pertinent information is tedious ​ Autosomal traits: genes located on autosomes ( 44 chromosomes (22 pairs) common for Male and Female) ​ Achondroplasia: autosomal dominant condition (impaired conversion of cartilage into bones during development) dwarf ​ Cystic fibrosis: autosomal recessive condition ( buildup of mucus in respiratory and digestive ​ Genetic counseling organs) -​ Performed in accredited health ​ Sickle cell anemia : recessive institutions mutation of hemoglobin gene. Gas -​ Advice is given to a family with a transport is impaired and the red genetic condition blood cell may become stuck in -​ Advice is also given to families at small blood vessels. risk of having a genetic condition -​ hemoglobin gene: gene that -​ Elaborates on the provides instructions for making a -​ genetic, psychological, protein called hemoglobin. developmental aspects Hemoglobin is a protein in red blood cells that carries oxygen from the ​ Pedigree’s terminologies lungs to the rest of the body. ​ Pedigree uses: -​ determination of the mode of inheritance -​ predicting genetic risks -​ identification of genotypes ​ Pedigree application: -​ basic research -​ genetic counseling Lesson 4: Sex linkage and recombination Affected: confirmed to have a genetic condition ​ Recombination is a mechanism where the homologous pairs of Proband: individual who first sought medical chromosomes exchange genes. attention ​ Sex linkage is termed as such Consanguineous: couple in the family that is because their phenotypic related by blood manifestation and inheritance  patterns vary between males and genotype of an X-linked trait in females. Therefore, genes that go females will result in a carrier along with either sex chromosome female. are said to be sex-linked. ​ Sex influenced trait -​ controlled by autosomal genes. -​ The genes are found on both sexes, but one expresses it more than the other. ​ Sex-limited Trait ​ controlled by autosomal genes. ​ The genes are also found on both sexes, but only one sex expresses it. eg. breastfeeding Recombination increases genetic diversity. This is the reason why you and your sibling Lesson 5: Gene Interaction look different even if your genes are inherited from the same parents. ​ Extension of Mendelian -​ The expression of the alleles does not follow complete or simple dominance. -​ May have greater number of allelic variations for a single gene -​ May have greater number of phenotypic variations for a single ​ Human Chromosomes trait -​ The 1st to 22nd pairs are called the -​ Gives offspring ratios that are autosomes, and the 23rd pair is different from the 3:1 and 9:3:3:1 of termed as the sex chromosome. Mendel -​ Genes that go along with either sex chromosome are said to be ​ Incomplete dominance (partial sex-linked. dominance) -​ two allele system ​ When the trait is linked to the X -​ Blending of homozygous chromosome, it is called an phenotypes X-linked trait. -​ At most three phenotypic classes -​ more common in males than -​ Heterozygote with the intermediate females phenotype -​ eg. color blindness (Ishihara chart eg. is used as a test for color blindness.) -​ eg. hemophilia - rare inherited bleeding disorder (bleed longer after an injury compared to an ordinary person) ​ If the trait is linked to the Y chromosome, it is called a Y-linked trait. -​ only common in males since only males have the Y chromosome. -​ eg. hypertrichosis pinnae auris trait, which is characterized by having a hairy ear. ​ Sex related inheritance -​ As opposed to Mendelian inheritance wherein the heterozygous genotype expresses the dominant trait, the heterozygous ​ Codominance  -​ two allele system -​ Simultaneous expression of two alleles -​ No blending of homozygous phenotypes -​ At most three phenotypic classes -​ Heterozygote shows both alleles eg. ​ Mn blood system -​ Blood type determined by antigens -​ Antigens being membrane glycoprotein -​ Two antigens: M antigen and N ​ Gene interaction antigen -​ Involves the interaction between two -​ Antigens detected by the immune different gene loci system -​ The interaction controls the -​ Presence of an antigen through expression of only one biological agglutination trait eg. -​ Epistasis involves masking of the expression of a gene by another gene -​ Epistatic gene masks the expression of the hypostatic gene ​ Recessive epistasis ​ Multiple alleles ABO Blood Group -​ Determined by the presence of antigens A and B in the surface of RBCs ​ Dominant epistasis -​ Three different alleles: IA (A antigen), IB (B antigen), and i (no antigen) -​ IA and IB are codominant; both of them are dominant over i -​ Must be determined prior to any procedure related to blood transfusion eg.