BIOL 1140 1st Edition Lecture 13Outline of Last LectureI. Genetics TerminologyII. Genotype is the genetic basis of phenotypeIII. Dominant Alleles and recessive allelesIV. Patterns of genetic inheritanceV. Rules of inheritanceVI. Two-trait crossesVII. Incomplete dominanceVIII. Codominance IX. Biochemistry of ABOOutline of Current LectureI. Semi-dominance: Sickle-cell geneII. Polygenic inheritanceIII. Genotype and environmental affect phenotypeIV. Sex-linked inheritanceV. Sex-linked inheritance dependantsVI. Sex-influenced traitsVII. Alterations in chromosome numberVIII. Chromosomes may be alteredIX. Genes and behaviorX. Single GenesCurrent LectureI. Semidominance: Sickle-cell Genea. Two different alleles of hemoglobin genei. HbA: encodes normal hemoglobinii. HbS: encodes sickle cell hemoglobin b. Sickle-cell anemia: HbSHbS (homozygous)c. Sickle-cell trait: HbAHbS (heterozygous)i. Affected individual makes both types of hemoglobinII. Polygenic Inheritancea. Inheritance of phenotypic traits that depend on many genesi. Example: eye color, skin color, heightIII. Genotype AND environment affect phenotypeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Phenotype isn't determined genotype aloneb. Environment factors can profoundly influence phenotypei. Example: nutrition affects height, body size. IV. Sex-linked inheritance: X and Y chromosomesa. Sex chromosomesi. 23rd pair of chromosomesii. X and Y chromosomes carry many different genesb. Males: have one X and one Y chromosome c. Females: have two X chromosomesd. Malei. 50% x-carrying gametes, 50% y-carrying gametesii. Male gametes determine the gender of the offspringV. Sex-Linked Inheritance Dependentsa. Sex-linked genes are located on sex chromosomesi. Sex-linked or x-linked inheritanceii. Characteristics1. More males than females have the disease2. Passed to sons by mother3. Father cannot pass the gene to sonsiii. Examples: color blindness, hemophiliaVI. Sex-Influenced Traitsa. Sex-influenced traitsi. Genes are on autosomes (not the sex chromosomes)ii. Expression of trait is affected by presence of testosterone, estrogenb. Example: baldnessVII. Alterations in chromosome numbera. Nondisjunctioni. Failure of homologous chromosomes or sister chromatids to separateii. Results in eggs or sperms that contain one too many or one too few chromosomesiii. A child conceived with one of these eggs or sperm will inherit one to many or one too few chromosomes1. Usually fatal2. Can lead to disordersiv. Occurs in males and females, but becomes more frequent in older women (over 40)VIII. Chromosomes may be altereda. In numberi. Nondisjunction during meiosis1. Failure of homologous chromosomes or sister chromatids to separate2. Example: down syndromeb. In structurei. Deletions1. Piece of a chromosome breaks offii. Translocations1. Piece of chromosome breaks off and attaches to different chromosomeiii. Chromosomes can fuseIX. Genes and Behaviora. Genes: encode specific proteinsb. Proteins have specific functions leading to phenotypesc. Protein functioni. Hormones ii. Enzymesiii. neurotransmittersX. Single Genes Can Affect the nervous system and behaviora. Several single-gene effects on human behavior are knownb. Most affect the development, structure, or function of the nervous