Anna Montgomery Bio 109 Test Final Notes Chapter Nine Genetics Testing Your Baby child Includes amniocentesis and CVS Has risks associated with it Gregor Mendel Genetic testing Allows expectant parents to test for possibilities in their unborn Was the first person to analyze patterns of inheritance Deduced the fundamental principles of genetics Mendel studied garden sweet peas These plants are easily manipulated These plants can self fertilize o Girl part of the plant is the carpel o Male part of the plant is the stamen pollen o Can self fertilize or be carried by wind or bees cross Four characteristics of good genetic model organism KNOW FOR TEST o Readily available o Easily manipulated o Cost effective o Short generation kind He created true breeding varieties of plants Mendel then crossed two different true breeding varieties The offspring from these crosses are called the first filial or F1 creating hybrids generation Monohybrid Crosses A monohybrid cross is a cross between parent plants that differ in only one characteristic Mendel s Four Hypotheses heritable traits There are alternative forms of genes the units that determine For each inherited character an organism inherits two alleles one from each parent If the two alleles of an inherited pair differ the one determines the organism s appearance and is called the dominant allele the other has no noticeable effect on the organism s appearance and is called the recessive allele A sperm or egg carries only one allele for each inherited character because the two members of an allele pair separate from each other during the production of gametes Genetic Alleles and Homologous Chromosomes Homologous chromosomes o Have genes at a specific loci o Have allele of a gene at the same locus o See figure 9 7 Capital letters PP are homozygous for the dominant allele Lowercase letters aa homozygous for the recessive allele One of each Bb is heterozygous Homozygous is when an organism has identical same alleles for a gene gene Heterozygous is when an organism has different alleles for a Phenotype is an organism has different alleles for a gene Phenotype is an organism s physical traits Genotype is an organism s genetic makeup o There should be two copies alleles of each gene Mendel s principle of independent assortment says each pair of alleles segregates independently of other pairs during gamete formation Using a Testcross to Determine an Unknown Genotype A testcross is a mating between o An individual of unknown genotype o A homozygous recessive individual A family pedigree o Shows the history of a trait in a family o Allows researchers to analyze human traits Human Disorders Controlled by a Single Gene Many human traits o Show simple inheritance patterns o Are controlled by genes on autosomes know what autosomes means Recessive disorders Most human genetic disorders are recessive Individual can be carriers of these diseases Started class off with a worksheet that contains materials that will be on the final Variation on Mendel s Laws Some patterns of genetic inheritance are not explained by Mendel s principles Incomplete Dominance in Plants and People o In incomplete dominance F1 generation hybrids have an appearance that is in between the phenotypes of the two parents Hypercholesterolemia is a human trait that is incompletely dominant ABO Blood Groups An example of Multiple Allele and Codominance Two of the human blood type alleles A and B exhibit codominance o Both alleles are expressed in the phenotype o Review blood types Pleiotropy and Sickle Cell Disease Pleiotropy is the impact of a single gene on more than one characteristic o Sickle cell disease is an example Polygenetic Inheritance A trait is controlled by two or more genes Multifactorial Disorders Many diseases have a genetic component and a significant environmental component o Ex heart disease cancer mental illness asthma Often the hereditary component is poly genetic o Ex at least 15 known genetic loci which can have alleles that contribute to symptoms of asthma Sex Chromosomes and Sex Linked Genes Sex chromosomes influence the inheritance of certain traits Sex chromosomes are designated X and Y men and XX Sex chromosomes determine an individuals sex Sex Linked Disorders in Humans A number of human conditions result from sex linked X linked Red green color blindness is one example o It is characterized by a malfunction of light sensitive cells women genes in the eyes Hemophilia Hemophilia is a disease in which the blood does not clot properly Red indicates the hemophilia allele o Family tree circle is woman and square is man Cellular Reproduction Basic Concepts Two types of cell reproduction processes in humans March 31st 2014 o Mitosis o Meiosis Each body cell nucleus has 46 chromosomes 2N o 23 from father and 23 from mother For an organism to grow and develop cells have to reproduce So what happens when your skin epidermis cells produces new cells Goes through the cell cycle as it grows Nucleus and cell divide mitosis Cell Cycle First phase interphase o G1 o S o G2 Primary period of cell growth DNA is duplicated growth continues slowly Cell prepares for division growth continues slowly Mitosis o Nucleus divides Cytokinesis o Cell divides o New daughter cells are formed genetically identical to original cell Mitosis Stages Prophase I o Early mitotic spindles present o Chromosomes are present o Centrosomes can be seen Prophase II Metaphase Anaphase o Fragments of the nuclear envelope can be seen o Can see spindle microtubules o Chromosomes align in the middle o Daughter chromosomes split Telophase cytokinesis o Nuclear envelope forming o Cleavage furrow 17 5 Environmental Factors Influence Cell Differentiation All body cells have the same DNA yet there are great differences between the shape and function of different cell types Toti potent Differentiation or sister cell o Process by which a cell becomes different from its parent o Differentiation is based on different gene expression genes are turned on or turned off at various stages of development Meiosis Preparing for Sexual Reproduction Pg 415 In Meiosis o Haploid gametes are produced in diploid organisms o Two consecutive division occur meiosis I and meiosis II preceded by interphase o Crossing over occurs Interphase o Centrosomes with centriole pairs o Nuclear envelope o Chromatin Meiosis I Homologous chromosomes separate o Crossing over o Independent assortment Prophase I chromosomes o Spindles present Metaphase