Mendelian Genetics Packet 19 Saturday January 15 2022

Mendelian Genetics Packet #19 Saturday, January 15, 2022 1

Mendelian Genetics n n Who is Mr. Gregor Mendel? What is he famous for? n n The picture on the next slide will assist you Describe the experiments of Gregor Mendel Saturday, January 15, 2022 2

Saturday, January 15, 2022 3

Vocabulary n Gene n Region of DNA that controls a discrete hereditary characteristic of an organism n Heredity n The biological similarity of offspring and parents Saturday, January 15, 2022 4

Vocabulary n Locus n Particular place along the length of a chromosome where a given gene is located n Allele n One of several alternate forms of a particular gene n Usually giving rise to a characteristic form of phenotype Saturday, January 15, 2022 5

Saturday, January 15, 2022 6

Vocabulary n Phenotype n The manifest (evident/apparent to senses) characteristics of an organism n E. g. anatomical n Genotype n The specific allele composition of a cell Saturday, January 15, 2022 7

Vocabulary n Punnett Square n. A diagram used in the study of inheritance n Shows the result of random fertilization in genetic crosses. n Sex linkage n The location of a gene on a sex chromosome Saturday, January 15, 2022 8

Saturday, January 15, 2022 9

Vocabulary n Dominant Allele n An allele that expresses its phenotype effect even when heterozygous with a recessive allele n Recessive Allele n An allele whose phenotype effect is not expressed in a heterozygote Saturday, January 15, 2022 10

Punnett Square n #1 n Sex Determination in humans n #2 n Color Saturday, January 15, 2022 of Eyes 11

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Punnett Square n #3 n Sex linked Genetics n #4 n Blood n ABO Blood groups are examples of multiple alleles o f a single gene n Letters refer to carbohydrates found on the surface of red blood cells Saturday, January 15, 2022 13

Test Cross Saturday, January 15, 2022 14

Di-hybrid Cross Saturday, January 15, 2022 15

Di-hybrid Cross Saturday, January 15, 2022 16

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Rh Factor Determines whether someone has positive or negative blood n A protein antigen that is on the surface of blood cells and if that antigen is present, the individual is positive n n A +; O +; AB + n If the antigen is not present, then the individual is negative n A -; O -; AB - Saturday, January 15, 2022 19

Rh Factor II n n n If an RH-negative mother is exposed to blood from an Rh-positive fetus, the mother’s blood will produce antibodies that will attack the blood of the fetus--potentially killing the unborn child. This is why, blood types should be determined before having children If, the male and female are negative, and positive, the mother must receive medication to prevent her immune system from attacking the child. Saturday, January 15, 2022 20

Incomplete Dominance n Occurs when hybrids have an appearance between the phenotypes of the parental varieties. n Example n The n color between red and white Pink Saturday, January 15, 2022 21

Incomplete Dominance Saturday, January 15, 2022 22

Saturday, January 15, 2022 23

Codominance Situation in which the phenotypes of both alleles are exhibited in a heterozygote n Example n n Red Flower crossed with a White Flower n The child will display flowers with red and white spots n Both alleles are exhibited Saturday, January 15, 2022 24

Codominance Saturday, January 15, 2022 25

Epistasis n Phenomenon in which one gene alters the expression of another gene that is independently inherited. Saturday, January 15, 2022 26

Saturday, January 15, 2022 27

Albino Picture in printed version of packet. Saturday, January 15, 2022 28

Saturday, January 15, 2022 29

Vocabulary n Sex Linkage n. The location of a gene on a sex chromosome Saturday, January 15, 2022 30

X-Linked Recessive Disorder Males will show this trait if they have the recessive allele on the X chromosome n Females will show this trait if they have the recessive allele on both X chromosomes n Hemophilia n n Inability to have clotting of blood Saturday, January 15, 2022 31

X-Linked Dominant Disorder n Baldness n X BX b n This female will not go bald due to lack of testosterone n X BX B n This individual will start to lose her hair in the future Saturday, January 15, 2022 32

Humans Saturday, January 15, 2022 33

Females (XX on Chromosome #23 --two X Chromosomes) Saturday, January 15, 2022 34

Males (XY on Chromosome #23) Saturday, January 15, 2022 35

X vs. Y Saturday, January 15, 2022 36

Autosomal Diseases Huntington Disease n n n Produced by a single dominant allele No symptoms appear until 30’s and 40’s Symptoms n n n Uncontrollable body movements Degeneration of the nervous system Usually fatal 10 -20 years after onset of symptoms Saturday, January 15, 2022 37

Autosomal Diseases Sickle Cell Anemia n Caused by a change in polypeptides found in hemoglobin n n Caused ONLY by co-dominance n n Hemoglobin is the protein that carries oxygen in red blood cells The recessive allele causes the change in the polypeptide chain People that are heterozygous for sickle cell anemia are partially resistant to malaria n Malaria n n Caused by the Protist Plasmodium falciparum n Carried by mosquitoes Symptoms n n Fatigue (feeling tired) Palness Jaundice (Yellowing of the skin and eyes) Shortness of breath Saturday, January 15, 2022 38

Sickle Cell Anemia Saturday, January 15, 2022 39

Vocabulary n Ploidy n Degree of repetition of the basic number of chromosomes n Diploidy n Chromosomes repeat 2 X n n Remember, in humans, you have one copy of a chromosome from the maternal father and one from the maternal mother Euploidy n “True” ploidy n Having 2 copies of each chromosome Saturday, January 15, 2022 40

Aneuploidy n “Not True” ploidy n n Having more or few than two of each homologous pair Non-Disjunction n An event that occurs occasionally during meiosis in which a pair of chromosomes fail to separate so that the resulting germ (sex cell) has either too many or too few chromosomes Saturday, January 15, 2022 41

Saturday, January 15, 2022 42

Sex Chromosome Aneuploidy Turner Syndrome n 2 n - 1 n 45 XO n 44 autosomes + 1 X chromosome n n n There is the absence of a sex chromosome Female in appearance but their female sex organs do not develop at puberty and they are sterile Short in stature Shows normal intelligence but some cognitive functions are defective 1 in 5000 female births show Turner Syndrome Saturday, January 15, 2022 43

Turner Syndrome Saturday, January 15, 2022 44

Sex Chromosome Aneuploidy Klinefelter Syndrome n 2 n + 1 n 47 XXY n 44 n autosomes + 3 sex chromosomes There is an extra X chromosome Male in appearance and they too are sterile n Female type pubic hair pattern n May have breast development n Saturday, January 15, 2022 45

Klinefelter Syndrome Saturday, January 15, 2022 46

Sex Chromosome Aneuploidy XYY Males that are usually fertile n Predisposition to be more violent in behavior n Gametes never YY or XY--meiosis is normal n After age of 35, extra Y chromosome often degenerates and is not passed onto offspring n Saturday, January 15, 2022 47

Sex Chromosome Aneuploidy XXX Normal and fertile females n May be some mental retardation n Eggs will produce only X after meiosis--not XX n Saturday, January 15, 2022 48

Autosomal Aneuploidy Down Syndrome n Caused by an extra copy of chromosome #21 n There are three copies of chromosome #21 in their somatic cells 0. 15 percent of all live births n Growth failure and mental retardation n Big toes widely spaced n Congenital heart disease n Mean life expectancy is about 17 years and only 8 % survive past age 40 n Saturday, January 15, 2022 49

Down Syndrome Saturday, January 15, 2022 50

Hermaphrodite Named for the Greek god Hermes and Greek goddess Aphrodite n Individual functions as both a male and female n Define Sequential Hermaphroditism n n Name three organisms that show this characteristic Saturday, January 15, 2022 51