Pedigree Packet

4/11/2018 Example of Pedigree Charts □� •M·-i-i • Is it Autosomal or X-linked? �Answer •Autosomal •f) 6.o Answer Example of Pedigree Charts •Dominant or Recessive? □ •Mi □ •i-0 �□ Answer •Recessive °I 6 -M ¥ □ � •Dominant Interpreting a Pedigree Chart 2. Determine whether the disorder is dominant or recessive. - If the disorder is dominant, one of the parents must have the disorder. - If the disorder is recessive, neitl]er: parent has to have the dtsorder because they can be heterozygous. Example of Pedigree Charts •Dominant or Recessive? ¥ lJ. Summary • Pedigrees are family trees that explain your genetic history. • Pedigrees are used to find out the probability of a child having a disorder in a particular family. •To begin to interpret a pedigree, determine If the disease or condition is autosomal or X-linked and dominant or recessive. □ □ 6Thr1■ f � l Ot □6 --­ -•... ..-• -• • • • , ! o!.. ._!_ !. • -­ .t� · ·--- Pedigree Chart -Cystic Fibrosis •--. �� ■-..,...e �: ...... c-­ N-,: n...,. ■-,-• • =-=.!.'";!.. u"':-. ... _I •-·---� .':. .,_ .............. •"-- Iii_, ,. �-, ........ "-- •• to..,._ •,_,. a•-------- 2 Genetics Matching Worksheet Name;___________ Date:____ Per.:__ •Biology Match the words in the first column to the best available answer in the second column. __ heredity I) diagram used by biologists to predict the outcome of a genetic cross ___ genetics 2) refers to an individual with two different alleles for a trait monohybrid - -- breeding 3) condition in which both alleles for a gene are expressed when present ___ true-breeding 4) refers to an individual with two identical alleles for a trait allele 5) an alternative form of a gene dominant 6) condition in which a trait in an individual is intermediate between the phenotype of its two parents recessive 7) the offspring from crosses among individuals of the Fl generation ___ homozygous 8) the first two individuals that mate in a genetic cross ___ heterozygous 9) characteristic of an organism that is influenced by several genes __ genotype 10) genetic trait that is expressed when it's allele is homozygous or heterozygous __ phenotype 11) genetic trait that is not expressed when the contrasting form of the trait is present ___ Punnett Square 12) a genetic cross of an individual whose phenotype is dominant but whose genotype is unknown test cross __ probability co dominance 13) study of heredity 14) the existence of more then two alleles 15) displaying only one form of a particular trait in offspring __ multiple alleles 16) cross involving one pair of contrasting traits __ polygemc trait 17) the first offspring from a cross of two varieties in the parental(P) generation ___ P generation 18) transmission of genetic traits from parent to offspring ___ FI generation 19) the likelihood that a specific event will occur ___ F2 generation 20) observable characteristics of an organism incomplete --- dominance 21) the genetic makeup of an organism os indicated by its set of alleles STUDYING PEDIGREES ACTIVITY Introduction: A pedigree is a visual chart that depicts a family history or the transmission of a specific trait. They can be interesting to view and can be important tools in detennining patterns of inheritance of specific traits. Pedigrees are used primarily by genetic counselors when helping couples decide to have children when there is evidence of a genetically inherited disorder in one or both families. They are also used when trying t o determine th e predisposition ofsomeone t o carry a hereditary disease fo r example, familial breast cancer. A horlzonkll kne CONIK!iigGIROit �ofanaJe19'1(�nt 0 "'°"l"I0:1"· \ ��- loq«II• indko-1 l'oOt o pe1son 4xpl'•twi� The Components of a Pedigree: ••·c.::. �.­ DO·-"""""'""' □ 0 p:o,o,:u,l '4e.i. I;' ,.vq1Jnu IC.' 31) .oOlal'f>I =-�9 1..;i1..r') Squares are used to indicate males in a family. Circles are used to indicate females. If the individual is "affected" by the trait (dominant or recessive) we darken the shape. A line between a male and a female indicates a marriage or union. A line drawn down from the marriage line indicates offspring. Sometimes, you will see some shapes filled in only half wav this notation indicates a J,ybrid (heterozygous) or carrier of the trait. Read pages 396-397 (Seel. 14.1) in your textbookfor more information. o ■- n l� Name: ______________ A pedigree is a chart that shows the inheritance of a trait in a family. It usually tracks a particular trait or disease through several generations. A square represents a male individual. A circle O represents a female. A shape that is filled in means that individual has the traiL An empty shape means he/she does not show the trait. A straight horizontal line between a male and female represents a "marriage" or mating line. A vertical line descending from a marriage line represents the offspring of the parents. ■ Here ·s an example: In this pedigree the parents had four offspring; two male and two female. The mother and one of the sons show the trait, but no one else does. □ • The pedigree only shows the phenotype. not the genotype and not whether a trait is dominant or recessive. For example, some members of this family are allergic to strawberries (s) and some are not (S). Here is the same pedigree with the genotypes. See if it you can see why some individuals show the trait and some do not. Period: You can look at a pe< ligrce and determine whether baits arc dominant or recessive, and you can also tell ifit is sex­ linked or autosomal. A sex-linked recessive charaacrisric is delcnnined h}' an allele that is carried only on the X chromosomes. The shorterY chromosome does not c.any an allele for a sex-linked rrait. Since there is only one X in his genotype, XY. a male who c:uries a particular recessive allele on the X chromosome will have the sex-linked condition. A female who carries a recessive allele in one X chromosome will not show the condition if there is a dominant .:illcle on her other X chromosome. She will e.xpress the recessive condition only if she inherits two rcccssi\le alleles- one from each parent. Her chances of inheriting the condition are thus greatly reduced. One sex linked trait is hemophilia, a condition in which the blood doc:s not clot properly. Most people who have hcmophilia are men. View the pedigree below and interp�l the diagram to answer the questions. A. I nterpreting a human pedigree. lo.:. Use Figure A to answer the questions below. .-n � Ss ss Ss I. 2. Number all individuals on lhe pedigree al the top of each shape. In a pedigree., a square represents a male. If it is darke,ied he has h,mophilirr; if clear. he had normal blood clotting. a. Haw many maks are /here? ---....,..,--,,b Hou, ma,ry malu ha1-e hemopliilia? _ _ _ __ 3. A circle represents a female. I f it is darlcen-ed, she has hemophilia; if open she is normal. a How manyfemale are then?_______ b. Hol'I manyfemales htn� liemophilia? ____ ss Ss 6 Ss Here are a few rules of logic to help you unde.rstand the genetics behind the pedigree I. If neither parent show the trait: a. the trait cannot be dominant. b. the trait could be recessive and either parent or both could be heterozygous carrie.rs. 2. If one parent shows the trait: a. the trait could be dominant and the affected parent could be heterozygous while the unaffected parent is nol a carrier b. the trait could be recessive and the affected parent is homozygous while the unaffected parent could be a heterozygous carrier 3. If both parents show the trait: a. che trait could be dominant and both parents could be heterozygous carriers which means that some of the children could be unaffected b. the trait could be recessive meaning that both parents would have to be homozygous and all the children would have to be affected Problems: Pedil!fee 1 shows a family of parrots. One of the offspring shows the trait for blue feathers. (R = red feathers, r = blue feathers) 1. Do you think blue feachers are dominant or recessive?_______ 2. What must the genotypes of the parents be? _ Date: Pedigree Worksheet Pedigree Worksheet □ _ _ _ _ __ _ 3. What two genotypes could the other offspring have? _____ _ rn 6 16&,-u II III IV ffi.o �6 •• �6ti 4. A marriage is indicarcd by a horizontal line connecting a circle to a square. a. How many marriages are there'! _ _ _ _ _ _ 5. A line perpendicular to a marriage line indicates the offspring. lflhe line e-ids with either a circle or a square, the couple had only one child. However, iflhc line is connected to another horizontal line, rhen sever.ii children were produced, each indicated by a short vertical line connected lo the horizontal line. The fir3t child born appears to lhe lefi .:10d the last bomto thetig!ll a. Haw many children did 1hefirs1 couple (couple in row I) l,avr? _____ b. How ma11y childrr!n did tire 1/rird couple (co11plc in ro••· Ill) hm-e?_____ 6. Le,-el I represent the first generalion, level II represents the second generation. a How many gr!neratiOIJS are tht!re? _ ____ b Haw ma11_v m�mbers are there in llK! /011r1/1 �,ieration? _ _ ___ 7. The genotypes of 1he malc:s in a pedigree for sex-linked inheritance are easy 10 dctcnninc since normal blood cloning (N) is domin11..111 and hemophilia l�-rec-tlsive (n). Since 1h�c alleles arc on the X chromosome only, iJ m�dc repr�nt,d hy � s clearsqu:ue:.�vlll ha\'e the _gen�t! X Y. A �h:rke-ncd. square will be X"Y. ;l?lx:I 11nrhrac.h lndlvrd�! en Utt: pgl1°n'ta What is 11,e genotype for- f,,dil,·iduol #/? _ _ _ PM,,OIJ'pe? _· _ _ _ b What is 1hc genotypefor /11dividual :!/0? ___ Pl�notype? ___ c What is 1l,c genotype/or tlwfirst born male in geMrr11ion /JI? __ Phenotype? ___ _ 8. frn,nl., with h•�ilia !me on c:••n;< no!)"JK" 101demffy. They are all X"X". il< llh roocnlve allek:s must lie present rOf .1 rl!'male lo kl\� hcmophilia. ffetz:' damfo:'.:b,l tlllde h; picsent (XN), lhe indh·idm..111111:�d be nomul for clotting. a H01r manyfema/�s l,awt r/Je genotype X' X'? ____ _ 9. Females who do not show the trail for hemophilia may be homozygous dominant (X�X ) or he1erozygous cx x"). A heterozygous female is culled iJ carrier. Examination of oO"spring can often determine which genotype the parents have. rr;;viy d1ild tRin t1r tJ:u,g,hl.a) has hcmophilia., lhen lhe fc-mafc must be he1en:,,�·�e1us:·. I rhn'·san hill hcmaphilia, he has .., "' SCEliO')'pC X Y. He lnhair� lhe Y from the falher, so the o,hrr allele is his S,CnOC)'pc (X ) had tg t:amc r101':'II the molhcr. n n n If a d4uiJuc has hemophilia (X X ), she inherited an x from each parent, thus making lhc ger101ype for the normal ,.,. motbc:rX�;.., _ a. JYha1 wo1t/d be the genoty�for the.female wl10 mar-ri�s imo the family in g�nt!ralion Ill? ___ Pedigree 1 •-A s =-- \L.\ A nalyzing Simple Pedigrees: Example 1: Tracing the path of an autosomal recessive trait A pedigree is just like a family tree except that it focuses on a specific genetic trait A pedigree usually only shows the phenotype of each family member. With a little thought, and the hints below, you may be able to determine the genotype of each family member as well! Trait: Falconi anemia Forms oftbe trait: J.. The dominant form is normal bone marrow function - in other words, no anemia. J.. The recessive form is Falconi anemia. Individuals affected show slow growth, heart defects, possible bone marrow failure and a higll rate of leukemia. Hints for analyzing pedigrees: I) If the individual is homozygous recessive, then bolh parents MUST have at least one recessive allele (parents are heterozygous or homozygous recessive). A t ypical pedigree for a family that carries Falconi anemia. Note that carriers are not indicated with half­ colored shapes in this chart. 2) If an individual shows the dominant trait, then at least one of the parents MUST have the dominant phenotype. This one will be pretty obvious when you look at the pedigree. 3) If both parents are homozygous recessive, then ALL offspring will be homozygous recessive. NOTE: In a pedigree, the trait of interest can he domina11t or recessive. The majority of bannfal genetic conditions arc only seen when an individual is homozygous recessive - examples of conditions caused hy recessive alleles include cystic fibrosis {a disease of tbe secretary i:fands, including those that make macus and sweat), Falconi anemia (a blood disorder), albinilm (a lack of pigmentation), and pbenylketonuria (a metabolic disorder). Some genetic conditions are caused by dominant alleles (and may therefore be expressed in homoeygous dominant or heterozygous individuals}- examples of conditions caused by dominant a lleles include polydactyly (presence of extra fingers), achondroplasia (a type of dwarf"1Sm), neurolibromalosis (a nervous disorder), and a disease known as familial hypen:holeslerolemia lo which affected individuals suffer from heart disease due lo abnormally high cholesterol levels -.:! WJ.Jma Carla ff 1--:�t:�:,::�.:-: CllI:i31Dpber For Questions 1-9, use the pedigree chatt shown below. Some of the labels may be used more than once. F­ Analysis Questions. 1. A male 2. A female ____ 3. A marriage To answer questions #1-5, use the letter "f' to indicate the recessive Falconi anemia allele, and the letter "F" for the normal allele. ___ _ 4. A person who expresses the trait I. What is Arlene's genoiypc:? ____ 5. A person who does not express the trait _ ___ 6. A connection between parents and offspring ____ 7. How many generations arc shown on this chart? •�n 2. What is George's genotype? � 3. What are Ann & Michael's genotypes? 4. Most likely, Sandra's genotype is Assumi11g tht! chart above ;s tracing the dominant traU of "White Forelock (F)" throug/1 the family. Fis a tuft of w/1/te hair on theforl!l,ead. 5. List three people from the chart (other than George) who are most likely carr;ers of Falconi anemia. ____8. What is the most likely genotype of individual "Afl? (FF, Ff or ff'?) _ _ _ 9. What is the most likely genotype of individual "C"? (FF, Ff or ff!) 2 3 lC: