Recessive, Dominant, And Sex-Linked Trait
Recessive, Dominant, and Sex-Linked TraitDisorders by Recessive Alleles:Recessive, Dominant,& Sex-Linked Disorders· some genetic traits depend on dominant andrecessive alleles· some gene expression depends on thechromosome it is onautosome or sex chromosome· people with a disorder (affected) must have bothrecessive alleles (tt, rr, bb)· parents that are homozygous dominant areconsidered normal (TT, RR, BB)· parents that are heterozygous for a particulardisorder are considered carriers and can pass thetrait onto their offspring (Tt, Rr, Bb)· Diseases/Traits: Albinism, Cystic Fibrosis, PKU(phenylketonuria), Tay-Sachs DiseaseAAAanormal CarrierAaaaCarrier affectedAlbinism····Genetics Practice #11 in 17,000 birthsno pigmentation in hair, skin, eyeseye sensitivity and vision problemsUV radiation (sun) can easilydamage skinCraig and Nina are married and have four children.Both Craig and Nina have brown eyes and hair andlight-medium skin. However, 2 of their 4 childrenhave albinism. (Use the letters AA, Aa, or aa.)1. What is Craig's genotype?2. What is Nina's genotype?3. What is the probabilitythat their next child willalso have albinism?LiberiaHondurasLiberiaCystic Fibrosis· 1 in approximately 2000 births· defective CFTR gene.protein pump in cell membranenot made properly or at all· mucus clogs lung, liver, and pancreas· affects young children to young adults· high mortality rateClick for CF· life expectancy currently into the 30sAwareness(if given the best care/treatment)Video· NO cure yetGenetics Practice #2A couple who are both carriers of the gene for cysticfibrosis have two children who have cystic fibrosis.(Use the letters FF, Ff, or ff.)1. What would be thegenotypes of the parents?2. What would be thegenotype for their childrenwith CF?3. What is the probability thattheir next child will havecystic fibrosis?Breathing Treatment
Recessive, Dominant, and Sex-Linked TraitPKU (Phenylketonuria)· 1 in 10,000 births· cannot digest phenylalanine and it builds up causingsevere complications including brain damage andeven death· PKU diet does not allow consumption of meat, fish,poultry, milk, eggs, cheese, ice cream, legumes, nuts,or many products containing regular flour· NO cure yetTay-Sachs····most common in people of Jewish ancestrymetabolic disorderfat builds up and destroys the brainlife expectancy is about 3 yearsCLick for Awareness Videodisorders caused by dominant allelesAchondroplasia· people with a dominant allele disorder need tohave one allele to inherit the disease· homozygous dominant and heterozygous individualswould be affected· if a parent has a dominant allele, there is a 50/50chance of passing it on to their offspring· Diseases/Traits: achondroplasia and Huntington'sdisease· most common form of dwarfism· Aa genotype achondroplasiaAAAaaffected affectedAaaaaffected normalGenetics Practice #3Matt and Amy Roloff have four children. AlthoughMatt and Amy are both little people, they do nothave the same type of dwarfism. Amy hasachondroplasia, which is a dominant allele disorder.There children are: twins Zach and Jeremy, Molly,and Jake. Three of the four children are averageheight. Zach has achondroplasia like his mother.Show the results of theRoloff family in a Punnettsquare. Matt (aa) isnormal or does NOThave achondroplasia.Amy has achondroplasia(Aa).Huntington's Disease· 1 in 10,000· gradual deterioration of brain tissue during middle age· shortened life span
Recessive, Dominant, and Sex-Linked TraitSex-linked traitsChromosome Review· some traits and disorders are located on the sexchromosomes (23rd pair)· genes located on the sex chromosomes (X, Y) aresaid to be "sex-linked"· the probability of inheriting a particular traitdepends on if your are a boy or girl· must use XX and XY in your Punnett squares· Diseases/Traits: colorblindness, hemophilia,Duchene's Muscular Dystrophy, ALD(adrenoleukodystrophy)· XX female and XY male· all eggs contain one X· sperm contain an X or a YX X Y YSex-linked Punnett SquareXNXnXnN nX Xn nX XYXNYnX YMore Males Than Females· Why are X-linked traitsmore common in malesthan females?· males have just one Xchromosome· thus, all X-linked alleles areexpressed in males,even if they are recessive· females need two allelesfor it to be expressedNormalColorblindness· 1 in 10 males and 1 in 100 females· cannot detect red from green (most common)· Punnett Square Example:Mom is a carrier and Dad is NormalXCarrier nd Test #1
Recessive, Dominant, and Sex-Linked TraitColorblind Test #2Colorblind Test #3Colorblind Test #4Colorblind Test #5Colorblind Test #6Genetics Practice #4Jeff and Emily are married and expecting their firstchild. Jeff has normal vision and so does Emily, but sheis a carrier for colorblindness. (MUST USE XX and XY.)1. What is the probability that theirchild will be colorblind?2. They find out that they will behaving twins (one boy and onegirl).3. What is the probability that theirson will be colorblind?4. What is the probability theirdaughter will be colorblind?Carrier? Normal?
Recessive, Dominant, and Sex-Linked TraitHemophilia· 1 in 10,000 males· defective gene for clotting factor XIII· "Royal" diseaseGenetics Practice #5Sofia, whose blood clots normally, has a hemophilicfather. Her husband's (Tommy) blood clotsnormally. Their first child was a girl and their secondchild was a boy.1. What is Sofia's genotype andphenotype?2. What is Tommy's genotypeand phenotype?3. What are the possiblegenotypes for their daughter?4. What are the possiblegenotypes for their son?5. What are the chances their3rd child will be a girl that isalso a carrier for hemophilia?Duchene's Muscular Dystrophy· 1 in 3000 males· progressive weakening and loss of skeletal muscle· rarely live past early adulthoodGenetics Practice #6Elizabeth and Sam have an 18 month old son namedScotty. He was late to walk, stumbles easily, and hasdifficulty getting up and moving around. After manytests, it was determined that Scotty inherited Duchene'sMuscular Dystrophy (DMD), which is an X-linked trait. Bothparents are unaffected.1. What is Elizabeth's genotype andphenotype?2. What is Sam's genotype and phenotype?3. What is the genotype for their son, Scotty?4. What is the probability that they will havea girl with DMD?5. Elizabeth is expecting another child. Whatis the probability she will have anotherchild with DMD?6. She finds out that the child will be a girl.What is the probability that she will benormal and NOT carry the gene for DMD?ALD (adrenoleukodystrophy)· 1 in 20,000· fat builds up in the brain and disrupts normal activity· NO cure yet
Recessive, Dominant, and Sex-Linked Trait Sex-linked traits ·some traits and disorders are located on the sex chromosomes (23rd pair) ·genes located on the sex chromosomes (X, Y) are said to be "sex-linked" ·the probability of inheriting a particular trait depends on if your are a boy or girl ·must use XX and XY in your Punnett squares
Dominant, Dominant; Dominant, recessive; recessive, Dominant; recessive, recessive 3. If we look at each gene separately, we still get the expected 3:1 ratio e.g. Consider only seed color in the F2 generation: Yellow (both Smooth and wrinkled together): 3/16 9/16 12/16 ¾ or 75% expressed the Dominant trait, while only ¼ (3/16 1/16
A. Sex-Linked Inheritance 1. Genotypes Genotypes for sex-linked traits are written using the X and Y chromosomes to show path of inheritance. Male-pattern baldness is a sex-linked recessive trait. If H normal head of hair and h baldness – bald male _; bald female _. – Females can be _ for sex-linked recessive .
SEX LINKED INHERITANCE The characters for which genes are located on sex or ‘X’ chromosomes which occurs in different numbers in two sexes and the absence of its allele in the ‘Y’ chromosome are known as sex linked traits. Such genes are called sex linked genes and linkage of such genes is referred to as sex linkage.
Recessive traits and disorders are only manifest when the mutant allele is present in a double dose, i.e. homozygosity. Individuals heterozygous for such mutant alleles show no features of the disorder and are perfectly healthy, i.e. they are carriers. The family tree for recessive traits differs markedly from that seen in autosomal dominant traits
Recessive mutations in either gene cause albinism. Parent 1 was aaBB and parent 2 was AAbb. Thus, children were AaBb (non-albino). . autosomal recessive b. X-linked recessive c. autosomal dominant d. X-linked dominant 8 pts. . Sex chromosomes b. Autosomes c. Centrosomic chromosomes d. Both a and b e. All of the above
Sex-Linked Recessive Weakening/loss of muscle (missing proteins) Sickle Cell Anemia Autosomal Recessive Abnormal blood cell shape (oxygen deprivation) PKU Autosomal Recessive Cannot breakdown phenylalanine (amino acid) Tay-Sachs Autosomal Recessive Lack enzyme to breakdown lipids for brain function
Dominant Dominant Dominant Dominant Dominant Recessive Recessive ssues 1 in 4x106 live births. How do different mutations in LMNA ,a protein expressed in most differentiated somatic cells, cause different tissue-specific disease phenotypes? . Progeria cells in the laboratory, and has improved disease in Progeria mice. .
The modern approach is fact based and lays emphasis on the factual study of political phenomenon to arrive at scientific and definite conclusions. The modern approaches include sociological approach, economic approach, psychological approach, quantitative approach, simulation approach, system approach, behavioural approach, Marxian approach etc. 2 Wasby, L Stephen (1972), “Political Science .
