2 Lesson Objectives Minds ON Success Criteria from last week Friday’s RecapPedigrees, Gender and X-Linked TraitsQuiz Take UpDisputed Maternity CaseHomeworkREMINDERS:Quiz – tomorrow after lessonWednesday/Thursday: Group presentationsThursday: Unit ReviewFriday: Unit Test---bring other work to do in case you get finished early!!
3 Minds ONgenetics/1aih9s3qnCorrelative relationship vs. Causal relationship: discuss….
4 Success CriteriaLast Week’s Learning Goals are posted. What are some of the things we need to know about or how to do in order to be successful on a quiz or to know that we have had a full understanding of the material?
5 Friday’s Recap Types of Dominance: Complete Dominance: Occurs when a dominant trait completely masks the recessive allele.Incomplete Dominance: Occurs when neither gene is dominant or recessive; the gene effect is mixed; we use 2 different letters for the homologous pair since neither is dominant.Co-Dominance: Occurs when neither gene is dominant or recessive; gene effects are NOT mixed; therefore, both genes are expressed at the same time!
8 Autosomal Traits We have been looking at autosomal traits so far: Refers to a trait passed on through the autosomal (non-sex) chromosomesAutosomal dominant: One or two copies of the trait was passed from one or both parents to cause the trait to appearAutosomal recessive: Two copies of the recessive trait must be passed on from both the parents in order for it to appear
9 Predicting Gender Two sex chromosomes determine gender: X and Y Female Genotype: XXMale Genotype: XYPredict the probability of a couple having a boy using a Punnett Square
10 Predicting Gender50% chance of a boy50% chance of a girl
11 X-Linked Traits All genes found on the ‘X’ chromosome are “linked”. Many of the genes on the ‘X’ are not on the ‘Y’.The ‘X’ is larger and has many genes that are not related to gender…(i.e. colour vision, blood clotting etc.)
12 Are You Colour Blind?Can you see something in the dots?
13 X-Linked TraitsRefers to a trait that is passed on through the X (female sex)chromosomeIf a recessive gene is on the ‘X’:- In males it will always be expressed since there is no homologous pair on the ‘Y’.- Therefore (sorry guys) recessive, X-linked diseases are much more common in males!
14 An Example of an X-Linked Disorder Hemophilia: Inability to Stop Bleeding Since gender and the gene are important, both must be noted. Dominant allele – H Recessive allele – h 𝑋 𝐻 – dominant gene on ‘X’ 𝑋 ℎ – recessive gene on ‘X’ Y – no gene on the ‘Y’
15 Hemophilia Female genotypes 𝑋 𝐻 𝑋 𝐻 – Normal 𝑋 𝐻 𝑋 ℎ – Normal but a ‘Carrier’𝑋 ℎ 𝑋 ℎ – Hemophiliac (very rare)Male genotypes𝑋 𝐻 Y– Normal𝑋 ℎ Y- HemophiliacPredict the offspring using a Punnett Square for:Mother carrier and a normal father
17 PedigreesPresentation of family information that is easy to read; can show genetic patterns of diseaseCircles = females; Squares = males; Diamond = unknown genderDeceased = diagonal line throughUnaffected = Clear/white; Affected = filled in/black; Carrier = shadedMarriage = Individuals attached side by sideChildren = Vertical line downSiblings = Individuals coming down off shared horizontal line
18 Seeing Genetic Patterns of Disease Using a Pedigree Chart Autosomal Disorders are disorders that are passed through the non- sex chromosomes (autosomes)Autosomal Dominant: If a disease is autosomal dominant, it means you only need to get the abnormal gene from one parent in order for you to inherit the disease. One of the parents may often have the diseaseAutosomal Recessive: An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to developX/Y-Linked Disorders are disorders that are passed through sex chromosomes (X / Y chromosomes)
20 An Example of X-Linked Traits Using a Pedigrees Muscular Dystrophy is a disease that causes weakening of the muscular- skeletal system, inhibiting those affected from locomotion. There are many forms of this disease.The Duchenne form of this disease is caused by a mutation on the X chromosome. It is an X-linked recessive disorder. It is more severe than the Becker form of the disease.This means that substantially more boys than girls are going to be affected by this disease
22 Try it…Sally and Brian got married and had 3 daughters, Brianna, Roxanne and Racheal. Sally learned that she is a carrier of Duchenne muscular dystrophy. Brianna got married to Mike and had two sons, Will and Ryan. Mike appears to be healthy; however Will has muscular dystrophy but Ryan does not. Draw a pedigree.