Mrs. Howland Biology 10 Rev. Feb 2016 4/28/2017 7:27 PM Unit 8: Human Heredity Mrs. Howland Biology 10 Rev. Feb 2016 © 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

What can be INHERITED? TRAITS

Why LOOK at inheritance? Can predict DISORDERS Pedigree analysis Inheritance patterns Phenotypes  Genotypes

Information about INHERITANCE Inheritance may be studied by looking at: Karyotypes Pedigrees Physical traits to determine genotypes Patterns: sex-influenced, X-chromosome inactivation Heterozygous advantage Mistakes in meiosis (nondisjunction) Prenatal genetic screening

LOOKING BACK… HOMOLOGOUS CHROMOSOMES = Chromosomes that are the same size and have the same gene sequence PAIRS of homologous chromosomes have 2 different alleles of the same gene, located at the gene locus

Karyotypes Looking at chromosomes KARYOTYPE = Display of condensed chromosomes arranged in pairs

Karyotypes REMEMBER ~ Each chromosome has 2 sister chromatids joined at the centromere; karyotype shows chromosome pairs MAKING A KARYOTYPE: Pictures are taken during meiosis Pictures are cut and arranged to show all pairs of chromosomes in one view

Sex Determination 22 pairs are autosomes (the same for everyone!) 1 pair determines sex (male or female) XX pair = female XY pair = male SEX-DETERMINING CHROMOSOMES NOTE: This shows both X and Y as single types, but they are present as a PAIR! (XX or XY)

Male vs. Female KARYOTYPE SEX CHROMOSOMES SEX CHROMOSOMES AUTOSOMES AUTOSOMES

MISTAKES during meiosis NONDISJUNCTION = Paired chromosomes do not properly separate during cell division

NONDISJUNCTION can occur during Meiosis I OR Meiosis II, causing different effects:

VIDEO: Chromosomal Disorders https://www.youtube.com/watch?v=k4Lps1kIyR0

Down Syndrome Down syndrome is caused by an extra copy of chromosome 21. This is called trisomy

Downs Syndrome Affects 1 in every 800-1000 babies Caused by NONDISJUNCTION Caused by TRISOMY in chromosome 21

Turner Syndrome Turner Syndrome = chromosomal disorder in which female is born with only ONE ‘X’ chromosome

Turner Syndrome What happens when a female has only ONE X chromosome? SYMPTOMS: Short stature Webbed neck Swollen hands and feet Spots on skin Underdeveloped ovaries; no menstruation; infertility

Klinefelter Syndrome Klinefelter Syndrome = Chromosomal disorder in which individuals have TWO ‘X’ chromosomes and ONE ‘Y’ chromosome

Klinefelter Syndrome What happens when an individual has XXY sex chromosomes? SYMPTOMS: Tall; long lets Poor muscle tone Female breasts Small testicular size Poor or no male hair growth

Williams Syndrome Williams Syndrome = autosomal dominant disorder in which several of 26-28 specific genes) are DELETED from chromosome 7 NOT inherited Caused by mistake in formation of gametes Only needs 1 chromosome with deletion(s) to cause disease Occurs every 1/10,000 births

Williams Syndrome SYMPTOMS: Low birth weight Characteristic facial features Cardiovascular disease Excessively social personality Developmental delays; learning disorders

SEX DETERMINATION During segregation, egg and sperm cells get one sex chromosome, X or Y OFFSPRING: 50% MALE 50% FEMALE

SEX-INFLUENCED TRAITS Some inherited traits are located on the sex chromosomes = sex-influenced traits (also called sex-linked) Traits located on the X chromosome Are usually recessive FEMALES can have 3 phenotypes, including carrier (heterozygous genotype) MALES have only ONE X chromosome  if the X chromosome has the recessive allele, the male WILL express the trait!

SEX-INFLUENCED TRAITS EXAMPLE: Colorblindness A recessive trait carried on the X chromosome KEY: XB = Dominant, Normal Xb = Recessive, Colorblind Males have only one X chromosome, so if the X has the recessive gene, then they are colorblind!

SEX-INFLUENCED TRAITS EXAMPLE: Colorblindness A recessive trait carried on the X chromosome KEY: XB = Dominant, Normal Xb = Recessive, Colorblind Males have only one X chromosome, so if the X has the recessive gene, then they are colorblind!

SEX-INFLUENCED TRAITS EXAMPLE: Male pattern Baldness A recessive trait carried on the X chromosome

SEX-INFLUENCED TRAITS EXAMPLE: Male pattern Baldness A recessive trait carried on the X chromosome KEY: XB = Dominant, Normal Xb = Recessive, Baldness

Hemophilia ~ Sex-linked disorder

SEX-INFLUENCED TRAITS YOU TRY IT! Hemophilia = bleeding disorder where blood does not clot normally XH Xh KEY: XH = Dominant, Normal Xh = Recessive, hemophilia X * What is the ratio for the offspring (phenotype/genotype)? * What are the phenotypes of the parents? Y

VIDEO: Sex-linked disorders https://www.youtube.com/watch?v=Eb56RCTh-OY