Chromosomal Abnormalities. Nondisjunction Incorrect number of chromosomes  nondisjunction  chromosomes don’t separate properly during meiosis.

Slides:



Advertisements
Similar presentations
Chromosomal Abnormalities
Advertisements

Chapter 15~ The Chromosomal Basis of Inheritance
February 23, 2009 Objective: Discuss the effects of nondisjunction
Introduction to Human Genetics
AP Biology Errors of Meiosis Chromosomal Abnormalities.
Chapter 15~ The Chromosomal Basis of Inheritance.
Karyotypes.
AP Biology March 22, 2012  BellRinger  If two genes are located close together on the same chromosome, how might this affect expected inheritance predictions?
Gene Cloning and Karyotyping. Gene Cloning Techniques for gene cloning enable scientists to prepare multiple identical copies of gene- sized pieces of.
Human Karyotypes Human Karyotypes. Normal Female: 46, XX.
Nondisjunction Disorders. Down Syndrome (trisomy 21) 47, XX, +21 / 47, XY, +21 the result of an extra copy of chromosome 21 characteristic facial features,
Down Syndrome (trisomy 21)
Errors of Meiosis Chromosomal Abnormalities Chromosomal abnormalities Incorrect number of chromosomes – nondisjunction chromosomes don’t separate properly.
Genetic Disorders A disease caused by a different form of a gene called a variation, or an alteration of a gene called a mutation.
Cell Cycle #4 - Errors of Meiosis Chromosomal Abnormalities.
Abnormal Meiosis: Nondisjunction.
AP Biology Errors of Meiosis Chromosomal Abnormalities.
Karyotyping Chromosomes are extracted from a cell, stained, photographed and paired for genetic analysis in the lab. Karyotypes are used to identify chromosomal.
Karyotyping Biology Miss Schwipperty. Questions  How many chromosomes come from your Father?  How many chromosomes come from your Mother?  What are.
Karyotypes and Nondisjunction
KARYOTYPING AND NON-DISJUNCTION. What is karyotyping? A method of identification of chromosomes Pictures of chromosomes are taken as the cell undergoes.
Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D pairs! This is 46 total; we get 23 from mom & 23 from.
Introduction to Human Genetics But what happens when meiosis goes wrong? What when wrong? Happens meiosis wrong? When wrong? What meiosis goes wrong? Boehm.
Karyotypes.
Chromosomes. Karyotype – the total chromosome constitution of an individual.
Errors in Meiosis Karyotypes & Chromosomal AbnormalitiesKaryotypes & Chromosomal Abnormalities.
Do Now ●Hand in your labs in the bin. ●What are karyotypes used for? ●What are three purposes that they serve?
 Occurs when chromosomes fail to separate during meiosis  EITHER  Homologues chromosomes during anaphase I  OR  Sister chromatids during anaphase.
Human Genetics: Karyotypes 46 TOTAL 23 homologous pairs.
How many chromosomes do humans have? How many of the 46 are autosomes?
When Meiosis goes wrong
Sex Determination & Nondisjunction Disorders June 13, 2016.
Errors of Meiosis Chromosomal Abnormalities (Ch. 15)
AP Biology AP Question of the Day Which is true about a testcross? A. It is a mating between 2 hybrid individuals B. It is a mating between a hybrid and.
Genetic Disorders.
Do Now Look at the karyotype below, what is the gender of the individual? How do you know? Is the karyotype considered normal? Why or why not?
1. Alterations of chromosome number or structure cause some genetic disorders Nondisjunction occurs when problems with the meiotic spindle cause errors.
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosome Abnormalities
Chromosomes Honors Biology.
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Nondisjunction GT pg (Section 13.10) chromosomal mutation, p.408 (Last paragraph)?? Reg- p. 401, top 374.
Chromosomal Abnormalities
Chromosomes and Inheritance
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Chromosomal Abnormalities
Errors of Meiosis Chromosomal Abnormalities.
Chromosomal Abnormalities
Chromosomal Abnormalities
Presentation transcript:

Chromosomal Abnormalities

Nondisjunction Incorrect number of chromosomes  nondisjunction  chromosomes don’t separate properly during meiosis

How does it occur? Problems with the meiotic spindle cause errors in daughter cells  tetrad chromosomes do not separate properly during Meiosis 1 (Where do tetrads separate?)  sister chromatids fail to separate during Meiosis 2

Figure Meiotic nondisjunction

What happens? Baby will have wrong chromosome number  Trisomy cells have 3 copies of a chromosome  Monosomy cells have only 1 copy of a chromosome

Karyotype Humans have 23 pairs of chromosomes (46 chromosomes total) Karyotypes show the 22 pairs of autosomes and 1 pair of sex chromosomes Males have XY sex chromosome Females have XX sex chromosome Can show if there is nondisjunction present

Figure 13.x3 Human female karyotype shown by bright field G-banding of chromosomes

Down Syndrome Trisomy 21  3 copies of chromosome 21  1 in 700 children born in U.S.  Chromosome 21 is the smallest human chromosome but still severe effects  Frequency of Down syndrome correlates with the age of the mother

Figure Down syndrome

Sex chromosomes  Human development more tolerant of wrong numbers in sex chromosome  But produces a variety of distinct conditions in humans  XXY = Klinefelter’s syndrome male  XXX = Trisomy X female  XYY = Jacob’s syndrome male  XO = Turner syndrome female

Klinefelter’s Syndrome  XXY male  one in every 2000 live births  have male sex organs, but are sterile  feminine characteristics  tall  normal intelligence

Jacob’s syndrome male  XYY Males  1 in 1000 live male births  extra Y chromosome  somewhat taller than average  slight learning disabilities  delayed emotional immaturity  normal intelligence, normal sexual development

Trisomy X  XXX  1 in every 2000 live births  produces healthy females  Why?

Turner’s syndrome  Monosomy X or X0 1 in every 5000 births varied degree of effects webbed neck short stature immature sterile females