learning targets “i can…” -describe homologous chromosomes and identify the chart used to...
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Learning Targets“I Can…”
-Describe homologous chromosomes and identify the chart used to organize homologous chromosomes.
-Create a karyotype from a given set of chromosomes.
-Identify the sex chromosomes on a karyotype to determine the gender of an individual.
-Diagnose any nondisjunction errors in a given karyotype.
Karyotype
Sex Determination
Assignment for today:
• Create a karyotype from the given set of chromosomes
• Determine:1. The gender of your child2. If there are any missing or extra chromosomes and where3. The name of the disorder (if there is one)4. The symptoms of the disorder
Defects in the number of chromosomes can come
from chromosome NONDISJUNCTION
during meiosis
Down Syndrome(aka Trisomy 21)
Normal Meiosis
• Chromosomes separate from each other during . . . – Anaphase I– Anaphase II
Nondisjunction during meiosis
NONDISJUNCTION increases with the mother’s age
• No one is sure why this happens!
• After age 35, amniocentesis is suggested to diagnose extra or missing chromosomes
• Nondisjunction errors are RANDOM!
Nondisjunction of 21st Chromosome (Most Common)
Nondisjunction of Sex Chromosomes
Assignment for today:
• Create a karyotype from the given set of chromosomes
• Determine:1. The gender of your child2. If there are any missing or extra chromosomes and where3. The name of the disorder (if there is one)4. The symptoms of the disorder
References• http://www.stjohnsmercy.org/images/chromosome.gif• http://ghr.nlm.nih.gov/handbook/illustrations/chromosomes.jpg• http://www.biotechnologyonline.gov.au/images/contentpages/chrom
osomes.jpg• http://openlearn.open.ac.uk/file.php/1638/SK220_1_011i.jpg• http://www.genetics.com.au/images/factsheets/fs29-2.gif• http://www.miscarriage.com.au/images/pages/t21karyo.jpg• http://www.biology.arizona.edu/human_Bio/problem_sets/
human_genetics/graphics/klinefelters.gif• http://www.genetics.com.au/images/factsheets/fs28-1.gif
• http://www.mydr.com.au/files/images/categories/babies/amniocentesis.gif