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How many chromosomes should a “normal” human have?Are females XX or XY? How do the words: DNA, gene and chromosomes relate?
12.2: Chromosomal Disorders
Chromosomal disorders: Errors in the number or structure of a chromosome
Non-disjunction Homologous chromosomes or sister chromatids fail to separate during meiosis. Result: Gametes with abnormal # of chromosomes
Trisomy Having 3 of a particular chromosome.Examples Trisomy 21: Down syndrome Trisomy 18: Edwards syndrome - feet with rounded bottom - crossed legs, clenched hands
Trisomies of Sex ChromosomesXXX Female XXY: Klinefelter Male XYY: Male Turner’s Syndrome XO Female 45 Chromosomes
Chromosomal DuplicationsPart of a chromosome is repeated. Vary from fatal to developmental abnormalities. Often leads to cancer in somatic cells
Chromosomal DeletionsPart of a chromosome is deleted. Ex: Williams Syndrome Partial deletion of chromosome 7
Chromosome Inversion Fragment breaks and reverses on the same chromosome. Not as lethal.
Chromosome TranslocationFragment of one chromosome attaches to ANOTHER, DIFFERENT chromosome. If there is an UNEQUAL swap of segments, results can serious. List of Chromosome Disorders
Transposons Single genes that can move around.“Jump” from one chromosome to another. If they insert in the middle of an existing gene, that gene will be disrupted.
What is a Karyotype? Karyotype: picture of an individual’s chromosomes arranged in homologous pairs. Chromosomes are usually extracted during METAPHASE.
Chapter 15~ The Chromosomal Basis of Inheritance
February 23, 2009 Objective: Discuss the effects of nondisjunction
Introduction to Human Genetics
Chapter 24: Patterns of Chromosome Inheritance
12.4 MUTATIONS I. Kinds of Mutations
AP Biology Errors of Meiosis Chromosomal Abnormalities.
Xy = XX= female male Female karyotype Male karyotype.
1copyright cmassengale. Aorganized picture arranged in pairs by size An organized picture of the chromosomes of a human arranged in pairs by size from.
3.3 Meiosis cont..
Errors of Meiosis Chromosomal Abnormalities Chromosomal abnormalities Incorrect number of chromosomes – nondisjunction chromosomes don’t separate properly.
Compare Critical differences between Mitosis and Meiosis: Tetrads form (Pro I) Crossing over can occur (Pro I) Tetrads line up and are separated (Meta.
Abnormal Meiosis: Genetic Disorders. Review: Human Chromosomes There are 46 chromosomes (23 homologous pairs) in each somatic cell 22 pairs of autosomes.
Meiosis and Human Reproduction
Ch. 12.1: DNA stores Information Objectives: 1.Describe how DNA is packed within the nucleus. 2.Explain the significance of the Human Genome Project. Vocab:
1. CHROMOSOMES 2 CHROMOSOME NUMBER All cells in the human body (SOMATIC CELLS) have 46 or 23 pairs of chromosomes Called the DIPLOID or 2n number.
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