KARYOTYPING What is a karyotype A karyotype is

KARYOTYPING

• What is a karyotype? • A karyotype is a photograph of an individual's chromosomes arranged in pairs.

• The photograph is taken during mitosis when all of the chromosomes have been duplicated and condensed. • Male or Female? ?

Meiosis Type of cell division where one body cell produces four gametes, each containing half the number of chromosomes as the original cell.

Mitosis v. Meiosis Use your book (chapter 9) To list differences between Mitosis and Meiosis **Do this after your karyotyping activity is complete

MITOSIS PROPHASE METAPHASE ANAPHASE TELOPHASEE Fig. 10 a p. 171

Mitosis v. Meiosis Use your book (chapter 9) To list differences between Mitosis and Meiosis **Do this after your karyotyping activity is complete

MEIOSIS I PROPHASE I METAPHASE I ANAPHASE I TELOPHASE I

MEIOSIS II PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II

MEIOSIS II in-text, p. 163

Meiosis • Sexual reproduction Formation of new individual by a combination of two haploid sex cells (gametes). • Fertilization- combination of genetic information from two separate cells that have one half the original genetic information • Gametes for fertilization usually come from separate parents – Female- produces an egg – Male produces sperm

Meiosis • Both gametes are haploid, with a single set of chromosomes • The new individual is called a zygote, with two sets of chromosomes (diploid). • Meiosis is a process to convert a diploid cell to a haploid gamete, and cause a change in the genetic information to increase diversity in the offspring.

Definitions • Diploid - a cell with two of each kind of chromosome. Represented as 2 n. • Haploid - a cell with one of each kind of chromosome. Represented as n. • Homologous chromosomes - pairs of chromosomes that have genes for the same traits. • Allele - alternate forms of a gene for each variation of a trait of an organism.

Definitions • Gametes - sex cells – Sperm - Male gamete – Egg - Female gamete • • Zygote - a fertilized egg cell In humans gametes contain 23 chromosomes

• 9. 5 Reading Guide • Get this done before you leave today!!

(Y) (X) one pair of duplicated chromosomes

Crossing Over • During Prophase I of meiosis, homologous chromosomes may exchange genetic material. This results in new combinations of alleles on chromosomes.

Mistakes in Meiosis • Nondisjunction - the failure of homologous chromosomes to separate during meiosis. • • • Trisomy - meiosis which results in one extra chromosome Monosomy - meiosis which results in one missing chromosome Triplody - meiosis which results in an extra set of chromosomes

Abnormal Karyotypes 1. Trisomy 21 or Down's syndrome 2. Fragile 5 or Cri Du Chat (cry of cat) Syndrome 3. Sex-linked non-disjucntions - Jacob Syndrome (extra XYY-) - Klinefelter Syndrome (extra X-XXY) - Turner Syndrome (missing X 0) - Fragile X - Triple X Syndrome (XXX)

n+1 n-1 chromosome alignments at nondisjunction alignments at at anaphase I metaphase I n-1 anaphase II

GROUP REVIEW • You will be in your lab groups • Use your review to answer the questions I’ve listed for you at your table. • You will have 8 minutes to complete your two questions. • We will then present to the class your findings.

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