1 / 19

Chromosomes

Chromosomes Objectives: Explain how karyotypes can be used to identify chromosomal abnormalities Identify the chromosomes responsible for a person’s sex Chromosomes Supercoiled complex of DNA and proteins DNA codes for LOTS of things The codes must be neatly organized

salena
Download Presentation

Chromosomes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chromosomes Objectives: • Explain how karyotypes can be used to identify chromosomal abnormalities • Identify the chromosomes responsible for a person’s sex

  2. Chromosomes • Supercoiled complex of DNA and proteins • DNA codes for LOTS of things • The codes must be neatly organized • The codes are organized into genes • Chromosomes are stacks of genes

  3. Supercoiling

  4. Chromosomes • Chromosomes found in metaphase will have 2 chromatids and will be attached by a centromere • The chromatids are identical

  5. Chromatin • DNA usually exists in chromatin • Chromatin is a uncoiled DNA and protein complex • Chromatin only supercoils when cells are entering mitosis or meiosis

  6. Harvesting Chromosomes • Chromosomes develop from chromatin during prophase • They are clearly seen in metaphase since there is no nuclear membrane

  7. Harvesting Chromosomes • Cells are frozen in metaphase • Chromosomes are then treated and stained • They are viewed under a microscope • A photograph is taken • The photograph is enlarged and the chromosomes are cut out

  8. Karyotype Equipment

  9. Karyotypes • Homologous chromosomes are paired • The pairs are arranged by size and in order with their centromeres aligned

  10. Ploidy • Not all organisms have 23 pairs of chromosomes • 2N = diploid • N = haploid • 2N = 46 for humans • N = 23 for humans • Find the ploidy of the organisms listed

  11. Sex Chromosomes • The first 22 pairs of chromosomes are called autosomes • The 23rd pair of chromosomes are called sex chromosomes • They code for whether the individual will be male or female • If the 23rd pair is homologous the individual is a female • If the 23rd pair is non-homologous the individual is a male

  12. Sex Chromosomes • The chromosomes are referred to as X and Y • XX = female • XY = male • The Y has significantly less genes on it than the X

  13. Sex Chromosomes Male Female

  14. 2n=46. Human We use karyotypes to find genetic disorders. And to determine the sex of the individual.

  15. Karyotypes Homework • Find the pairs • Arrange them in pairs, in order of size, with the same line going through each pair’s centromeres • Paste the pairs in your comp book • Is the person a male or a female? • Is there a genetic disorder?

  16. Karyotype Homework • Google karyotype • Print one of a non-human organism • Paste it to your compbook • Remember to identify what organism you chose

  17. Socks Male FYI: Socks aren’t really organisms.

More Related