1 / 13

This video is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported license.

Useful Genetics Professor Rosie Redfield The University of British Columbia. This video is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported license. Lecture 1E. What’s a chromosome?. ??. Outline:. One very long DNA molecule Information for 100s or 1000s of genes

uma
Télécharger la présentation

This video is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported license.

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. Useful Genetics Professor Rosie Redfield The University of British Columbia This video is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported license.

  2. Lecture 1E • What’s a chromosome? ?? Outline: One very long DNA molecule Information for 100s or 1000s of genes Regulatory signals We each have 2 versions of each of 23 kinds Learning objectives: • Relate the physical and informational properties of chromosomes • Recognize different representations • Use gene, allele and locus correctly

  3. Chromosome structure: • One very long molecule of DNA. • (e.g. human X = 1.5 x 108 bp) • Bound to and wrapped around proteins • Chromosome information: • One very long DNA sequence. • Genes and other functions embedded in nonfunctional sequence.

  4. For a molecule of DNA to function as a chromosome, it must carry specific information: Signals recognized by DNA replication proteins (‘origins’ where DNA replication starts and ‘telomeres’ at the chromosome ends). A ‘centromere’ signal that creates an attachment point for the fibers that pull replicated chromosomes apart in cell division. (Genes)

  5. Human chromosomes are fairly typical: • 23 different ones (2 versions of each) • Named 1 to 22, from largest to smallest, and X and Y (the two versions of the ‘sex chromosomes’ • ~50 – 250 million base pairs long • ~400 – 4000 genes on each (Some unusual organisms encode all their genes in only a few very large chromosomes, and some have them in hundreds of tiny chromosomes.)

  6. How are genes arranged on the chromosomes? Not neatly! Not compactly!

  7. NM_080574 C20orf70: chromosome 20 open reading frame 70 Images from HapMap http://hapmap.ncbi.nlm.nih.gov/

  8. Question: Chromosome 20 is about 60 x 106 bp long and has about 900 genes. If all its genes are like the one highlighted below, how much of its DNA codes for protein? ~0.03% ~0.3% ~3% ~30% NM_080574 C20orf70: chromosome 20 open reading frame 70

  9. Essential terminology: locus, gene, allele LOCUS: the location of a gene or other DNA sequence on a chromosome. (refers to any/all alleles of that gene) ALLELE: a non-identical version of a gene or, more generally, of a DNA sequence. GENE: Usually, a segment of DNA specifying a protein or functional RNA. (Often used where ‘allele’ or ‘locus’ would be clearer.)

  10. How chromosomes are represented: Chromosomes are not shaped like blobby Xs or skinny butterflies. The bands drawn on chromosome ‘ideograms’ do not represent genes. How I will usually represent chromosomes

  11. How chromosomes are represented: Chromosomes are not shaped like blobby Xs or skinny butterflies. The bands drawn on chromosome ‘ideograms’ do not represent genes. How I will usually represent chromosomes

  12. What we’ve done The physical and informational content of chromosomes Regulatory signals control chromosome function How genes are ‘arranged’ on chromosomes terminology: origin, telomere, centromere, locus, allele How chromosomes are represented

  13. Coming up.... ? Lecture 1F • Life cycles and ploidy

More Related