Ro_Lecture15

Ro_Lecture15 - Eukaryotic chromosomes Bacterial DNA is in a...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Eukaryotic chromosomes Bacterial Eukaryotic DNA is in a nucleoid body DNA is in chromosomes There is one large DNA molecule There are many molecules Circular Linear The DNA in the diploid nucleus is ~2 meters long. It is present in a nucleus that is a 1000 cubic microns. Function of chromosomes Packaging Regulation Total human DNA is 3x10 9 bp Smallest human chromosome is 5x10 7 bp The DNA in this chromosome is 14 mm long The chromosome is 2um long 7000 fold packaging!
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Chromosome characteristics Centromere Telomere Chromosome arms
Background image of page 2
3 Karyotype Karyotype gives species specific chromosome organization It is usually a microscopic classification The number of chromosomes The size of each chromosome Position of centromere on each chromosome Chromosomes can be stained Telocentric Acrocentric Metacentric
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Chromosome number (haploid) Organism size number Yeast (S. cerevisiae) 12 16 Mold (Dictyostelium) 70 7 Arbidopsis 130 5 Lily 50,000 12 Nematode (C. elegans) 97 6 Fly (Drosophila) 180 4 Fugu 365 1 Mouse 3000 20 Human 3000 23 Evolutionary significance of variability In number and length is not known
Background image of page 4
5 Chromosome size Chromosome size (human) Chr Mb 1 246.1 2 243.6 3 199.3 4 191.7 5 181.0 6 170.9 7 158.5 8 146.3 9 136.3 10 135.0 11 134.4 12 132.0 13 113.0 14 105.3 15 100.2 16 90.0 17 81.8 18 76.1 19 63.8 20 63.7 21 46.9 22 49.3 X 153.6 Y 22.7
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Banding Cells in metaphase can be fixed and stained with dyes Some dyes that stain chromosomes give a characteristic banding pattern. In a diploid, homologous chromosomes have the same banding pattern Stained chromosomes are photographed, cut and arranged in decreasing size
Background image of page 6
7 Karyotype The human karyogram. The chromosomes are shown with the G-banding pattern obtained after Giemsa staining. Chromosome numbers and band numbers Constitutive heterochromatin is very compact chromatin which has few or no genes
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
8 Karyotyping Karyotyping provides a rapid means to identify alterations in the number of chromosomes In humans ~50% of conceptions are aneuploid Over 70% of spontaneous abortions and early embryonic deaths are caused due to Aneuploidy 1 in 170 live births is partially aneuploid ~5-7% of early childhood deaths are to aneuploidy Humans have a rate of aneuploidy that is 10 times greater other mammals Non-dysjunction in meiosis is the primary cause Monosomy- one chromosome of a pair is missing
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 28

Ro_Lecture15 - Eukaryotic chromosomes Bacterial DNA is in a...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online