BIO 402/502 Advanced Cell & Developmental Biology I. Section IV: Dr. Berezney. Lecture 1. The Cell Nucleus and its Genome. Organization of Eukaryotic Genome. Contrasting features of prokaryotic and eukaryotic genomes with respect to size, percent of coding region and number of genes.
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Section IV: Dr. Berezney
The Cell Nucleus and its Genome
Globin gene family; demonstrate that: prokaryotic DNA is a unique sequence of DNA whereas eukaryotic DNA is composed of highly repetitive, moderately repetitive and unique sequences. gene amplification:e.g, human type 1 interferon gene cluster is 480 kb in size and is composed of dozens of repeating genes and pseudogenes.Gene duplication or amplificationis a result of“unequal crossover”during meiosis & is a general mechanism of evolution of tandemly repeated DNA sequences. This is due to misalignment on the two homologous chromosomes. This also leads togene deletions.Gene Families & Pseudogenes
F demonstrate that: prokaryotic DNA is a unique sequence of DNA whereas eukaryotic DNA is composed of highly repetitive, moderately repetitive and unique sequences. luorescence In Situ Hybridization (FISH)For detection of specific DNA sequences (e.g., genes) in the nucleus of cells and chromosomes on metaphase spreads
Four step procedure
Gene 1 biotin-dNTPs biotin labeled gene 1
Gene 2 digoxyigenin-dNTPs dig labeled gene 2
dig-alexa 594 (red); collect images on microscope
For detection of specific DNA sequences (e.g., genes) in the nucleus of cells and chromosomes on metaphase spreads.
Chromosome 7 (red) / 12 (blue) Translocation
2.8 A 3-D structure
Loops of DNA
Chromosome scaffold with DNA halo
Nuclear matrix remaining after extraction of whole cells
Chr #18 & 19 in human lymphocyte interphase nucleus
Nuclear matrix with DNA halo
In situ evidence for a chromatin loop organization
Chromosome 1 (red),
Chromosome 9 (green)