Upload
collin-jefferson
View
223
Download
0
Tags:
Embed Size (px)
Citation preview
Eukaryotic Chromosome Organization
Chromosome Organization• if all of the DNA was stretched out, it would measure
1.8 metres in length
• How does it fit into a typical human cell nucleus, 10 micrometres in diameter?
• there is a hierarchical organization
• DNA is coiled around a group of 8 stabilizing proteins called histones, forming nucleosomes
Chromosome OrganizationSee animation: http://www.biostudio.com/c_
%20education%20mac.htm
Histones
Linkers
Nucleosome(8 histones)
Solenoid(6 nucleosomes)
Supercoil
Prokaryotic DNA
Prokaryotic DNA
• primary DNA is single circular chromosome
• supercoiling happens in prokaryotes
• plasmids are other circular pieces of DNA contained in prokaryotes
• plasmids can be exchanged through conjugation
Telomeres
Telomeres• telomeres are non-coding, repetitive
sequences at the ends of chromosomes
Telomeres
Telomeres
Telomeres
• during replication, the last 5’ end primer on the lagging strand is removed but not replaced with DNA
• This shortens the telomeres on each subsequent replication cycle
» http://www.youtube.com/watch?v=8_bNfQd7Smc
QuickTime™ and a decompressor
are needed to see this picture.
Telomeres• after many replications, telomeres will eventually
disappear, allowing coding DNA to be damaged• cell senescence- deteriorated functioning with
age as chromosomes shorten• Hayflick limit = total number of times a normal
cell can divide (about 50 in humans)
Dolly the Sheep
Anti-Aging
Dani Walker “Stop Aging Now TS-X Telomere Supplement”
20
Homework
1. Read 6.5 for review.
2. Read 6.6 & answer:
a. What is the DNA sequence found in telomeres?
b. What is telomerase? What is its function? Where is it found?
c. What is the role of telomeres in aging?
d. What is the role of telomeres in cancer?
e. Complete the tables provided.