Download Chapter 11: Organization of DNA in Eukaryotes 11.2: mtDNA

Chapter 11: Organization of DNA in Eukaryotes
11.2: mtDNA
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Describe the Endosymbiotic hypothesis. Essentially, modern cells are a product of ancient eukaryotes engulfing free-living mitochondria and/or
chloroplasts, allowing these (believed to be) prokaryotes to reside inside of the cytoplasm in a symbiotic relationship. After some time, these
mitochondria and chloroplast could no longer live on their own outside of the eukaryote.
How large is mtDNA in humans? About 16,000 base pairs, or 16 kilobases
Does mtDNA have introns? What are introns? How is the presence or absence of introns significant?
Human mtDNA does NOT have introns. Introns are non-coding SEQUENCES of the double helix. The absence of INTRONS in human mtDNA means that
mutations will have a greater impact because all of the information is needed for normal cell structure and function; there is no “fluff”
What does human mtDNA code for? What are the products of mtDNA transcription and translation?
13 proteins for aerobic cellular respiration; 22 tRNA for translation; 2rRNA for translation
11.4: Eukaryotic Organization of DNA
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Chromatin
Uncoiled DNA present in the nucleus
During INTERPHASE.
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Histones
Proteins that allow DNA to spool around them due to the charge difference between the negatively charged DNA and the positively charged amino acids
that make up the structure of the histones. Histones act much like a spool, allowing the DNA to wrap around the perimeter of the structure to draw
DNA into a tightly-coiled mass.
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Nucleosome
The combination of DNA and histone protein comprises a nucleosome structure.
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Acetylation
Methylation
Phosphorylation
ALL are chemical modifications of the histone/DNA/nucleosome structure
Adds a charged particle that
Addition of a methyl group to
Addition of a phosphate group
changes the affinity of DNA and the nucleosome structure which
to the amino acids of the
histone.
may activate genes.
histone, changing the histone
to a negative charge.
Heterochromatin
vs.
Euchromatin
NON-coding REGIONS of chromosomes
CODING regions of chromosome
vs
Chromosomes
super-coiled DNA present in the nucleus
During MITOSIS/MEIOSIS