1.
GARRY D. LASAGA
DNA & MITOCHONDRIA
1
GARRY D. LASAGA

2.
Mitochondrial DNA
 Mitochondrial DNA is typically less than 1% of an animal
cell’s DNA population.
 Mitochondria contain their own genome in multiple
copies.
 Mitochondrial genome is distinct from that of the
nucleus.
 Mitochondria have their own DNA and express their
genes to produce proteins in the ETC.
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3.
0%
20%
40%
60%
80%
100%
Mitochondrial
DNA Nuclear DNA
1%
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4.
Mitochondrial DNA
 mtDNA is double stranded circular DNA
molecule
 mt DNA contain 37 genes for normal
mitochondrial function
 13 genes make enzymes involved in oxidative
phosphorylation
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5.
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6.
Specific genetic code
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7.
Maternal Inheritance of mtDNA
 mtDNA is maternally inherited in most species
(Gyllesten et al., 1991).
 mtDNA is nonrecombinant (Hayashi et al., 1985).
 During fertilization, the sperm only contributes its
nucleus (23 chromosomes).
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8.
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Because of its cytoplasmic
location in eukaryotes, mtDNA
does not undergo meiosis and
there is normally no crossing-
over, hence there is no
opportunity for introgression of
the father’s mtDNA.

9.
The Mitochondrial Genome
 16,569 base pairs (bp) in length (16-18 kbp)
 Encodes for 37 genes, 13 proteins, 22 tRNAs,
and 2 rRNAs
 Two general regions:
Coding region
Control region
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10.
NUCLEAR DNA MITOCHONDRIAL DNA
Found in the nucleus Found in the mitochondria
2 sets of 23
chromosomes
Each mitochondria may have
several copies of the single
mtDNA molecule
Maternal and paternal Maternal only
Can “discriminate
between individuals of the
same maternal lineage”
Cannot “discriminate between
individuals of the same maternal
lineage”

11.
NUCLEAR DNA MITOCHONDRIAL DNA
Double helix Circular
DNA is packed into
chromatin
DNA is not packed into
chromosome
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12.
Nuclear DNA vs. Mitochondrial DNA
• Nuclear DNA undergoes homologous recombination
• Maternal and Paternal DNA are mixed
• Mitochondrial DNA does NOT undergo recombination
Paternal
chromosome
Maternal
chromosome
Offspring inherit
mixed chromosomes
Circular
Mitochondrial
chromosome

13.
Mothers pass mitochondrial DNA
directly to offspring

14.
D-loop region
F
PT
A
S
1 2 3
LS
P
HS
P
O
H
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14 Human mtDNA contains only one longer
region, which is non-coding, and it is called
the non-coding region or the control
region.
 The signature form of mammalian mtDNA
is the displacement loop (D-loop)
molecule.
 It is a three-stranded structure with the
nascent leading H strand defining the
origin of leading-strand replication
(OH).