Nuclear DNA and Mitochondrial DNA

Nuclear DNA

• Present in almost every cell

• Combination from both parents; 23 chromosomes from each parent

Mitochondrial DNA

• Each cell contains thousands of mt, each containing copies of its DNA

• Mt DNA is in larger quantities in a cell

• Nuclear DNA is larger in size

Mt DNA is 16,569 bases in length and consists of 2 different regions

• Coding Region– Produces 13

proteins, 22tRNAs, 2rRNAs needed for cell respiration

– This region has very little variability

– So everyone’s DNA in this region will be nearly the same sequence of TGCAs

Coding RegionDNA RNA Protein Trait

Control Region

This region is highly variable within the human population

Consists of 2 subregions

HV1 = 342 bp HV2 = 268

Mt DNA is inherited from mom

• Every sibling will get their mt DNA from their mother

• Why?

• Egg contains 23 chromosomes and cell cytoplasm which contains thousands of maternal mt

• Sperm contains 23 chromosomes with very little cytoplasm

Zygote = Fertilized Egg

• When egg and sperm join only female mt survive and are passed onto to new baby.

Maternal Inheritance Pattern with Mt DNA

Mutations occur in the control region of mt DNA at a regular rate and are passed onto children by the mom.

• We can compare DNA from the controlling region to other living humans– See how related to you are to each other

• Compare to prehistoric remains of human fossils– Identify where you DNA originated– Identify ancestral relationships between

modern populations

• Compare your highly variable regions to other species

Mitochondrial Eve• Oldest women who

would have donated her mtDNA to every ancestor in the world

• Comparisons can be made by how many variations exist between her DNA and your DNA.

1. Isolate DNA from cheek cells2. Complete a PCR reaction

– Produce millions of extra copies of HV1 on the control region of mtDNA

3. Send amplified DNA away to be sequenced (Identify the exact sequence of TGCAs in HV1 in your mtDNA)

4. Compare your sequence ot classmates and database of prehistoric DNA

• 1. Isolating DNA

2. Polymerase Chain Reaction

• PCR

PCR Animation

PCR Animation

3. Sequencing DNAIdentify the exact sequence of nitrogen

bases in HV1 region

Sequencing DNA

4. Making Comparisons

Using a database you will compare your mt DNA with:

• your classmates

• prehistoric DNA taken from fossilized human remains.

• other species