Tuesday, June 28, 2011

Deep Ancestry - 01

Genetic testing is often used to determine deep ancestry. In the next few slides I'll discuss some of the recent genetic studies on Bengali Brahmins and what they suggest. So first I start with the fundamentals of genetics as applicable to genetic genealogy testing.

Fundamentals of Genetics


1. Our body is made up of cells.
2. Every cell in the human body contains 23 pairs of chromosomes (except reproductive cells (gametes) and mature red blood cells).

1. 1 set of chromosomes is given by each parent
2. Each set has 23 single chromosomes - 22 autosomes and an X or Y sex chromosome
3. Female - X-X, Male - X-Y
4. Each chromosome is a packet of compressed and entwined DNA.

1. A DNA molecule consists of two strands that wrap around each other like a double helix.
2. Each strand of DNA consists of a line of repeating units called nucleotides.

A nucleotide is composed of one sugar, one phosphate and one nitrogen base.

Four different bases are present:
A - Adenine
T - Thymine
C - Cytosine
G - Guanine

Base Pair
1. The strands of the helix are linked by hydrogen bonds between guanine and cytosine and between thymine and adenine.
2. Each such linkage is a base pair.

DNA Sequence
The particular order of the bases arranged along the sugar-phosphate backbone is called the DNA sequence.

a. A gene is a segment of a DNA molecule , located in a particular position on a specific chromosome, whose base sequence contains the information necessary for protein synthesis.
b. A gene is a unit of heredity.
c. Genes are concentrated in random areas along the genome, with vast expanses of noncoding DNA between.

The study of genes is called genetics.

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