A Very Short and Simple Genetics Primer

Perhaps, the strongest evidence for the existence of God originates in our genetics. This area of research presents a conundrum for atheists and skeptics. Why? Because there is not a single, repeatable experiment that comes close to demonstrating the origin of cells, chromosomes, genes and DNA. Yet, this is precisely the area of research, in my opinion, where natural theories must prove fruitful in order to be taken seriously.

It's one thing to assert that similar, physical structures imply a common ancestor, but, it's quite another to assert it at the cellular level.

For these reasons and others, the next series of arguments will make the case that belief in God as the originator of life is far more rational than the alternatives. To prepare for these arguments, a genetics primer is necessary to establish a foundation to build on.

Cells are the building blocks of life. They form colonies, they grow, and they reproduce. The human body is composed of approximately 200 different types of specialized cells like brain cells, skin cells, liver cells, and stomach cells. All total, they number around 100 trillion!

Regardless of their type, all cells share common traits:

• They have an outer protective membrane that surrounds and protects the cell's interior and which regulates the intake and outake of nutrients and waste products.
• The interior of all cells is filled with a watery substance called cytoplasm which contains the nutrients and machinery that carry on the functions of life.
• All cells contain DNA, the instructions that direct the cell and orchestrate its replication. Without DNA, cells would not know how to carry on the functions of life or reproduce. Some cells have a nucleus in which the DNA resides. Other cells don't. In these cells, the DNA resides in the cytoplasm. Humans have both kinds of cells.

Bacteria are single celled organisms that have no nucleus.

DNA is composed of a chain of molecules that contain all the information necessary for the life functions of a cell. The individual molecules that make up DNA are called nucleotides. There are only four: Adenine (A), Thymidine (T), Guanine (G), and Cytosine (C).

A nucleotide is a molecule containing nitrogen.

The nucleotides bond together in pairs using specific rules. Adenine and Thymine always bond together and are represented as AT; Cystosine and Guanine always bond together and are represented as CG.

The resulting pairs are called "base pairs."

Why these rules - why not AC or GT pairs? Because the hydrogen bonds necessary for their pairing only exist with AT and GC.

To use the analogy of a sentence, the base pairs are grouped to form words, for example:
ATT CTG TAA.

The words form sentences:
ATT CGA CAC. ATG GAA TAA TCA TA.

The sentences are called genes.

DNA has two strands of sentences (genes) each complementing the other to form a unified whole. In other words, if one strand of the DNA sequence is ATTCGAC, then the complementary strand must be TAAGCTG.

A->T
T->A
T->A
C->G
G->C
A->T
C->G

Since they are complementary, the sequence of one strand determines the other.

The hydrogen bonds between the letters twist the two strands so that it looks like a twisted ladder called a double helix with the base pairs as the rungs, bonded to a sugar-phosphate backbone as the ladder frame.

The sentences inside the double helix are referred to as the genetic code.

The DNA double helix strand is partitioned into packages called chromosomes. Humans have 46 chromosomes. 44 of them are paired together because of their similarities and two, called the XY pair determine gender. Two X chromosomes (XX) specifies female and one X, one Y (XY) specify male.

Chromosomes are the basic units of heredity.

Chromosomes contain genes. Genes are short segments of DNA that instruct the cell to make proteins. How? Proteins are made of chains of amino acids and and genes provide the instructions for making the amino acid chains.

Proteins are the basic biochemical units that drive all biological processes.

In every cell, human beings have approximately 30,000-35,000 genes providing instructions for 100,000 proteins!

Incidentally, for awhile, scientists thought much of our DNA was 'junk' for which no function had been identified. Recent research, however, has been completely refuted their assertion. See below.

Regarding reproduction, cells reproduce by splitting. When this occurs, the DNA double helix splits breaking the hydrogen bonds between the base pairs. As the DNA strands unwind, new hydrogen bonds form on each single strand from the cytoplasm in the cell ultimately resulting in two identical, double helix strands, one for each cell.

So, in summary: Cells, the smallest unit of life, are fundamental to living systems and manage the biochemical processes of life. Some cells have a nucleus, and some don't, however, all receive their instructions from DNA which is segmented into chromosomes. When cells reproduce, they split forming identical cells with identical DNA strands.

The following links provide additional information:

What is a Cell?
A Tour of the Basics
DNA for Dummies
Junk DNA