
Fact 3
Prebiotic forces cannot arrange DNA nucleobases that contain the stored information of the DNA strand.
DNA information requires not only the building blocks, but the building blocks must be organized in a specific sequence to produce a viable result. Information is also stored in proteins, carbohydrates, and RNA.
DNA Information-DNA (Deoxyribonucleic Acid) is the molecule that stores and transmits genetic information in all living organisms. It provides the instructions for building proteins and regulating cellular activities.
Structure of DNA
DNA is a double helix composed of two complementary strands of nucleotides. Each nucleotide consists of:
1. Sugar (Deoxyribose)
2. Phosphate Group
3. Nitrogenous Base
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
The nitrogenous bases pair specifically:
Adenine pairs with Thymine (A-T)
Cytosine pairs with Guanine (C-G)
The strands are held together by hydrogen bonds between the bases and form a double helixwith an antiparallel orientation.
Functions of DNA
1. Genetic Information Storage
Contains the instructions for all cellular functions.
2. Replication
DNA can copy itself to ensure genetic continuity during cell division.
3. Protein Synthesis
Transcription: DNA is used as a template to produce messenger RNA (mRNA)
Translation: mRNA is translated into proteins by ribosomes.
DNA in the Origin-of-Life Problem
DNA is central to life, but its formation under prebiotic conditions is a significant challenge:
1. Nucleotide Synthesis
Forming nucleotides (sugar + phosphate + nitrogenous base) under early Earth conditions is complex and inefficient.
2. Polymerization
Linking nucleotides into a stable chain (phosphodiester bonds) without enzymes is highly unlikely in prebiotic environments.
3. Chirality Problem
Nucleotides exist in both right- and left-handed forms, but life only uses right-handed sugars. Achieving this specificity prebiotically is unexplained.
3. RNA World Hypothesis
Some scientists propose that RNA (a simpler molecule capable of both storing genetic information and catalyzing reactions) came first, with DNA evolving later for stability.
The simplest known single-cell organism is Mycoplasma genitalium, a bacterium with one of the smallest genomes of any free-living organism. Here’s a quick breakdown:
1. Genome
Has around 580,000 base pairs and about 525 genes, which is remarkably small compared to other bacteria.