Chapter 4: Nucleic Acids & Origin of Life

Definitions: nucleic acid, nucleosides, nucleotides , oligonucleotides, polynucleotides, DNA, RNA, and the bonds that stabilize DNA and RNA, purine, pyrimidine, ATP, GTP, cAMP, replication, transcription, translation, gene expression, genome, gene, phosphodiester linkages, ribozymes, protocells, reverse transcriptase. Concepts: the DNA double helix, the molecular structure of nucleotides, differences between DNA and RNA, complementary base-pairing rule, antiparallel nature of DNA, directionality of nucleic acids, information flow in biological systems (central dogma of molecular biology), what is our closest living relative?, evidence that life may have come from outside of Earth, chemical evolution and the experiment of Stanley and Urey, did the Stanley Urey experiment include oxygen gas?, conditions in which polymers might have been first synthesized, What evidence that supports the “RNA World” hypothesis? Explain the importance of the cell membrane to the evolution of living things. In which ways are protocells a reasonable model for the evolution of cells? What is the evidence that ancient rock contain fossils of cells? Cyanobacteria are believed to have been among the first organisms. True/False

Nucleic acid

1. Polymers of nucleotides that store and transmit genetic information.

Nucleoside

1. A pentose sugar and a nitrogenous base (no phosphate group).

Nucleotide

Monomer of nucleic acids, consisting of a sugar, phosphate, and nitrogenous base.

Oligonucleotides

Short chains of nucleotides involved in gene expression.

Polynucleotides

Long chains of nucleotides (e.g., DNA, RNA).

DNA

Double-stranded nucleic acid that stores genetic information.

RNA

Single-stranded nucleic acid involved in protein synthesis.

Purine

Double-ring nitrogenous bases (adenine, guanine).

Pyrimidine

Single-ring nitrogenous bases (cytosine, thymine, uracil).

ATP

Adenosine triphosphate, the primary energy carrier in cells.

GTP

Guanosine triphosphate, involved in protein synthesis.

cAMP -

Cyclic adenosine monophosphate, a secondary messenger in cell signaling.

Replication

The process of copying DNA.

Transcription

The process of converting DNA to RNA.

Translation

1. The process of synthesizing proteins from RNA.

Gene expression - .

The process by which genes produce proteins.

Genome -

The complete set of genetic material in an organism.

Gene -

A segment of DNA that codes for a protein

Phosphodiester linkage

Bond linking nucleotides in DNA/RNA.

Ribozymes -

RNA molecules with enzymatic activity.

Protocells -

Primitive cell-like structures that may have led to life.

Reverse transcriptase -

Enzyme that converts RNA into DNA.

Concepts

DNA double helix

Structure and function of DNA.

Molecular structure of nucleotides

Components of a nucleotide (sugar, phosphate, nitrogenous base).

Differences between DNA & RNA

Structure, function, and types of nitrogenous bases.

Complementary base-pairing rule

A-T, C-G in DNA; A-U, C-G in RNA.

Antiparallel nature of DNA

The two strands of DNA run in opposite directions.

Directionality of nucleic acids

Nucleic acids grow in a 5' to 3' direction.

Central Dogma

DNA → RNA → Protein

Closest living relative

1. Chimpanzees share the most DNA with humans.

Evidence life may have come from outside Eart

Some meteorites contain organic molecules.

Chemical evolution & Stanley-Urey experiment

Simulated early Earth conditions to produce organic molecules.

Did the experiment include oxygen gas? -

No, early Earth atmosphere lacked oxygen.

Conditions for polymer synthesis

Solid mineral surfaces, hydrothermal vents, hot pools.

Evidence for RNA World Hypothesis

RNA can store genetic information and catalyze reactions.

Importance of cell membrane -

Essential for the evolution of life, maintains homeostasis.

Protocells as a model for evolution

Simple vesicles capable of containing molecules and reactions.

Ancient rock fossils of cells

Evidence of early microbial life in 3.5 billion-year-old rocks.

Cyanobacteria as first organisms

True; early cyanobacteria performed photosynthesis and produced oxygen.