Lecture Topic 11: The Origin and Diversity of Life (Chapter 26)

These flashcards cover key concepts about the origin and diversity of life, including origins of life theories, experimental results, and taxonomic classification.

What are the three main theories about the origin of life on Earth?

Special Creation, Extraterrestrial Origin, and Spontaneous Origin.

What are the fundamental properties of life?

Cellular organization, sensitivity, growth, development, reproduction, regulation, homeostasis, and heredity.

What was the likely composition of Earth’s early atmosphere?

Earth’s early atmosphere is thought to have consisted primarily of carbon dioxide (CO2), water vapor (H2O), ammonia (NH3), and methane (CH4), with very little or no free oxygen (O_2).

Describe the methods and results of the Miller and Urey experiment (1953).

The Miller and Urey experiment simulated early Earth conditions by combining water, methane, ammonia, and hydrogen in a closed system with electrodes to discharge sparks (simulating lightning). The results showed that various organic molecules, including amino acids, could spontaneously form from these inorganic precursors, supporting the idea of abiogenesis.

What is the 'Bubble Hypothesis'?

It suggests that lipid bubbles could increase the probability of metabolic reactions leading to the development of cell membranes.

How do taxonomists name and group organisms?

Taxonomists name organisms using a binomial nomenclature system (Genus species) and group them into a hierarchical structure based on shared evolutionary characteristics, moving from broad categories (Domain) to more specific ones (Species).

Why are the three domains of life considered monophyletic, but the six kingdoms are not?

Each represents a single, complete evolutionary branch, including one common ancestor and all its descendants. The others either exclude some descendants of their common ancestor or include organisms from multiple evolutionary origins.

What is a prokaryote?

A single-celled organism that lacks a membrane-bound nucleus and other membrane-bound organelles. Its genetic material is located in the cytoplasm.

What is a eukaryote?

An organism whose cells contain a membrane-bound nucleus and other membrane-bound organelles. Its genetic material is enclosed within the nucleus.

Approximately when did Appearance of prokaryotes in evolutionary history occur?

Approximately 3.8 BYA

Identify and describe the three general categories of prokaryotes within the Domain Archaea.

Methanogens: Anaerobic archaea that produce methane (e.g., from CO2 and H2) as a byproduct of their metabolism. - Extremophiles: Archaea that thrive in extreme environments, such as very high temperatures (thermophiles), high salinity (halophiles), or very low pH (acidophiles). - Nonextreme Archaea: Archaea that live in more moderate environments, similar to many bacteria.

Explain the role of endosymbiosis in the evolution of eukaryotes.

Endosymbiosis is the theory that eukaryotic cells evolved from prokaryotic cells living inside larger prokaryotic cells. Specifically, mitochondria and chloroplasts are believed to have originated from free-living bacteria that were engulfed by ancestral eukaryotic cells and formed a symbiotic relationship, eventually becoming organelles.

Approximately when did Oxygen-generating photosynthesis in evolutionary history occur?

Approximately 2.5 - 2.0 BYA

Approximately when did Single-celled eukaryotes in evolutionary history occur?

Approximately 2.0 - 1.5 BYA

Approximately when did Multicellular eukaryotes in evolutionary history occur?

Approximately 1.5 - 1.0 BYA