Biology Chapter on Early Life and Cell Functions

Early Life on Earth

• Abiogenesis is the hypothesized process of life arising from non-living matter, a key part of early life development.
• RNA world hypothesis posits that RNA, not DNA, served as the primary genetic material in early life.
• Miller-Urey experiment simulated early Earth conditions and produced organic compounds like amino acids, strengthening the theory of abiogenesis.

Extremophiles

• Extremophiles are organisms that thrive in extreme environments
• Archaea are known for their ability to survive in harsh conditions like high temperatures, salinity, or acidity.

Cyanobacteria

• Cyanobacteria are photosynthetic bacteria that played a crucial role in changing Earth's atmosphere.
• They released oxygen as a byproduct of photosynthesis, transforming the early Earth's atmosphere from an oxygen-poor to an oxygen-rich environment.

Endosymbiotic Theory

• The endosymbiotic theory proposes that eukaryotic cells evolved from prokaryotic cells.
• It explains the origin of mitochondria and chloroplasts as the result of larger cells engulfing smaller bacteria.
• This symbiotic relationship provided a mutual advantage for both the engulfing and the engulfed bacteria.

Characteristics of Life

• Metabolism is the sum of all chemical reactions within an organism.
• Homeostasis is the maintenance of a stable internal environment.
• Reproduction is the ability to create new organisms.
• Growth and development refers to the increase in size and complexity of an organism.
• Adaptation is the ability to change over time.

Ribosomes

• Ribosomes are cellular organelles responsible for protein synthesis.
• They translate genetic information from mRNA to create protein chains.

Chloroplast

• Chloroplasts are found in plant cells and are responsible for photosynthesis.
• Thylakoids are the membrane-bound compartments within chloroplasts.
• Chlorophyll, a green pigment found in thylakoids, absorbs light energy for photosynthesis.

Calvin Cycle

• The Calvin cycle is the light-independent stage of photosynthesis.
• It uses carbon dioxide and energy from light-dependent reactions to produce glucose.

Lysosomes

• Lysosomes are small, membrane-bound organelles in cells.
• They contain enzymes that break down waste materials, cellular debris, and engulfed substances.

Mitochondria

• Mitochondria are called the “powerhouses of the cell.”
• They are responsible for cellular respiration, the process of breaking down glucose to create ATP, the cell's energy currency.