General Biology: Ecosystems, Cell Types, Gene Expression, and Feedback Mechanisms

Vocabulary flashcards covering core topics from the lecture transcript, including ecosystem chemical cycling and energy flow, eukaryotic vs. prokaryotic cells, gene expression steps (crystallin synthesis), and biological feedback mechanisms.

African Acacia Tree Ecosystem Interactions

Ecological interactions involving leaves absorbing light energy and taking in $CO_2$ while releasing $O_2$, tree roots absorbing water and minerals, animals consuming leaves and fruit, and decomposers returning minerals to the soil from fallen leaves.

Energy Flow

The unidirectional pathway of energy through an ecosystem, originating as light energy from the sun, converted by plants into chemical energy, utilized by organisms to perform work, and ultimately lost as heat.

Chemical Cycling

The circular path of matter within an ecosystem, where plants take up chemicals from the soil and air, pass them to consumers, and decomposers return them to the soil.

Decomposers

Organisms that break down organic waste such as fallen leaves, returning essential chemicals and minerals to the soil.

Eukaryotic Cell

A complex cell type characterized by containing cytoplasm, membrane-enclosed organelles, and a membrane-enclosed nucleus with DNA distributed throughout.

Prokaryotic Cell

A cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles, with DNA present throughout the cell (shown at a $1,\text{m}$ scale).

Nucleus

A membrane-enclosed structure within eukaryotic cells that houses the cell's genetic material (DNA).

Membrane-Enclosed Organelles

Specialized internal compartments surrounded by membranes that are present in eukaryotic cells but absent in prokaryotic cells.

Crystallin

A transparent protein that is tightly packed inside eye lens cells to enable optical transparency.

Gene Expression

The process by which cells use information encoded within a gene to synthesize a functional protein.

Transcription

The biological process in which sequence information in a DNA gene is copied into mRNA (for example, the mRNA sequence UGGUUUGGCUCA).

Translation

The process in which the genetic code carried by mRNA is translated to synthesize a chain of amino acids.

Protein Folding

The process by which an amino acid chain folds into its specific three-dimensional conformation to form a functional protein, such as crystallin.

Negative Feedback

A regulatory feedback mechanism in a pathway where an accumulation of an end product (such as excess D) blocks an earlier step to reduce its own production.

Positive Feedback

A regulatory feedback mechanism in a pathway where an accumulation of an end product (such as excess Z) stimulates a step to accelerate its own production.