Microbes, Protists, Fungi, and Photosynthesis

Vocabulary practice flashcards covering microbial biology, protist locomotion, fungal anatomy, and the biochemical mechanisms of photosynthesis.

Prokaryote

A single-celled organism that lacks a nucleus and membrane-bound organelles, characterized by a single circular chromosome and optional extrachromosomal plasmids.

Plasmid

A small, extrachromosomal circular DNA molecule found in prokaryotes that exists separately from the main bacterial chromosome.

Peptidoglycan

A polymer consisting of sugars and amino acids forming the cell wall structure unique to bacteria.

Pseudopeptidoglycan

A polysaccharide-based component found in the cell walls of certain archaea, differing chemically from bacterial peptidoglycan.

Gram-Positive Cell Wall

A bacterial cell wall structure consisting of a thick, multilayered peptidoglycan layer embedded with teichoic and lipoteichoic acids situated exterior to the plasma membrane.

Biofilm

A microbial community anchored to a surface and held together by an extracellular gummy-textured matrix.

Stromatolite

A layered, rock-like structure produced by mineral-binding activities of microbial mats consisting of bacteria and archaea.

Binary Fission

The primary method of asexual reproduction in prokaryotes, wherein a single parent cell replicates its genetic material and divides into two genetically identical daughter cells.

Transformation

A mechanism of horizontal gene transfer in which a bacterium absorbs naked DNA fragments directly from its surrounding environment.

Conjugation

The direct transfer of genetic material between two bacterial cells joined physically by a specialized pilus.

Transduction

The transfer of bacterial DNA from one host cell to another mediated by an infecting bacteriophage virus.

Bioremediation

The engineered use of living organisms, particularly prokaryotes, to break down environmental pollutants and toxic compounds into less harmful forms.

MRSA

Methicillin-resistant Staphylococcus aureus, a virulent bacterial strain that has developed resistance to commonly used beta-lactam antibiotics.

Protist

An informal term encompassing a diverse group of eukaryotic organisms that do not belong to the animal, plant, or fungi kingdoms.

Pseudopodia

Temporary cytoplasmic extensions used by amoeboid protists for both locomotion and engulfing prey via phagocytosis.

Cyst

A dormant, protected survival stage formed by certain protists during adverse conditions such as nutrient limitation or extreme temperatures.

Zooxanthellae

Photosynthetic dinoflagellate symbionts that reside inside coral tissues and contribute roughly $25\%$ of all aquatic photosynthetic productivity.

Saprobe

An organism that feeds on nonliving or decaying organic matter by secreting digestive enzymes and absorbing the released nutrients.

Hypha

A long, branching, microscopic filamentous thread that serves as the basic structural and vegetative unit of most fungi.

Mycelium

The dense, underground or substrate-penetrating network formed by a tangled mass of fungal hyphae.

Septa

Internal perforated cross-walls that separate fungal hyphae into distinct compartments while allowing cytoplasmic streaming and nutrient transport.

Chitin

A tough, structural polysaccharide found in the cell walls of fungi as well as the exoskeletons of arthropods.

Exoenzymes

Enzymes synthesized by fungal cells and secreted into the external environment to break down macromolecules prior to cellular absorption.

Arthrobotrys

A genus of predatory soil fungi that captures nematode worms using specialized hyphal constricting loops before releasing digestive enzymes.

Mycorrhizae

Mutualistic symbiotic associations formed between fungal hyphae and vascular plant roots that enhance plant nutrient and water absorption.

Lichen

A composite mutualistic organism consisting of a fungal partner and a photosynthetic partner, typically green algae or cyanobacteria.

Photoautotroph

An autotrophic organism that uses sunlight as an energy source and carbon dioxide as a carbon source to synthesize organic compounds.

Mesophyll

The internal middle tissue layer of a leaf situated between the upper and lower epidermis where the highest density of chloroplasts resides.

Stomata

Specialized microscopic pores located on plant leaf surfaces that open and close to regulate the exchange of $\text{CO}_2$ and $\text{O}_2$.

Thylakoid

A membrane-bound disc-like compartment located inside a chloroplast where the light-dependent reactions of photosynthesis take place.

Stroma

The fluid-filled internal space surrounding the thylakoid stacks (grana) inside a chloroplast, representing the site of the Calvin cycle.

Photosystem II

A multiprotein-pigment complex in the thylakoid membrane that uses absorbed photon energy and electron transport to pump $\text{H}^+$ protons into the thylakoid lumen.

Photosystem I

A thylakoid membrane complex that absorbs photon energy to re-energize electrons, ultimately transferring them to reduce $\text{NADP}^+$ to $\text{NADPH}$.

ATP Synthase

A membrane-bound protein complex that utilizes the potential energy of a proton ($\text{H}^+$) gradient across the thylakoid membrane to phosphorylate $\text{ADP}$ into $\text{ATP}$.

Calvin Cycle

The light-independent biochemical reactions taking place in the stroma that convert $\text{CO}_2$ into three-carbon sugar molecules using $\text{ATP}$ and $\text{NADPH}$.

RuBisCO

The enzyme that catalyzes the initial carbon fixation step of the Calvin cycle by attaching $\text{CO}_2$ to ribulose-1,5-bisphosphate (RuBP).

Glyceraldehyde 3-Phosphate (G3P)

The three-carbon sugar product synthesized and exported by the Calvin cycle, which plants use to assemble glucose and other carbohydrates.