Endosymbiotic Theory and Eukaryotic Cell Structure (Video)

Flashcards covering endosymbiotic theory, prokaryotic vs. eukaryotic cells, and key organelle structure and function from the lecture notes.

What is the endosymbiotic theory?

Mitochondria and chloroplasts originated as free-living bacteria that were engulfed by an ancestral host cell, forming a mutualistic relationship.

Which two domains comprise the prokaryotes?

Eubacteria and Archaebacteria (archaeobacteria).

Where are archaeobacteria commonly found and what are they called?

They are extremophiles found in hot springs, highly saline, and other harsh environments.

What evidence supports mitochondria as having evolved from free-living bacteria?

Mitochondria are similar in size to bacteria (about 1–2 μm), contain their own circular DNA, have prokaryote-like ribosomes, and have two membranes.

What evidence supports chloroplasts as having evolved from bacteria?

Chloroplasts contain their own DNA and ribosomes, have double membranes, and resemble cyanobacteria.

What are the three layers of a typical bacterial cell envelope?

Capsule (glycocalyx), cell wall (peptidoglycan), and plasma membrane.

What is the function of the bacterial capsule or slime layer?

Protection from desiccation and environmental stress, and aiding in adhesion to surfaces.

What are the main shapes of bacteria and their names?

Bacilli (rod-shaped), cocci (spherical), and spirilla (spiral/corkscrew shapes).

What is the difference between Gram-positive and Gram-negative bacteria?

Gram-positive have a thick peptidoglycan wall and stain purple; Gram-negative have a thinner wall with an outer membrane and stain pink/red.

What structures enable bacteria to exchange DNA?

Pili (fimbriae) forming a conjugation tube; plasmids can be transferred between cells.

What is the endomembrane system?

An interconnected system of membranes including rough and smooth endoplasmic reticulum, Golgi apparatus, and vesicles that modify, package, and transport proteins and lipids.

What is the nucleus and what does it contain?

A membrane-bound organelle containing nuclear DNA organized into chromatin and chromosomes; the nucleolus resides within for ribosomal RNA production.

What is the nucleolus responsible for?

Ribosomal RNA synthesis and assembly of ribosomal subunits.

What is the role of mitochondria and chloroplasts in energy metabolism?

Mitochondria produce ATP through respiration; chloroplasts perform photosynthesis in plant cells; both contain their own DNA and ribosomes.

What is the central vacuole in plant cells used for?

Storage and maintenance of turgor pressure to support cell rigidity.

What are plasmodesmata?

Channels through plant cell walls that connect neighboring plant cells and allow transport and communication.

What is a key difference between plant and animal cells regarding centrioles?

Plant cells typically lack centrioles (no centriole-based microtubule organizing center), while animal cells have them.

Why is water considered the universal solvent in biology?

Water is a polar molecule that dissolves many substances and facilitates molecular interactions, protein folding, and macromolecule structure.

What are lysosomes and peroxisomes?

Digestive organelles; lysosomes break down biomolecules; peroxisomes detoxify reactive molecules like hydrogen peroxide and participate in metabolism; both are part of cellular digestion and turnover.

Where is DNA located in eukaryotic cells?

Nuclear DNA in the nucleus; mitochondria and chloroplasts also contain their own DNA.