Endosymbiosis, Energy Metabolism, and Thermodynamics - Flashcards

Flashcards covering endosymbiotic theory, organelle evidence, energy/metabolism classifications, and basic thermodynamics as discussed in the lecture notes.

What does the endosymbiotic theory propose about the origin of eukaryotic cells?

Eukaryotes originated as a hybrid of an archaeal host and engulfed bacteria; mitochondria came from an engulfed aerobic bacterium and chloroplasts from a photosynthetic bacterium, forming a permanent symbiotic relationship.

What evidence supports the endosymbiotic theory for mitochondria and chloroplasts?

Both organelles are similar in size to bacteria, contain circular double-stranded DNA, divide by binary fission, and have ribosomes more like bacterial ribosomes; ribosomal RNA sequences also point to bacterial origin.

Why can mitochondria numbers in a eukaryotic cell range from about 1,000 to nearly a million?

Because cells have high energy demands and mitochondria supply ATP, leading to large numbers to meet those needs.

How is it believed plants acquired chloroplasts in addition to mitochondria?

An ancestral cell with mitochondria acquired a second symbiotic bacterium capable of photosynthesis, giving rise to chloroplasts.

What are the key size and genetic similarities between mitochondria/chloroplasts and bacteria?

They are similar in size to bacteria, contain circular double-stranded DNA, and replicate by binary fission.

What are the three major components of the cytoskeleton?

Microtubules, intermediate filaments, and microfilaments (actin).

What are two key plant vs. animal cell differences noted in the lecture?

Plants have cell walls made of cellulose and often chloroplasts; both plant and animal cells have nuclei, mitochondria, and microtubules.

Define phototrophs and chemotrophs.

Phototrophs obtain energy from light; chemotrophs obtain energy from chemical compounds.

Define chemoorganotrophs and chemolithotrophs.

Chemoorganotrophs derive energy from organic compounds; chemolithotrophs derive energy from inorganic compounds.

Define autotrophs and heterotrophs in terms of carbon sources.

Autotrophs use carbon from CO2; heterotrophs obtain carbon from organic compounds.

What are the three system types based on exchange of matter and energy?

Isolated (no exchange), closed (exchange energy but not matter), and open (exchange both energy and matter).

What is energy in the context of biological systems?

The ability to cause change.

What is work in biological systems?

Any process that requires energy to cause a change (e.g., synthesis, transport, movement).

What does the first law of thermodynamics state?

Energy cannot be created or destroyed; it can be transformed or transferred between forms or locations.

What is Gibbs free energy and what does a negative ΔG indicate?

Gibbs free energy change measures spontaneity; a negative ΔG indicates an exergonic (spontaneous) reaction under the given conditions.

What is the difference between standard state thermodynamics and physiology?

Standard state thermodynamics uses standard conditions (often non-biological); physiology applies to living systems with non-standard, real-world conditions.

What is enthalpy in thermodynamics?

A measure of the total heat content or energy content of a system (related to heat transfer at constant pressure).

What is the difference between open, closed, and isolated systems in biology?

Open systems exchange both energy and matter with the surroundings; closed systems exchange energy but not matter; isolated systems exchange neither energy nor matter.

Give an example of a chemoorganotroph.

Humans; energy from organic compounds and carbon from organic sources.

What is the role of chloroplasts in plants according to the notes?

Chloroplasts are the photosynthetic organelles that enable plants to capture light energy and produce energy-rich compounds.

Why do mitochondria and chloroplasts have circular DNA?

This genomic feature reflects their bacterial ancestry and supports the endosymbiotic origin of these organelles.