Semiautonomous Organelles: Mitochondria, Chloroplasts, and Endosymbiosis Theory

Flashcards covering the structures, functions, and evolutionary origins of semiautonomous organelles like mitochondria and chloroplasts, including the endosymbiosis theory.

What are considered the two semiautonomous organelles in eukaryotic cells?

Mitochondria and chloroplasts.

Why are mitochondria and chloroplasts considered 'semiautonomous'?

They grow and divide, but depend on other parts of the cell for their internal components, such as importing most of their proteins from the cytosol.

According to the 'Energy and Matter' principle, what is the role of chloroplasts in living organisms?

Chloroplasts capture light energy and synthesize organic molecules.

According to the 'Energy and Matter' principle, what is the role of mitochondria in living organisms?

Mitochondria break down organic molecules and make ATP, which is used as an energy source for cellular processes.

What is the primary role of mitochondria in cells?

To make ATP by converting chemical energy stored in the covalent bonds of organic molecules into a readily usable form.

Describe the main structural components of a mitochondrion.

It has an outer membrane, an inner membrane separated by the intermembrane space, and the inner membrane is highly invaginated to form cristae, enclosing the mitochondrial matrix.

What is the advantage of the mitochondrion's highly invaginated inner membrane?

The invaginations, called cristae, greatly increase the surface area of the inner membrane, which is the site where ATP is made.

What is the primary function of chloroplasts?

To capture light energy and use it to synthesize organic molecules such as glucose through photosynthesis.

Describe the key structural components of a chloroplast.

It contains an outer membrane, an inner membrane, an intermembrane space, and a thylakoid membrane that forms flattened tubules, which stack to form grana, all within the stroma.

What are the three main types of plastids and their general functions?

Chloroplasts (photosynthesis, chlorophyll), Chromoplasts (synthesize/store yellow, orange, red carotenoid pigments), and Leucoplasts (lack pigment, e.g., amyloplasts store starch).

How do mitochondria and chloroplasts increase in number?

They increase in number via binary fission, or splitting in two, similar to bacteria.

What evidence supports the endosymbiosis theory regarding the genetic material of mitochondria and chloroplasts?

Mitochondria and chloroplasts contain their own genetic material (mitochondrial and chloroplast genomes), which are single, circular chromosomes like bacterial genomes, and their genes are similar to bacterial genes.

According to the endosymbiosis theory, from which specific types of ancient bacteria did mitochondria and chloroplasts evolve?

Mitochondria evolved from ancient proteobacteria, and chloroplasts evolved from ancient cyanobacteria.

What is one evolutionary change that occurred with genes originally found in the genomes of primordial proteobacteria and cyanobacteria within eukaryotic cells?

Many genes were transferred from the organelles (mitochondria and chloroplasts) to the nucleus of the eukaryotic cell.