Unit 6: Mitochondria And Chloroplasts(topic 1)

Mitochondria and chloroplasts are similar in structure as they both have double membranes, contain their own DNA, and are thought to have originated as separate prokaryotic organisms that were engulfed by ancestral eukaryotic cells.

Gram-negative bacteria, chloroplasts, and mitochondria all have two membranes as a common characteristic. This double-membrane structure is unique to these organelles and cells, providing them with specific functions and characteristics distinct from other cellular components.

The correct answer explains that the outer membrane contains porins allowing for the passage of ions and small molecules.

The inner membrane of a cell serves as a permeability membrane with specific proteins for transporting ions and molecules, not for storing nutrients, regulating cell division, or energy production.

Mitochondria and chloroplasts are believed to have originated from endosymbiotic events involving ancestral prokaryotic cells. While they share some similarities with Gram-negative bacteria, such as having double membranes, they lack certain features like the peptidoglycan wall present in the cell wall of Gram-negative bacteria.

The inner membrane of mitochondria plays a crucial role in electron transport chains and ATP synthase, which are essential for cellular energy production.

The matrix of the mitochondria is a semi-fluid substance where various biochemical reactions occur within the mitochondria. It is akin to the cytoplasm of the cell and contains essential components for cellular respiration.

The intermembrane space of the mitochondria plays a crucial role in the process of electron transport chain (ETC) by being the location where protons are pumped into, creating an electrochemical gradient essential for ATP synthesis.

The cytoplasm of the chloroplast is called Stroma as it is the colorless fluid surrounding the thylakoids in a chloroplast.

Thylakoids are specialized membrane-bound compartments that house the photosynthetic pigments and machinery necessary for photosynthesis. They are flattened membrane vesicles that occur in stacks called grana, where the light-dependent reactions of photosynthesis take place.

Thylakoids arise within chloroplasts and photosynthetic bacteria as a result of invaginations from the inner membrane. This process creates a system of interconnected membranes important for photosynthesis.

Chloroplasts have their own genome, which is located in the stroma, a semi-fluid substance inside the chloroplasts. This is where the genetic material of chloroplasts is housed.

Thylakoid membranes in the chloroplast play a crucial role in photosynthesis by containing chlorophyll, ATP synthase, and the Electron Transport Chain essential for light absorption and energy conversion.

The stroma of the chloroplast contains enzymes for the Calvin cycle, the chloroplast's genome, and a protein synthesizing system. Mitochondria, ribosomes, and lysosomes are not typically found in the stroma of chloroplasts.

The thylakoid spaces lie within the thylakoids in the chloroplasts, and during the process of photosynthesis, the electron transport chain (ETC) pumps protons into these spaces to create a proton gradient for ATP synthesis.

Chloroplasts and mitochondria share similarities with bacteria in terms of genome size, shape, and lack of a centromere.

Chloramphenicol and streptomycin are known major translation inhibitors in mitochondria, chloroplasts, and Gram(-) bacteria due to their mechanisms of action that disrupt protein synthesis in these organelles and bacteria.

Ferrodoxin is a protein that plays a key role in transferring electrons during cellular respiration, particularly within the electron transport chain. This process is essential for generating ATP, the cell's main energy source.

The correct way to determine if a chloroplast or mitochondria derives from a bacteria is by analyzing the DNA sequence of a protein and creating a phylogenetic tree to see how much it has changed within the structures over time. The other methods mentioned are not reliable indicators of bacterial origin.

The genomes of mitochondria and chloroplasts have evolved to become much smaller compared to free-living bacteria due to a process known as endosymbiosis. Some genes were lost because their functions were no longer needed or were duplicated by functions of nucleus-encoded proteins. The DNA was not destroyed, transferred to the host cell's nucleus, or mutated beyond functionality.

The smaller genomes of mitochondria and chloroplasts are a result of many genes being transferred to the cell's nucleus over time.

The decreased genome size in mitochondria and chloroplasts has led to the transfer of most genetic material to the nuclear genome, where the vast majority of proteins needed for their function are now encoded.

Mitochondria have their own set of genes that encode a small number of proteins, primarily those with hydrophobic characteristics that are essential for mitochondrial function.

Proteins that are not synthesized in the MIT or CHLOR are actually produced in the cytosol and then specifically targeted to these organelles for their functional roles.

Proteins targeted for transport into the MIT or CHLOR have a specific targeting signal at the N-terminus that guides them to their correct destination.

Proteins destined for CHLOR or MIT contain specific signal sequences that target them to these organelles. The protein is produced in the cytoplasm and then directed to its correct location based on these signal sequences.

Proteins do not randomly float or get shot into organelles. The attachment process is specific and involves binding of signal sequence to a receptor in the organelle membrane.

The correct definition of the contact site is where a receptor-protein complex diffuses within the membrane to a specific location where inner and outer membranes touch, facilitating communication and signaling within the cell.

The correct answer describes the process of protein being unfolded, moved across the membrane, and refolded with the assistance of the protein transporter complex. The incorrect answers provide alternative scenarios that do not accurately reflect the protein's transformation at the contact site.