Organelles of the Eukaryotic Cells Flashcards
What proportion of a eukaryotic cell’s volume is occupied by organelles
Organelles occupy about half of the volume of a eukaryotic cell.
What are the main components of the eukaryotic cytoplasm
The cytoplasm includes the cytosol and cytoplasmic organelles suspended within it.
What is the function of mitochondria
Mitochondria are involved in energy metabolism and other metabolic functions.
What are the functions of the endoplasmic reticulum (ER)
The ER synthesizes specific proteins for membranes or secretion, modifies proteins, and synthesizes lipids.
What is the function of peroxisomes
Peroxisomes are sites of oxidative metabolism.
What is the role of endosomes in the cell
Endosomes process endocytosed particles on their way to lysosomes or vacuoles.
What is the function of lysosomes and vacuoles
They contain digestive enzymes to degrade endocytosed particles, old organelles, and macromolecules.
Why do eukaryotic cells need internal membranes
Because large cells have a low surface area to volume ratio, internal membranes expand membrane surface for energy production and specialization.
What are the advantages of subcellular compartmentalisation in eukaryotes
It allows metabolic specialisation and reduces competition between intermediates.
What does it mean when organelles are topologically equivalent
Molecules can travel between compartments without crossing a membrane or entering the cytosol.
How do mitochondria and chloroplasts differ from other organelles
They have a double membrane, an endosymbiotic origin, and are isolated from vesicular trafficking.
What forms the junctions between cristae and the intermembrane space in mitochondria
Multiprotein complexes MICOS and OPA1.
What creates the curvature of mitochondrial cristae
The angle between ATP synthase dimers at the tips of cristae.
What is the ‘respirasome’
A supercomplex formed by all ETC components on the side of cristae to funnel protons to ATP synthase.
How do cristae act as insulated transformers of metabolic energy
Narrow necks and dense ETC protein packing limit proton diffusion and leakage.
What causes thylakoid stacking in chloroplasts
PSII-LHCII complexes which increase surface area and light capture.
What are etioplasts and gerontoplasts
Etioplasts are chloroplast progenitors; gerontoplasts are aging chloroplasts.
What are chromoplasts and desiccoplasts
Chromoplasts store carotenoid pigments; desiccoplasts exist in desiccation-tolerant plants.
What do elaioplasts, proteinoplasts, and amyloplasts store
Lipids, proteins, and starch, respectively.
How many genes are in the human mitochondrial genome
37 genes: 13 for ETC subunits, 22 tRNAs, and 2 rRNAs.
How many genes are in the Arabidopsis chloroplast genome
117 genes: 87 for proteins, 8 for rRNAs, and 37 for tRNAs.
Why can mitochondria and chloroplasts not function independently despite having DNA
Most required proteins are encoded in the nucleus and imported from the cytoplasm.
How are proteins imported into mitochondria
They must be unfolded by chaperones to pass through the translocase pore.
What are the four chloroplast protein import pathways
Sec pathway, SRP-like pathway, TAT pathway, and spontaneous insertion pathway.
