Organelles Flashcards
Peroxisome
Small, spherical organelles
HEXAGONAL structure in interior is crystal of enzymes
Sequesters reaction to produce hydrogen peroxide (H2O2) - very strong oxidant
Catalyzes breakdown of H2O2
The Nucleus
Contains chromosomes
Location of RNA transcription
Contains NUCLEOLUS: ribosome assembly
Double membrane
Membrane has pores
Transcription in Eukaryotes
mRNA must exit nucleus before translation
- slow (lag between transcription and translation
+ time for quality control and mRNA processing
Evolution of nucleus
- Anaerobic archaeum loses cell wall
- Increase size -> unstable
- Plasma membrane infolding, preventing destabilization
- Membrane wraps around chromosome, forming nucleus with double membrane
Mitochondria
ALL eukaryotes have
Aerobic respiration machinery -> more efficient ATP generation (MORE POWER)
Genes ≈ aerobic bacteria
Chloroplasts
ALL plants
Photosynthetic machinery —> make sugars from inorganic carbon
Genes ≈ cyanobacteria
Mitochondria AND chloroplasts
Double membrane
Genomes: have own chromosomes and they are CIRCULAR (like bacteria)
Independent replication: Mitochondeia and chloroplasts divide independently of their “host” cells
Evolution of mitochondria (endosymbiosis)
ANaerobic ingests AErobic
Evolution of chloroplasts (endosymbiosis)
Aerobic eukaryote ingests photosynthetic bacteria
O2 levels (cellular evo)
Eukaryotes evolved from anaerobic archeon by ingesting aerobic bacterium to defend against deoxidation
Heaviest organelles
Cell walls, nuclei (weight)
Medium-weight organelles
Mitochondria, chloroplasts (weight)
Lightest organelles
Microsomes (broken up bits of ER and golgi)
Vesicles
Smooth endoplasmic reticulum
Layers of membranes
Somewhat interconnected with RER
NO RIBOSOMES
separate enough that stuff does not diffuse easily between them, have distinct function
Golgi complex
Looks like ER but NOT interconnected
Difficult to identify
