Organelles Flashcards
Centrosome
*centrosomes with centrioles only in animal cells
region where the cell’s microtubles are initiated; contains a pair of centrioles
Plasmodesmata
*plant cells only
cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells
(communcation between cells)
Lysosome
*part of endomembrane system
*animal cells only
- a membranous sac of hydrolytic enzymes that can digest macromolecules
- Some types of cells can engulf other cells by phagocytosis and form food vacuoles
- A lysosome fuses with food vacuole and digests the molecule
- Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules (autophagy)
Mitochondria
Only in eukaryotic cells
- sites of cellular respiration (a metabolic process that generates ATP)
- bounded by double membrane, have proteins made by free ribosomes, contain own DNA
- Powerhouse of cell, found in nearly all eukaryotic cells
- have smooth outer membrane and inner membrane
- outer membrane is folded into a cristae which presents a large SA for enzymes that sythesize ATP
- Inner membrane drives process of ATP and has 2 compartments: intermediate space and mitochondrial matrix (some metabolic steps of cellular respiration occur here)
Chloroplasts
Only in plants
- part of plastids
- contain green pigment chlorophyl, as well as enzymes, and other molecules that function in photosynthesis
- found in leaves and other green organs of plants and in algae
- Chloroplast structure includes: Thylakoids (membranous sacs stacked to form granum) and stroma (internal fluid)
- Contain own DNA
- have proteins made by free ribosomes, have double membrane
Peroxisome
Function: contains enzymes that transfer hydrogen atoms from substrates to oxygen, producing hydrogen peroxide as a by-product; H2O2 is converted to water by another enzyme. (oxygen is used to break down different types of molecules)
Structure: specialized metabolic compartment bounded by a single membrane
Endoplasmic Reticulum
- accounts for more than half the total membrane in many eukaryotic cells
- continuous with nuclear envelope
- rough ER, smooth ER
- part of endomembrane system
Golgi Apparatus
- part of endomembrane system
- consists of flattened membranous sacs called cisternae (pita bread)
- FedEX
- modifies products of ER
- manufactures cetrain macromolecules
- sorts and packages materials into transport vesicles
Ribosomes
- particles made of ribsomal RNA and protein
- Submicroscopic particles
- Function: protein synthesis
- Which is carried out in 2 places:
- In the cytosol (free ribsomes)
- On the outside of the ER or nuclear envelope (bound ribosomes)
Nucleus
Function: houses chromosomes, which are made of chromatin (DNA+proteins); contains nucleoli, where ribosomal subunits are made; pores regulate entry and exit of materials (nuclear envelope)
Structure: surrounded by nuclear envelope (double membrane) perforated by nuclear pores; nuclear envelope continous with ER
In the nucleus: DNA and proteins form genetic material called chromatin
DNA molecule is associated with prteins (histone proteins)
Chromatin is a mixture of several nucleosomes
Nucleosomes = histone protein + DNA
Several chromatin together = chromosome
Rough ER
- Part of endomembrane system
- Ribosome-studded surface
- These ribosomes secrete glycoproteins
- Distributes transport vesicles (proteins surrounded by membranes)
- is a membrane factory for the cell
Cytoskeleton
- Helps to support cell and maintain its shape
- network of fibers extending througout the cytoplasm
- Interacts with motor proteis to produce motility
- (structure, support, motility, regulation)
- organizes cell’s structures and activities, anchoring many organelles
- Microtubules
- Microfilaments
- Intermediate filaments
Vacuoles
- part of endomembrane system
- Food vaculoes (phagocytosis)
- Contractile vacuoles (pump excess water out - freshwater plants)
- Central vacuoles (found in many mature plants, hold organic compounds and water, gives plant turgidity)
Cell Wall
- Prokaryotes, fungi, and some protists
- Protects plant cell, maintains its shape, and prevents excessive uptake of water
- Made of cullolose fibers embedded in other polysaccharides and proteins
- Multiple Layers
- Primary cell wall (relatively thin and flexible)
- Middle Lamella (thin layer between primary walls of adjacent cells
- SEcondary cell wall (some) (added between the plasma membrane and the primary cell wall
- Plasmodestmata (channels between adjacent plant cells, communication)
Smooth ER
- Part of endomembrane system
- No ribosomes
- Sythesizes lipids
- Metabolizes carbohydrates
- Detoxifies poision
- Stores calcium
