Eukaryotic Organelles and Functions ✅ Flashcards
Draw and label a eukaryotic cell.
.
What are two types of organelles are there in eukaryotic cells?
non-membranous and membranous
What are the non-membranous cell organelles in the eukaryotic cell?
- Ribosomes
- Microtubules
- Microfilaments
- Chromosomes
What are the membranous cell organelles in the eukaryotic cell (one membrane)?
- Plasmolema
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Vacoules
What are the membranous cell organelles in the eukaryotic cell (two membrane)?
- Mitochondria
- Plastids
- Nucleus
- Chloroplasts
What does the endomembrane system include?
- Nuclear envelope
- Endoplasmic Reticulum
- Golgi Apparatus
- Lysosomes
- Vesicles
- Plasma membrane
What does the ER enclose?
A series of intercommunicating channels called “CISTERNAE”.
What does ER stand for?
Endoplasmic Reticulum
What is the function of the ER?
ER is a major site for vital cellular activities:
- biosynthesis of proteins
- biosynthesis of lipids.
What are the two types of endoplasmic reticulums?
- rough ER
- smooth ER
What is the function of the rough ER?
The rough ER is the site for the synthesis of most membrane-bound proteins.
(production of membrane-associated proteins, proteins of many membranous organelles, and proteins to be secreted by exocytosis.)
What is the function of the smoth ER?
1) lipid biosynthesis,
2) detoxification of potentially harmful compounds,
3) sequestration (storing) and controlled release of Ca2+ ions.
How does the rough ER look like?
- saclike and parallel stacks of flattened cisternae,
- cisternae are limited by membranes that are continuous with the outer membrane of the nuclear envelope
What is a ribosome?
A ribosome is a complex structure, containing many different proteins and at least three ribosomal RNAs.
What is the function of ribosomes?
Ribosomes are a site of protein synthesis.
What do free ribosomes synthesize?
Free ribosomes synthesize PROTEINS for USE in the CYTOPLASM.
What do ribosomes bound to the ER synthesize?
Ribosomes bound to the endoplasmic reticulum membrane synthesize PROTEINS that are EXPORTED from the cell or INCORPORATED into the membrane.
What is the sedimentation coefficient?
The sedimentation coefficient (s) of a particle characterises its sedimentation during centrifugation.
What is “protein trafficing”?
The movement of newly synthesized proteins in a cell.
What is protein traffic characterised by?
Protein traffic is characterised by common principles that make up protein targetting molecular mechanism.
What is the role of the endomembrane system?
Modify, package, and transport lipids and proteins.
What is the effect of protein trafficing?
- Protein activity and stability are changing.
- Proteins are targeted to specific sites in the cell or secretion to the outside of the cell.
Why does the RER have a highly regulated system?
To PREVENT nonfunctional proteins being forwarded to the pathway for secretion or to other organelles.
What happens with proteins that cannot be folded or assembled properly by chaperones?
proteins undergo ER-associated degradation (ERAD), in which unsalvageable proteins are translocated back into the cytosol, conjugated to ubiquitin, and then degraded by proteasomes.
RER vs SER cisternea.
RER- flattened cisternea
SER- tubular cisternea
What happens during ER-associated degradation (ERAD)?
Unsalvageable proteins are translocated back into the cytosol, conjugated to ubiquitin, and then degraded by proteasomes.
What does ERAD stand for?
ER-associated degradation.
What are proteins controlled by (the regulated system)?
Chaperones.
What are the structures within the golgi apparatus?
- Cisternae
- Vesicles (in the end of cisternae)
- Dictyosomes (a group of parallel, flattened cisternae with flared ends)
What are the three major “regions” of the Golgi apparatus?
Cis face
- mannosidase I
- golgi-recieving region
Medial
- mannosidase II
- enzymatic modifications
Trans face
- galactosyltransferase sialyltransferase,
- distinguishing region
What is the function of the different golgi apparatus faces?
- Cis-face: golgi-receiving region
- Medial region: enzymatic modifications
- Trans-face: distinguishing region
What are the different enzymes at different cis, medial, and trans levels?
Cis face: mannosidase I
Medial: mannosidase II
Trans face: galactosyltransferase sialyltransferase.
What are the functions of the golgi apparatus?
- Modifying secretory products
- Sorting secretory products
- Forming transport vacuoles.
The golgi apparatus completes post-translational modifications of proteins produced in the RER and then packages and addresses the proteins to their proper destinations.
What is the golgi apparatus?
A dynamic organelle consisting of stacked membranous cisternae in which proteins made in RER are processed further and packaged for secretion or other roles.
How, and in what do proteins enter the recieving face of the Golgi?
Proteins in transport vesicles enter the cis or receiving face of the Golgi.
What happens with the proteins in transport vesicles once they already enter the Golgi through medical cisternea?
They move through medial cisternae of the Golgi network for enzymatic modifications, and are released in other vesicles at the trans face.
Where do modified proteins exit by?
Released in other vesicles at the trans face of the golgi apparatus.
Explain the movement of proteins through the golgi apparatus.
Proteins in transport vesicles enter the cis or receiving face of the Golgi, move through medial cisternae of the Golgi network for enzymatic modifications, and are released in other vesicles at the trans face.
What is the vesicle movement through the Golgi apparatus guided by?
specific coat proteins such as COPII and COPI.
What is COPII and COPI?
specific coat proteins that guide vesicle movement through the golgi apparatus.
What are important protein modifications that occur in the Golgi Apparatus?
- sulfation reactions
- glycosylation reactions
What happens to proteins once they exit the Golgi Apparatus?
Modified proteins leave the Golgi apparatus with COAT PROTEINS that DIRECT movement to lysosomes, the plasma membrane, or secretion by exocytosis.
What is the function of coat proteins?
direct movement of modified proteins to lysosomes, the plasma membrane, or secretion by exocytosis.
What is a polyribosome? polysome?
A cluster of ribosomes linked together by a molecule of messenger RNA and forming the site of protein synthesis.
Where are proteins broken down? longer-acting proteins? shorter lived proteins?
longer acting proteins- lysosomes
short living proteins- 26S proteasome
What is the max number of lysosomes that an animal cell can contain?
100 lysosomes
What is the max number of lysosomes that a phagocytic macrophage cell can contain?
up to 1000.
What are lysosomes composed of?
- peroxysomes
- mitochondria fragments
What are lysosomes?
Lysosomes are:
- spherical membrane-enclosed vesicles
- function as sites of intracellular digestion
- numerous in cells active after the various types of endocytosis.