| What is the function of cytoplasm? | Acts as a medium for mechanical and chemical reactions. |
| Describe rough endoplasmic reticulum (RER). | - A network of flattened membranous sacs (cisternae).
- It extends from the nuclear membrane throughout the cytoplasm.
- Contain ribosomes attached on the surface, sometimes stringed up by the mRNA (eg. polyribosomes/polysomes). |
| What type of proteins does RER synthesize? | - Secretory proteins.
- Integral membrane proteins.
- Soluble proteins enclosed within the endomembrane system (ER, golgi, lysosomes). |
| Describe cytoplasm. | - The cytoplasm is located outside the nucleus and enclosed within the plasma membrane.
- It consists of the liquid cytosol and cellular organelles. |
| Describe endoplasmic reticulum. | - A system of membrane-enclosed tubules and flattened sacs (cisternae).
- It encloses a space that is separated from the cytosol. |
| What are the types of endoplasmic reticulum? | Smooth endoplasmic reticulum (SER); Rough endoplasmic reticulum (RER). |
| Explain how RER modifies newly synthesized proteins. | RER modifies newly synthesized proteins by:
- having oligosaccharyltransferase add CHO from dolichol to the nascent proteins
- then the molecular chaperone assists in the folding of the proteins |
| What is the function of SER in liver cells? | - SER contains glucose-6-phosphatase which releases the glucose from glucose-6-phosphate to form a phosphate group and free glucose.
- The free glucose then goes into the bloodstream. |
| What is formed during the folding of proteins in the RER? | Disulfide bonds are fromes by disulfide isomerase. |
| Describe smooth endoplasmic reticulum (SER). | - Made up of interconnected membranous tubules.
- There is no ribosome attached to its surface.
- Has specialized function depending on the cell type. |
| Label the following structures according to the order shown: | 1. trans-Golgi network
2. Medial cisternae
3. cis-Golgi network |
| What is the function of SER in endocrine cells of the gonad and adrenal cortex? | Synthesize steroid hormone. |
| What is the function of SER in skeletal muscle cells? | - As SER contains a high concentration of calcium-binding proteins, it functions to regulate the release of calcium ions for muscle contraction. |
| Describe the Golgi Apparatus. | Consists of flattened membrane-enclosed sacs (cisternae) arranged in a curved stack and vesicles. |
| What are the functions of RER? | Synthesize proteins and modify newly synthesized proteins. |
| What are the functions of SER? | - Synthesize lipid, phospholipids and steroids.
- Perform detoxification in the liver. |
| Explain what happens in trans-Golgi. | In trans-Golgi, proteins are segregated into different types of vesicles. |
| What are the functions of Golgi apparatus? | - Processing: protein trimming, amino acids modification, glycosylation to produce membrane proteins, secretory and lysosomal proteins.
- Synthesize complex polysaccharides (eg. mucopolysaccharide aka glycosaminoglycans).
- Sort and pack proteins in vesicles to be sent to proper destinations. |
| Describe lysosome. | - Small membrane-bound organelle (25nm–1µm).
- The cell's digestive organelle.
- Contains ~50 different types of hydrolytic enzymes to digest every type of biological macromolecules.
- All enzymes are acid hydrolases –> pH 4.6 in the lysosomal compartment.
- Has a high internal proton concentration (low pH) maintained by a proton pump at the membrane.
- Has highly glycosylated integral proteins that serve as a protective lining. |
| State 3 types of hydrolytic enzymes that can be found in lysosome. | (Any of these 3 that we learned in the slide)
- Nuclease.
- Protease.
- Poly- and oligosaccarideases.
- Spingolipid and lipid-hydrolyzing enzymes.
-Phosphatases. |
| What is A and B? | A: External material breakdown.
B: Autophagy. |
| Explain what happens in cis-Golgi. | In cis-Golgi, the proteins that need to be shipped back to the ER and those to be further processed in Golgi are sorted out. |
| What are the functions of lysosome? | - Responsible for the breakdown of ingested external materials.
- Responsible for organelle turnover (destruction of the cell's own organelles). This is also called autophagy.
- Allow cells to continually renew itself by using digested products (eg. simple sugar, aa)—nutrients for reuse. |
| Fill in the blanks for the following pathway:
ER —> ________ —> ________ —> _________ | ER —> vesicles —> cis-Golgi —> trans-Golgi |
| The deficiency of GM1 β-galactosidase causes __________ in which the patient suffers from _________ and death by the age of 2. | The deficiency of GM1 β-galactosidase causes GM1 Gangliosidosis in which the patient suffers from mental retardation and death by the age of 2. |
| What is the motor protein that carries 'cargos'/objects on the actin microfilament? | Myosin. |
| The deficiency of ___________ causes __________ in which the patient suffers from mental and motor retardation, and death. | The deficiency of hexosaminidases A causes Tay-Sachs in which the patient suffers from mental and motor retardation, and death. |
| What is the role of mitochondria in apoptosis? | Mitochondria releases pro-apoptotic proteins including a group of cysteine proteases (caspases) that proteolytically dismantle most cellular structures. |
| Describe the synthesis of the different types of protein by cytosolic ribosomes. | Different types of proteins synthesized:
- Proteins destined to remain in the cytosol.
- Peripheral proteins of the inner surface of the plasma membrane.
- Proteins that are transported to the nucleus.
- Proteins that are transported to the peroxisomes and mitochondria. |
| The deficiency of ceramidase causes __________ in which the patient suffers from painful, deformed joints, ________, and death within a few years. | The deficiency of ceramidase causes Farber's lipogranulomatosis in which the patient suffers from painful, deformed joints, skin nodules, and death within a few years. |
| State the following organelle: | Mitochondrion. |
| State the function of mitochondrion. | Produce energy in the form of ATP. |
| What is the site for Tricarboxylic Acid Cycle? | Matrix in the mitochondrion. |
| What are the organelles classified in the endomembrane system? | - Endoplasmic reticulum (ER).
- Golgi apparatus.
- Endosomes. |
| The mutation of mitochondrial DNA causes Leber's Hereditary Optic Neuropathy (LHON). Briefly describe the disease. | - Leber's Hereditary Optic Neuropathy (LHON) is an inherited form of vision loss.
- Starts with clouding. |
| What are the functions of the peroxisome? | Contains > 50 enzymes which are involved in diverse activities, which are:
- Oxidation of the very-long-chain fatty acids (VLCFAs).
- Synthesis plasmalogens phospholipids (nyelin sheath of axon in the brain).
- Synthesis and degradation of hydrogen peroxide. |
| What is the statement below referring to? "Tough, rope-like fibers extended across the cytoplasm" | Intermediate filaments. |
| Describe microfilament. | Solid, thinner structure composed of the protein actin. |
| Briefly describe the following organelle: | - Simple, membrane-bound organelle.
- Contains a dense crystalline core of oxidative enzymes. |
| What are the functions of the endomembrane system? | - Functions as the secretory or biosynthetic pathway: RER —> GA —> PM, Lysosome, secreted. - Allows a constitutive or regulated secretion. - Functions as the endocytic pathway: Lysosomes, endosomes. |
| Describe microtubule. | Rigid tube composed of the protein tubulin. |
| State the functions of the cytoskeleton. | - Provides structural support.
- Serves as an internal framework for the positioning of various organelles.
- Serves as the site for anchoring mRNA.
- Serves as a highway network that directs intracellular movement.
- The force-generating apparatus that moves cells from one place to another.
- Cytoskeletal elements make up the apparatus for chromosome separation and cytokinesis during mitosis and meiosis. |
| What are kinesin and dynein, and where are they found? | - Motor proteins.
- Found on microtubules in the cytoskeleton. |
| Briefly describe the endomembrane system. | Endomembrane system is a dynamic integrated network of shuttling materials. |
