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35 Cards in this Set
- Front
- Back
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Name one unicellular eukaryote that aggregates and specialises when food is scarce |
Dictyostelium discoidium |
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Give six functions of the plasma membrane in eukaryotes |
-Regulate transport of nutrients into the cell -Regulate transport of waste out of the cell -Maintain ideal chemical conditions in the cell -Provide a site for chemical reactions not likely to take place in an aqueous environment -Detect signals in the extracellular environment -Interact with other cells or the extracellular matrix (in multicellular organisms) |
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How thick are the two membranes of the nucleus? |
5-7nm |
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What is the biggest difference between the inner and outer nuclear membrane? |
Outer is continuous with the rough ER, inner is not |
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What is the purpose of the nucleolus? |
Rich in protein and RNA - involved with synthesis of ribosomal RNA and ribosomes |
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Give four functions of the endoplasmic reticulum |
Most lipid synthesis (smooth) Most membrane protein synthesis (rough) Ca2+ storage Detoxification |
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Describe the chemical composition of ribosomes |
50% rRNA and 50% protein |
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Give two roles of mitochondria |
Site of ATP synthesis in aerobic respiration Plays a role in apoptosis |
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What is cytoplasmic inheritance? |
Traits are inherited by structures in the cytoplasm (mitochondria and chloroplasts etc) rather than chromosomes in the nucleus. |
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Are products of mtDNA exported? |
No |
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Name a genetic disease caused by a mutation to the mitochondrial genome |
Leber Hereditary Optic Neuropathy |
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What have the golgi apparatus and plasma membrane got in common? |
Both have membranes of 5-7nm thickness. This allows vesicles budding off the golgi apparatus to be able to fuse with the plasma membrane |
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Give the role of the golgi apparatus |
Packages lysosomal proteins and proteins to be secreted from the cell |
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What are the three regions of the golgi apparatus |
Cis, medial, trans |
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Name an organelle not present in plants |
Lysosome - vacuole plays some roles of lysosomes |
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What is the interior pH of lysosomes? |
3.5-5.0 |
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What happens if an enzyme is missing from lysosomes due to a genetic defect? |
Accumulation of material - lysosomal storage disease - fatal in adolescence |
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Give three biological process lysosomes are vital for |
- Fusing to phagosomes (formed through phagocytosis) to form a secondary lysosome - Fusing to endosomes (formed through endocytosis) to form a secondary lysosome - Degradation of organelles (autophagy) by fusing to autophagosomes |
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What are the two roles of peroxisomes? |
Beta-oxidation of fatty acids Oxidation of toxins |
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Are persoxisomes double or single membraned? |
Single |
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Give two enzymes present in peroxisomes |
Catalase and urate oxidase |
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Give four roles of the cytoskeleton |
Cell movement Cell shape maintenance Intracellular trafficking of organelles Co-ordinated movement of tissues
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What are the three major components of the cytoskeleton? |
Microfilaments, Microtubules, Intermediate filaments |
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Describe the structure of microfilaments |
Composed of a double helix of G-actin subunits. Polymerisation at one end and depolymerisation at the other can lead to 'treadmilling' or movement |
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Name some roles of microfilaments |
Microvilli, cell cortex, adherens belt, Filipodia, Lamellipodium/ leading edge, Stress fibres, contractile ring, muscle contraction through interaction with myosin |
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Describe the structure of microtubules |
Hollow tubes of alpha and beta tubulin |
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Give two roles of microtubules |
Forms trackways in cells along which motor proteins drag vesicles, organelles etc
Separation of chromosomes during mitosis/meiosis |
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Name one type of intermediate filament in each of the five numbered classes, its location and its role |
(1) Acidic filament, epithelial cells, tissue strength (2) Basic filament, epithelial cells, tissue strength (3) Desmin, muscle, sarcomere organisation integrity (4) Neurofilaments, neurons, axon organisation (5) Lamins, nucleus, nuclear structure and organisation |
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What is normally the largest structure in a plant cell? |
Vacuole (may be 80% of the cell's composition) |
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What are the roles of the vacuole? |
Store of water, salt and nutrients Degradation of macromolecules Inflow of water maintains turgor Expansion of vacuoles involved in cell elongation |
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What are glyoxisomes? |
Specialised peroxisome that carry out the glyoxalate cycle to convert fatty acids into sugars. Found in germinating seeds |
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Other than chloroplasts, name one organelle where photorespiration takes place |
Specialised peroxisomes |
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What is the cell wall composed of? |
Cellulose cross linked by hemicellulose, pectin and lignin, an insoluble phenolic polymer |
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What are plasmodesmata? |
Structures in the cell wall that connect the cytosol of different plant cells in higher structures. |
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What two parts are plasmodesmata composed of? |
Annulus and desmotubule |
