Dr Hettema Flashcards
What are the two problems eukaryotic cells have with regards to their large size?
- Low surface area/volume ratio
- Problems with keeping concentration of reactants sufficiently high
What are some ways used to increase surface area/volume ratio?
- Flattened cells e.g. Human skin fibroblasts
- Microvilli from intestinal mucosa
How are concentrations of reactants kept sufficiently high?
Compartmentalisation of cellular functions
What is the cytoplasm?
The viscous contents of a cell that are contained within the plasma membrane excluding the nucleus
What are organelles?
Any discrete intracellular structure that is specialised for carrying out a particular function
What is the cytosol?
Unstructured aqueous phase of the cytoplasm excluding organelles. membranes and insoluble material (cytoskeleton)
What are the functions of the plasma membrane?
- Encloses the cellular contents, provides barrier
- Regulates compound movement
- Maintains cell shape - Communicates with other cells and extracellular environment
- Attachment to extracellular structures
- Location of certain reactions
- Regulates compound movement
What are the properties of the nucleolus?
- Granular body consisting of RNA and protein
- Site of rRNA synthesis and ribosome subunit assembly
What are the properties of the nuclear pores?
- Where the nuclear envelopes inner membrane and outer membrane come together
- Exchange between cytoplasm and nucleus
What are the two major pathways of the endomembrane system?
- Secretory pathway
- Endocytic pathway
What is the pathway of the secretory pathway?
- Endoplasmic reticulum
- Golgi
- Secretory vesicles
What is the pathway of the endocytic pathway?
- Endosomes
- Lysosomes
- Autophagosomes
- Phagosomes
What is the function of the endocytic pathway?
- Directs material to lysosomes
- Uptake of small macromolecules by invagination of the plasma membrane
- Uptake of particles from the outside of the cell
- Degradation of aged organelles by lysosomes
What are the properties of endosomes?
- Bound by a single membrane
- Varied shape
- Sort proteins for degradation or re-use
What are the properties of lysosomes?
- Bound by a single membrane
- Heterogeneous morphology
- High contents of hydrolytic enzymes involved in the breakdown of polymers at low pH
What are the properties of the sER?
- No ribosomes on outer surface
- Lipid biosynthesis
- Modify hydrophobic chemicals to make them more water soluble
What are the properties of the Golgi complex?
- Stack of flattened vesicles
- Processing and packaging of secretory and membrane proteins
- Sorting of proteins for various destinies in the cell
- Processing and packaging of secretory and membrane proteins
What are the properties of the mitochondria?
- Site of most cellular respiration reactions
- Contain own genome, replication machinery and ribosomes
What are the properties of the peroxisomes?
- Single membrane
- Frequently crystalline core
- H2O2- producing oxidation of fatty acids and a variety of other substrates
- Catalase degrades H2O2
What are the properties of the vacuole in a plant cell?
- Storage of small molecules
- Lysosome-like activities
- Turgor pressure
What are the properties of the cell wall in a plant cell?
- Consists of cellulose microfibrils
- Rigid structure
- Plasmodesmata connect neighbouring cells
- Acts against turgor
What are the properties of the chloroplast in a plant cell?
- Internal membrane system (thylakoids)
- Contains own genome, replication machinery and ribosomes
- Photosynthesis
What are the properties of the cytoskeleton?
- Provides stability and movement
- Movement of cells or intracellular movement of material
How is the cell moved?
- Protusion of the leading edge
- Adhesion of the leading edge
- Deadhesion of the trailing edge
- Movement of the cell body
