week 2 CTL Flashcards
Explain the principle of complementarity of structure and function
- Structure dictates function
- Structure and function are intrinsically linked
- although every cell in the human body contains the same DNA, cells are able to differentiate and become structurally diverse in order to carry out their specific functions
- Cellular structures can determine the specific functions of tissue, organ and system at large.
What are the three main features of cells
1) Cells have plasma membrane allowing cells to be self-contained forming a barrier
2) cells have a cytoplasm with many organelles and structures for functioning
3) cells have a nucleus the control centre controlling activity and the life cycle
Main functions of the plasma membrane
1) TRANSPORT - via embedded transmembrane proteins
2) Cell-cell recognition via glycoproteins
3) ANCHORAGE/site of attachment for cytoskeleton and ECM allowing for cell motility and binding
4) ENZYMATIC Activity via embedded proteins with enzymatic activity
5) RECEPTORS FOR SIGNAL TRANSDUCTION e.g. hormone receptors
6) INTERCEULLUAR BINDING via CAMS
Compare and contrast the different types of cell junctions
1) TIGHT JUNCTIONS: formed due to the fusion of integral proteins on adjacent cells. Form a tight impermeable barrier restriction ICF and ECF movement, therefore, acts as a barrier to the movement of molecules.
2) GAP JUNCTIONS: formed by connexons which are highly specialised integral proteins that form pored between cells. Permeable junctions that allow the movement of small molcules and ions between cells (highly specialised) found in cardiac muscle cells.
3) DESMOSOMES: These are anchoring junction with cytoskeletal reinforcements. They are perfect for resisting shearing/tearing forces as the cytoskeleton resists these forces preventing cellular damage. Also impermeable junction.
Primary VS secondary transport
Primary transport uses the hydrolysis of ATP to drive ion movement across a channel e.g. sodium-potassium ATPase
Secondary transport uses the energy stored witin the electrochemical gradients established by the sodium-potassium pump to drive the movement of a molcule against its concentration gradient into the cell through a symporter.
What are the types of passive transport
1) Simple diffusion
2) Carrier mediated simple diffusion
3) Channel mediate simple diffusion
4) osmosis
Vesicular transport
- Endocytosis- movement into the cell (phagocytosis is cell eating, pinocytosis is cell drinking)
- Exocytosis (movement out of the cell, most commonly associated with vesicular excretion or secretion out of the cell e.g. hormones or the ejection of waste products.
Mitochondria
- the powerhouse of the cell
- Has an inner and outer membrane, outer is smooth and featureless inner is folded into cristae, outer is highly permeable to substances inner is very selectively permeable
- Site of cellular respiration
0 Has its
Mitochondrial structure and key functional points
- the powerhouse of the cell
- Has an inner and outer membrane, outer is smooth and featureless inner is folded into cristae, outer is highly permeable to substances inner is very selectively permeable
- Site of cellular respiration
- Has its own DNA and ribosomes
Endoplasmic reticulum structure and key functions
This is an extensive interconnected system of fluid filled cisternae, it is continuous with the outer nuclear membrane.
SMOOTH ER
- Site of detoxification of drugs, alcohol and xenobiotic substances
- Steroid hormone and lipid synthesis
- Carb and lipid metabolism
- Intracellular store of calcium (cardiac muscle cells)
ROUGH ER
- Synthesis of all proteins secreted from the cell
- Central role in synthesis of cell membrane proteins
(LESS FUNCTIONAL DIVERSITY WITH RER)
GOLGI APPARATUS STRUCTURE AND FUNCTION
Golgi body has a cis and trans face.
Cis face receives proteins from RER, as they move along the gogli apparatus proteins are modified.
Modified, packages and sorts/ships enzymes (proteins) and lysosomes
TRANS face ships vesicles that either become lysosomes, secretory vesicles that undergo exocytosis from cell or part of the cell membrane.
Lysosomes structure and function
They are the waste removal in the cell
digests all materials that enter the cell via endocytosis
- They remove worn-out or damaged organelles and cellular components
- they then self-destruct via AUTOLYSIS
Cytoskeleton structure and function
Made up of 3 types of filaments
smallest is microfilaments e.g. involved in cell movement and contractility
Intermediate filament e.g. keratin in epithelial cell provides structural integrity not involved in movement. Supports things like desmosomes (scaffolding)
Microtubules: these are involved in cell motility and cell movement supports microvilli and forms parts of mitotic spindle
centrostomes/ centrioles
9 complex of microtubules forms centriole
Centrioles provide microtubule support, and is involed in cell division as it directs formation of the mitotic spindle
