Session 2 - General Characteristics, Structure And Function Of A Cell Flashcards
What are membranous organelles?
Cell organelle that are surrounded with a plasma membrane are isolate from the cytosol.
Give 5 examples of membranous organelles.
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Glogi apparatus
Endosomes
Mitochondria
What are non-membranous organelles?
Cell organelles that have no plasma membrane and are in direct contact with the cytosol.
What are the functions of the cell membrane?
- Physical isolation
- Regulates exchange with environment - ions and nutrients enter and waste and cellular products are released through diffusion, osmosis, active transport and phagocytosis.
- Monitors the environment - the extracellular fluid composition and chemical signals
- Structural support - anchors cells and tissues
Explain the mosaic model of the cell membrane.
It is about 8,5 -10 nanometers in cross section and has a double layer of phospholipid molecules. The majority of the lipid molecules are cholesterol. The cell membrane also contains integral and peripheral proteins as well as carbohydrates.
List the 6 membrane proteins are explain their functions.
- Structural proteins - junctions with neighbouring cells
- Linkers - anchor intracellular skeleton to extracellular matrix
- Enzymes - catalyse reactions
- Receptor proteins - bind and respond to ligands (ions and hormones)
- Carrier proteins - transport specific solutes through the membrane
- Channels - regulate water flow and solutes through the membrane
What is endocytosis?
A type of vesicular transport that used ATP to transport objects into the cell.
What is exocytosis?
A type of vesicular transport that uses ATP to transport objects out of the cell.
What are the categories of cellular transport?
- Diffusion
- Carrier-mediated transport
- Vesicular transport
What happens during phagocytosis?
Pseudopodia engulf large objects in phagosomes and transport them into through the cell membrane.
What is the function of endosomes?
They sort and recycle protein internalised by endocytosis.
What is the function of the rough endoplasmic reticulum?
Protein synthesis
What are the functions of the smooth endoplasmic reticulum?
- Synthesises steroid hormones
- Responsible for the oxidation, conjugation and methylating process to neutralise certain hormones and detoxify poisonous substances.
- Involved in metabolism (breaking down) of glycogen
- Synthesises triglyceride
- Resynthesises absorbed fatty acids and glycerol to form neutral fats
- Plays a role in muscle contraction by concentrating and releasing calcium 2+ ions.
What are the functions of the glogi apparatus?
- Involved in protein production as proteins undergo changes in the sacculae.
- Produces secretory vesicles, enzymes or hormones
- Adds carbohydrates to proteins - glycoproteins
What are the functions of the lysosome?
- Breaking down large molecules
- Attack bacteria
- Recycling basic components of broken down damaged organelles
- Ejecting waste products by exocytosis
- Autolysis/post-mortem degeneration of tissues
- Defend the body against certain bacterial invaders