Cells Structure and Function : Introduction Flashcards
What are the 3 cell theories?
- All living organism are composed of one or more cells
- The cell is the basic unit of structure and organisation
- All cells arise only from pre-existing cells
What are the 3 universal similarities between cells?
- DNA as the heritable material, RNA as a messenger and proteins as the workers
- Major cellular organelles - function and arrangements within the cell
- ATP as an energy source
What does Prokaryote cell and Eukaryote cell have in common?
Both have plasma membrane, cytosol, DNA, RNA, protein and ribosomes
What’s the difference between Prokaryote and Eukaryote cell?
Eukaryotic cells have membrane-bound organelles and are much larger.
Prokaryote cells lack a membrane-bound nucleus
What is the cytoplasm?
The cytoplasm is everything inside the plasma membrane including the organelles. Not including the nucleus.
What is the cytosol?
It is the fluid portion of the cytoplasm.
(Water plus dissolved and suspended substances eg. ions, ATP, proteins, lipids)
What are the major organelles in the cytoplasm?
Endoplasmic Reticulum (smooth and rough)
Golgi Apparatus
Lysosomes
Mitochondria
Ribosome
What components are in the endomembrane system?
G.L.E.N
Nucleus
Endoplasmic Reticulum
Golgi Appparatus
Lysosomes
What are components in the Cytoplasm?
Endoplasmic Reticulum (Smooth and Rough ER)
Plasma membrane
Ribosomes
Golgi Apparatus
Lysosome
Mitochondria
Cytoskeleton (Microfilaments, Intermediate filaments, Microtubules)
What is the Plasma membrane?
Selectively permeable barrier controlling the passage of substances in and out of the cell.
Double layer of phospholipids with embedded proteins. Physical barrier separating the inside/outside of cell.
Most of our body is hydrophilic. Fats are hydrophobic. Fats in cell membrane provide a barrier to water
What is Hydrophilic and Hydrophobic ?
Hydrophilic is water loving.
Hydrophobic is water hating
What is a phospholipid?
Hydrophilic polar heads (phosphate)
Hydrophobic lipid tails (fatty acids)
Arranged as double layer around cytoplasm, tail to tail.
What are Plasma membrane proteins?
Membrane proteins mediate movement of hydrophilic substances. Are often amphipathic which means they have both hydrophilic and hydrophobic regions
What are the two types of Plasma Membrane proteins?
Integral proteins and Peripheral membrane proteins
What are Integral proteins?
Embedded (partially or fully) into the membrane. Eg, Transmembrane proteins are integral membrane proteins that fully span the entire membrane, contacting both extracellular and cytoplasmic areas
What are Peripheral membrane proteins?
Associated with the membrane, but not actually embedded in it. Allow cell-cell identification and facilitate intercellular communication
What is the function of Plasma membrane proteins?
(C.A.S.E I.T)
- Transport
- Enzymatic activity
- Signal transduction
- Cell-cell recognition
- Intercellular joining
- Attachment to the cytoskeleton and extracellular matrix (ECM)
What does Transport do in the Plasma membrane protein?
Channels, transporter, may be general or selective, gated or not.
What does the Enzymatic Activity do in the plasma membrane protein
Carry out chemical reaction, may or may not be a part of a team of enzymes
What is Signal transduction do in the plasma membrane protein?
External signalling molecule causing communication of information to the inside of the cell
What does cell-cell recognition do in the plasma membrane?
Use of glycoproteins. (carbohydrates + protein) as molecular signatures of the extracellular side of the cell
What does Intercellular joining do?
Intercellular junctions are specialized regions of contact between the plasma membranes of adjacent cells. They are essential to any multicellular organism, providing the structural means by which groups of cells can adhere and interact. For example, gap junctions or tight junctions
What does Attachment to the cytoskeleton and extracellular matrix (ECM)
For example, Fibronectin mediates contact between cell surface integrins and ECM (E.g collagen) Can facilitate movement.
Membranes are not static
The membrane is a mosaic of molecules bobbing in a fluid of bilayer of phospholipids. Cell specific and dynamic repertoire of membrane-bound proteins present as required