2. cytoplasm - cell morphology
& fuctionality - organelles
Tags
Created January 7, 2025 619 PM
Common cell characteristics
1. Double lipid bilayer cell membrane
2. Cell organelles
3. Synthesis of macromolecules
4. Energy production
5. Communication with other cells
Cell structure
Protoplasm: cytoplasm, nucleoplasm (eycariotic cell containing nucleus)
Cytoskeleton: microtubules, filaments → movement, shape, signaling
Organelles: metabolically active structures with specific function
Inclusions: accumulation of metabolites, nutrients, pigments
PLASMA MEMBRANE
consists of:
1. phospholipids,
2. cholesterol,
3. proteins, with oligosaccharide chains covalently linked to many of the
phospholipids and proteins
2. cytoplasm - cell morphology & fuctionality - organelles 1
, Functionality
Maintain the structural integrity of the cell
Selective permeability of molecules and materials - selective barrier
Regulates cell to cell interactions
Recognises through receptors antigens, foreign substances and abnormal
cells
Separates cytoplasm – external environment
Contains different transport systems for specific molecules
Keeps constant the ion content of cytoplasm
→ selective barrier
Visible by TEM
Cell membrane or plasmalemma
Trilaminar appearance:
2 electron-dense dark lines
1 electron – lucent clear band (unstained middle): creation of a barrier to
water-soluble
Phospholipid bilayer, intra «swimming» of proteins
Lipids consist of phospholipids, cholesterol + glycolipids
Phospholipids offer membrane fluidity, through spreading inside the bilayer.
Cholesterol does less fluid the areas that is positioned
Glycolipids seems to participate in intracellular communication
phospholipid bilayer structure
2. cytoplasm - cell morphology & fuctionality - organelles 2
, Amphipathic: having both hydrophilic heads and hydrophobic tails in a single
molecule or lipid compound
Two non polar (hydrophobic or water repelling) long-chain fatty acids
Charged (hydrophilic or water - attracting) polar head bearing a phosphate
group
Organization in double layer – stability
Cholesterol – amphipathic – affects packing of fatty acids → major effect on
membrane fluidity
Glycocalyx
a layer of glycolipids + glycoproteins on the surface of many cells types
⇒ functions in cell–cell recognition, communication, adhesion
Cell “coverageˮ – surface coating
Carbohydrate (oligosaccharide) chains connected covalently with
transmembrane proteins and
lipids exposed at the external membrane surface
Different distribution of membrane polypeptides, varied density and thickness
Intense dyeing with pigments e.g. Alcian blue
Role
Cell protection from natural/chemical damage, non-suitable proteins
Antigenic and functional properties provision to cell
Cell recognition and adhesion T-lymphocytes antigen-presenting cells )
Facilitation of blood clotting and inflammatory reactions
Reduction of friction between blood cells and endothelial cells lining the
vessels
2. cytoplasm - cell morphology & fuctionality - organelles 3
& fuctionality - organelles
Tags
Created January 7, 2025 619 PM
Common cell characteristics
1. Double lipid bilayer cell membrane
2. Cell organelles
3. Synthesis of macromolecules
4. Energy production
5. Communication with other cells
Cell structure
Protoplasm: cytoplasm, nucleoplasm (eycariotic cell containing nucleus)
Cytoskeleton: microtubules, filaments → movement, shape, signaling
Organelles: metabolically active structures with specific function
Inclusions: accumulation of metabolites, nutrients, pigments
PLASMA MEMBRANE
consists of:
1. phospholipids,
2. cholesterol,
3. proteins, with oligosaccharide chains covalently linked to many of the
phospholipids and proteins
2. cytoplasm - cell morphology & fuctionality - organelles 1
, Functionality
Maintain the structural integrity of the cell
Selective permeability of molecules and materials - selective barrier
Regulates cell to cell interactions
Recognises through receptors antigens, foreign substances and abnormal
cells
Separates cytoplasm – external environment
Contains different transport systems for specific molecules
Keeps constant the ion content of cytoplasm
→ selective barrier
Visible by TEM
Cell membrane or plasmalemma
Trilaminar appearance:
2 electron-dense dark lines
1 electron – lucent clear band (unstained middle): creation of a barrier to
water-soluble
Phospholipid bilayer, intra «swimming» of proteins
Lipids consist of phospholipids, cholesterol + glycolipids
Phospholipids offer membrane fluidity, through spreading inside the bilayer.
Cholesterol does less fluid the areas that is positioned
Glycolipids seems to participate in intracellular communication
phospholipid bilayer structure
2. cytoplasm - cell morphology & fuctionality - organelles 2
, Amphipathic: having both hydrophilic heads and hydrophobic tails in a single
molecule or lipid compound
Two non polar (hydrophobic or water repelling) long-chain fatty acids
Charged (hydrophilic or water - attracting) polar head bearing a phosphate
group
Organization in double layer – stability
Cholesterol – amphipathic – affects packing of fatty acids → major effect on
membrane fluidity
Glycocalyx
a layer of glycolipids + glycoproteins on the surface of many cells types
⇒ functions in cell–cell recognition, communication, adhesion
Cell “coverageˮ – surface coating
Carbohydrate (oligosaccharide) chains connected covalently with
transmembrane proteins and
lipids exposed at the external membrane surface
Different distribution of membrane polypeptides, varied density and thickness
Intense dyeing with pigments e.g. Alcian blue
Role
Cell protection from natural/chemical damage, non-suitable proteins
Antigenic and functional properties provision to cell
Cell recognition and adhesion T-lymphocytes antigen-presenting cells )
Facilitation of blood clotting and inflammatory reactions
Reduction of friction between blood cells and endothelial cells lining the
vessels
2. cytoplasm - cell morphology & fuctionality - organelles 3
