Cell Biology
Cell Biology
General
Cyto = Cells
Cytology = Study of Cells
Cyte:
Erythrocytes= Red Blood cells
Keratinocytes= Skin Cells
Cytochemistry= Cell Chemistry
Small units bound by a plasma membrane (or a cell wall)
Contains aqueous fluid cytosol:
- Chemical cytoplasm
- Structural support cytoskeleton
- Membrane bound organelles
All living entities must:
- Harness energy
- Respire
- Grow and Develop
- Reproduce
- Respond to stimuli
Harness Energy:
Phagocytosis= Cell Eating
Pinocytosis= Cell Drinking
Respire:
Respire substrates
Requires O2 to drive catabolism
Respiration of fuels
Grow and Develop:
Hypertrophy= Cells Grow
Proliferate- Mitosis= Cell division
Hyperplasia= Rapid cell division
Specialise/Differentiate
Reproduce:
Mitosis
Meiosis
Somatic= Of the body
,Respond to Stimuli:
Cells move= Cytohemotaxis
Phagocytic cells can ingest materials= Macrophages
Divide in response to mitogens
Move in response to morphogens
Mitogen= Chemical substances normally a protein that stimulates a cell to divide
Cell Membrane
General
- Plasma Membrane separates the cellular contents from the outside
- Internal membrane separates the content of different organelles from the rest of the cell
- No membrane, no gradients, no energy
- Membrane lipids are ampholytic and they associate to form a permeability barrier that most
solutes cannot freely diffuse across
Hydrophobic head (Polar heads)
Hydrophilic tail (Fatty acyl chains)
- Amphiphilicity of membrane lipids means that they readily self-associate in water
- Cylindrical shape means that they favour a bilayer of two leaflets, rather than a micelle
- The propensity to form membrane sheets favour the formation of liposomes (membrane lipid balls)
- Acyl chain can flex within the bilayer
- Membrane lipids can rotate within the bilayer
- Membrane lipids can diffuse laterally within the leaflet
- Flip-flop, the movement of membrane lipid from one leaflet to the other is rare
Glycerophospholipid= Glycerol link
Sphingolipid= Serine link
Serine:
- The major lipid components of most biological membrane are also arranged asymmetrically
between the two leaflets of the bilayer
,Cholesterol:
- Head group hydroxyl of cholesterol associates with the head group of the neighbouring
glycerophospholipid
- Steroid ring and acyl chain intercalate with the acyl chain of the glycerophospholipid
- Add cholesterol to a glycerophospholipid bilayer and it becomes more densely packed, less fluid
and less permeable
Sphingolipid:
- Glycerophospholipids with cis-unsaturated fatty acid
- Sphingolipids with longer straighter fatty acid, thicker membrane, tightly packed into a liquid
crystalline phase
- Cholesterol therefore modulates the behaviour of the membrane dependant on the other lipid it
interacts with
- Cholesterol is enriched along with sphingolipid in membrane invagination that one impact for
endocytosis
Taurocholate= Natural detergent
Vitamin D= necessary for bone formation
Cortisol= Stress hormone
Testosterone and Oestrogen= The primary male and female sex hormones vary by reduction of a
hydroxyl and methylation
Glycolipids:
- Based on Ceramide
- Contains sugary head group
- NANA (Sialic acid) carries a negative charge
- confined to the outer leaflet of plasma membrane
- GM, ganglioside is the receptor for cholera toxin
- Protect the cell from hostile environment
- Important in cell-cell contact
- Localise to and may be important in lipid raft generation/ functions
, Cell organelles: structure function relationships:
The cell surface:
- Surrounded by a plasma membrane
- single membrane
- membrane is selectively permeable
- Selectively permeable because lipids are amphipathic
- Integral and Peripheral membrane proteins
- Transport hydrophilic solutes
What are cell walls?
- Plant cells and bacteria have a cell wall surrounding the plasma membrane
- Rigid structured support
- Further limits passage of molecules into/out of the cell
Plants:
- Plant cell walls composed of complex carbohydrates:
- Cellulose
- Hemicellulose
- Pectin
- Other polymers embedded into the cell wall
- Lignin and Actin
Bacteria:
- Cell wall composed of peptidoglycans
- Can be surrounded by gelatinous polysaccharide layers (Glycocalyx)
- Capsule
- Slime layer
- Can stain with gram’s solution
- Gram positive bacteria: thick peptidoglycan which prevents the stain to wash out
- Gram negative bacteria: thin peptidoglycan which washed out the stain
Cell Biology
General
Cyto = Cells
Cytology = Study of Cells
Cyte:
Erythrocytes= Red Blood cells
Keratinocytes= Skin Cells
Cytochemistry= Cell Chemistry
Small units bound by a plasma membrane (or a cell wall)
Contains aqueous fluid cytosol:
- Chemical cytoplasm
- Structural support cytoskeleton
- Membrane bound organelles
All living entities must:
- Harness energy
- Respire
- Grow and Develop
- Reproduce
- Respond to stimuli
Harness Energy:
Phagocytosis= Cell Eating
Pinocytosis= Cell Drinking
Respire:
Respire substrates
Requires O2 to drive catabolism
Respiration of fuels
Grow and Develop:
Hypertrophy= Cells Grow
Proliferate- Mitosis= Cell division
Hyperplasia= Rapid cell division
Specialise/Differentiate
Reproduce:
Mitosis
Meiosis
Somatic= Of the body
,Respond to Stimuli:
Cells move= Cytohemotaxis
Phagocytic cells can ingest materials= Macrophages
Divide in response to mitogens
Move in response to morphogens
Mitogen= Chemical substances normally a protein that stimulates a cell to divide
Cell Membrane
General
- Plasma Membrane separates the cellular contents from the outside
- Internal membrane separates the content of different organelles from the rest of the cell
- No membrane, no gradients, no energy
- Membrane lipids are ampholytic and they associate to form a permeability barrier that most
solutes cannot freely diffuse across
Hydrophobic head (Polar heads)
Hydrophilic tail (Fatty acyl chains)
- Amphiphilicity of membrane lipids means that they readily self-associate in water
- Cylindrical shape means that they favour a bilayer of two leaflets, rather than a micelle
- The propensity to form membrane sheets favour the formation of liposomes (membrane lipid balls)
- Acyl chain can flex within the bilayer
- Membrane lipids can rotate within the bilayer
- Membrane lipids can diffuse laterally within the leaflet
- Flip-flop, the movement of membrane lipid from one leaflet to the other is rare
Glycerophospholipid= Glycerol link
Sphingolipid= Serine link
Serine:
- The major lipid components of most biological membrane are also arranged asymmetrically
between the two leaflets of the bilayer
,Cholesterol:
- Head group hydroxyl of cholesterol associates with the head group of the neighbouring
glycerophospholipid
- Steroid ring and acyl chain intercalate with the acyl chain of the glycerophospholipid
- Add cholesterol to a glycerophospholipid bilayer and it becomes more densely packed, less fluid
and less permeable
Sphingolipid:
- Glycerophospholipids with cis-unsaturated fatty acid
- Sphingolipids with longer straighter fatty acid, thicker membrane, tightly packed into a liquid
crystalline phase
- Cholesterol therefore modulates the behaviour of the membrane dependant on the other lipid it
interacts with
- Cholesterol is enriched along with sphingolipid in membrane invagination that one impact for
endocytosis
Taurocholate= Natural detergent
Vitamin D= necessary for bone formation
Cortisol= Stress hormone
Testosterone and Oestrogen= The primary male and female sex hormones vary by reduction of a
hydroxyl and methylation
Glycolipids:
- Based on Ceramide
- Contains sugary head group
- NANA (Sialic acid) carries a negative charge
- confined to the outer leaflet of plasma membrane
- GM, ganglioside is the receptor for cholera toxin
- Protect the cell from hostile environment
- Important in cell-cell contact
- Localise to and may be important in lipid raft generation/ functions
, Cell organelles: structure function relationships:
The cell surface:
- Surrounded by a plasma membrane
- single membrane
- membrane is selectively permeable
- Selectively permeable because lipids are amphipathic
- Integral and Peripheral membrane proteins
- Transport hydrophilic solutes
What are cell walls?
- Plant cells and bacteria have a cell wall surrounding the plasma membrane
- Rigid structured support
- Further limits passage of molecules into/out of the cell
Plants:
- Plant cell walls composed of complex carbohydrates:
- Cellulose
- Hemicellulose
- Pectin
- Other polymers embedded into the cell wall
- Lignin and Actin
Bacteria:
- Cell wall composed of peptidoglycans
- Can be surrounded by gelatinous polysaccharide layers (Glycocalyx)
- Capsule
- Slime layer
- Can stain with gram’s solution
- Gram positive bacteria: thick peptidoglycan which prevents the stain to wash out
- Gram negative bacteria: thin peptidoglycan which washed out the stain
