Learning Objectives for Cell Bio & Neuroscience
Lecture 2 - Cell Types and Cell structure
All living organisms are made up of one or more cells
The cell is the basic unit of all living organisms
Cells arise from existing cells by division
Mitochondria are not cells, they cannot reproduce independently. They require host cells for
replication
Same goes for Viruses
All cells are surrounded by a plasma membrane
All cells perform metabolism
Functions of the plasma membrane
• Barrier: maintaining different composition of external and internal compartments
• Communication
• Import and export
Prokaryotes and eukaryotes
Organisms are classified into two types → according to whether or not their cells contain a nucleus
and other organelles
• Prokaryotes: no nucleus, single cell (bacteria)
• Eukaryotes: nucleus, single or multicellular
Prokaryotes
Traditionally two main classifications:
1. Bacteria
This is bacteria that is considered ‘familiar’
Such as E.coli and Streptococcus
2. Archaea
This type of prokaryote lives in unusual environments
e.g. halophiles: high salt environments
thermoacidophiles: hot sulphur springs
Feature of a typical bacterium
• Size 1 um to a few um
• Varying shapes
Spherical cells
Rod-shaped cells
Spiral cells
, • Can reproduce in 20 minutes
Plasma membrane
Cell wall (made of peptidoglycan: a protein and oligosaccharide complex)
Cytosol: contains ribosomes
DNA → typically single and circular which contains many proteins
Eukaryotes
Can be single celled or multicellular:
• Plants
• Animals
• Fungi
• Protozoans
• Algae
• Yeast
Eukaryotic cells
• Have DNA in a membrane-enclosed nucleus
• Organelles are membrane bound
• Also contains a cytoskeleton
• Cells 5-50um
• However the size and shape vary
The Nucleus
▪ Diameter is a few um
▪ Surrounded by a double membrane
o The nuclear envelope ….. which
o Encloses the nucleoplasm
▪ Contains the DNA, packaged with proteins as chromosomes
▪ Site of RNA synthesis i.e. TRANSCRIPTION
RER
Rough due to ribosomes on the outside
This is where most synthesis occurs for certain proteins
Since protein synthesis occurs in ribosome → passes through the membrane into the LUMEN where
it is then transported
SER
Lacks ribosomes
The amount of it and the function of SER depends on cell type:
e.g. steroid hormone synthesis
Golgi Complex
A stack of flattened membrane vesicles
Proteins are modified by enzymes
Vesicles transport proteins onto their next destination
,e.g. release from the cell (EXOCYTOSIS)
to the membrane
or to other organelles such as Lysosomes
Lysosomes
Have a membrane
Found in animal cells
Break down unwanted proteins that are taken up by the cell
Peroxisomes
Degrade fatty acids and toxic compounds
Oxidation produces hydrogen peroxide
Fatty acid oxidation produces heat and precursors for biosynthetic pathways
Mitochondria
Oval/ sausage shaped
Main site of ATP production
Takes up to 25% of cytoplasm
The outer membrane contains 50:50 lipid: protein
Inner membrane 20:80 lipid: protein
➔ Specialised proteins involved in ATP production
Inner membrane forms folds (cristae) that protrude into the central matrix
Mitochondria may derive from symbiotic bacteria
Cytosol
Outside membrane-bound organelles
Contains
• Cytoskeleton: which is a network of protein fibres
These maintain the shape of the cell, are involved in cell movement and moving
organelles and particles within cell
• Inclusion bodies
• Metabolic enzymes
Sub-cellular fractionation
Separation of different organelles in large numbers
Homogenised cells need to be held in a solution with a similar pH, salt content and tonicity to the
interior of the cell
Keep them cold
1. Differential-velocity centrifugation
Centrifugation at successively increased speeds
Increased centrifugal force pellets different subcellular fractions
However, this process does not give pure fractions
2. Equilibrium-density centrifugation
Can give further purification of differential velocity centrifugation fractions
Separates according to density
, Testing for organelle-specific molecules can assess purity of organelles
For example
Catalase indicates Peroxisomes are present
Cytochrome c indicates Mitochondria
Lecture 4
Lecture 5
• Basement membrane/basal lamina underlies all epithelia and
surround some non-epithelial cell types
• This membrane located under all the epithelium in your body
• Main components of basement membrane
o Collagen IV
o Laminin
o Nidogen
o Perlecan
Two types of matrices
- Basement membrane
- Fibrillar matrix
To maintain the structure of our body, cells have to bind to each
other
Cells also have to bind to the both matrices
This is called cell adhesion
Cell Adhesion
▪ The fact that cells adhere to something, like other cells or ECM
▪ The activity of cells to adhere
▪ Relatively macroscopic observation
Cell Junction
▪ The structure of cells that enables cell adhesion = Junctional Complexes
Pair of discs at the border of two cells → desmosomes
Lecture 2 - Cell Types and Cell structure
All living organisms are made up of one or more cells
The cell is the basic unit of all living organisms
Cells arise from existing cells by division
Mitochondria are not cells, they cannot reproduce independently. They require host cells for
replication
Same goes for Viruses
All cells are surrounded by a plasma membrane
All cells perform metabolism
Functions of the plasma membrane
• Barrier: maintaining different composition of external and internal compartments
• Communication
• Import and export
Prokaryotes and eukaryotes
Organisms are classified into two types → according to whether or not their cells contain a nucleus
and other organelles
• Prokaryotes: no nucleus, single cell (bacteria)
• Eukaryotes: nucleus, single or multicellular
Prokaryotes
Traditionally two main classifications:
1. Bacteria
This is bacteria that is considered ‘familiar’
Such as E.coli and Streptococcus
2. Archaea
This type of prokaryote lives in unusual environments
e.g. halophiles: high salt environments
thermoacidophiles: hot sulphur springs
Feature of a typical bacterium
• Size 1 um to a few um
• Varying shapes
Spherical cells
Rod-shaped cells
Spiral cells
, • Can reproduce in 20 minutes
Plasma membrane
Cell wall (made of peptidoglycan: a protein and oligosaccharide complex)
Cytosol: contains ribosomes
DNA → typically single and circular which contains many proteins
Eukaryotes
Can be single celled or multicellular:
• Plants
• Animals
• Fungi
• Protozoans
• Algae
• Yeast
Eukaryotic cells
• Have DNA in a membrane-enclosed nucleus
• Organelles are membrane bound
• Also contains a cytoskeleton
• Cells 5-50um
• However the size and shape vary
The Nucleus
▪ Diameter is a few um
▪ Surrounded by a double membrane
o The nuclear envelope ….. which
o Encloses the nucleoplasm
▪ Contains the DNA, packaged with proteins as chromosomes
▪ Site of RNA synthesis i.e. TRANSCRIPTION
RER
Rough due to ribosomes on the outside
This is where most synthesis occurs for certain proteins
Since protein synthesis occurs in ribosome → passes through the membrane into the LUMEN where
it is then transported
SER
Lacks ribosomes
The amount of it and the function of SER depends on cell type:
e.g. steroid hormone synthesis
Golgi Complex
A stack of flattened membrane vesicles
Proteins are modified by enzymes
Vesicles transport proteins onto their next destination
,e.g. release from the cell (EXOCYTOSIS)
to the membrane
or to other organelles such as Lysosomes
Lysosomes
Have a membrane
Found in animal cells
Break down unwanted proteins that are taken up by the cell
Peroxisomes
Degrade fatty acids and toxic compounds
Oxidation produces hydrogen peroxide
Fatty acid oxidation produces heat and precursors for biosynthetic pathways
Mitochondria
Oval/ sausage shaped
Main site of ATP production
Takes up to 25% of cytoplasm
The outer membrane contains 50:50 lipid: protein
Inner membrane 20:80 lipid: protein
➔ Specialised proteins involved in ATP production
Inner membrane forms folds (cristae) that protrude into the central matrix
Mitochondria may derive from symbiotic bacteria
Cytosol
Outside membrane-bound organelles
Contains
• Cytoskeleton: which is a network of protein fibres
These maintain the shape of the cell, are involved in cell movement and moving
organelles and particles within cell
• Inclusion bodies
• Metabolic enzymes
Sub-cellular fractionation
Separation of different organelles in large numbers
Homogenised cells need to be held in a solution with a similar pH, salt content and tonicity to the
interior of the cell
Keep them cold
1. Differential-velocity centrifugation
Centrifugation at successively increased speeds
Increased centrifugal force pellets different subcellular fractions
However, this process does not give pure fractions
2. Equilibrium-density centrifugation
Can give further purification of differential velocity centrifugation fractions
Separates according to density
, Testing for organelle-specific molecules can assess purity of organelles
For example
Catalase indicates Peroxisomes are present
Cytochrome c indicates Mitochondria
Lecture 4
Lecture 5
• Basement membrane/basal lamina underlies all epithelia and
surround some non-epithelial cell types
• This membrane located under all the epithelium in your body
• Main components of basement membrane
o Collagen IV
o Laminin
o Nidogen
o Perlecan
Two types of matrices
- Basement membrane
- Fibrillar matrix
To maintain the structure of our body, cells have to bind to each
other
Cells also have to bind to the both matrices
This is called cell adhesion
Cell Adhesion
▪ The fact that cells adhere to something, like other cells or ECM
▪ The activity of cells to adhere
▪ Relatively macroscopic observation
Cell Junction
▪ The structure of cells that enables cell adhesion = Junctional Complexes
Pair of discs at the border of two cells → desmosomes
