Eukaryotic & Prokaryotic Cells
- Understand that cell theory is a unifying concept that states that cells are a fundamental unit of structure, function and organisations in all living organisms
- Understand that in coimplex organisms, ells are organised into tissues, organs and organ systems
- Know the ultrastructure of prokaryotic cells and the strucutre of organelles, including: nucleoid, plasmids , 70S ribosomes and cell wall
- Be able to distinguish between Gram positive and Gram negative bacterial cell walls and understand why each type reacts differently to some antibiotics
- Know the ultrastructure of ekaryotic cells and the functions of organelle, including: nucleus, nucleolus, 80S ribosomes, rough and smooth endoplasmic reticulum, mitochondria, centrioles, lysosomes, Golgi apparatus, cell wall, chloroplasts, vacuole and tonoplast
- Know how magnification and resolution can be achieved using light and electron microscopy
- Understand the improtance of staining specimens in microscopy
Parts of the cell
Nucleus - Largest organelle which is roughly spherical surrounded by a double membrane called a nuclear envelope which contains openings called nuclear pores. The outer membrane is fused to the endoplasmic reticulum. Inside the nucleus is nearly all the cells genetic material and instructions for making proteins. It also makes mRNA. Inside the nucleus is chromatin - which contains DNA and histones and is seen as dark patches, and the
Nucleolus - with no membrane the nucleolus is a dense spherical structure in which ribosomes and RNA are created and leave through the nuclear pores.
Ribosomes - many different types (XS / YS, S being a svedberg which is how quickly and what size the sediment from the centrifuge is.) Ribosomes are extreemly small and are found on the Rough Endoplasmic Reticulum and free floating in the cytoplasm. The ribosome is used in protein synthesis and the production of mRNA .
Eukaryotes
Membrane - Made up of lipids and proteins
The cytoskeleton
Nucleolus - with no membrane the nucleolus is a dense spherical structure in which ribosomes and RNA are created and leave through the nuclear pores.
Ribosomes - many different types (XS / YS, S being a svedberg which is how quickly and what size the sediment from the centrifuge is.) Ribosomes are extreemly small and are found on the Rough Endoplasmic Reticulum and free floating in the cytoplasm. The ribosome is used in protein synthesis and the production of mRNA .
Eukaryotes
Membrane - Made up of lipids and proteins
- The phospholipid bilayer
- Polar phosphate group attached to lipid
- A simple lipid bilayer allows fat soluble organic molecules to pass through it
- Ionic chemicals can pass through due to proteins
- Membrane proteins
- Proteins float in the lipid membrane like icebergs
- Proportion of phoslipids with unsaturated fatty acids = the freedom of the movement
- The more unsaturated fatty acids, the more fluid in the membrane
- Some proteins are a dipole so the hydrophobic part is buried in the lipid bilayer
- Main function is to help substances across the membrane
- Proteins can form temporary / permanent pores or channels that allow molecules to pass through. These are called gated channels
- Gated channels are either active carrier systems or could be gaps
- Proteins could act as specific receptor molecule
- They can also be glycoproteins which act as cell receptors
- It is spherical, with a double membrane that contains nuclear pores
- Can control events in the cytoplasm
- It contains DNA, RNA and proteins
- The DNA is bound to protein to form chromatin
- Nucleolus
- Extra dense area of DNA and protein
- Involved in production of ribosomes
- Found in the cytoplasm
- Produces ATP that can be used to drive the cell
- Number of mitochondria is proportional to the amount of energy that cell produces
- Has a double membrane
- Contains unique genetic material
- Replicates independently of cell
- Inner structure is important for use
- Inner membrane is folded to form cristae (means a large surface area)
- Contains a fluid matrix - the reaction medium
- Stalked particles – contain reaction enzyme
- Come in pairs
- Made up of a bundle of nine tubules
- Used in cell division and form microtubules
- Microtubules pull the chromosomes
The cytoskeleton
- 3D web like structure that fills the cytoplasm
- Made up of microfilaments
- Made of globular protein tubulin
- Gives cytoplasm structure
- Keeps organelles in place
- Non-permanent in animal cell
- Membrane line
- Lost and formed when needed
- Used as a store of energy
- Site of protein synthesis
- 80S or 70S ribosomes
- Made up of two smaller sub units
- Created in mitochondria
- RER isolates and transports proteins
- Proteins are stored and transported in RER
- RER covered in ribosomes
- SER is for lipids and steroids
- Made up of flattened membrane pockets (cisternae)
- Formed by vesicles fusing together
- Proteins are “processed”
- Carbohydrates or lipids could be added
- Contains digestive enzymes
- They can destroy worn out cells
- Apoptosis