Lesson 2 - Cytoplasmic organelles Flashcards
What are all the organelles called that are inside the cell?
Intracytoplasmic organelles
Example of intracytoplasmic organelles
Lysosomes
Mitochondria
What do the endoplasmic reticulum and golgi apparatus look like?
Maze-like structures
Plasma membrane is what kind of bilayer
lipoprotein bilayer
In the Smooth Endoplasmic Reticulum, the lipoprotein bilayers are thinner than:
thinner than cell membranes
2 surfaces of the SER
Cytoplasmic (Outer surface)
Luminal (inside surface)
3 forms of SER
- Vesicular (grain-like)
- Lamellar (sheet-like, layers)
- Tubular (tubes)
General function of the ER
Act as the second-in command to the nucleus: transport to and from the nucleus
5 Main functions of the SER
- Metabolism of small molecules
- Cellular detoxification - very high levels of a certain substance like sugar breaks it down into manageable levels .e.g alcohol is broken down into urine, breath.
- Fat (lipid) synthesis
- Manufactures steroid hormones
- Breaks down glycogen (glycogenolysis)
The 3 specialised forms of SER are:
freely convertible, meaning that the SER is a highly dynamic pleomorphic (able to assume different forms) organelle
Why is the RER rough?
Because there’s small cellular organelles on its wall called ribosomes. These ribosomes have black dots on them which appears rough, hence the name.
By what protein are ribosomes attached to the RER?
Ribophorin
Because the RER has ribosomes on it, the RER’s 3 functions are:
Protein processing
Preparing proteins for transport
Manufactures enzymes for lysosomes (vesicles/organelles that help with digestion_
What is the main enzyme constituent of the endoplasmic reticular membrane?
G6P (glucose) - used to break down glucose
Process of protein synthesis
When a nucleus needs nutrients, RNA is sent from 3’ end to 5’ end to ER. This attracts ribosomes.
A molecule then deactivates the ribosome.
As the ribosome gets closer to the RER, the ribosome attaches to a membrane protein.
A codon is then squirted out which says which protein is required.
The ER now knows what protein is required so it collects all the amino acids and forms a protein
Ribosomes then keep moving and get recycled into the endoplasmic reticulum to be used again
2 functions of Golgi apparatus
- Protein synthesis
- Membrane synthesis
2 faces of golgi apparatus
- Cis (forming) face - this is where the protein has been transferred to from the ER after the protein has been created
- Trans (maturing) face - The protein travels through and at the maturing face, the protein enters a vesicle that fuses with the cell membrane and the protein is then secreted into the cell
Mitochondria
Look up diagram - need to know what the intracellular organelles look like
4 Functions of the mitochondria
- Produce TCA, ETC enzymes for ATP
- Generate ATO from citric acid, steroid (e.g. testosterone),
- FA oxidation (break down of fatty acids)
- Nucleic acid synthesis
Since ciliated cells in the respiratory tract require a lot of energy, what do the cells need?
A lot of mitochondria which will produce the ATP required to move towards the mouth to have mucus expulsion
What is the mitochondrial DNA called?
mtDNA
What does the mtDNA produce?
Different types of RNA: mRNA, rRNA and tRNA synthesis
Creates enzymes for ETC
What happens if you have mitochondrial disease?
Some organs may not have enough mitochondria and hence, not enough energy to function
What is the name of the main digestive enzyme in lysosomes?
Acid hydrolase
2 types of lysosomes
- Primary: enzyme is inactive lysosome but carry all the required materials
- Secondary: as soon as the ribosome comes in contact with an endosome (a collection of tiny lysosomes), the enzyme becomes active. It then attaches to a molecule to digest it.
How is a lysosome used in digestion?
They break P-N (phosphate-nitrogen) and S-N bonds. Acid hydrolase weakens the bond to use the material that comes out of the broken down molecule.
Since hydrolase is acidic, the pH must be acidic to activate the enzyme.
Problem with lysosomal disease
Normally, fat comes into the cell, lysosomes then break it down. But, with this disease, there’s nothing to break the fat down so then the fat attaches to the cells and eventually, the cells die because of this and then causes programmed cell death (all the cells around it die)
Another name for microbodies
Peroxisomes
Functions of peroxisomes
Oxidation (converts hydrogen peroxide to hydrogen and oxygen
Contains amino acid oxidase which metabolizes D-amino acids
In the liver, oxidises fatty acids in conjunction with mitochondria
3 elements within a cell to get things transported quickly
Microtubules
Microfilaments
Intermediate filaments
3 Functions of microtubules
Cell motility
Chromosome movement
Ciliary beating
Main function of intermediate filaments
Cytoskeletal function: contractile units in muscle
Main function of microfilament
Muscle contraction and cytoplasmic streaming
Another name for inactive enzymes
Proenzymes
How are enzymes activated
Chemical messengers
How are cell-ide
6 important trans-membrane proteins
- Receptor
- Enzyme
- Channel - allows ions to pass in and out of the cell
- Gated channel - opens when there is a need for a certain solute
- Cell-identifying markers - allows white blood cells to know which cells are good and bad so they dont eat the good cells
- Cell-adhesion molecule (CAM) - holds cells together
How do ions get in/out of cells?
Proton pumps grab hydrogen ions and pushes them out. Hydrogen is then diffused into a sucrose-H cotransporter and creates proteins and is now sucrose in the body.
Why does hydrogen need to get pumped outside of the cell?
Because its acidic and our body needs to be alkaline
