Cells Flashcards
What is cell membrane made up of?
LPS
- Lipids
- Proteins
- Sugars
What is the purpose of the cell membrane?
- It provides a boundary between the living cell and the external world.
- It has a hydrophobic layer which prevents polar and large molecules from passing through.
- Provides a method for things to be communicated on the outside.
What can pass through the membrane?
- Moderately non-polar molecules can pass through.
- Highly hydrophobic molecules will enter and not leave.
How can you break the lipid bilayer barrier?
Tunnel
By adding molecules which tunnel and disrupt the membrane or by adding specific carriers which will bring another molecule across the membrane (Ion carriers)
What does Amphotericin B do?
Polar channel, leaky
- It has a big hydrophilic line and a big hydrophobic line - one part will want to sit in the membrane and one part is polar so it doesn’t want to sit in the membrane.
- It is organised to be a rod-shaped molecule.
- The non-polar part will be in contact with the lipid tails and the polar part will gather together and create a polar channel going through the membrane and stops the membrane from doing what it normally does (stops it separating the inside and outside).
- By inserting into the membrane it makes them leaky which Can be used to treat fungal infections.
- This is an example of disrupting the membrane.
What does Valinmycin do?
Peptide, electron density
- It is an ion carrier which breaks down the lipid bilayer.
- It is partly peptide with lots of esters, and it has side chains that are greasy and hydrophobic so they’ll want to sit in the membrane.
- The middle section has a lot of electron density from all the carbonyl groups and the partial negative charge is good for binding potassium ions.
- The negative charge on all the oxygens creates a perfect hole for the potassium to sit in the middle.
- The potassium is surrounded by hydrophobic parts so the molecule can slide into the membrane and pass through because it has a hydrophobic exterior and that will in general disrupt the ion balances in the cells and result in their death.
- This method works against human and bacterial cells.
What is the nucleus composed of?
LPD
- DNA
- Proteins
- LIpid membrane
What is the nucleus for and what is stored there?
It is where genetic information is stored and used as DNA.
What are nucleosomes composed of?
DNA wrapped around histone proteins.
Where does transcription of DNA and RNA occur?
Nucleus
What is the function of DNA?
To encode proteins made in the cytoplasm.
What is the cytoplasm made up of?
WSP
- Water
- Small molecules
- Proteins
What happens in the cytoplasm?
It is where most metabolism (processing of small molecules) happens.
What is cytoplasm a medium for?
Signal transduction
What are the mitochondria composed of?
LPDRS
- Lipids
- Proteins
- DNA
- RNA
- Small molecules
What happens in the mitochondria?
- The production of ATP by ATP synthase which sits on the inner membrane.
- They also have their own DNA, transcription & translation machinery
What is the endoplasmic reticulum composed of?
LPR
- Lipids (phospholipids)
- Proteins
- RNA
What are the two types of endoplasmic reticulum?
- Smooth
- Rough
Where is the endoplasmic reticulum found?
It surrounds the nucleus.
Where does the rough character on the endoplasmic reticulum come from?
The presence of ribosomes.
What does the endoplasmic reticulum act as?
Intracellular transport system
What do the ribosomes on the endoplasmic reticulum do?
They produce proteins which get exported outside the cell.
What is the smooth endoplasmic reticulum involved in? Give an example.
Synthesis
- Involved in lipid biosynthesis - enzymes
- Lovastatin is an example of this which reduces cholesterol by inhibiting an enzyme.
What is the golgi apparatus composed of?
- Lipids (phospholipids)
- Proteins
What is the Golgi apparatus responsible for?
Vesicles
It receives proteins from the endoplasmic reticulum in vesicles and applies post-translational modifications to them to give them more chemistry.
Give examples of types of post-translational modifications.
- Phosphorylation
- Glycosylation
- Sulfation
Where is the Golgi apparatus found?
Near the endoplasmic reticulum.
What happens in the ribosome?
tRNAs
It is where mRNA is translated into proteins via tRNAS.
Where are ribosomes found?
- Cytoplasm
- Mitochondria
- Rough endoplasmic reticulum
What are endosomes?
Compartments
Lipid-bilayer bounded compartments within the cell.
What do endosomes do?
Bud off
- The bud off from the Er and Golgi to transport or excrete proteins.
- They allow the cell to uptake materials
- They can evolve into lysosomes.
Why is lysosomal escape important?
Nucleic acid
Lysosomal escape is critical for nucleic acid therapeutics and other nanoparticle therapies since large molecules cannot diffuse through the membrane
How are bacteria different from other cells?
- They are smaller than animal cells
- They have a cell wall & membrane
- DNA is freely floating
