Week 4 Flashcards
(43 cards)
What is a molecule of DNA in a cell?
A chromosome.
What is a solute, solvent, and solution?
Solute: the minor component in a solution, dissolved in the solvent.
Solvent: able to dissolve other substances.
Solution: a type of mixture involving two or more substances.
What are cells mostly?
Water. Most substances inside a cell are dissolved solutes. (eg. sodium ions, ATP, proteins).
What is the molecular difference between a solid and a liquid?
In a liquid, molecules are free to move around, always in motion. -this is also true for a solution.
In a solid, the particles still move but by vibrating around a fixed position.
Why does diffusion happen (eg. dye in water)?
Happens because of random movement, and the molecules per chance end up spread out. (check later cause of concentration gradient theory).
What is diffusion used for in the cell?
It is the main way molecules get from one place to another.
Eg. enzyme and reactant randomly go around the cell until they combine and react.
What is the state of the membrane?
It is fluid/flexible. The phospholipids and particles are free to move within the membrane.
What happens to the membrane as the shape of the cell changes?
The membrane flows over the outside and conforms to the shape.
What is the network of protein filaments inside a cell called?
The cytoskeleton.
What is the analagous network (to cytoskeleton) called in animals?
Extracellular membrane.
Do plants have an extracellular membrane?
No, as they instead have cell walls that provide shape and strength.
What is a membrane lipid made up of?
A hydrocarbon fatty acid tail with a carboxylic acid group that joins together with a glycerol molecule through an ester linkage. Glycerol can conbine with 3 acyl groups.
What is tyiacylglycerol?
A common form of far (energy) storage.
What is a saturated fat?
A molecule with the max number of Hydrogen possible, making the molecules quite linear. EG. butter.
What is an unsaturated fat?
A molecule with at least 1 double bond which introduces a kink/bend with consequences for cell membranes. EG. oil.
What is a phospholipid?
A glycerol with 2 fatty acid tails - 1 is saturated and 1 is not.
The 3rd carbon is bonded to a phosphate functional group which leads to a hydrophilic head group with 5 types of other things (only need to know choline)
What do phospholipids form?
A cell membrane or a micelle. They form a semipermeable layer.
What does containing unsaturated fats allow phospholipids to do?
Allows them to remain fluid enouhg to allow and restrict molecules passing through. You do not a membrane to be too fluid or viscous.
Besides phospholipids. what is another thing in the membrane that contributes to fluidity?
Sterols, eg cholesterol. A precursor to steroids. Made is bodies and obtained in diet, sits in the membrane to add a bit more fluidity and prevents the phospholipids from sticking together too much.
When temperatures increase, cholesterol stabilises the membrane and stops it from falling apart.
Plants use Phytosterol.
What are the two types of membrane protein placements?
Integral: spans entire or part of membrane.
Peripheral: Links to surface or integral proteins. Are not stuck in the membrane.
What are some jobs of membrane proteins?
- Transport - Allows solutes to cross membrane, especially of hydrophilic charge
- Enzymatic activity
- Signal transduction - A signalling molecule binds to a receptor and a signal is transmitted
- Cell-cell recognition
- Attachment to the cytoskeleton and extracellular matrix. - Proteins can form a connection.
- Intercellular joining - Cells that recognise each other will bind to one another.
What causes transmembrane proteins to stop in the membrane?
A stop signal.
In what process do vesicles leave the cell?
Exocytosis.
What are phospholipids as components of the Cell membrane?
Tails form a hydrophobic core preventing large hydrophilic molecules and charged molecules from entering or leaving a cell.
