Topics 2A/2B- Gas Exchange, cell membranes and Transport/Proteins and Genetics Flashcards
(23 cards)
What a is the definition of diffusion?
A passive process which occurs when a net movement of particles moves from an area of higher concentration to and area of lower concentration of particles, down a concentration gradients.
It is the net movement because particles move in both directions, but the overall change is the particles going to the area of lower concentration.`
How are gas exchange surfaces, such as those which reside in the lungs, specially adapted for efficient diffusion?
What tissue does the lungs have which are highly adapted anatomically for efficient gas exchange?
They have high surface area to volume ratios.
They’re thin, which provides a shorted diffusion distance.
The organism helps to maintain a steep concentration gradient of gases across the exchange surface.
Alveolar epitheliums
What occurs at the alveoli
How are they specially adapted in the lungs?
Oxygen inside the alveoli diffuses across the alveolar endothelium and enters the blood. Carbon dioxide equally diffuses from the blood into across the capillary endothelium and enters the alveoli, where it is exhaled out.
There is many of the alveoli, meaning that there is a very large surface area. The alveoli epithelium and caillary endothelium are one cell thick, so the diffusion pathway is short. There is a good blood supply to the alveoli, so the concentration gradient is maintained. Constant inhalation and exhalation of gases additionally maintains the concentration gradient.
What is ficks law?
Rate of diffusion is directly proportional to:
The area of the diffusion surface x The concentration difference/thickness of membrane.
Why is the phospholipid bilayer called the fluid mosaic model?
It is arranged with phospholipids and protein molecules which are free to move around within it. The variety of different proteins are alike to the different shapes which you would see on a mosaic tile arrangement.
What is the purpose of cholesterol within the phospholipid bilayer?
It forms bonds with the phospholipids surrounding it, which allows some rigidity within the membrane. It however has the opposite effect when environments are cool, the cholesterol makes the membrane more fluid.W
What is meant by the term partially permeable?
Small molecules are able to move through gaps between the phospholipids, but large molecules and ions are only able to pass through the bilayer by using the special channel, membrane and carrier proteins found within the bilayer.
What is facilitated diffusion?
What type of proteins are involved in this process?
Explain how it occurs.
A passive process which occurs when transporting large molecules (such as amino acids and proteins) or ions in or out of a cell.
Carrier proteins and channel proteins.
Carrier proteins are responsible for transporting the large molecules such as proteins and amino acids. This occurs when such a molecule binds to the carrier proteins, where it changes shape and moves the large molecule out of the cell toward an area of lower concentration by diffusion.
Channel proteins are pore like structures in the membrane which facilitate the diffusion of ions/charged molecules across a concentration gradient.
How does active transport differ from facilitated diffusion?
It is not passive process, as ATP is required to move molecules.
This is because the molecules at hand are being transported to areas of higher concentration from areas of lower concentration.
Do endocytosis/exocytosis required ATP?
Yes
Describe the process of golgi apparatus secreting a protein.
The golgi apparatus packages the proteins into a vesicle, where vesicles pinch off of the cell membrane and travel through the cytoplasm. They will reach their target destination and will fuse with the cell surface membrane and will enter by endocytosis.
What bonds are present in the following structures?
Secondary structure
Tertiary structure
Quaternary Structure
Secondary-
Hydrogen bonds
Tertiary-
Ionic bonds
Disulphide bridges
Hydrophobic and hydrophilic interactions
Hydrogen bonds
Quaternary-
Influenced by all the bonds which can form in the tertiary structure.
What structures are formed in the secondary structure?
alpha helix
Beta pleated sheet
How does an amino acids structure affect the way in which the protein folds?
The different variable groups/ R groups present in the amino acids mean that different bonds are able to form. For example, cysteines tend to form many disulphide bridges.
Globular vs Fibrous Proteins.
Globular-
They are soluble. This is because they have hydrophilic groups on the outside of their structures, and hydrophobic structures on the inside of their structures, so water is attracted to the outskirts of the structures but repelled from the inside. This means they are ideal for transport in liquids. A good example is haemoglobin, which is a key component of blood which has sites for iron to bind. Rather than being tightly coiled and rope like, they are round and compact in shape, almost like a tumbleweed, although tumble weeds arent compact but you get the idea.
Fibrous-
Insoluble, because they have hydrophobic R groups on the outside of their structure, and hydrophilic groups within the structure. They are tightly coiled structures, and are subsequently strong, and are commonly found in supportive tissues such as ligaments. Common examples include collagen, its found in elastic and muscular tissue, which needs to be strong to elastically recoil.
What are the two theories of enzyme reactions?
Which is the better theory?
Lock and Key, The induced fit model
The lock and key model is the idea that an enzyme and substrate perfectly fit into eachother, like how a key fits in a lock perfectly due to complementary shapes active site in enzyme and substrate.
The induced fit model is better theory and is the idea that when the enzymes active site binds to the substrate forming an enzyme substrate complex, the active site of the enzyme changes shape slightly to better fit the substrate molecule.
How is an enzymes properties related to its tertiary structure?
How does pH or temperature changes outside of the optimim effect this?
How would a gene mutation effect this?
The active sites shape is determined by the teriary structure of the enzyme. Since the enzymes active site is so specific, it means usually only one enzyme works for one substrate molecule, and every enzyme has a different tertiary structure.
If the temperature or pH of an enzymes environment is not optimum, the bonds within the enzymes active site may break, changing the shape of the enzymes active site, meaning that the enzymes active site is no longer complementary to the substrate molecule- the enzyme is denatured.
A gene mutation effects what amino acids are coded for, and therefore what primary structure of protein is formed. Although DNA is degenerate, there is still a chance that the amino acid produced from a mutated codon is different from the original. This means that upon folding, different bonds may form, like if more cycsteine groups are present, then there will possibly be more disulphide bridges, and therefore the tertiaru structure will be different, and will not longer fit to the complementary shape of the active site.
What enzyme breaks down hydrogen peroxide?
Catalase
How would you measure how fast a substrate us removed from something?
Amylose breaks down starch into maltose.
You would choose varying starch concentrations, including a solution with just water as a negative control. You would place an equal volume of each concentration of starch solution in each cuvette. You would place an equal concentration and volume of iodine solution in each cuvette , which turns blue-black in the present of starch. You would get a cuvette and fill with water, and zero a calorimeter with a red filter in it. You would then add the starch solutions to the cuvettes and read the absorbance values in regular intervals, like 10 seconds, for a fixed period like 60 seconds. Repeat 3 times for each concentration to obtain a mean value. Plot a graph of absorbance against time, and draw a tangent at t=0 to calculate an initial rate of reaction. Use the repeats to calculate average rate of breakdown of starch in Aumin^-1.
What is a singular unit of DNA/RNA called?
A mononucleotide.
What is the function of RNA?
To transfer genetic information from DNA to the ribosomes.
In a DNA double helix, in what way is the double-helix structure composed?
The two strands fun in antiparallel directions. One end is knows as the 5’ end and the other is known as the 3’.
What does DNA degeneracy and Non-overlapping mean?
Non-overlapping means that the codons are separate form each other, and don’t share bases.
Degeneracy means that there are multiple combinations of triplet code which code for the same amino acids, so random mutations dont always result in a different order of amino acids.
