KAPLAN 1 Bio Flashcards
Why gastric pH should be precisely controlled?
Gastric enzymes are most active at low pH. Enzymes such as pepsin have optimum activity in an environment of 2 or 3 pH. Extremely low pH will denature the protein, however. That’s why a complex negative feedback is in place to maintain a narrow pH range within the stomach.
Simultaneous release of 1000 to 10,000 molecules involves which process?
Exocytosis. Process like primary active transport and facilitated diffusion move usually between one and three molecules across the cell membrane.
What are Competitive, uncompetitive, non- competitive inhibition effects on Km and Vmax?
Where does the inhibitor binds?
In competitive inhibition Km increases (affinity is decreased) Vmax remains the same. The inhibitor binds to the free enzyme ONLY. Competing with the substrate for the active site
In non-competitive inhibition the Km remains the same and Vmax is reduced. It binds allosterically and it can bind to the enzyme ES complex and to the free enzyme.
Uncompetitive inhibitors reduce BOTH the Km and the Vmax. And they bind ONLY to the ES complex. It binds at a different site than the active site.
Hydropathy plot with two picks indicates what about the cellular membrane-spanning regions in this protein?
A hydropathy plot indicates hydrophilicity as negative values and hydrophobicity as positive values. The two peaks on the graph where the y values change from negative to positive indicate that they favor the opposite (hydrophobic) site of the membrane in two regions.
Some of the osmosis, diffusion and facilitated diffusion differences are?
Osmosis is the movement of solvent from regions of higher concentration to lower. Where as diffusion is the movement of SOLUTE from regions of higher concentrations to lower. Facilitated diffusion requires a carrier molecule or pore such as an ion channel.
Fermentation is what kind of process and occurs when?
Fermentation is an anaerobic process that occurs after glycolysis.
Which of the following molecules is present in both aerobic and anaerobic respiration and is not affected by oxygen presence? Which molecules are present in aerobic respiration only and are affected by the presence of oxygen.
- Triose phosphate isomerase
- Cytochrome c oxidase
- ATP synthase
- Pyruvate dehydrogenase
Triose phosphate is present in both aerobic and anaerobic respiration and is not affected by the amount of oxygen provided.
Cytochrome c oxidase, ATP synthase, Pyruvate dehydrogenase are enzymes present during aerobic respiration and are affected by the amount of oxygen present.
Initially breastfed infants nutrition consists of? What does this mean to disorders such as MCAD?
MCAD is a disorder that affects fatty acid oxidation. Breastfed infants initially are fed mostly proteins given that during he initial period of breast feeding happens before milk let down. Babies that are blotted-fed do are introduced to fatty acids almost immediately. Therefore breastfed infants will show a delay before showing the symptoms of MCAD.
Most inactive proteins have modifications of?
The active site, which is part of the tertiary structure. The tertiary structure is often the one that determines wether the enzyme will be functional. Benign mutations do not change the tertiary structure.
Why is mitochondrial DNA primarily derived from the mother?
Because the sperm mitochondria disintegrates and or falls apart after fertilization within the egg and are not replicated when division begins.
Transcription of gene will result in?
Transcription of a specific gene will always result in the same primary transcript (pre-mRNA). He primary transcript can be processed in several different ways by nuclear spliceosomes leading to the formation of several differing mRNA’s and different proteins.
In commensalism?
One species benefits and the other is unaffected.
Some facts about the cecum, jejunum and rectum are?
Where is recolonizing bacteria often found of these three?
Is the blind outpouching of the large intestine. The cecum is where normal gut bacteria resides.
The jejunum is the middle portion of the small intestine, which is primarily involved in absorption.
The rectum is the site for solid waste storage, not a harbor for bacteria.
Which enzyme is responsive for the last step in DNA repair?
DNA ligase links the recently repair bases and is the final step in DNA repair.
What are the three possible stop codons?
UAA, UAG, and UGA
