Cell Physiology 2 Flashcards
Lec 15 & 16
What is metabolism?
chemical processes in the body that are performed by cells.
What is the difference btwn anabolism and catabolism?
anabolism: building molecules and using NRG. catabolism: breaking down molecules and producing NRG.
What are the 3 steps in protein synthesis?
- DNA transcription 2. mRNA translation 3. after translation
What is the process of DNA transcription?
a DNA template is copied into mRNA. DNA uncoils to expose gene base sequence (triplet), RNA strand is formed by using code on DNA template to add complementary RNA nucleotides. happens in nucleus.
What is the process of mRNA translation?
mRNA becomes proteins. first mRNA associates with ribosomes, each codon codes for one aa. tRNA with an attached aa and anticodon (complimentary to codon) binds to matching RNA. peptide bond is formed to attach aa to growing peptide chain. overall; the sequence of DNA bases determines the mRNA sequence which determines the aa sequence for making the protein.
What happens after translation if proteins were produced on free ribosomes?
they are released into cytosol, go to the nucleus, or mitochondria.
What happens after translation if proteins were produced on RER?
released into lumen of RER, where they are modified by addition of sugars (glycoprotein). then they are transferred to the golgi complex via vesicles. in the golgi they are further modified by carb changes/additions that act as an address to send them to the right destination, and lipid additions. modified proteins are then packed into vesicles and sent to their destination in either cell membrane, secretion, lysosomes.
What are lysosomes?
membrane-bound organelles containing digestive enzymes (acid enviro for breakdown)
What are enzymes, how are they made, and what does that mean for the cell?
proteins so made by protein synthesis. cell. can make more or less of an enzyme as conditions change.
How do enzymes affect reaction rates?
they increase them but are not used up in the reaction. chemical rxns occur very slowly in the human body, at a rate thats not compatible with life, so enzymes used to speed up rates of rx so that the body can stay alive.
What are enzymes sensitive to?
pH and temperature bc they affect their shape, which is critical to a proteins fxn.
Explain a chemical rxn with enzymes.
substrates (the chemical the enzymes work on) on the left with an arrow leading to the product on the right. the enzyme that brings about the rxn is beneath the arrow. some rxns can go in either direction meaning that it can go right or left (substrates and end products starting at left or right)
What is ATP catabolism?
the breakdown of adenosine triphosphate to release energy.
what is the composition of ATP?
adenine and ribose = adenosine, and 3 phosphates. NRG is stored in the covalent phosphate bonds.
What happens when you breakdown atp?
ATP with high energy bonds is broken –> ADP + Pi (inorganic phosphate) + NRG. the nrg produced is used for rxns like prot synth, active memb transport, and mm contraction. little atp is stored so the body has to constantly make it
What is the purpose of cellular respiration?
production of atp using glucose.
how does glucose enter most cells and why?
enters skel mm cells, and liver cells, by carrier mediated facilitated diffusion (passively form high to low conc). happens bc glucose conc is usu lower in cells than in the bl bc its being used up in the cell for cellular resp and glycogen synth.
What are the exception cells for ow glucose enters them?
some kidney cells, and small intestine cells bc they’re transporting glucose out of the lumen of the organ where it has a low conc into the cell that has a higher conc. so glucose is transported by secondary active transport.
How does insulin increase glucose transport in carrier mediated cells?
insulin adds more glucose transport proteins to membrane, which transport more glucose into cells from blood.
What is the overall chemical rxn?
1 glucose (C6H12O6) + 6 O2 –> 6 CO2 + 6 H2O + 32 ATP + heat
What are the steps in cellular respiration (list)?
- glycolysis in cytosol 2. enters mitochondria 3. krebs cycle 4. electron transport chain.
What happens in glycolysis and what are the products?
the splitting of sugars, so glucose with 6 carbons gets split into 2 pyruvate acid with 3 carbon each. byproducts are H+, 2 atp, and 10 enzymes. anaerobic process that happens in cytosol.
What happens in step 2 of cellular respiration?
it theres no oxygen, pyruvic acid becomes 2 lactic acids. if there is oxygen, 2 pyruvic acid go into the mitochondria where they become 2 acetyl CoA with 2 carbons each. byproducts are 2 CO2 and H+.
What happens in the Krebs cycle and what are the byproducts?
2 acetyl CoA go into krebs cycle which produces 4 CO2, 2 atp, H+, and 8 enzymes.
What happens in the ETC and what are the products?
all the H+ form the previous steps goes into the cycle along with 6 O2. most of atp is then formed (28 max), and get 6 H2O and 4 enzyme complexes.
What are the 3 substrates in the bod that can be used to produce atp?
- carbohydrates 2. proteins 3. fats
How do carbs become atp?
theyre either stored in liver or skel mm as glycogen or ingested as part of the diet and are broken down to form glucose (ie glucose –> pyruvic acid –> acetyl coa –> byproducts to atp)
How do proteins become atp?
some aas can be converted into pyruvic acid or enter krebs cycle depending on bodys need to form glucose or atp.
How do fats become atp?
primary storage form of energy in the body (triglycerides). broken down to form acetyl coa –> atp.
