Topic 8: Cell Physiology II Flashcards
what is metabolism?
-chemical processes in the body performed by cells
-made up of anabolism and catabolism
what is anabolism?
-building molecules
what is catabolism?
-breakdown of molecules
what are the 2 stages of protein synthesis?
-DNA transcription (DNA > mRNA)
-mRNA translation (mRNA > protein)
what are the steps in the stage of DNA transcription?
-DNA uncoils at the site of a gene to expose the genes base sequences
-an RNA strand is formed using code on the DNA template to add complementary RNA nucleotides
what is the complementary base for A in RNA?
-uracil (thymine in DNA)
what are the steps in the stage of mRNA translation?
-mRNA associates with ribosomes
-tRNA with the anticodon for the specific amino acid codon binds to matching RNA
-peptide bonds form to attach amino acids to the growing peptide chain (protein)
what can proteins be?
-enzymes
-hormones
-structural components of cells
what happens to proteins produced on free ribosomes (in the cytosol) after translation?
-they are released into the cytosol, go to the nucleus, or go to the mitochondria
what happens to proteins produced by ribosomes on the rough ER?
-they are released into the lumen of the rough ER
-in the lumen they are modified by the addition of sugars (form glycoproteins)
-proteins then get transferred to the golgi complex in vesicles
what happens to proteins once they reach the golgi complex?
-they are further modified
-either by carbohydrate changes/additions or by lipid additions (lipoproteins)
-finalized proteins are packaged in vesicles and sent to their destination
what is the final location of proteins produced by ribosomes on the rough ER?
-cell membrane, outside the cell (secretion), or lysosomes
what are lysosomes?
-membrane bound organelles that contain digestive enzymes
-have an acidic environment
what is significant about an enzyme being a protein?
-a cell can produce more or less of an enzyme as conditions change (goes through protein synthesis)
what do enzymes do for reactions?
-increase the reaction rate without getting used up in the reaction
-at body temp, chemical reactions are very slow (does not allow the body to stay alive)
-therefore enzymes allow our bodies to stay alive by speeding up reaction rates to a compatible rate with life
-each enzyme is very specific to a reaction
what are enzymes sensitive to? what does this cause?
-sensitive to temperature and pH
-pH and temperature can affect the enzymes shape (therefore changing its function)
-shape is critical to function for proteins
can all reactions go both ways?
-NO
-some can only take place in one direction
what is an example of a reaction taking place with an enzyme?
-starting with CO2 and H20 (substrates)
-carbonic anhydrase (enzyme)
-end with H2CO3 (product)
-this reaction can take place in both directions (if starting with H2CO3, it would become the substrate)
what type of steps in a pathway are reactions that can only go in one direction typically?
-regulatory steps
-control the rate of the pathway
what is ATP catabolism?
-the breakdown of ATP to release energy
-energy produced is used for reactions such as protein synthesis, active transport, and muscle contraction
what makes up ATP?
-adenine + ribose (adenosine)
-3 phosphates
where is the energy stored in ATP?
-phosphate bonds (covalent)
-these bonds are very high energy
why must the body constantly make ATP?
-very little ATP is stored
-used constantly within the body
what is cellular respiration?
-production of ATP using glucose
how does glucose enter most cells (ex: skeletal muscle cells + liver cells)?
-by carrier mediated facilitated diffusion (facilitated transport)
why is the glucose concentration in the cell typically lower than that in the blood? what is an exception to this?
-constantly being used up in the cell for cellular respiration or glycogen synthesis (storing of glucose)
-cells of the small intestine and certain kidney cells
-both of these cells transport glucose out of the lumen of the organ where it has a low concentration to inside the cell where it has a high concentration (does so through secondary active transport)
how can glucose transport be increased in cells that use carrier mediated facilitated transport?
-the action of insulin
-acts to add more glucose transport proteins to the cell membrane
what is the overall chemical reaction in cellular respiration?
-1 glucose (C6H12O6) + 6 O2 > 6 CO2 + 6 H2O + 32 ATP + heat
what are the steps in cellular respiration?
-glycolysis (anaerobic + in the cytosol)
-krebs cycle (aerobic + in the mitochondria)
-electron transport chain (aerobic + in the mitochondria)
what substrates in the body can be used to produce ATP?
-carbohydrates
-proteins
-fats
how do carbohydrates get used as a substrate in cellular respiration?
-carbohydrates are stored as glycogen in the liver or ingested as part of the diet
-they are broken down to form glucose
how do proteins get used as a substrate in cellular respiration?
-some amino acids can be converted to pyruvic acid or can enter the krebs cycle
-depending on the bodies needs they may be used to form glucose (in the liver or kidney)
-or used to produce ATP by acting as pyruvic acid or intermediates in the krebs cycle (most cells)
how do fats get used as a substrate in cellular respiration?
-primary storage form of energy in the body (as triglycerides)
-broken down to form acetyl CoA and then made into ATP
