Lecture 3- Cell chemistry and nutrition Flashcards
what are macronutrients?
elements required in large amounts to build macromolecules (they are the building blocks of cell material)
what are the macromolecules and how much of the dry weight of the cell do they consume?
C, H, O, N, P, S
make up 90% of cells dry weight
what is a protein made of?what percent of dry weight do proteins consume?
amino acids
55%
what macronutrients do proteins have?
C, H, O, N and S
what are lipids made of? what macromolecules do they contain?
C, H, O and P
fatty acids and glycerol
what are carbohydrates made of? what macromolecules do they contain?
C, H, O and N
sugars
what are nucleic acids made of? what macromolecules do they contain?
nucleotides
C, H, O, N, P
what are 4 inorganic macronutrients?
K, Mg, Ca, Fe
what do inorganic macronutrients do?
serve as metabolic co- factors
what is the function of potassium?
enzymes involved in protein synthesis require K+
what is the function of iron?
electron carriers require Fe2+
what is the function of Mg?
helps stabilize membranes and nucleic acids
what is the function of Ca2+?
helps stabilize cell walls and plays a role in heat stability of endospores
what are micronutrients?
elements required in very small amounts and usually serve as cofactors for enzymes
what percentage of the cell is carbon? what percentage of the cell is oxygen? what percentage of the cell is nitrogen?
C: 50%
O: 17%
N: 13%
what are growth factors?
small organic molecules required for growth
there are 3 classes of growth factors, what are they?
amino acids: (20 amino acids are needed for protein synthesis)
purines and pyrimidines
vitamins
function of purines and pyrimidines?
needed to make nucleotides (adenine, guanine, thymine, cytosine, uricil) for DNA and RNA
they are thus the building blocks for DNA and RNA
what is the function of vitamins?
small molecules used to make organic cofactors
non protein component that is required by some enzymes
what are the 3 requirements of growth factors?
- many have no growth factor requirements (E.coli)
- some bacteria require many growth factors
- addition of growth factors to medium may promote growth (have to do in lab)
what are some growth factors?
PABA
Folic acid
biotin
B12
B1
B6
nicotinic acid
vitamin K
lipoic acid
what can be said about H and O in respect to cell nutrition? where is it found?
found in H2O and organic media components
what can be said about P in respect to cell nutrition? how is it provided? why? where is it limiting?
provided as phosphate salt (PO43-) because its usually acquired as PO43- in the environment
in freshwater systems phosphate salt is often limiting (because it turns the lakes green)
what does limiting mean? what happens when it runs out?
if you run out of a nutrient or you don’t have much of it compared to other nutrients
when it runs out, growth stops despite other nutrients present
what are the 3 possible sources of nitrogen?
inorganic N
organic N
atmospheric N2
what can be said about inorganic N in respect to cell nutrition? how is it provided? what is it used to make? does it need to be reduced?
provided as salts
must be reduced to NH3 (used to make amino acids)
what can be said about organic N in respect to cell nutrition? how is it provided? does it need to be reduced?
provided as N rich organic molecules
does not need to be reduced
what can be said about atmospheric N2? is it reduced? what is it used to make? what can it be done by?
N2 is reduced to 2NH3 (nitrogen fixation)
NH3 is used to make amino acids
energetically expensive
can only be done by some bacteria and archaea (NOT EUKARYOTES)
what are two possible sources of sulfur?
inorganic S
organic S
what can be said about inorganic S in respect to cell nutrition? what is it provided as? does it need to be reduced?
provided as salts (MgSO4)
must be reduced to the level of S2 (used to make amino acids)
what can be said about organic S in respect to cell nutrition?
premade amino acids
less energy to assimilate
what are the two groups an organism can be placed in based on how they obtain carbon?
heterotrophs
autotrophs
what do heterotrophs do? what do they use? are they reduced?
use organic carbon
one or more C is reduced (ex. C atom with one or more H’s)
ex. carbohydrates, organic acids, amino acids
what do autotrophs do? what do they use? do they require energy?
use inorganic carbon (CO2) as their sole source of carbon
requires energy to assimilate
photosynthesis
