Chapter 24 Carbohydrate/ lipid/ protein metabolism Flashcards
where does digestion of carbohydrates happen? what enzyme? what are examples of the types digested?
mouth via salivary alpha-amylase
starch
glycogen
sucrose
lactose
where does the digestion of polysaccharides happen? what enzyme?
stomach
& small intestine
- pancreatic alpha-amylase
- maltase
- sucrase
- lactase
where do monosaccharides go once they are digested?
absorbed through small intestine lining & enter through bloodstream
what protein allows for the entry of glucose into the host cell?
insulin
once entered the cell, what occurs to allow for glucose to remain inside the cell to undergo glycolysis? how does this help keep it in the cell?
phosphorylation occurs
phosphate functional group is polar which keeps glucose from being able to cross the nonpolar inter-cell membrane space
why every intermediate in glycolysis contains a phosphate
keeps it within the cell as it gets broken down
what is the energy investment phase of glycolysis? what type of enzymes are used? ender/exergonic?
where ATP is converted to ADP
using transferase (spec. kinase) enzymes
endergonic reaction
what is the energy generating phase of glycolysis? what type of enzymes are used? ender/exergonic?
where ADP is converted to ATP
oxidoreductase + transferase
exergonic
how is it that more ATP is produced than consumed in glycolysis
the energy investment phase only occurs once using 2 ATP
its product is two molecules that then each produce 2 ATP leading to net 2 ATP
why is pyruvate the end stage of glycolysis? why can’t more ATP be created?
it no longer has a phosphate functional group to keep it polar and remain inside the cell, so it is able to/will leave the cell
what type of enzyme is used? ender/exergonic?
isomerase
neutral
what type of enzyme is used? ender/exergonic?
transferase
endergonic
what type of enzyme is used? ender/exergonic?
oxidoreductase & transferase
exergonic
what type of enzyme is used? ender/exergonic?
transferase
exergonic
what type of enzyme is used? ender/exergonic?
isomerase
neutral
what type of enzyme is used? ender/exergonic? what type of reaction?
lyase
neutral
dehydration
what type of enzyme is used? ender/exergonic?
transferase
exergonic
what is the net result of glycolysis?
what does the body do to other sugars such as fructose, galactose, and mannose?
uses other sugars to form the different reactants within glycolysis
what happens to pyruvate after formed in glycolysis when there is oxygen present? what is the reaction called?
is used to form acetyl-CoA to be used in Kreb’s cycle
Pyruvate oxidation
why is it that pyruvate can only be easily converted into acetyl-CoA when oxygen is present?
if oxygen is not plentiful, we will not be able to have NAD+ available for this reaction
what is the net reactants/products of glycolysis?
what is the net reactants/products of pyruvate oxidation?
what is the net reactants/products of citric acid cycle?
what is the total energy output of one glucose?
what happens when there is not enough oxygen in the body to properly undergo Kreb’s cycle? when does this occur?
to keep glycolysis going, the body regenerates NAD+ by reducing pyruvate to lactate
occurs during exercise in which the body release lactase which causes soreness
what is fermentation?
the production of energy under anaerobic conditions
what is alcoholic fermentation?
the anaerobic breakdown of glucose to ethanol and CO2 by the action of yeast enzymes
what type of enzyme? ender/exergonic?
oxidoreductase
endergonic
what is gluconeogenesis?
synthesis of glucose from noncarbohydrates such as lactate, amino acids, or glycerol
(essentially glycolysis but in reverse)
is gluconeogenesis ender/exergonic? is it anabolic or catabolic?
endergonic
anabolic
why is it that gluconeogenesis cannot be done completely in revese? what is the workaround?
the net delta G is overall endergonic if done in complete reverse, and this is unfavorable.
2 processes of exergonic are needed in order to perform the reaction (Co2 and ATP as reactants)
fill in the blanks
fill in blank. what type of enzyme? ender/exergonic?
ligase
endergonic
is the loss of CO2 ender/exergonic? what about the GTP to GDP?
both exergonic
what is the definition of triglyceride mobilization?
hydrolysis of triacylglycerols in adipose tissue and release of fatty acids into the bloodstream
when does mobilization of triglycerides occur?
when insulin is low and glucagon is high (glucose short supply)
what happens to the glycerol that is hydrolyzed from triglycerides?
delivered to liver or kidneys and then converted into dihydroxyacetone phosphate to be entered into the 5th step of glycolysis or gluconeogenesis
what is an oxidoreductase?
involves addition of O2 to a substrate
reduction of a substrate
or removal of two atoms to form a double bond
what is a transferase?
transfer of amino groups between substrates
transfer of a phosphoryl group between substrates
what is a hydrolase?
using water to break down a substrate into 2 new molecules
what is an isomerase?
isomerization of a substrate
what is a lyase?
removal of H2O from substrate to give double bond
replacement of a carboxyl group by a hydrogen
addition of small molecule to a double bond
what is a ligase?
using two substrates to create 1 new product
what are examples of oxidoreductases?
oxidase
reductase
dehydrogenase
what are examples of tranferases?
transaminases
kinase
what are examples of hydrolases?
lipase
protease
nuclease
what are examples of lyases?
dehydrase
decarboxylase
synthase
what are examples of ligases?
synthetases
carboxylases
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
what type of enzyme?
what type of reaction?
ender/exergonic?
oxidoreductase
dehydrogenation
exergonic
what type of enzyme?
what type of reaction?
ender/exergonic?
lyase
hydration
neutral
show what would happen if a kinase was introduced?
what is beta oxidation?
4 step process that turns an 18 carbon fatty acids to produce 9 Co-A within 8 cycles
what type of enzyme?
what type of reaction?
ender/exergonic?
oxidoreductase
dehydrogenation
exergonic
what would be the outcome if this was a hydration reaction? what enzyme?
lyase
what type of enzyme?
what type of reaction?
ender/exergonic?
oxidoreductase
oxidation
exergonic
what would be the product? what enzyme?
transferase
how many cycles will an 18 carbon go through beta oxidation? how many products will it produce?
8 cycles
9 acetyl-CoA
what type of cycle is beta oxidation? linear, spiral, or cyclic?
spiral
can the body gain more energy by using fats or sugar?
fats gain 2.3 times more energy per gram of fat than per gram of glucose
what is lipogenesis?
pathway for making of fatty acids from acetyl-CoA
is lipogenesis the exact reaction of beta oxidase in reverse?
not the exact reverse reaction
where does beta oxidation occur? where does lipogenesis occur?
beta: in mitochondria
lipo: in cytosol
when you buy carboxylic acids with odd number of carbons, why is it more expensive?
in nature, carboxylic acids are mostly found with even number of carbons. even lipogenesis and beta oxidation produces lipids with even number of carbons
Triacylglycerol synthesis starts with what reactants?
with glycerol 3-phosphate + fatty acids
what is transamination?
use of existing amino acids to make new ones
what is oxidative deamination?
removal of amino group to produce an alpha keto group
what are the essential amino acids? how many are there?
amino acids that cannot be synthesized in the body, and are needed from diet
9
how many nonessential amino acids?
11
All nonessential amino acids derive their amino groups from what amino acid? how is glutamate formed?
glutamate
from reductive amination of ketoglutarate
what is the process of creating other amino acids from glutamate?
transamination
what is reductive amination?
conversion of keto acids to amino acids by reactions with NH4+
what is the normal blood glucose range?
65-100 mg/dL
what is hypoglycemia? what are symptoms?
lower than normal blood glucose concentration
weakness, sweating, rapid heartrate
what is hyperglycemia? symptoms?
higher than normal blood glucose concentrations
increased urine flow
what is the function of insulin? when is it found circulating?
- used to tell cells to accept glucose into the cell
found when blood glucose is high
what is the function of glucagon? when is it found circulating?
- keeps existing glucose out of cells/ break down glycogen + find other ways to make glucose (glucose sparing)
found when blood glucose is low
what hormone speeds up glycogen breakdown only in the muscles?
epinephrine
how long can the body use glycogen reserves?
15-20 hours
what does the brain use when glycogen supply is depleted?
proteins
how many grams of protein are used per day to metabolize glucose for the brain?
75 grams of protein per day
when glycogen supply is depleted, what does the rest of the body use to get its energy supply replenished?
what is wrong with this process?
what is the workaround?
beta oxidation begins to convert lipids into acetyl-CoA to be used in citric acid cycle to then make ATP
citric acid cycle cannot keep up with the demands of being the only one to make ATP
ketogenesis is the work around
what are the reactants and products of ketogenesis?
reactants: 2 acetyl-CoA
product: ketone bodies such as 3-Hydroxybutyrate, acetoacetate, and acetone
how much ATP does ketogenesis make compared to citric acid cycle?
keto: 1.25 ATP per acetyl-CoA
TCA: 10 ATP per acetyl-CoA
would ketogenesis be considered energy-effecient?
no, it is very inefficient; it’s used as a last ditch effort to provide ATP when the body believes it is starving
how many kcal in 1 gram of protein?
how many kcal in 1 gram of fat?
protein: 4 kcal
fat: 9 kcal
how many kcals does ketogenesis make?
uses 25 g of protein = 25 x 4 = 100 kcal
uses 180 g of fat = 180 x 9 = 1620 kcal
what is the purpose of the keto diet?
restrict carbohydrate consumption to make your body believe it is starving for carbs so that it switches to burning fat as its main energy source
what is diabetes mellitus?
chronic condition due to either insufficient insulin or failure of insulin to promote glucose uptake in cells
what is type 1 diabetes?
autoimmune disease - attacks pancreatic cells. fewer pancreatic cells cause there to be less insulin production
this causes glucose to build up in the blood
what is type II diabetes?
there is plenty of insulin, but the cells receptors for insulin become tolerant of insulin, so insulin cannot perform its job correctly and cell does not uptake glucose
what two conditions cause citric acid cycle to become overwhelmed? what is a likely outcome of this?
starvation & diabetes
ketogenesis
one of the ketone bodies has a ketone functional group, but the other two do not. what functional group do they have?
carboxylic acids
what is ketoacidosis?
lowered blood pH due to accumulation of the ketone bodies (spec. the carboxylic acids)
who is most likely to be affected by ketoacidosis?
prolonged keto dieters
diabetics
starving people
glutamine is formed from what amino acid?
glutamate
asparagine is formed from what amino acid?
aspartate
tyrosine is formed from what amino acid?
phenylalanine
ketone bodies eventually break down, what do they produce?
CO2 and acetone
