Exam 3 Flashcards
describe the mitochondria
- produces most of the energy (ATP)
- double lipid bilayer
- contains own set of DNA
where does the citric acid cycle occur in the mitochondria?
matrix
where does the ETC occur in the mitochondria?
inner surface of cell membrane
what are the folds called in the inner membrane of the mitochondria?
cristae
what is the purpose of cristae?
increase surface area
define metabolism
the sum of all the chemical reactions that take place in an organism
define catabolism
break down, release energy
define anabolism
building larger molecules
define activation
process that starts/increases the action of an enzyme
define inhibition
any process that slows or stops the action of an enzyme
define feedback and allosteric
enzyme regulation
what are the three major types pathways?
- a linear sequence
- a cyclic sequence
- a spiral sequence
4 stages of metabolism
- digestion
- acetyl-coa production
- citric acid cycle
- ATP production
Explain Stage 1 of Metabolism: Digestion
- breaking down food
- enzymes in saliva, stomach, and si
- carbs break down into glucose
- proteins break down into AA and tryglyceride
- small molecules go into the blood for transport
Explain Stage 2 of Metabolism: Acetyl-CoA Production
- break carbon atoms into 2 carbon acetyl groups
- acetyl groups attach to coenzyme A by a bond between sulfur of the thiol group (cysteine)
- acetyl-coa is the intermediate in the metabolism of all food molecules
Explain Stage 3 of Metabolism: Citric Acid Cycle
- within the mitochondrion
- break down acetyl-coa to produce energy equivalents (FADH2 and NADH)
Explain Stage 4 of Metabolism: ATP Production
- energy production
- produce ATP and H2O from NADH and FADH2
calorie vs Calorie
1 calorie = 1000 kcal/Calorie
deine calorie (small c)
unit of heat measurement
- amount of energy to raise the temp of one gram of water one degree Celsius
define basal metabolism
energy used by a body at rest to maintain involuntary, life supporting processes
examples of basal metabolism
breathing, heart beating, growing new cells, maintaining body temperature
how much of our bodies energy goes to basal metabolism?
2/3
minimum amount of energy expenditure per unit time to stay alive for males
1 kcal/hr/kg
minimum amount of energy expenditure per unit time to stay alive for females
0.95 kcal/hr/kg
why do taller people have a higher basal metabolism regulation (BMR)?
more surface area means more heat lost from the body, which causes the metabolism to speed up in order to maintain body temperature
2 major types of energy carriers
- ATP (adenosine triphosphate)
- reduced coenzymes (FAD/FADH2 + NAD+/NADH)
define FAD
flavin adenine dinucleotide
define NAD+
nicotinamide adenine dinucleotide
What is ATP?
the body’s energy transporting molecule
ATP to ADP: exergonic or endergonic
exergonic
- gibs free energy = negative
ADP to ATP: exergonic or endergonic
endergonic
- gibs free energy = positive
how much ATP do humans use at rest per day?
45 kg / 99 lbs
define coupled reactions
- energetically unfavorable reactions are coupled to energetically favorable reactions so the overall energy change is favorable
- allows energy stored in one chemical compound to be transferred to other compounds
where does excess energy go in a coupled reaction?
releases as heat and contributes to maintaining body temperature
example of coupled reactions: glycolysis
the phosphorylation of glucose is unfavorable BUT can be made more favorable if coupled with the hydrolysis of ATP
- glycolysis: Gibbs free energy = +3.3 kcal/mol
- ATP: Gibbs free energy = -7.3 kcal/mol
define oxidation
lose elections, more O bonds –> C bonds
define reduction
gain elections, less O bonds –> H bonds
NAD+ is reduced to ______
NADH
NADH is oxidized to _________
NAD+ and 2H+
what is NAD/NADH used for?
add H to substates (reducing agent)
FAD is reduced to ______
FADH2
coenzyme vs electron carrier
because the reduced coenzymes have picked up electrons (in H bonds) that are passed along in subsequent reactions they are often referred to as electron carriers
define citric acid cycle
a series of biochemical reactions that breaks down acetyl groups to produce energy carried by reduced coenzymes and CO2
what is the first step and product of the citric acid cycle?
oxaloacetate
Citric Acid Cycle: Step 1
acetyl group is transferred from acetyl-coa to oxaloacetate produced in step 8
Citric Acid Cycle: Step 3
isocitrate loses CO2 and is oxidized to yield alpha-ketoglutarate
Citric Acid Cycle: Step 8
the cycle of reactions is completed by oxidation of malate to regenerate ocaloacetate
Citric Acid Cycle: outputs
NADH (3), FADH2 (1), GTP/ATP (1)
how many steps are in the citric acid cycle?
8
what is the reformed starting material for every cycle of the citric acid cycle?
oxaloacetate
Citric Acid Cycle: co-product
CO2 (2)
why is acetyl-coa important?
it is a favorable release of energy
Citric Acid Cycle: Steps 3, 4, 8
NAD+ is reduced to NADH and H+
(there are 3 NADH and H+ produced in one cycle)
Citric Acid Cycle: Step 6
FAD is reduced to FADH2
(there is one FADH2 produced in one cycle)
Citric Acid Cycle: Step 5
GDP —-> GTP/ATP
(one ATP produced in one cycle)
how is the citric acid cycle regulated?
- regulated by the bodies need for ATP
- ADP accumulation activates it
how to slow down ATP production?
NADH is present in excess and acts as an inhibitor of isocitrate dehydrogenase
Citric Acid Cycle: in
- Acetyl-CoA
- GDP
- CoA
- (NAD+ and FAD)
where does the citric acid cycle occur?
in the matrix of the mitochondria
where do the reduced coenzymes (NADH and FADH2) come from for the ETC?
the citric acid cycle donates FADH2 and NADH
in the ETC what reactions occur to release energy?
oxidation-reduction reactions
is the ETC exergonic or endergonic?
each reaction in the series is exergonic (favorable)
where does the ETC occur?
the inner membrane of the mitochondria
what is the hydrogen gradient?
the H+ gradient is between the inner and outer membrane of the mitochondria, it takes energy to flow back into the membrane and the energy is captured during the ETC
what are the electron acceptors in the ETC?
- cytochromes
- quinones
how many complexes are in the ETC?
4
what is the function of the complexes in the ETC?
- contains electron carriers
- each complex is at a lower energy level
what is the final acceptor of the ETC?
O2
(aerobic respiration)
what is oxidative phosphorylation?
the synthesis of ATP from ADP using energy released in the ETC
what is the ATP Synthase? How does it produce energy?
- an enzyme complex
- H ions return through the matrix by going through the ATP synthase releasing potential energy as they move through the concentration gradient driving ADP phosphorylation (creating ATP)
Where does glycolysis occur?
cytoplasm
Where does the citric acid cycle occur in the mitochondria?
matrix
Where does glycolysis occur?
cytosol
reactants of glycolysis
- glucose
- ADP
- ATP
- NAD+
reactants of the citric acid cycle
- pyruvate
- NAD+
- FAD
reactants of the ETC
- O2
- FADH2
- NADH
products of glycolysis
- pyruvate
- ATP
- NADH
products of the citric acid cycle
- ATP
- CO2
- NADH
- FADH2
products of the ETC
- ATP
- H2O
how many ATP produced from glycolysis per 1 glucose?
2 ATP
how many ATP produced from citric acid cycle per 1 glucose?
2 ATP
how many ATP produced from the ETC per 1 glucose?
32 ATP
define glycolysis
the biochemical pathway that breaks down a molecule of glucose into 2 molecules of pyruvate plus energy (2 ATP and 2 NADH)
what is alpha amylase?
- an enzyme that breaks glycosidic bonds in carbohydrates (used in the first step of metabolism: digestion)
when alpha amylase is produced in the salivary glands where is it released?
the mouth
when alpha amylase is produced in the pancreas where is it released?
the small intestine
what is the major fuel for our body?
glucose
what is glucose turned into once entering a cell?
glucose-6-phosphate
is glucose-6-phosphate exergonic or endergonic?
exergonic
what happens to glucose after turning into glucose-6-phosphate? can it leave the cell?
because it is phosphorylated it cannot cross the cell membrane, thus trapping it inside the cell
what animal tissues is glucose a major source for?
- embryo
- nervous system
- kidney
- brain
- RBC
- tumors
how can plants use glucose?
the cell wall
why would drugs target the glucose in bacteria?
glucose is used to make the bacterias cell wall
how many total steps of glycolysis?
10 enzyme catalyzed reactions
glycolysis products
- 2 pyruvate
- 2 ATP
- 2 NADH and H+
- (2 H2O)
glycolysis reactants
- glucose
- 2 NAD+
- 2 HOPO3^2-
- 2 ADP
what is step one of glycolysis?
phosphorylation
- adding a phosphate group to glucose in the 6th position
- requires ATP
define hexokinase
enzyme assisting in the production of glucose-6-phosphate
what is the allosteric inhibitor of hexokinase?
glucose-6-phosphate
what are the three things that glucose-6-phosphate can do?
- glycolysis –> made into pyruvate
- liver –> glycogen
- pentose phosphate pathway –> DNA + RNA precursor
how many ATP total from aerobic respiration?
38 ATP
what are three major monosaccharides?
- d-fructose
- d-galactose
- d-mannose
what happens to other sugars that enter the body?
they are converted to glucose and eventually join the glycolysis pathway
what is fruit sugar?
fructose
what is milk sugar?
galactose
what is starches/legumes sugars?
mannose
which sugar enters upstream of glucose-6-phosphate?
galactose
which sugar enters after glucose-6-phosphate?
fructose (enters as fructose-6-phosphate)
what are the three fates of pyruvate?
- acetyl-coa
- lactate/lactic acid
- ethyl alcohol
what is the fate of pyruvate in aerobic cells?
acetyl-coa
what is the fate of pyruvate in anaerobic muscle?
lactic acid
what is the fate of pyruvate in anaerobic yeast?
ethyl alcohol
location of glycolysis
cytosol of the cell
location of the citric acid cycle
mitochondria - matrix
location of the ETC
mitochondria - membrane
what is the aerobic oxidation of pyruvate?
pyruvate moves across the outer mitochondrial membrane then carried by a transporter protein (MPC) across the inner mitochondrial membrane
define MCP
mitochondrial pyruvate carrier
define pyruvate dehydrogenase complex
catalyzes the conversion of pyruvate to acetyl-coa
3 steps of aerobic oxidation of pyruvate
- a carboxyl group is removed from pyruvate releasing CO2
- an oxidation reaction occurs reducing NAD+ to NADH
- an acetyl group is transferred to coenzyme A, resulting in acetyl-coa
what causes anaerobic respiration?
because there is no longer oxygen, NADH cannot be reoxidizes during the ETC
what does lactate in anaerobic respiration do?
reoxidizes NAD+ BUT it is a major loss of energy
if only anaerobic respiration occurs, how many ATP are produced?
2 ATP from glycolysis
why would microorganisms have evolved to function in anaerobic conditions?
because they can not move to areas with oxygen
define fermentation
microorganisms evolved to have numerous anaerobic strategies for energy production
what products are made from anaerobic respiration/fermentation?
- beer
- wine
- alcoholic beverages
- bread
what causes bread to rise?
CO2 causes bread to rise and the alcohol evaporates while baking
how much ATP comes out of glycolysis?
two ATP
how much ATP comes out of pyruvate oxidation
6 ATP
how much ATP comes out of TCA cycle per glucose?
2 ATP
what is a normal glucose concentration?
65 to 110 mg/dl
define hypoglycemia
lower than normal blood glucose concentration
define hyperglycemia
higher than normal blood glucose concentration
what is the blood glucose concentration for uncontrolled diabetes?
> 140 mg/100ml
what is the glucose concentration for someone in a pre diabetic state?
100-125 mg/100ml
what are normal blood sugar levels?
70-100 mg/100ml
what blood glucose would make someone unresponsive?
<30mg/100ml and >500mg/ml
what two hormones regulate blood glucose?
insulin and glucagon
where are insulin and glucagon released?
the pancreas
when is insulin released?
when blood glucose is HIGH to speed up glycolysis
when is glucagon released?
when blood glucose is LOW to get glucose in the blood
how does glucagon get more glucose in the blood?
can take glycogen stored in the liver
how much of our energy is stored in glycogen?
less than 1% energy reserve, it is used up in 15-20 hrs at normal activity
what does the metabolism do when glucose and glycogen resources are gone (starvation)?
breaks down proteins, creates ketone bodies
what is the keto diet?
- minimize carbs
- body uses fats/proteins as energy supply
- ketone production (mostly from the liver)
what are ketone bodies?
chemicals produced in the liver when there is not enough insulin in the blood and it must break down fat instead of glucose for energy
what is the optimal range of ketone bodies?
10-30 blood ketones
why can ketones be bad?
ketones are acidic chemicals that can build up in the blood (spill over into urine and lungs giving a fruity odor)
define ketoacidosis
too many ketones in the body
what can can happen if you get ketoacidosis?
lead to coma and diminished brain function
define type II diabetes
produces insulin, back lacks recognition
how can someone get type II diabetes?
it can develop over time
treatment for type II diabetes
drugs that increase insulin or insulin receptor levels are an effective treatment because more undamaged receptors are put to work
what is the most common type of diabetes?
type II diabetes
define type I diabetes
not producing insulin
how can someone get type I diabetes?
can be inherited
what is the treatment for type I diabetes?
must supply insulin through a syringe
what factors can increase the risk of diabetes?
- high blood pressure
- high fat and cholesterol
- smoking
- overweight
- sedentary lifestyle
why can glucose levels cause cataracts?
elevated glucose is reduced to sorbitol which can cause cataracts
what are some complications of diabetes?
- heart disease
- stroke
- kidney disease
- blindness
- neuropathy
- skin problems
how to manage diabetes?
- diet low in fat and salt
- increased exercise
- stop smoking
- checking bg and bp
(type I: give insulin)
define glycogenolysis
breakdown of glycogen
define glycogenesis
synthesis of glycogen
define gluconeogenosis
synthesis of glucose from noncarbohydrates (lactate, glycerol, AA)
when is gluconeogenosis needed?
- fasting and early starvation
- exercise (lactate covering to glucose)
why is lactate production moved to the liver?
gluconeogenosis requires energy, so shifting the pathway to the liver frees the muscles from the burden of producing more energy
what is the cori cycle?
converts lactate into pyruvate, the substrate for gluconeogenosis
how is glycerol (fat) used in gluconeogenosis?
glycerol is converted to dihydroxyacetone and enters the gluconeogenosis pathway at step 7
how are carbons from AA (proteins) used in gluconeogenosis?
the carbons will enter as pyruvate or oxaloacetate
when does gluconeogenosis occur?
when fasting (the body maintains glucose)
where does gluconeogenosis occur?
- primarily in liver cells
- also epithelial cells of kidney and intestine
define gylcogenesis
the formation of glycogen from glucose
when does glycogenesis occur?
when there is excess glucose and ATP insulin will promote the storage of glycogen in the liver and muscle cells
what does glycogen look like?
branched polymer of glucose
3 steps of glycogenesis
- glucose –> glucose-6-phosphate
- glucose-6-phosphate –> glucose-1-phosphate
- glucose-1-phosphate –> glycogen
how does muscles use the glucose freed from glycogenolysis?
use immediately
how does the liver use the glucose freed from glycogenolysis?
moves the glucose through the body
examples of lipids
- food (butter and oils)
- steroids
- soap
- our body (phospholipids)
What physical property to lipids share?
They are hydrophobic
define amphipathic
both hydrophilic and hydrophobic
types of simple lipids
- fatty acids
- waxes
- triacylglycerols
What are fatty acids?
- animal fats and oils that have 12-22 carbon atoms
- long chain carboxylic acid
what are waxes?
- secreted in animal skin, preform external protective functions
- long straight hydrocarbon chains in both r groups
what are triacylglycerols?
- carboxylic acid trimesters of glycerol and 3 carbon trialcohol
- make up the stored fats in our bodies
- major source of energy
two parts of a fatty acid
- long hydrogarbon chain (hydrophobic)
- carboxylic acid group (hydrophilic)
define micelle
a spherical cluster formed by the aggregation of amphipathic so that the hydrophobic ends are at the center and hydrophilic is in the outside
define membranes as a lipid bilayer
- polar head (hydrophilic) on the outside
- non polar tail (hydrophobic) on inside
- 2 parallel sheets
define liposome
a spherical structure in which a lipid bilayer surrounds a water droplet
what is the fluid mosaic model?
- represents structure of the cell membrane
- fluid = moving
- mosaic = contains many molecules
What is a triacylglycerols made up of?
glycerol backbone with 3 FA tails
define saturated
single carbon bonds only
define unsaturated
one or more carbon double bonds (cis bonds)
why are oils liquid?
they are highly unsaturated
why are some fats solid?
they are highly saturated
why do saturated fats have a higher melting point?
they are linear and pack together
why do unsaturated fats have a lower melting point?
there are kinks that make it difficult to pack together
difference between cis and trans fatty acids?
- cis = kink
- tans = linear
why are trans fats bad?
they pack well making it thick, we cannot digest it
why are cis double bond healthier?
the chains don’t pack as well, promotes fluidity of cell membranes
why is it bad to hydrogenate (saturate) double bonds in vegetable oils?
not every bond gets saturated and some of the natural cis bonds that were healthier are converted to trans fats which are not as healthy
What are some foods that contain trans fats?
- buttered microwavable popcorn
- pizza dough
- pastries and baked goods
- coffee creamers
- deep fried chicken
some complex lipids
- phospholipids
- sphingomyelins
- glycolipids
what is a phospholipid made up of?
- phosphate head (hydrophilic)
- 2 FA tails (hydrophobic)
what are phospholipids used for?
- cell membrane
- cellular signaling
- transportation of cholesterol
- dynamic
what are sphingomyelin made up of?
- 1 fatty acid tail
- 1 phospholipid head group
- 1 amide bound fatty acid tail
main function of sphingomyelin
essential to the structure of cell membrane and in nerve cell membranes
what are glycolipids made up of?
- 1 fatty acid tail
- 1 amide bound fatty acid tail
- 1 sugar head group
main functions of glycolipids
- maintains cellular surface
- signaling molecule
- immune system (blood type)
what is a non-glycerol lipid?
an example
sterols
what are sterols derived from?
cholesterol
what is the most abundant animal sterol?
cholesterol
what are bile acids used for?
emulsifies fat, used to digest greasy hydrophobic things
define eicosanoids
special type of localized intercellular chemical messenger
define saponification
hydrolysis of fats and oils carried out by strong aqueous bases to form soap
define soap
the mixture of salts and fatty acids formed by saponification of animal fats
define micelle
a spherical cluster formed by the aggregation of soap or detergent molecules so that their hydrophobic ends are in the center and hydrophobic ends are on the outside
How does soap work?
hydrophobic end dissolves in water and the hydrophobic ens dissolves in grease and once suspended in micelles it can be rinsed off
define cell membrane
barrier between interior of cell and the world, hydrophobic gatekeeper
cell membranes are made up of:
- phospholipids
- glycoproteins
- proteins
- cholesterol
2 types of membrane associate proteins
- peripheral protein (one side of bilayer)
- integral proteins (completely through the membrane)
define active transport
moving substances across the cell membrane using energy
types of passive transport (don’t use energy)
- passive transport (high to low concentration)
- simple diffusion (channel protein)
- facilitated diffusion (protein that changes shape)
where are tiacylglycerols digested?
begins in the stomach
define pancreatic lipase
partially hydrolyzes the emulsified triglycerides producing mainly mono and diaclyglycerols, FA, and glycerol
where are smaller FA and glycerol absorbed
because they are water soluble they are directly absorbed through the vili
where are insoluble acylglycerols and larger FA absorbed?
in the intestine they are packaged into lipoproteins (chylomicrons) and enter through the lymphatic system
define chylomicron
a lipoprotein that brings the bulk of lipids through the micelle, transport from small intestine to liver
define VLDL
- very low density lipoproteins
- transport TAG from liver to tissues
define LDL
- low density lipoprotein
- carry cholesterol from liver
why are lots of LDL bad?
can cause the formation of arterial plaque
define HDL
- high density lipoprotein
- move cholesterol from dead cells back to liver
what lipoprotein do we want lots of?
HDL
list the lipoproteins largest to smallest?
- chylomicron
- VLDL
- IDL
- LDL
- HDL
define hyperlipidemia
too much LDL, narrowing of the arteries due to plaque build up of cholesterol
define serum albumin
transports lipids directly
risk factors of heart disease
- high cholesterol (LDL)
- low HDL
- cigarette smoking
- high blood pressure
- diabetes
- obesity
- family history
define statins
inhibits cholesterol synthesis
liver functions
- detoxify dangerous molecules
- keep blood glucose levels steady
- stores extra energy as TAGs by synthesizing FA
what are acetyl groups used for?
- TAG synthesis
- ketone synthesis
- steroid synthesis
- TCA and beta oxidation
- phosphorylation
What happens to TAG after being broken down into fatty acids and glycerol?
moves out of the cell carried by albumin to target cells in the bloodstream, travels to the kidney or liver
Oxidation of FA: 3 Processes
- activation (using energy to convert FA to acetyl-coa)
- transport (acetyl-coa to matrix)
- oxidation (beta oxidation)
define beta oxidation
4 steps to remove an acetyl group from the fatty acid tail (spiral processes)
how much ATP is used in activation for the oxidation of a fatty acid?
2 ATP
how much greater is the energy yield from FA than CHO?
3 times
why is there more energy storage of fat than glycogen?
greater energy per unit from fat than glycogen
liver cell fuel
FA
fat cell fuel
glucose
brain cell fuel
glucose
heart muscle fuel
FA
red blood cells fuel
glucose
when are TAG stored?
when energy needs are low (extra fat, carbs, proteins, alcohol are stored as TAG)
define lipogenesis
provides a link between carbohydrate, lipids, and protein metabolism (2 carbons at a time)
T/F the greater fat you have the longer you will survive without food?
True
define the digestion of proteins
the hydrolysis of all peptide binds to produce a collection of amino acids
where does protein digestion occur?
- stomach
- small intestine
how are proteins digested in the stomach?
- low ph denatures the protein
- pepsin is activated to break the peptide bonds
how are proteins digested in the small intestine
pancreatic zymogens break the bonds
what is the most important pancreatic zymogen in the small intestine for breaking down proteins?
trypsin
why is trypsin so important?
without trypsin, all other proteases in the small intestine would be inactive
what happens after dietary proteins are turned into amino acids?
AA are then actively transported across the cell membrane in the intestine and then directly absorbed into the bloodstream
define amino acid pool
the entire collection of free amino acids in the body (used for metabolism, signaling and synthesis)
what is the general scheme of AA catabolism?
- remove amine group
- use NH2 for synthesis of small molecules
- N goes to urea cycle
- corporation of c-skeletons into the compounds that enter the citric acid cycle
define urea cycle
the cyclic biochemical pathway that produces urea for excretion
what goes into the urea cycle?
NH3 (ammonia) and CO2 (aspartate and 2 ATP)
what come out of the urea cycle?
urea
what animals do not need to do the urea cycle?
fish
define ketogenic AA
enter ketogenesis through acetyl-coa
define glycogenic AA
enter cycle as oxaloacetate (citric acid cycle)
what AA are ketogenic ONLY?
lysine and leucine
how many AA are nonessential?
11
how many AA are essential?
9
during the biosynthesis of nonessential AA what are amine groups derived from?
glutamate
define phenylketonuria (PKU)
failure to convert phenylalanine to tyrosine
- can cause mental retardation
- keep away from food with aspartame
- mandated blood screening in babies
