fnu 203 chapter 8 exam

catabolic reactions ___________________________ to release energy, whereas anabolic reactions ____________________, requiring energy.

break down molecules, build molecules

cellular energy is held in

ATP molecules

in anaerobic conditions, cells can only produce

limited amounts of energy in the cytoplasm

when sufficient oxygen is available (aerobic conditions),

pathways that occur in mitochondria produce far more ATP

glycolysis, the first phase of glucose catabolism, occurs in the

cytoplasm

glycolysis is an anaerobic process that results in the

conversion of glucose to two pyruvate molecules and a net gain of 2 ATP molecules

under anaerobic conditions, pyruvate is converted to

lactic acid

the liver can use lactic acid to

remake glucose via the Cori cycle

under aerobic conditions, pyruvate is converted

into acetyl CoA for entry into the citric acid cycle

the citric acid cycle is

a sequence of chemical reactions that results in the release of CO2, hydrogen ions, and electrons from intermediates of citrate

oxaloacetate

citric acid cycle's starting compound, is reformed in the cycle

the coenzymes, _________________ pick up hydrogen ions and shuttle electrons that were released during glycolysis and the citric acid cycle to the _________, resulting in the production of _______.

FAD and NAD+, electron transport chain, ATP

glycogenolysis is the

utilization of stored glycogen in the liver and in muscles to supply the glucose needed for short- term energy needs

fatty acid catabolism occurs in the

mitochondria via beta- oxidation

ketogenesis occurs when

acetyl CoA molecules from fat catabolism are converted to ketones, an alternative fuel source for certain tissues

amino acids are catabolized for

energy after undergoing deamination and transamination

the remaining carbon skeleton may be used to make

glucose, fatty acids, or ketone bodies

energy is stored in the body primarily as

glycogen and triglycerides

where is most of the glycogen stored in the body?

liver and muscle cells

what is the main storage site for triglycerides?

adipose tissue

fatty acid synthesis from excess carbohydrates can occur in the

liver, muscle cells, and adipocytes

metabolically, cells can easily convert

fatty acids to triglycerides

what is burned first for fuel?

dietary carbohydrates

in the absence of carbohydrates, what is used for energy?

fatty acids

the enzymes and reactions that facilitate ATP production and energy storage in the body are coordinated and regulated by

specific hormones

in the fed state, what promotes anabolic pathways, including protein production and glycogen and fat storage?

insulin

in the fasted state, what acts mainly on the liver to stimulate glucose and ketone production by increasing _____________, ________________, and __________________.

glucagon, glycogenolysis, gluconeogenesis, and ketogenesis

the metabolic responses to an overnight fats include the use of

liver glycogen stores, as well as gluconeogenesis, to maintain adequate blood glucose levels

during starvation, multiple catabolic hormones, including ___________ and ____________, instruct cells to release all fuel sources into the bloodstream.

glucagon and cortisol

where is ethanol (alcohol) primarily metabolized?

in the liver

low doses of alcohol are converted to

acetyl CoA using alcohol dehydrogenase and aldehyde dehydrogenase enzymes

what is alcohol metabolism influenced by?

sex, age, body size, frequency of drinking, genetics

excess alcohol consumption can lead to numerous health problems, including

fatty liver and cirrhosis of the liver

enzymes change once they facilitate a reaction.

false

catabolic reactions fuel anabolic reactions.

true

energy can be created and destroyed.

false

beta- oxidation occurs in the mitochondria.

true

what is the breakdown of glycogen into glucose molecules?

glycogenolysis

the cori cycle is an efficient way to provide glucose to the body.

false

lactic acid is turned into lactate and taken up into the __________________, put in the cori cycle and sent to the _______________

liver, bloodstream

lactic acid is used in aerobic conditions.

false

glycolysis is an aerobic process.

false

during glycolysis, how many pyruvate are formed?

2

oxygen is used in many oxidation reactions.

true

what can pick up two hydrogen ions and two electrons?

FAD

what are the organic cofactors that help enzymes catalyze reactions called?

coenzymes

what involves metabolic reactions that build larger molecules from smaller ones?

anabolism

what cannot be metabolized for energy by human cells?

vitamins

series of specific chemical reactions in the cell are known as

chemical pathways

obesity causes increased risk for insulin resistance.

true

the human body can withstand what kind of fasting because glycogen can be used for energy

short- term

consuming excessive protein can lead to increased accumulation of body fat.

true

higher number of carbon atoms in a fatty acid means higher number of acetyl CoA produced via beta- oxidation.

true

during beta- oxidation, fatty acids are

oxidized to yield acetyl CoA molecules for the citric acid cycle

when excess carbohydrates are consumed, acetyl CoA molecules accumulate in cytoplasm.

true

insulin instructs liver cells to

synthesize fatty acids

nonalcoholic fatty liver disease can be caused by

excess fructose consumption

one of the ways that the body can waste excess energy is through a process called

adaptive thermogenesis

many B vitamins are components of coenzymes that work with enzymes in energy metabolism.

true

glucose is metabolized in a process called beta- oxidation.

false

acetyl CoA is a molecule that accumulates in tissues when oxygen is not available.

false

glucagon promotes glycogen and fat storage.

false

body size, gender, and prior drinking history affect an individual's rate of alcohol metabolism.

true

what are substances that the human body can use as fuel?

carbohydrates, lipids, proteins, and alcohol

which form of energy is stored in macronutrients?

chemical energy

what is the difference between catabolism and anabolism?

catabolism breaks down larger molecules into smaller ones; anabolism builds larger molecules from smaller ones

what is a coenzyme?

organic compound that assist enzymes with chemical reactions

what is ATP and what is its role in living cells?

ATP is a high energy phosphate compound that serves as the energy currency of cells. cells use ATP to pay for work that needs to be performed in cells.

what is the primary advantage of aerobic metabolism over anaerobic metabolism?

aerobic is in the presence of oxygen, which participates in oxidation reactions. oxygen is vital for metabolism

distinguish between glycolysis and the citric acid cycle and the electron transport chain

glycolysis: anaerobic, six carbon glucose is broken down into three carbon molecules of pyruvate, 2 NADH and 2 net ATP are formed, each 3 carbon pyruvate is broken down into acetyl CoA, a 2- carbon molecule, NAD+ picks up hydrogen ions to form NADH, and CO2 is released citric acid cycle: converts the two- carbon acetyl CoA into CO2 and H2O molecules, occurs twice for each glucose molecule that enters, NADH and FADH2 are formed, while more CO2 is released. each molecule of acetyl CoA results in one molecule of ATP electron transport chain: enzymes that make water and ATP during aerobic metabolism, oxygen accepts two hydrogen ions and two electrons to form water

describe the functions of NAD+ and FAD in the production of ATP

they shuttle transfer electrons from the molecule being broken down to other molecules being built up

what happens to fatty acids during beta- oxidation?

they are cleaved in to 2- carbon segments that are converted into acetyl CoA. except for the final cleavage reaction, one NADH and FADH2 are produced each time a two- carbon segment is removed from the fatty acid. The NADH and FADH2 that result from beta- oxidation yield about 4 ATP when they shuttle electrons into the ETC.

describe how cells utilize fatty acids as a source of energy when glucose is in short supply

HSL facilitates lipolysis by removing the 3 fatty acids from the glycerol backbone of a triglyceride. the glycerol and fatty acid molecules exit adipocytes and enter the bloodstream. the fatty acids bind to albumin, then it circulates to tissues, where it can be picked up and used for energy

what process must an amino acid undergo before it can be used for energy?

the nitrogen group must be removed by deamination or transamination

explain the differences between the glucogenic and ketogenic pathways of amino acid metabolism

glucogenic amino acids are broken down into either pyruvate or intermediates of the citric acid cycle. ketogenic amino acids enter the catabolic energy pathways as acetyl CoA, meaning they can be converted into ketone bodies when glucose availability is low

trace the path of triglycerides from the liver to storage in adipose tissues

absorption of triglycerides results in an influx of fat into the liver, some fat remains, but most is incorporated into VLDLs. the liver releases VLDL into the bloodstream, adipocytes, and other cells can access those lipids, particularly fatty acids, through the action of lipoprotein lipase. this enzyme breaks the three fatty acids off the glycerol backbone of a triglyceride molecule, as a result, the free fatty acids and glycerol can enter cells. after entering, three fatty acids can be attached to a glycerol molecule, recreating the triglyceride molecule. triglyceride synthesis is the primary route for storing excess fatty acids and carbohydrates, especially in adipocytes

how does excess carbohydrate consumption increase body fat deposits?

when carbs are consumed, glucose is catabolized to make ATP, inhibiting the breakdown of fatty acids. the extra glucose molecules spare fatty acids by enhancing the production of triglycerides for fat storage.

describe the conversion of amino acids into glucose or ketones

the liver and the kidneys are able to use glucogenic amino acids to make glucose. ketogenic amino acids have carbon skeletons that can be converted into acetyl CoA. ketogenic amino acids cannot be used to make glucose because acetyl CoA cannot be converted back to pyruvate.

which hormone(s) promote anabolism and which promote catabolism?

insulin: anabolic / glucagon, cortisol, and epinephrine: catabolic

what conditions stimulate insulin secretion vs. glucagon secretion?

after a carb- containing meal, beta cells detect the rise in blood glucose levels and secrete insulin. in the fasted state, as a response to blood glucose levels that drop to below normal levels, alpha cells of the pancreas secrete glucagon.

discuss the metabolic processes that occur during an overnight fast

as blood glucose levels fall during early part of an overnight fast, pancreas secretes glucagon, liver increases glycogenolysis, blood glucose levels are maintained. when glycogen supply in liver is empty, glucagon stimulates liver cells to convert glucogenic amino acids derived from body tissues into pyruvate and then glucose. during this time, the liver and muscle tissue use mainly fatty acids for fuel.

list the major metabolic responses that occur in muscle, adipose tissue, and the liver during starvation

glycogenolysis, lipolysis, proteolysis, and ketogenesis

explain the difference between glycogenesis and glycogenolysis

glycogenesis is the pathway that links glucose units together for storage as glycogen; glycogenolysis is the pathway that breaks down glycogen into glucose molecules; needs the coenzyme PLP

explain the difference between lipogenesis and lipolysis

lipogenesis is the making of fatty acids; lipolysis is the breaking down of fatty acids

describe the two major pathways that the body uses to metabolize alcohol

microsomal ethanol- oxidizing system (MEOS) and alcohol dehydrogenase pathway

what is BAC?

blood alcohol concentration

summarize the effects of alcohol on the liver

a moderate drinker can metabolize 12-15 g of alcohol per hour. excess circulates in bloodstream until liver can metabolize it

what is the legal limit for BAC in the United States?

0.08%

what are effects of alcohol in the body?

brain functioning is impaired and brain is damaged, increased stroke risk, increases cancer risk in mouth, throat, and voice box, increases risk of esophagus cancer, causes flushing of skin and heat loss, increases breast cancer risk, damages heart muscle, resulting in enlargement of the heart and heart failure; causes hypertension, irritates stomach lining and increases stomach cancer risk, causes liver cells to fill with fat, eventually resulting in hepatitis, cirrhosis, and liver failure; increases liver cancer risk, impairs pancreatic function, can cause inflammation of pancreas, and increases risk of pancreatic cancer, interferes with nutrient absorption in the small intestine, increases fat deposits in abdominal region, increases risk of colon and rectal cancer

why is consuming alcohol mixed with caffeine more dangerous than alcohol alone?

caffeine can mask some alcohol effects by increasing feelings of alertness. they may not realize their level of impairment, which can increase the risk of overconsumption

how is the catabolism of fructose and galactose different from the catabolism of glucose?

the catabolism of fructose only occurs in the cells of the liver; liver is the only organ that can use fructose for energy. fructose is eventually broken down into two products that feed into the glycolytic pathway. galactose is converted in a 2- step process into glucose, which is then catabolized via the glycolytic pathway. occurs mainly in the liver