Lecture 3- Cellular Respiration and Metabolism

Question 1

What is cellular respiration?

Answer 1

The breaking down of glucose and converting it into ATP (either using oxygen or not)

Question 2

what is the point of cellular respiration?

Answer 2

to make ATP

Question 3

where does glycolysis happen in the cell?

Answer 3

it happens in the cytoplasm of the cell

Question 4

does glucose have to come into the cell to start glycolysis?

Answer 4

yes, it starts in the extracellular compartment, and to start glycolysis it has to enter the cytoplasm of the cell. In order for the glucose to be broken down, it needs to enter the cell.

Question 5

what is the formula of glucose once it enters the cell + what happens?

Answer 5

once glucose enters the cell, ATP is transferred and becomes ADP (the Pi is understood). Then the glucose becomes G6P; Glucose 6-phosphate. It is called G6P because the 6 tells you that the phosphate group is attached to carbon 6 of the glucose molecule.

Question 6

what happens after G6P?

Answer 6

It becomes F6P which is Fructose 6-phosphate. The structure between G6P and F6P is different but the chemical formula is the same (?)

Question 7

what happens after F6P?

Answer 7

ATP is invested, and ADP comes out. It becomes Fructose 1, 6-biphosphate.

Question 8

What happens after Fructose 1, 6-biphosphate?

Answer 8

The structure is divided into two equal parts, and the rest of the process of glycolysis happens twice.

Question 9

what does the glycolysis cycle end up with?

Answer 9

it ends up with 2 pyruvate

Question 10

does glycolysis require oxygen?

Answer 10

no, since it happens in the cytoplasm

Question 11

summarize glycolysis

Answer 11

one 6-carbon molecule of glucose becomes two 3-carbon pyruvate molecules. two steps of glycolysis require energy input from ATP. there is a net of 2 ATP, and the total number of ATP used is 4 (or 2??). 2 NADH’s are produced.

Question 12

what is the formula for glycolysis?

Answer 12

Glucose + 2 NAD+ + 2 ADP + 2 Pi —-> 2 Pyruvate + 2 ATP + 2 NADH + 2 H20

Question 13

once we are in the pyruvate state, what do we have to assess?

Answer 13

we have to assess whether or not we have enough oxygen and the condition of the cell.

Question 14

what are two conditions under pyruvate metabolism?

Answer 14

1. under anaerobic condition
2. under aerobic condition

Question 15

what is anaerobic condition?

Answer 15

it is when there is not enough oxygen in the cell; a low/lack of oxygen. when pyruvate goes into anaerobic respiration, it uses NADH to convert it to lactate. This happens in the cytoplasm (NADH goes in and becomes NAD+; going from high energy to a low energy state).

Question 16

are there two pyruvates that go under anaerobic condition?

Answer 16

yes, 2 pyruvates become 2 lactate and use 2 NADH.

Question 17

what is the net NADH and ATP for anaerobic metabolism/respiration?

Answer 17

0 NADH and 2 ATP

Question 18

what happens in aerobic condition/respiration?

Answer 18

Pyruvate is converted to Acetyl CoA and CO2; energy is released and NAD+ (low energy state) becomes NADH. This happens twice (are 2 NADH produced)

Question 19

how many molecules are in Pyruvate and Acetyl CoA?

Answer 19

Pyruvate is a 3-carbon molecule and Acetyl CoA is a 2-carbon molecule. The other carbon molecule becomes CO2.

Question 20

where does aerobic condition happen?

Answer 20

in the mitochondria; the pyruvate starts in the cytosol and crosses both the outer and inner membranes to the mitochondrial matrix.

Question 21

where does pyruvate metabolism occur?

Answer 21

in the mitochondrial matrix

Question 22

what does it mean when there is fed-state metabolism? what is under the influence and what happens to the enzymes?

Answer 22

there is food in your system, so there is an influence of insulin. the enzymes for glycogen breakdown are inhibited.

Question 23

what are two processes of fed-state metabolism?

Answer 23

Glycogenesis and Lipogenesis

Question 24

after digesting food and we absorb everything into our bloodstream, what do we have an abundance of nearby in the blood? what do we have to do to combat this abundance?

Answer 24

we have an abundance of glucose in the blood. so we have to release insulin and have a net glycogen synthesis.

Question 25

what do the cells (esp liver cells do) when there is a release of insulin?

Answer 25

the cells (esp liver cells) will start to grab all the glucose and take it into the cell and synthesize glycogen.

Question 26

what is glycogensis?

Answer 26

it is glycogen synthesis in the liver, skeletal muscles, and heart. (liver stores glycogen).

Question 27

can the liver, skeletal muscle, and heart muscles all share glycogen?

Answer 27

no, only the liver can.

Question 28

the heart cannot stop, so we need a reserve of what?

Answer 28

since it cannot stop, we need a reserve of energy, such as glycogen, just incase it's not getting enough of it from the blood.

Question 29

what is the process of glycogenesis?

Answer 29

Glucose ---> (ATP -> ADP + Pi) --> Glucose 6-phosphate --> Glucose 1-Phosphate --> Glycogen

Question 30

what is the process of lipogenesis?

Answer 30

it is fat (triglyceride) synthesis; this happens when there's a lot of glucose

Question 31

during lipogenesis, what are the glycerol and fatty acids made from?

Answer 31

1. the glycerol can be made from glucose through glycolysis 2. fatty acids are made when 2-carbon acyl units from Acetyl CoA are linked together (which is why fatty acids are usually an even number)

Question 32

study diagram of lipogenesis here

Question 33

what are the 4 processes of fasted-state metabolism?

Answer 33

Glycogenolysis, Protein Metabolism, Lipolysis, and Gluconeogenesis.

Question 34

what happens in the fasted-state metabolism?

Answer 34

It is when there is no food intake, so the body tries to maintain glucose levels in the blood without eating. We want to break down glycogen (from the liver).

Question 35

what are we under the influence of fasted-state metabolism?

Answer 35

under the influence of glucagon.

Question 36

what is glycogenolysis?

Answer 36

the process of breaking down glycogen and releasing it (liver only)

Question 37

what is the process of glycogenolysis?

Answer 37

the opposite of glycogenesis. Glycogen --> Glucose 1-Phosphate --> Glucose 6-Phosphate --> (ADP + Pi -> ATP) ---> Glucose

Question 38

What is protein metabolism?

Answer 38

Another process of fasted-state metabolism; it breaks down protein.

Question 39

what are the 3 sub-steps of protein metabolism?

Answer 39

1. Hydrolysis: breaking down the amino acid structure by breaking peptide bonds with the help of the enzyme peptidase. 2. Deamination: Removes the amino group from the free amino acids broken down by the previous step. 3. Urea Formation: When the NH3 is converted to urea. Formula: NH3 (ammonia) ---H+---> NH4+ (ammonium) ----> Urea (then excreted). This is because NH3 is toxic.

Question 40

what is the process of lipolysis in fasted-state metabolism?

Answer 40

It breaks down triglycerides (the glycerol and fatty acids)

Question 41

what are the steps of lipolysis?

Answer 41

1. Lipases digest triglycerides into glycerol and 3 fatty acids. 2. Glycerol becomes a glycolysis substrate. 3. B-oxidation chops the 2-carbon acyl units off of the fatty acids. 4. Acyl units then become Acetyl CoA and can be used in the citric acid cycle.

Question 42

study diagram of lipolysis here

Question 43

what is the step of gluconeogenesis of fasted-state metabolism?

Answer 43

it generates glucose from non-carbohydrate substrates (such as amino acids, and glycerol)

Question 44

when does gluconeogenesis occur?

Answer 44

it occurs during fasting, starvation, low carb diet, or intense exercise (which is under anaerobic respiration).

Question 45

do we have to spend a lot of energy on gluconeogenesis?

Answer 45

yes

Question 46

study diagram of gluconeogenesis here