Lecture 3- Cellular Respiration and Metabolism Flashcards
What is cellular respiration?
The breaking down of glucose and converting it into ATP (either using oxygen or not)
what is the point of cellular respiration?
to make ATP
where does glycolysis happen in the cell?
it happens in the cytoplasm of the cell
does glucose have to come into the cell to start glycolysis?
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.
what is the formula of glucose once it enters the cell + what happens?
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.
what happens after G6P?
It becomes F6P which is Fructose 6-phosphate. The structure between G6P and F6P is different but the chemical formula is the same (?)
what happens after F6P?
ATP is invested, and ADP comes out. It becomes Fructose 1, 6-biphosphate.
What happens after Fructose 1, 6-biphosphate?
The structure is divided into two equal parts, and the rest of the process of glycolysis happens twice.
what does the glycolysis cycle end up with?
it ends up with 2 pyruvate
does glycolysis require oxygen?
no, since it happens in the cytoplasm
summarize glycolysis
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.
what is the formula for glycolysis?
Glucose + 2 NAD+ + 2 ADP + 2 Pi —-> 2 Pyruvate + 2 ATP + 2 NADH + 2 H20
once we are in the pyruvate state, what do we have to assess?
we have to assess whether or not we have enough oxygen and the condition of the cell.
what are two conditions under pyruvate metabolism?
- under anaerobic condition
- under aerobic condition
what is anaerobic condition?
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).
are there two pyruvates that go under anaerobic condition?
yes, 2 pyruvates become 2 lactate and use 2 NADH.
what is the net NADH and ATP for anaerobic metabolism/respiration?
0 NADH and 2 ATP
what happens in aerobic condition/respiration?
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)
how many molecules are in Pyruvate and Acetyl CoA?
Pyruvate is a 3-carbon molecule and Acetyl CoA is a 2-carbon molecule. The other carbon molecule becomes CO2.
where does aerobic condition happen?
in the mitochondria; the pyruvate starts in the cytosol and crosses both the outer and inner membranes to the mitochondrial matrix.
where does pyruvate metabolism occur?
in the mitochondrial matrix
what does it mean when there is fed-state metabolism? what is under the influence and what happens to the enzymes?
there is food in your system, so there is an influence of insulin. the enzymes for glycogen breakdown are inhibited.
what are two processes of fed-state metabolism?
Glycogenesis and Lipogenesis
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?
we have an abundance of glucose in the blood. so we have to release insulin and have a net glycogen synthesis.
what do the cells (esp liver cells do) when there is a release of insulin?
the cells (esp liver cells) will start to grab all the glucose and take it into the cell and synthesize glycogen.
what is glycogensis?
it is glycogen synthesis in the liver, skeletal muscles, and heart. (liver stores glycogen).
can the liver, skeletal muscle, and heart muscles all share glycogen?
no, only the liver can.
the heart cannot stop, so we need a reserve of what?
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.
what is the process of glycogenesis?
Glucose —> (ATP -> ADP + Pi) –> Glucose 6-phosphate –> Glucose 1-Phosphate –> Glycogen
what is the process of lipogenesis?
it is fat (triglyceride) synthesis; this happens when there’s a lot of glucose
during lipogenesis, what are the glycerol and fatty acids made from?
- the glycerol can be made from glucose through glycolysis
- 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)
study diagram of lipogenesis here
what are the 4 processes of fasted-state metabolism?
Glycogenolysis, Protein Metabolism, Lipolysis, and Gluconeogenesis.
what happens in the fasted-state metabolism?
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).
what are we under the influence of fasted-state metabolism?
under the influence of glucagon.
what is glycogenolysis?
the process of breaking down glycogen and releasing it (liver only)
what is the process of glycogenolysis?
the opposite of glycogenesis. Glycogen –> Glucose 1-Phosphate –> Glucose 6-Phosphate –> (ADP + Pi -> ATP) —> Glucose
What is protein metabolism?
Another process of fasted-state metabolism; it breaks down protein.
what are the 3 sub-steps of protein metabolism?
- Hydrolysis: breaking down the amino acid structure by breaking peptide bonds with the help of the enzyme peptidase.
- Deamination: Removes the amino group from the free amino acids broken down by the previous step.
- Urea Formation: When the NH3 is converted to urea. Formula: NH3 (ammonia) —H+—> NH4+ (ammonium) —-> Urea (then excreted). This is because NH3 is toxic.
what is the process of lipolysis in fasted-state metabolism?
It breaks down triglycerides (the glycerol and fatty acids)
what are the steps of lipolysis?
- Lipases digest triglycerides into glycerol and 3 fatty acids.
- Glycerol becomes a glycolysis substrate.
- B-oxidation chops the 2-carbon acyl units off of the fatty acids.
- Acyl units then become Acetyl CoA and can be used in the citric acid cycle.
study diagram of lipolysis here
what is the step of gluconeogenesis of fasted-state metabolism?
it generates glucose from non-carbohydrate substrates (such as amino acids, and glycerol)
when does gluconeogenesis occur?
it occurs during fasting, starvation, low carb diet, or intense exercise (which is under anaerobic respiration).
do we have to spend a lot of energy on gluconeogenesis?
yes
study diagram of gluconeogenesis here
