Class 4&5 - Metabolism & Nutrition Flashcards
A typical cell has about ___ ATP molecules
1 million
A molecule of ATP lasts about __ before being used
1 minute
__% of energy released in catabolism is used for cellular functions, the rest is converted into heat to maintain the body’s temperature
40%
Oxidation reactions involve the ___ of ___ from an atom, which _____ its potential energy.
REMOVAL, ELECTRONS, DECREASES
Redox reactions involve the ____ of ____ to a molecule which ____ its potential energy
ADDITION, ELECTRONS, INCREASES
What are the two biological coenzymes in the human body? What are they derivates of?
NAD+ (niacin)
FAD (riboflavin)
Oxidation reactions usually involve loss of ___ atoms. Reduction reactions usually involve gaining these atoms.
Hydrogen
What is phosphorylation?
addition of a phosphate group to a molecule
What is substrate-level phosphorylation?
when a phosphate group is transferred to ADP directly from a substrate (Kreb’s cycle)
Substrate-level phosphorylation occurs in the…
cytosol
Oxidative phosphorylation occurs in the…
mitochondria
What is oxidative phosphorylation?
when electrons are liberated from electron donors to electron acceptors (such as oxygen, like in the ETC)
Oxidation = removal of electrons from an atom. Oxidative phosphorylation means these electrons are then transferred to electron acceptors (reduction), which then power ATP synthesis.
good job
Oxidation is usually an _____ reaction
exergonic
A highly reduced compound has many ___ atoms
hydrogen
a lower energy, oxidized compound has many ____ atoms
oxygen
Oxidation of glucose means that…
hydrogen atoms are removed (electrons removed/released)
How does the addition of a phosphate group to a molecule affect its potential energy?
increases it (release of the phosphate group will release energy) - it’s temporary energy storage
Transferring a high energy phosphate group directly to ADP is an example of…
substrate-level phosphorylation
Carbs represent what percentage of the body’s weight?
2-3%
Hydrolytic enzymes in the S.I. break carbs down into what simple sugars?
glucose
fructose
galactose
Glucose constitutes about __% of the simple sugars absorbed in the intestines
80%
The only sugar normally found in blood is..
glucose
Glucose may follow 1 of 4 paths in the body:
ATP production
amino acid synthesis
glycogen synthesis/glycogenesis
triglyceride synthesis
What happens when glucose is phosphorylated? Does this use or create ATP?
it becomes glucose-6-phosphate
uses ATP
The liver can store about ___ of glycogen. Skeletal mm can store about ____.
125g (liver)
375 (skeletal mm)
Once the glycogen storage capacity is reached in the body, what happens to excess glucose?
triglyceride synthesis –> stored in adipose tissue
Glucose enters intestinal cells for absorption via ____, but the rest of the body’s cells via _____.
secondary active transport (requires ATP)
facilitated diffusion (does not require ATP)
What method of secondary active transport does glucose enter body cells via?
Na+/glucose symporters
How is insulin able to increase uptake of glucose into cells?
stimulates insertion of GluT transporters into the cell membrane
Insulin is NOT required for glucose uptake in what types for cells?
actively working skeletal mm cells
Glucose entry is ALWAYS on/active/possible in what two types of cells?
hepatocytes and neurons
Only ____ contain the enzymes to convert G6P back into glucose
hepatocytes
The process of glycolysis oxidizes one glucose molecule to produce what 6 molecules?
2 pyruvic acid
2 ATP (well it produces 4 but consumes 2)
2 NADH + H+
If oxygen is scarce after glycolysis, pyruvic acid will be reduced to form ____, which also allows for regeneration of _____
lactic acid
NAD+
How do 2 pyruvic acid + 2 NAD H + H+ become 2 lactic acid + 2 NAD+?
Each pyruvic acid molecule gains 2 H+ molecules (4 H+) to create 2 lactic acid + 2 NAD+
If conditions are aerobic, pyruvic acid will enter ____ via a _______
mitochondria via a transporter protein
Within the mitochondria, pyruvic acid is converted into _______
acetyl coenzyme A
Where does the Krebs cycle occur?
matrix of the mitochondria
The Krebs cycle starts with ____ and ends with ____
citric acid
oxalecetic acid
For each turn of the Krebs cycle, how much ATP is produced?
1
What is the most important outcome of the Krebs cycle?
Formation of NADH and FADH2, which will later yield many more ATP from the ETC
How much CO2 is liberated from the Krebs cycle?
6 molecules
How does the ETC work?
it’s a series of integral proteins in the very folded inner membrane of the mitochondria that function as electron carriers -> each carrier is oxidized or reduced as it picks up or gives up electrons. As electrons pass through, energy is released and ATP is formed.
What is the final ETC electron acceptor?
oxygen
For every molecule of NADH + H+, how many ATP are generated?
For every molecule of FADH2, how many ATP are generated?
NADH + H+ = 2-3 ATP
FADH2 = 1-2 ATP
Cellular respiration will generate either __ or __ ATP molecules per molecule of glucose catabolized
30-32
The final result of cellular respiration is:
6 CO2 + 6 H2O + 30-32 ATP
Glycogenesis in the liver and skeletal muscle is stimulated by ____
insulin
Glycogenolysis splits up glycogen into G6P via ____ which is stimulated by either ___ or ____.
via phosphorylation
glucagon & NE
Lactic acid generated in muscle cells from glycolysis can be converted back into glucose by….
the liver
Gluconeogenesis is the generation of new glucose from _____
non-carb sources
What 3 non-carb molecules in the body can be converted into glucose?
amino acids (60% of them)
lactic acid
glycerol
Amino acids and lactic acid can be converted into…
pyruvic acid
What hormones stimulate gluconeogenesis?
cortisol and glucagon
True or false: thyroid hormones can mobilize proteins or triglycerides to make them available for gluconeogenesis
true
True or false: fatty acids can be converted directly into glucose
false
