Chapter 25 Flashcards
Metabolism
All the chemical reactions that occur in the body
Catabolism
Exergonic reactions that produce more energy than they consume releasing the chemical energy stored in organic molecules
Anabolism
Chemical reactions that combine simple molecules and monomers to form the bodies complex structural and functional components; endergonic reactions Consuming more energy than they produce
What happens to the energy released in catabolism?
40% is used for cellular functions
The rest is converted to heat which helps maintain normal body temperature
Oxidation
Removal of electrons from an atom or molecule the result being a decrease in the potential energy of the atom or molecule
Dehydrogenation reactions
The loss of hydrogen atoms, which happens in most biological oxidation reactions
Reduction
Addition of electrons to a molecule, result in an increase in the potential energy of the molecules
What are the two enzymes that are commonly used by animal cells to carry hydrogen atoms?
- Nicotinamide adenine dinucleotide (NAD), Derivative of the B vitamin niacin
- Flavin adenine dinucleotide (FAD), Derivative of B2 (riboflavin)
Oxidation-reduction or redox reactions are what?
Paired reactions that are coupled such as: When one substance is oxidized (exergonic reaction) another is simultaneously reduced
Phosphorylation
The addition of a phosphate group to a molecule which increases its potential energy
What are the three mechanisms of phosphorylation that organisms use to generate ATP
- Substrate level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
Substrate level phosphorylation
Generate ATP by transferring a high energy phosphate group from an intermediate phosphorylated metabolic compound-a substrate-directly to ADP. in human cells this process occurs in the cytosal
Oxidative phosphorylation
Removes electrons from organic compounds and passes them through a series of electron acceptors called electron transport chain, to molecules of oxygen. this process occurs in the inner mitochondrial membrane of the cells
Photophosphorylation
Occurs only in the chlorophyll-containing plant cells or in certain bacteria that contain other light- absorbing pigment
What is the body’s preferred source for synthesizing ATP
Glucose
What are the different fates of glucose?
- ATP production - Body cells that require immediate energy glucose is oxidized to produce ATP
- Amino acid synthesis - Cells throughout the body can use glucose to form several amino acids which can then be incorporated into proteins
- Glycogen synthesis - hepatocytes and muscle fibres can perform glycogenesis in which hundreds of glucose monomers are combine to form the polysaccharide glycogen
- Triglyceride synthesis - When glycogen storage areas are filled up hepatocytes can transform the glucose to glycerol and fatty acids that can be used for lipogenesis the synthesis of triglycerides, triglycerides are then deposited in adipose tissue which has virtually unlimited storage capacity
What are the four sets of reactions in cellular respiration?
- Glycolysis - in which one glucose molecule is oxidized and then two molecules of pyruvic acid are produced the reactions also produce two molecules of ATP in to energy containing NADH + H+
- Formation of acetyl Coenzyme A - A transition step that prepares pyruvic acid for entrance into the Krebs cycle also produces energy containing NADH + H+ plus carbon dioxide
- Krebs cycle reactions these reactions oxidize acetyl CoA and produce CO2, ATP, NADH + H +, and FADH2
- Electron transport chain reactions - these reactions oxidize NADH + H+ and FADH2 and transfer the electrons through a series of electron carriers
Aerobic
With oxygen
Anaerobic
Without oxygen
Aerobic respiration
Reactions that require oxygen such as the Krebs cycle and electron transport chain
Glycolysis does not require oxygen which makes it what kind of reaction?
It can occur under aerobic or anaerobic conditions
Anaerobic glycolysis
When glycolysis occurs by itself under anaerobic conditions
Glycolysis
Chemical reactions split a six carbon molecule of glucose into two 3 carbon molecules of pyruvic acid, Consumes to ATP molecules it produces for ATP molecules for a net gain of two ATP molecules for each glucose molecule that is oxidized
What is the fate of pyruvic acid?
- If oxygen is scarce, Then pyruvic acid is reduced via an anaerobic pathways by the addition of two hydrogen atoms to form lactic acid. Lactic acid rapidly diffuses out of the cell and enters the blood the hepatocytes remove lactic acid from the blood and convert it back to pyruvic acid
- In aerobic conditions most cells convert pyruvic acid to acetyl coenzyme A, this molecule links glycolysis which occurs in the cytosol with the Krebs cycle which occurs in the matrix of the mitochondria pyruvic acid enters the mitochondrial matrix with the help of a special transporter protein