Biochemistry And Metabolism Flashcards
Micronutrients: carbohydrates
Sugars and starch
Monosaccharides
Glucose - C6H12O6
Micronutrients: lipids
Insoluble in water
Triglycerides - 3x fatty acids and 1x glycerol
Micronutrients: proteins
Basic structural material of the body
E.g. enzymes, haemoglobin, contractile proteins of muscle
Amino acids - amine group and organic acid group
Adenosine triphosphate (ATP)
Form of energy
ATP -> ADP + Pi
Temporal store
Used up quickly
ATP: used for
Transport work - solutes across membrane
Mechanical work - contractile proteins shorten
Chemical work - energy absorbing reactions
Stored ATP
Very small amounts
80-100g
High turnover
Supply first 2-6 seconds
ATP-PC system
CP -> C + P
P + ADP -> ATP
Coupled reaction
Direct phosphorylation
First 10 seconds
No oxygen
ATP-PC system: Creatine kinase
Enzyme
Catalyses direct phosphorylation
Damaged muscle - lost in bloodstream
Catabolism of glucose
C6H12O6 + 6O2 -> 6CO2 + 38ATP + heat
Glycolysis
Krebs cycle
Oxidative phosphorylation - ETC
Glycolysis
Glucose (6C) broken into 2 pyruvic acid (3C)
2 ATP used
4 ATP produced
Net - 2 ATP
2NAD+ -> 2NADH + H+
Glycolysis: no/little oxygen outcome
Pyruvic acid converted to lactic acid
Muscle fatigue
Acidosis
NADH + H+ -> NAD+
Anaerobic pathway - 2 ATP
Glycolysis: oxygen available outcome
Pyruvic acid enters the mitochondria
Krebs cycle Oxidative
Aerobic pathway - potential 38ATP
Transition
Pyruvate dehydrogenase converts pyruvate to acetyle-coenzyme A
Redox reaction
NAD+ -> NADH + H+
Carbon - CO2
Krebs cycle
Mitochondria
Carbon -> CO2
3NAD+ - NADH + H+
FAD -> FADH2
2 cycles for 1 glucose - 2 pyruvates
Oxidative phosphorylation: ETC
NADH + H+ and FADH2 pass hydrogens and electrons to oxygen via electron transport chain to form H2O
Oxygen is the final acceptor
38ATP
NADH + H+ - 3 or 2.5 ATP
FADH2 - 2 or 1.5 ATP
NAD
Derived from the B vitamin niacin
NAD+ + 2H -> NADH + H+
FAD
Derived from the B vitamin riboflavin
FAD + 2H -> FADH2
Catabolism of lipids
Glycerol - glycolysis, Kreb’s cycle and ETC
Fatty acids - split into 2C fragments, Beta-oxidation, in mitochondria. Converted to Acetyle-CoA, Kreb’s cycle and ETC
Catabolism of lipids: fat yields
ATP yield per molecule - 129
ATP yield per carbon - 8.1
ATP yield per molecule of oxygen - 5.6
Catabolism of lipids: respiratory exchange ratio
RER
Oxygen used : carbon dioxide produced
0.71
Determine predominant energy source used
Catabolism of lipids: ketones
Acids that your body makes when it breaks down fat for energy
Ketogenesis
Acetyl-CoA converted to ketones
Catabolism of lipids: when does ketones happen
Low carbohydrate diet
Starvation
Uncontrollable diabetes mellitus
Catabolism of lipids: effects of ketones
Kussmaul’s respiration - deep and fast, remove excess CO2 and increase pH
Ketone breath - smells like pear
Ketones in urine
Coma, death
Catabolism of proteins
Amine group (NH2) removes - deamination
Converted into ammonia (NH3) then urea
Remaining part converted to pyruvate or acetyl-CoA
Krebs cycle and ETC
Metabolism
All (bio) chemical reactions occurring in the body
Catabolic pathways
Breakdown complex molecule to simpler ones
Exothermic - release heat and energy/ATP
E.g. cellular respiration
Anabolic pathways
Build up of complex molecules of life
Endothermic - requires energy/ATP input
E.g. biosynthetic reactions; protein synthesis
Absorptive state
In the fed state - following digestion, nutrients absorbed into blood stream
4 hours, 12 hours per day
Anabolism - storing
Catabolism - breaking down
Insulin
Absorptive state: at rest
Free glucose - produce ATP
Lipids used - synthesis
Amino acids - protein synthesis
Glycogenesis
Fatty acids, amino acids and glucose stored as fat - lipogenesis
Post-absorptive state
In the fasting state - following absorption, nutrients stored or being used
Late morning, late afternoon, night
Brain and Red blood cells
Glucagon
Post-absorptive state: at rest
Glycogen - glycogenolysis, free glucose
Triglycerides - lipolysis, fatty acids and glycerol
Gluconeogenesis
Carbohydrate - glycogen: stored glycogen
Muscle glycogen - one site glucose for contraction
Liver glycogen - systemic control, blood glucose
Carbohydrate - glycogen: glycogenesis
Glucose molecules linked together to form glycogen
Absorptive state
Anabolic pathway requiring ATP
Insulin
Carbohydrate - glycogen: glycogenolysis
Glycogen splitting
Post-absorptive state - blood glucose levels low
Muscles - glucose-6-phosphate
Liver - enzymes to remove phosphate
Glucagon, epinephrine and cortisol
Carbohydrate - glycogen: gluconeogenesis
‘New’ glucose from non-carbohydrate sources
Lactic acid
Glycerol
Amino acids
Fats - lipids
Most concentrated energy source
50% of fat storage - subcutaneous adipose tissue
Lipocytes - expand with stored fat until used
Fats - lipids: lipogenesis
Glucose, fatty acids and amino acids converted into fat
Absorptive state
Insulin
Fats - lipids: lipolysis
Triglycerides broken into glycerol and fatty acids
Post-absorptive state
Fatty acids - Beta-oxidation
Glycerol - gluconeogenesis
Glucagon, epinephrine, cortisol and thyroid hormones
Protein: protein synthesis
Formation of protein structures from amino acids
Transcription
Translation
Non-essential amino acids
Body can synthesise them
Essential amino acids
Body cannot synthesise them
Must get them from our diet
Protein: protein catabolism
Protein catabolised for energy or converted into fat
Amino acids deaminated - NH2 -> NH3 -> urea
Remainder of molecule is a ketoacid
Protein: ketoacid
Enter Kreb’s cycle - fully catabolised for energy
Converted to glucose
Converted to fat
Anabolic hormones: insulin
Released - elevated blood glucose levels
Effect - lowers blood glucose levels
Promotes - glucose uptake, glycogenesis, lipogenesis, protein synthesis
Inhibits glycogenolysis
Catabolic hormones: glucagon
Released - decreased blood glucose levels
Effect - raises blood glucose
Promotes - glucose release, glycogenolysis, lipolysis, protein catabolism
Inhibits - glycogenesis
Catabolic hormones: epinephrine
Released - stress and exercise
Effect - raises blood glucose, increases availability and use of fatty acids by tissues, glucose conserved for bran and red blood cells
Increases - glycogenolysis, lipolysis
Catabolic hormones: cortisol
Released - long-term stressed and prolonged exercise
Effect - raises blood glucose, increases availability and use of fatty acids by tissues, glucose conserved for bran and red blood cells
Increases - gluconeogenesis, protein catabolism, lipolysis
Catabolic hormones: thyroid hormones
Changes in response to exercise
Effect - raises blood glucose, increases availability and use of fatty acids by tissues, glucose conserved for bran and red blood cells
Increases - lipolysis, glycogenolysis, gluconeogenesis
Enhances - Beta-oxidation
Dieting, prolonged fast, low carbohydrate diet: low insulin levels
Reduced glucose uptake - increase use of fat for energy
Increased lipolysis - greater production of ketones
No glycogen storage
Reduced protein synthesis
Increased hepatic glucose release
Dieting, prolonged fast, low carbohydrate diet: elevated levels of glucagon and cortisol
Increased lipolysis
Increased amino acid catabolism
Increased gluconeogenesis
Breakdown of body proteins
