Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-2
Summary of Metabolism
CarbohydratesFats
Free fatty acids + glycerol
Fatstores
Glucose
Excess glucoseGlycogen
stores
Aminoacids
Proteins
DIET
Lipogenesis
Brainmetabolism
Range of normalplasma glucose
Gluconeogenesis
Bodyprotein
Glycogenolysis
GlycogenesisProtein
synthesis
Metabolism inmost tissues
Free fattyacid pool
Urine
Excess nutrients
Lipo
gene
sis
Lipolysis
Glucose pool
Amino acidpool
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-2 (1 of 4)
Summary of Metabolism
Carbohydrates
Fatstores
Glucose
Excess glucoseGlycogen
stores
DIET
Lipogenesis
Brainmetabolism
Range of normalplasma glucose
Glycogenolysis
Glycogenesis
Metabolism inmost tissues
Urine
Glucose pool
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-3
Metabolism
Summary of biochemical pathways for energy production
Glucose
Someaminoacids
Someaminoacids
Lactate
Glycogen
Glucose 6–phosphateLiver only
Fattyacids
Electron transportsystem
CO2
NH3
O2
CoA Ketonebodies
(in liver)
Glycerol
2 ATP
ATP + H2O
GLYCOLYSIS
Pyruvate
Pyruvate
Acetyl CoA
NH3
Cytoplasm
Mitochondria
Citricacidcycle
2 ATP
Anaerobic conditions
Aerobic conditions
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-4
Metabolism
Push-pull control of metabolism
Carbohydrate Metabolism Primarily glucose
Fruktosa dan galaktosa memasuki jalur-jalur pada berbagai titik
Semua sel dapat memanfaatkan glukosa untuk produksi energi Glukosa serapan dari darah ke sel-sel
biasanya dimediasi oleh insulin dan transporter
Liver is central site for carbohydrate metabolism Glucose uptake independent of insulin The only exporter of glucose
Blood Glucose Homeostasis Beberapa jenis sel lebih memilih
glukosa sebagai sumber energi (ex., CNS) 80-126 mg/dl is normal range of blood
glucose in fasted state < 200 mg/dl is normal range of blood glucose in post prandial
Uses of glucose: Energy source for cells Muscle glycogen Fat synthesis if in excess of needs
Fates of Glucose Fed state
Storage as glycogen Liver Skeletal muscle
Storage as lipids Adipose tissue
Fasted state Metabolized for energy New glucose synthesized
Synthesis and breakdown occur at
all times regardless of state...
The relative rates of synthesis and
breakdown change
High Blood Glucose
Glucose absorbed
Insulin: Glucagon
Pancreas
Muscle
Adipose Cells
Glycogen
Glucose absorbed
Glucose absorbed
immediately after eating a meal…
Glucose Metabolism Four major metabolic pathways:
Energy status of body regulates which pathway gets energy
Immediate source of energy Pentophosphate pathway Glycogen synthesis in liver/muscle Precursor for triacylglycerol synthesis
Fate of Absorbed Glucose 1st Priority: glycogen storage
Stored in muscle and liver 2nd Priority: provide energy
Oxidized to ATP 3rd Priority: stored as fat
Only excess glucose Stored as triglycerides in adipose
Glucose Utilization
Glucose
PyruvateRibose-5-phosphate
GlycogenEnergy Stores
Pentose Phosphate Pathway
Glycolysis
Adipose
Glucose Utilization
Glucose
PyruvateRibose-5-phosphate
GlycogenEnergy Stores
Pentose Phosphate Pathway
Glycolysis
Adipose
Liver 7–10% of wet weight Use glycogen to export glucose to the
bloodstream when blood sugar is low Glycogen stores are depleted after
approximately 24 hrs of fasting (in humans) De novo synthesis of glucose for glycogen
Glycogenesis
Glycogenesis Skeletal muscle
1% of wet weight More muscle than liver, therefore more
glycogen in muscle, overall Use glycogen (i.e., glucose) for energy only
(no export of glucose to blood) Use already-made glucose for synthesis of
glycogen
Glucose Utilization
Glucose
PyruvateRibose-5-phosphate
GlycogenEnergy Stores
Pentose Phosphate Pathway
Glycolysis
Adipose
Glycolysis Urutan reaksi yang mengubah glukosa
menjadi piruvat Jumlah energi yang dihasilkan relatif kecil Reaksi glikolisis terjadi dalam sitoplasmaTidak memerlukan oksigen
Glucose → Pyruvate →Lactate (animals)
Acetyl-CoA (TCA cycle)Ethanol (yeast)
First Reaction of Glycolysis
Perangkap glukosa dalam sel (ireversibel dalam sel otot)
Heksokinase digunakan oleh sebagian besar tanaman, hewan,dan mikroba untuk memfosforilasi glukosa
Glukokinase dalam jaringan hati
Pyruvate Metabolism Three fates of pyruvate:
Conversion to lactate (anaerobic) Conversion to alanine (amino acid) Entry into the TCA cycle via pyruvate dehydrogenase pathway
Anaerobic Metabolism of Pyruvate
Problem: Selama glikolisis, NADH terbentuk dari NAD + Tanpa O2, NADH tidak dapat dioksidasi menjadi
NAD + Tidak ada lagi NAD +
Semua dikonversi menjadi NADH Tanpa NAD +, glikolisis berhenti ...
Anaerobic Metabolism of Pyruvate
Solution: Hidupkan NADH kembali ke NAD + dengan membuat laktat
(asam laktat)
COO–
C O
CH3
COO–
HC OH
CH3
LactatePyruvate
Lactate dehydrogenase
NADH + H+ NAD+
(oxidized) (reduced)
(oxidized)(reduced)
Anaerobic Metabolism of Pyruvate
ATP yield Two ATPs (net) are produced
in the anaerobic breakdown of one glucose The 2 NADHs are used to reduce 2 pyruvate
to 2 lactate Reaction is fast and doesn’t require oxygen
Pyruvate Metabolism - Anaerobic
Pyruvate LactateNADH NAD+
Lactate Dehydrogenase
Laktat dapat diangkut oleh darah ke hati dan digunakan dalam glukoneogenesis
Pyruvate Metabolism Three fates of pyruvate:
Conversion to lactate (anaerobic) Conversion to alanine (amino acid) Entry into the TCA cycle via pyruvate dehydrogenase pathway
Pyruvate metabolism Convert to alanine and export to blood
COO–
C O
CH3
COO–
HC NH3+
CH3Alanine amino transferase
(AAT)AlaninePyruvate
Glutamate -Ketoglutarate
Keto acid Amino acid
Pyruvate Metabolism Three fates of pyruvate:
Conversion to lactate (anaerobic) Conversion to alanine (amino acid) Entry into the TCA cycle via pyruvate dehydrogenase pathway
Pyruvate Dehydrogenase Complex (PDH) Prepares pyruvate to enter the TCA cycle
Electron Transport Chain
TCA CycleAerobic Conditions
TCA Cycle Dalam kondisi aerobik Link siklus TCA piruvat
untuk fosforilasi oksidatif Terjadi pada mitokondria Menghasilkan 90% dari energi yang
dilepaskan dari makanan
Strateginya adalah untuk mengoksidasi asetil-KoA menjadi CO2 dan menangkap energi NADH (FADH2) dan ATP
Metabolizes carbohydrate, protein, and fat
Membutuhkan koenzim sebagai pembawa H+ dan mengkonsumsi oksigen
Key reactions take place in the electron transport system (ETS) Sitokrom dari ETS melewati elektron ke
oksigen, membentuk air The basic chemical reaction is:
2 H2 + O2 2 H2O
Oxidative Phosphorylation and the Electron Transport System
Oxidation and Electron Transport Oksidasi nutrisi melepaskan energi
yang tersimpan mendonorkan elektron disertai dengan H + Electrons transferred to co-substrate
NAD+ + 2H+ + 2e- NADH + H+ FAD + 2H+ + 2e- FADH2
So, What Goes to the ETS???
From each molecule of glucose entering glycolysis:1. From glycolysis: 2 NADH2. From the TCA preparation step (pyruvate to acetyl-CoA): 2 NADH3. From TCA cycle (TCA) : 6 NADH and 2 FADH2
TOTAL: 10 NADH + 2 FADH2
Electron Transport Chain NADH + H+ and FADH2 enter ETC
Perjalanan melalui kompleks I - IV H + mengalir melalui ETC dan akhirnya
menempel pada O2 membentuk airNADH + H+ 3 ATPFADH2 2 ATP
Glucose Utilization
Glucose
PyruvateRibose-5-phosphate
GlycogenEnergy Stores
Pentose Phosphate Pathway
Glycolysis
Adipose
Pentose Phosphate Pathway Secondary metabolism of glucose
Produces NADPH Similar to NADH Required for fatty acid synthesis
Generates essential pentoses Ribose Used for synthesis of nucleic acids
Pentose Phosphate PathwayGlucose-6-phosphate
6-Phospho- glucono-lactone
6-Phospho- gluconate
D-Ribulose-5-phosphate
D-Ribose- 5-phosphateRNA or DNA
Glucose Utilization
Glucose
PyruvateRibose-5-phosphate
GlycogenEnergy Stores
Pentose Phosphate Pathway
Glycolysis
Adipose
Energy Storage Energi dari kelebihan karbohidrat (glukosa)
disimpan sebagai lemak dalam jaringan adiposa
Asetil-KoA (dari siklus TCA) didorong ke sintesis asam lemak pada saat kelebihan energi Ditentukan oleh rasio ATP: ADP
High ATP, acetyl-CoA goes to fatty acid synthesis Low ATP, acetyl CoA enters TCA cycle to generate
MORE ATP
Fates of Glucose Fed state
Storage as glycogen Liver Skeletal muscle
Storage as lipids Adipose tissue
Fasted state Metabolized for energy New glucose synthesized
Synthesis and breakdown occur at
all times regardless of state...
The relative rates of synthesis and
breakdown change
Gluconeogenesis Necessary process
Glucose is an important fuel Central nervous system Red blood cells
Not simply a reversal of glycolysis Insulin and glucagon are primary
regulators
Fasting Situation Where does required glucose come from?
Glycogenolysis
Lipolysis
Proteolysis
Kerusakan atau mobilisasi glikogen yang disimpan oleh glukagonGlukagon - hormon yang disekresi oleh pankreas selama masa puasa
Mobilization of fat stores stimulated by glucagon and epinephrine Triglyceride = glycerol + 3 free fatty acids Glycerol can be used as a glucose precursor
Pemecahan protein otot dengan pelepasan asam aminoAlanin dapat digunakan sebagai prekursor glukosa
Low Blood Glucose
Proteins Broken Down
Insulin: Glucagon
Pancreas
Muscle
Adipose Cells
Glycogen
Glycerol, fatty acids released
Glucose released
Dalam keadaan berpuasa, substrat untuk sintesis glukosa (glukoneogenesis) dilepaskan dari "penyimpanan" ...
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7 (2 of 5)
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Glucose
Liver glycogen becomes glucose.
or
Glycogen
Pyruvate
Lactate
Energy production
Glucose
Glycogenolysis
Gluconeogenesis
Gluconeogenesis Synthesis of glucose from non-carbohydrate
precursors during fasting in monogastrics
Terjadi terutama dalam hati, tetapi juga dapat terjadi pada ginjal dan usus halus
Glycerol Amino acids Lactate Pyruvate Propionate There is no glucose synthesis from fatty acids
Supply carbon skeleton
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Free fattyacids Free fatty
acids Glycerol
Aminoacids
KetonebodiesGlucose
Adipose lipidsbecome freefatty acids andglycerol thatenter blood.
Muscle glycogen can be used for energy.Muscles also use fatty acids and break down their proteins to amino acids that enter the blood.
Liver glycogen becomes glucose.
Brain can use only glucose and ketones for energy.
or
Triglyceride stores
Glycogen
Pyruvate
Lactate
Energy production
Glucose
Proteins
Ketonebodies
b-oxidationGlycogenolysis
Gluconeogenesis
Gluconeogenesis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7 (1 of 5)
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Glucose
Liver glycogen becomes glucose.
Glucose
Glycogenolysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7 (3 of 5)
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Aminoacids
Glucose
Liver glycogen becomes glucose.
or
Glycogen
Pyruvate
Lactate
Energy production
Glucose
Proteins
Glycogenolysis
Gluconeogenesis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7 (4 of 5)
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Free fattyacids Free fatty
acids Glycerol
Aminoacids
Glucose
Adipose lipidsbecome freefatty acids andglycerol thatenter blood.
Muscle glycogen can be used for energy.Muscles also use fatty acids and break down their proteins to amino acids that enter the blood.
Liver glycogen becomes glucose.
or
Triglyceride stores
Glycogen
Pyruvate
Lactate
Energy production
Glucose
Proteins
Glycogenolysis
Gluconeogenesis
Gluconeogenesis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22-7 (5 of 5)
Fasted-State Metabolism
FASTED-STATE METABOLISM
Liverglycogen
stores
Energyproduction
Energy production
Free fattyacids Free fatty
acids Glycerol
Aminoacids
KetonebodiesGlucose
Adipose lipidsbecome freefatty acids andglycerol thatenter blood.
Muscle glycogen can be used for energy.Muscles also use fatty acids and break down their proteins to amino acids that enter the blood.
Liver glycogen becomes glucose.
Brain can use only glucose and ketones for energy.
or
Triglyceride stores
Glycogen
Pyruvate
Lactate
Energy production
Glucose
Proteins
Ketonebodies
b-oxidationGlycogenolysis
Gluconeogenesis
Gluconeogenesis
KETOGENESIS
Ketogenesis adalah proses dimana BADAN KETON atau senyawa yang dihasilkan dari molekul asetil CoA sebagai hasil dari degradasi asam lemak.
72
Ketogenesis and Ketone BodiesIn ketogenesis:
Lemak tubuh terurai untuk memenuhi kebutuhan energi.
Senyawa Keto yang disebut bentuk badan keton.
73
Ketogenesis and Ketone BodiesIn ketogenesis: Sejumlah besar asetil KoA menumpuk. Dua molekul asetil KoA bergabung membentuk
asetoasetil KoA Asetoasetil KoA menghidrolisis untuk asetoasetat, tubuh
keton. Asetoasetat tereduksi menjadi b-hydroxybutyrate atau
kehilangan CO2 untuk membentuk aseton, kedua badan keton.
KETOGENESIS Badan keton diproduksi terutama di
mitokondria hepatosit. Sintesis terjadi sebagai respons terhadap
kadar glukosa rendah dalam darah, dan setelah kehabisan simpanan karbohidrat seluler, seperti glikogen.
Produksi badan keton kemudian berinisiatif untuk membuat energi tersedia yang disimpan sebagai asam lemak.
KETOGENESIS
Namun, jika jumlah asetil-KoA yang dihasilkan dalam fatty-acid β-oxidation menentang kapasitas pengolahan dari siklus TCA atau jika aktivitas dalam siklus TCA rendah karena jumlah rendah intermediet seperti oksaloasetat, acetyl-CoA kemudian digunakan sebagai pengganti dalam biosintesis badan keton melalui acetoacyl-CoA and β-hydroxy-β-methylglutaryl-CoA (HMG-CoA).
KETOGENESISREVIEW! Asam lemak menjalani
β-oxidation to form acetyl-CoA.
Biasanya, asetil-CoA selanjutnya teroksidasi dan energinya ditransfer sebagai elektron untuk NADH, FADH2, dan GTP dalam siklus Krebs.
KETOGENESIS The three ketone bodies are:
Acetoacetate - if not oxidized to form usable energy, it is the source of the two other ketone bodies below.
Acetone - is not used as an energy source, but is instead exhaled or excreted as waste.
β-hydroxybutyrate - it is not technically a ketone according to IUPAC nomenclature.
Each of these compounds are synthesized from acetyl-CoA molecules.
KETOGENESIS Ketogenesis mungkin atau tidak mungkin
terjadi, tergantung pada tingkat karbohidrat yang tersedia di sel atau tubuh. When the body has ample carbohydrates
available as energy source, glucose is completely oxidized to CO2.
When the body has excess carbohydrates available, some glucose is fully metabolized, and some of it is stored by using acetyl-CoA to create fatty acids.
KETOGENESIS
Ketika tubuh tidak memiliki karbohidrat bebas yang tersedia, lemak harus dipecah menjadi asetil-KoA untuk mendapatkan energi. Asetil-KoA tidak didaur ulang melalui siklus asam sitrat karena intermediet siklus asam sitrat (terutama oksaloasetat) telah habis untuk memberi makan jalur glukoneogenesis, dan akumulasi dihasilkan asetil-CoA mengaktifkan ketogenesis.
Ketogenesis menyediakan energi untuk fungsi-fungsi organ vital 'selama kelaparan yang berkepanjangan
KETOGENESIS
Badan keton dibuat pada tingkat moderat dalam tubuh kita, seperti saat tidur dan waktu lain bila tidak ada karbohidrat yang tersedia.
Namun, ketika ketogenesis yang terjadi lebih tinggi dari tingkat normal, tubuh dikatakan dalam keadaan ketosis. Badan keton terakumulasi dalam tubuh dapat menyebabkan efek negatif jangka panjang.
KETOGENESIS
Konsentrasi tinggi abnormal badan keton pada tubuh menghasilkan penurunan tingkat pH darah. kondisi ini disebut ketoasidosis.
Ketoasidosis sangat jarang terjadi. Hal ini, bagaimanapun, lebih terlihat pada orang yang menderita Diabetes mellitus (DM) dan pada mereka pecandu alkohol setelah pesta minuman keras dan kelaparan berikutnya.
Diabetes and Ketoacidosis Bila tidak ada cukup insulin dalam darah,
glukosa tidak digunakan secara efisien untuk menghasilkan energi. Dengan demikian, tubuh harus memecah lipid untuk energi.
Degradasi lipid menyebabkan keton menambah dalam darah. Keton kemudian meluas ke urin sehingga tubuh bisa menyingkirkan mereka. Aseton dapat dihembuskan melalui paru-paru. Keton yang membangun di dalam tubuh untuk waktu yang lama menyebabkan penyakit serius dan koma. (Ketoasidosis diabetik)
87
KetosisKetosis occurs: In diabetes, diets high in
fat, and starvation. As ketone bodies
accumulate. When acidic ketone
bodies lowers blood pH below 7.4 (acidosis).
88
Ketone Bodies and Diabetes The blood glucose is elevated within
30 min following a meal containing carbohydrates
The elevated level of glucose stimulates the secretion of insulin, which increases the flow of glucose into muscle and adipose tissue for synthesis of glycogen (+ stimulates glycolysis)
As blood glucose levels drop, the secretion of glucagon increases, which stimulates the breakdown of glycogen in the liver to yield glucose
89
Ketone Bodies and DiabetesIn diabetes: Insulin does not function properly. Glucose levels in muscle, liver, and adipose
tissue are insufficient for energy needs. As a result, liver cells synthesize
glucose from non-carbohydrate sources (gluconeogenesis) and fats are broken down to acetyl CoA.
The level of acetyl CoA is elevated. Excess acetyl CoA undergoes ketogenesis. Ketogenesis produces ketone bodies. Ketone bodies accumulate in the blood.
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