LEC 9 Flashcards
Metabolic Pathways Intro
Metabolism
The sum of all the chemical reactions in an organism
A single cell can have _____________ of different chemical reactions occurring at the same time
thousands
Metabolic pathways def
Reactions that are organized so that one reaction follows another
Metabolic pathway patterns (2)
Orderly and predictable
Metabolic pathways (2)
- Linear
- Cyclic
Metabolic pathways: Linear
The product (end material) of one reaction becomes the substrate (starting material) for the next reaction
Metabolic pathways: Cyclic
The substrate material enters the reaction, the product material exits but the basic chemical cycle repeats over and over
Metabolic pathway types (2)
- Anabolic
- Catabolic
Anabolic Reaction (2)
Building up of larger molecules from smaller molecules
dehydration synthesis
Catabolic Reaction (2)
Breaking down molecules to smaller, lower energy products
hydrolysis
“anabole”
throwing UP
“katabole”
throwing DOWN
Does an anabolic reaction need energy or release energy?
Needs energy
Does a catabolic reaction need energy or release energy?
Releases energy
Enzymes (4)
- Specific proteins needed for most metabolic pathways
- Take part in reactions
- Not changed or destroyed by the reaction
- Reused repeatly
Two important enzymes in energy production
- NAD+
- FADH
Co-enzymes (2)
- “Helpers” not proteins
- Assist during reactions by moving certain molecules from one part of the reaction to another
Cells get their energy from_______________
Catabolism of molecules that serve as chemical stores of energy (ie. glucose, lipids & proteins)
Most immediate source of energy
ATP
ATP
Adenosine triphosphate
Where is energy locked in ATP?
between phosphate bonds
How is energy released from ATP?
Removal of phosphate releases energy that is stored there and the cell can do work
Phosphorylation
Adding the inorganic phosphate back and re-creating ATP
ATP equation
ATP = ADP + Pi + energy
ATP Fuel Source
What is available (mostly glucose) (if no glucose, then stored fats, proteins)
Glucose source (2)
- food that has recently been consumed
- stored glycogen
What kind of reaction is glucose to ATP?
Catabolic
glucose to ATP reaction waste products
Carbon dioxide & water
Does the reaction of glucose to ATP need O2?
Yes
1 glucose molecule = __________ ATP
36 ATP
The Production of ATP Steps (4)
- Glycolysis
- Preparatory step
- Citric acid cycle
- Electron transport system
Where does glycolysis (STEP 1) take place?
in cytoplasm
Where do the preparatory step, citric acid cycle, electron transport system (STEP 2-4) take place?
mitochondria
preparatory step, citric acid cycle, electron transport system (STEP 2-4)
cellular respiration
At what steps is ATP produced?
Step 1, 3, 4
Glycolysis literal breakdown
“glyco” = sweet (refers to sugar)
“lysis” = to break
Glycolysis steps (2)
- Energy Investment Step
- Energy Yielding Step
Energy Investment Stage Step 1:
________ ATP molecules start the __________ of glucose
- two
- catabolism
Energy Investment Stage Step 2:
________ molecule breaking into ________ equal pieces (each with 3 ________ )
- glucose
- two
- carbons
Energy Investment Stage Step 3:
A __________ from each __________ is added to the two halves of the glucose. Each half is now called __________.
- phosphate
- ATP
- G3P (Glyceraldehyde-3-phospate)
G3P full form
Glyceraldehyde-3-phospate
Energy Yielding Stage Step 1:
Enzymes in the __________ cause the _______ G3P molecules to break down
- cytoplasm
- two (2)
Energy Yielding Stage Step 2:
Form _______
_______ molecules
- two (2)
- pyruvate
Energy Yielding Stage Step 3:
_____ ATP molecules are formed by substrate
___________
- Four
- phosphorylation
Energy Yielding Stage Step 4:
_____ ions and electrons (e-) are _________ during the breakdown of G3P
- H+
- released
Energy Yielding Stage Step 5:
H+ and e- are picked up by________ coenzymes called
________
- two (2)
- NAD+
Coenzyme NAD+ full form
Nicotinamide adenine dinucleotide
When does NAD+ become NADH?
During glycolysis
How does NAD+ become NADH? (2)
NAD+ picks up:
- One high energy hydrogen ion
- Two high energy electrons
________ NADH are produced during glycolysis
Two
Summary: Stage #1 - Glycolysis ATP (3)
- 2 ATP invested at start
- 4 ATP molecules produced through substrate level phosphorylation
- NET GAIN = 2 ATP
Summary: Stage #1 - Glycolysis Coenzyme activity
2 NAD+ molecules pick-up 1 hydrogen and 2 electrons each to become 2 molecules of NADH
(go to Stage #4)
Summary: Stage #1 - Glycolysis What’s left?
2 pyruvate molecules (go to Stage #2)
Cellular Respiration (3)
- In order to produce large quantities of ATP, pyruvate molecules must enter the mitochondria
- needs O2 (NO oxygen = pyruvate molecules can’t enter mitochondria = no more ATP being produced)
- STAGES 2 - 4
Cellular Respiration and NO O2?
NO oxygen = pyruvate molecules can’t enter mitochondria = no more ATP being produced
Stage #2 – Preparatory Step Location
inner membrane region
Stage #2 – Preparatory Step Step 1
Two (2) pyruvate molecules
Cross the outer and inner membranes of the mitochondria to arrive in the inner membrane region
Stage #2 – Preparatory Step Step 2 (3)
Each pyruvate molecule is converted into:
1. A 2-carbon acetyl group
2. Carbon dioxide (waste product)
3. NADH molecule
Stage #2 – Preparatory Step Step 3 (2)
Coenzyme A
1. Picks up an acetyl group to form acetyl CoA
2. The acetyl groups will be delivered to Stage #3
Summary: Stage #2 – Preparatory Step ATP
NONE
Summary: Stage #2 – Preparatory Step Coenzyme activity (2)
- 2 NAD+ molecules each pick-up 1 hydrogen and 2 electrons to become 2 molecules of NADH
(TO Stage #4) - Two ccoenzyme A pick-up an acetyl group each to become Acetyl CoA (TO Stage #3)
Summary: Stage #2 – Preparatory Step What’s left?
2 molecules of carbon dioxide are produced as waste
