cie alevel biology chapter 12 energy and respiration
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Course
Unit 12 - L Energy and Respiration (BIO9700)
Institution
CIE
-personalized notes made with many keywords from the marking scheme for easy revision and solving past paper questions
-got A for bi0logy AS and A2
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1) Adenosine is a nucleotide consisting of adenine, 5-carbon sugar and 3 phosphate group
held together by high-energy bond
2)The bonds attaching the 2 outer phosphate groups is called high-energy bonds because
more energy is released when they are broken than when the last phosphate is removed
-reactions are reversible
3)It is a universal energy currency as the cells ‘trades’ in ATP.
Describe the features of ATP that make it suitable as the universal energy currency. [6]
-ATP is a stored energy derived from respiration.
-It is present in all organisms to be used in active processes such as active transport,
exocytosis, DNA replication, muscular contraction and others.
-ATP can be broken down into ADP and then AMP by the process of hydrolysis. The process
is also reversible.
MITOCHONDRIA
STRUCTURE RELATED TO ITS FUNCTION
1)The main function is to make ATP by aerobic respiration.
2)It has an outer and inner membrane.
3)The inner membrane is folded inwards to increase surface area. It has ATP synthase and
ETC for the process of oxidative phosphorylation.
, 4)The outer membrane is permeable to pyruvate.
5)The intermembrane space contains a high concentration of protons so that protons will
diffuse from intermembrane space into the matrix.
6)The matrix contains coenzymes for Link Reaction.
REDUCTION - gain in hydrogen
OXIDATION - loss in hydrogen
AEROBIC RESPIRATION
1) GLYCOLYSIS
What? - the splitting of glucose
Where? - in the cytoplasm, occurs in both aerobic and anaerobic respiration
-Glycolysis can be split into 3 stages :
1. PHOSPHORYLATION OF GLUCOSE
-Glucose is phosphorylated to fructose bisphosphate by ATP.
Glucose + 2ATP → Fructose bisphosphate
2. THE SPLITTING OF THE PHOSPHORYLATED GLUCOSE
-fructose bisphosphate (6C) splits into two molecules of triose phosphate (3C)
Fructose bisphosphate → 2 Triose phosphate
3. OXIDATION OF THE SPLIT GLUCOSE TO FORM PYRUVATE
-Triose phosphate is dehydrogenated and transferred to NAD to form reduced NAD.
-2 molecules of reduced NAD are produced for each molecule of glucose entering glycolysis
-the end product is 2 pyruvates which enters the link reaction in the mitochondria
4H + 2NAD → 2NADH + 2H+
SUMMARY :
1. Glucose molecule with 6 carbon atoms eventually split into 2 molecules of pyruvate
(3 carbon)
2. Net gain of 2 ATP molecules per molecule of glucose broken down (use 2 ATP,
produce 4 ATP so net 2+ ATP)
3. Coenzyme NAD = remove hydrogen atoms from molecules (oxidation reaction) and
helps enzyme that catalyse oxidation reactions by accepting and carrying the
hydrogen atoms that have been removed
PRODUCT : 4 ATP , 2 pyruvate (3C), 2 NADH
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