Download Hughes respiration homework (2)

Bio 160
Respiration Homework
Hughes_____________________
Saunders
Name:_Walter G.
DIRECTIONS: Use Chapter 6 to help answer the questions and fill in the table below. Bring to class
completed at the beginning of lecture on the due date.
1. What is meant by a reduction-oxidation reaction (redox reaction).
Oxidation-reduction reactions (or redox) reactions, are a type of chemical reaction that involves atransfer of electrons between two species. An oxidationreduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an e-. They occur every
day and are vital to some of the basic functions of life.
Redox reactions are comprised of two parts, a reduced half and an oxidized half, that always occur together. The reduced half gains electrons and the oxidation
number decreases, while the oxidized half losses electrons and the oxidation number increases. Simple ways to remember this are the mnemonic devices OIL
RIG meaning "oxidation is loss" and "reduction is gain" or LEO says GER meaning "loss of e-= oxidation" and "gain of e- = reduced." There is no net change in the
number of electrons in a redox reaction. Those given off in the oxidation half reaction are taken on by another species in the reduction half reaction.
The two species that exchange electrons in a redox reaction are given special names. The ion or molecule that accepts electrons is called the oxidizing agent; by
accepting electrons it brings about the oxidation of another species. Conversely, the species that donates electrons is called the reducing agent; when reaction
occurs it reduces the other species. In other words, what is oxidized is the reducing agent and what is reduced is the oxidizing agent.
2. How is Cellular Respiration a good example of a redox reaction? Be specific as to what molecules
play which roles during the reaction (write out the chemical formula and highlight the molecular
roles).
Cellular respiration, is the oxidation of glucose (C6H12O6) to CO2 and the reduction of oxygen to water.
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
3. In your own words, describe the general purpose of cellular respiration? (In other words, what is
the ‘big picture’ of this chapter?)
Cellular respiration is the process in which we are converting glucose (C6H12O6) to ATP - a form of energy that can
be used by the cell.
Bio 160
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4. How can we obtain energy from food we eat? Where specifically is the energy in foods?
Our bodies digest the food we eat by mixing it with fluids (acids and enzymes) in the stomach. When the
stomach digests food, the carbohydrate (sugars and starches) in the food breaks down into another type of
sugar, called glucose. Glucose has energy stored in its chemical bonds,these bonds are broken in metabolic
processes such as cellular respiration.
Chemical bonds and electron energy? (-1)
TABLE 1. Fill in the table below.
Process
Overall Purpose?
Glycolysis
Glycolysis literally means "splitting
sugars." Glucose, a six carbon sugar,
is split into two molecules of a three
carbon sugar. In the process, two
molecules of ATP, two molecules of
pyruvic acid and two "high energy"
electron carrying molecules of
NADH are produced. Glycolysis can
occur with or without oxygen. In the
presence of oxygen, glycolysis is the
first stage of cellular respiration.
Without oxygen, glycolysis allows
cells to make small amounts of ATP.
This process is called fermentation .
Pyruvate Process

Step
A:
Pyruvate
is
decarboxylated
by
pyruvate
dehydrogenase with help from TPP.

Step B: The reactive carbon
(between the N and the S of the five
membered ring) of the TPP is
oxidized and transferred as the
acetyl group to lipoamide (which is
the prosthetic group of the
Reactants (What
molecules go in?)
Six carbon sugar
Products (What
comes out?)
Split into two
molecules of a
three carbon sugar
. And process, two
ATP,two molecules
of pyruvate acid
,and two high
energy electron
carrying molcules
of NADH are
produced. Without
oxygen small
amounts of ATP are
made(fermentation
).
Pyruvate, and Two - 2pyruvate+2NAD
three carbon sugars
++2coA→2acetyl
coA+2NADH+2C
O2
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dihydrolipoyl transacetylase). This
forms hydroxyethyl-TPP. An H+ ion
is required for the intermediate to
give off CO2.

Step C: E2 (dihydrolipoyl
transacetylase
with
cofactor
lipoamide) oxidizes hydroxyethyl- to
acetyl- and then transfers acetyl- to
CoA, forming acetyl-CoA.

Step D: Acetyl CoA was made
in the previous step. However, the
process is incomplete. The E2is still
attached to the acetyl CoA
molecule. So, E3 (dihydrolipoyl
dehydrogenase) oxidizes the thiol
groups of the dihydrolipoamide
back to lipoamide.

Step E: As a side reaction,
NAD+ becomes reduced to NADH.
Krebs Cycle
Complete oxidation of glucose, it harvests
the energy from glucose in the form of
The Krebs cycle
starts with a
reducing power, carried by NAD and
molecule of acetyl-
FADH. This energy is then brought to the
CoA.
electron transport chain where the
majority of ATP is produced.
Electron Transport
Chain
Each acetyl coenzyme
A proceeded once
through the citric acid
cycle. Therefore, in
total, it created 6
NADH + H+
molecules, two FADH2
molecules, four
carbon dioxide
molecules, and two
ATP molecules.
Water + ATP
Electron
transport
chains
are
redox
reactions that transfer electrons from an
electron donor to an electron acceptor.
The transfer of electrons is coupled to the
translocation
of
protons
across
a
membrane, producing a proton gradient.
The proton gradient is used to produce
useful work. About 32 work units are
produced per electron transport.
NADH
Bio 160
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