Transcript RESPITATION - Barbados SDA Secondary

RESPITATION
Releasing energy.
• Cellular respiration is the breakdown of
chemical substances, such as glucose,
within living cells of both plants and
animals for the purpose of releasing
energy.
• This energy is used to synthesize the
special phosphorus compound adenosine
triphosphate, or ATP.
• ATP serves as the energy carrier of the
cell and as a convenient form for the
temporary storage of chemical energy.
• Nearly all of a cell’s life processes are
powered by .ATP.
• The energy to produce ATP may come
from any of several sources, including
carbohydrates (primarily glucose), fats,
and even proteins if the cell is short of
food.
•
Cellular respiration involves several
steps.
1. The first step takes place in the
cytoplasm and involves partially breaking
down glucose, producing about 2
molecules of ATP for each glucose
molecule broken down.
• Anaerobic cells (cells that do not use
oxygen) rely totally on this step for all of
their energy
• In aerobic cells (cells that use oxygen),
additional steps take place in the
mitochondria, where food molecules are
combined with oxygen in a process known
as oxidation.
• The ATP which is produced (about 30
molecules of ATP for each original
molecule of glucose) is transported from
the mitochondria to all parts of the cell.
• ATP is a readily available source of
energy in the cells of all organisms.
• Respiration permits an organism to carry on
the functions necessary to maintain life.
• During the process, the organism’s cells
releases energy for their own use and
produce carbon dioxide and water as waste
products.
• The chemistry of respiration is the same in all
organisms, because all living things are built
on the same general pattern
• The pattern designed by the Creator
Himself’.
Opposite processes
• Both photosynthesis and respiration convert
energy into a form that living cells can use:
• However generally speaking, cellular respiration
is the opposite of photosynthesis.
• During photosynthesis, water molecules are first
split into hydrogen and oxygen and then the
hydrogen atoms are combined with carbon
dioxide to form glucose.
• The opposite occurs during resporation
• hydrogen is split from the glucose molecule and
is then united with oxygen to form water.
• All that remains of the glucose molecule, after it
is split apart, is the carbon dioxide.
You should be able to
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An organism is alive when all its cells are respiring.
understand the function of ATP;
describe the process of aerobic respiration;
distinguish between aerobic and anaerobic
respiration
• describe the uses of anaerobic respiration to Man
• understand that respiration takes place at the level of
the cell;
• understand simple investigations that show the
products of resoiration.
Aerobic respiration
• Respiration is the process by which the
energy in food is made available for a cell
to do the work necessary to keep it alive.
• When oxygen is used in the reaction, we
call it aerobic respiration. The process is
catalysed by enzymes and is also called
cellular, internal or tissue respiration.
Quiz
• What is the purpose of respiration?
A: During respiration, the energy from the
food eaten by an organism is made
available.
This energy can he used to carry out all the
characturistics of life, movement, growth,
reproduction, and so on.
Quiz
• When do animal cells and plant cells
respire?
• Animal cells respire all the time because
the animal is in constant need of energy.
Plant cells also respire all the time. During
the day. while sunlight is available, plants
also photosynthesise, hut they never stop
respiring.
How do the food and oxygen get to
respiring cells?
• Food -In animals food eaten is digested
and absorbed into the bloodstream.
• The end-products of digestion eventually
reach all the body cells.
• In plants the food made in photosynthesis
in the leaves travels around in phloem
tubes and eventually reaches all cells in
the plant.
• Oxygen — In vertebrates, oxygen comes
from the air that is inhaled into the lung
• It diffuses into the bloodstream and is
transported to all the body cells.
• In plan some of the oxygen comes from
photosynthesis and some through
diffusion in through the leaves and other
parts of the plant.
• In both plants and animals the type of food
used for making energy is usually glucose.
• Energy is released when it combines with
oxygen (the oxidation of glucose).
• Carbon dioxide is a waste product of this
reaction.
• In vertebrates it diffuses back into the
bloodstream, to he taken to the lungs and
exhaled out of the body.
• In plants it is used for photosynthesis
during daylight.
• Respiration or cellular respiration occurs in a
series of steps, each of which is catalysed
by enzymes.
• The overall process can be summarised in
words or by the equation below:
• glucose + oxygen →energy + carbon dioxide + water
• Equation:C6H1206 + 602 → energy + 6C02+ 6H2O
• During aerobic respiration glucose is
broken down completely into carbon
dioxide aria water.
• At each step in the breakdown of glucose,
energy is released.
• This is used to convert a chemical called
ADP into adenosine triphosphate (ATP).
• Each molecule of ATP acts as a little
‘packet’ of energy.
• The energy can be stored and used later
when needed.
Advantages of storing energy in small
packets
• There are many advantages of storing and
using energy in small packets like this.
• The energy can he released from ATP
wherever and whenever it is required by a
cell.
• The energy can he released rapidly.
• Energy is not wasted. A large amount of energy
is released by oxidising one glucose molecule
and many ATP molecules are formed. A cell may
not require very much energy at once. By storing
the energy in small packets of ATP molecules,
the cell can use small amounts of energy as
required.
• The energy can be used to drive many different
chemical reactions rapidly.
• Energy can he stored as ATP in one part of a
cell and transported and used elsewhere without
causing reactions in between.
• Energy production and utilisation are very
efficiently and carefully controlled by the
cell.
• Respiration occurs in an organelle called
the mitochondrion.
• Mitochondria are present in all cells,
animal and plant. and are sometimes
referred to as the ‘power houses’ of the
cell.
• The energy stored in ATP (adenosine
triphosphate) is released when it is
converted to ADP (adenosine
diphosphate)
• The energy stored in ATP
(adenosine triphosphate) is released when it
is converted to ADP
(adenosine diphosphate)
Quiz
• What is the important product of
respiration? What are the waste products
of respiration?
• The important product of respiration is
energy, which an organism needs to carry
out the characteristics of life. The waste
products of respiration are carbon dioxide
arid water.
Quiz
• Where does respiration occur?
• Respiration occurs in the
mitochondria of cells.
Quiz
• Give three reasons why it is advantageous
to store energy in small packets.
• Energy is released only when necessary;
only as much energy as is needed is used;
energy is released rapidly when it is
needed.
Anaerobic respiration
• Respiration can also occur without oxygen
and this type of respiration is called
anaerobic respiration.
• Both anaerobic and aerobic respiration
involve the breakdown of glucose,
• However in anaerobic respiration it is not
completely broken down.
• Habitats such as stagnant ponds and deep
underground have no oxygen.
• Organisms living there have can survive without
oxygen; they must respire anaerobically all the
time. These organisms include sonic worms,
some bacteria and some fungi.
• Parasites that live inside other organisms, such
as the gut parasite tapeworm and bacteria, also
live in conditions that lack oxygen. They must
also respire anaerobically.
• Living cells that normally respire aerobically can
also respire anaerobically if oxygen is lacking.
Animal and plant cells do this in different ways