Download Metabolism

The Overview
 Metabolism
Metabolism
Cycles of the Cell
is the sum of all the chemical
reactions for a cell.
 Cells typically have several types of
metabolic reactions (enzymatically driven),
but there are three that are the most
significant
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The Cell Cycle
 The
cell cycle is an orderly sequence of
events for the normal growth and
development of the cell through cellular
reproduction.
 There are several steps in the Cell Cycle:

Reproducing Chromosomes
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GO, G1, G2, S, Mitosis, Cytokinesis

Synthesis - is the
reproduction of
chromosomes of a cell.
Animal and plant
Chromosomes contain
instructions for making
protein for a cell
Chromosomes are made of
a single double, strand of
DNA
The Cell Cycle
 Most

of the cell cycle is spent in interphase.
Interphase includes the GO, G1, S and G2 steps
 Following
interphase, the mitotic stage of cell
division occurs.
 The Cell Cycle is important because all cells
grow and develop as a characteristic of life
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Furthermore, cells have a life span and thus
grow old and die
If cells are to grow old and die, they must
reproduce first and leave a working copy of
themselves before they do so.
The Cell Cycle - Cellular Growth and
Development and Reproduction
Respiration - Production of cellular energy
Photosynthesis - Sugar production
Reproduced
Chromosome
consisting of two
sister
chromatids
Step I - Interphase
 Remember
that the following steps are
included in interphase:


G1 stage – cell growth, accumulates materials
for DNA synthesis, cell doubles its organelles
S stage – DNA synthesis (reproduction) occurs
• DNA replication results in duplicated chromosomes

G2 stage – cell synthesizes proteins needed for
cell division
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The Cell Cycle
Mitosis
 During
mitosis, the spindle distributes the
chromosomes to each new cell

New cells are called daughter cell.
 The
spindle contains fibers made of
microtubules that disassemble and
assemble.
 Mitosis has four phases

Mitosis a Picture

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prophase, metaphase, anaphase, and
telophase.
Late Interphase
What does Mitosis look
like?
Here is a simple
diagram of the process
Think 
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Prophase
Metaphase
Anaphase
Telophase
Early Prophase
Late Prophase
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Metaphase
Anaphase
Telophase
Cytokinesis in animal cells
Mistakes in the Cell Cycle
 What
happens to cells when they do not
distribute the chromosomes equally?

Once cell will get more choromosomes than
they should…what does this do?
 What
happens to a cell that synthesizes the
DNA wrong?

Making Energy
The Respiration Pathway
The DNA sequence will be wrong and thus the
protein will either be wrong or incorrectly
made…what does this do?
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Respiration
 Respiration
- process of cells using sugar
to make energy for cell


ATP (Adenosine Tri-phosphate) is the
chemical energy for cells
ATP is made by sugar oxidation
Step One - Glycolysis
 Happens
in the cytoplasm
down sugar into two parts
(pyruvate)
 Glycolysis is a FERMENTATION pathway
 Breaks
 Respiration
takes place in two locations
with three steps

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The cytoplasm of the cell - glycolysis
The mitochondria if the cell has one phosphorylation

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Step 3 - Electron Transport
Phosphorylation
Step 2 - Krebs Cycle

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If a cell has mitochondria and oxygen is present
The two broken sugar particles (pyruvate) is
enzymatically processed into mitochondria
Broken down into carbon dioxide particles and
released out of the cell (this is what we breath
off)
Hydrogen retained from sugar particles and
used in the last step.

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Bacteria only undergo fermentation step, then stop
Takes place on membrane of mitochondria
ATP assembled in mass

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34 Total
+ 2 from fermentation = 36 per sugar molecule
Electron from hydrogen used to power the ATP
pump

NO ATP is made in excess
Bacteria do not have mitochondria and will not
do this step
Sugar (glucose) is broken in half by a series
of enzymes
2 ATP are made as a result of this pathway
Process does NOT need OXYGEN and thus is
said to be anaerobic (lacking oxygen)
Pump assembles ADP + Pi to make ATP
Oxygen MUST be present for this step to take place,
thus this step is aerobic (in the presence of oxygen)
Remember that fermentation only makes 2 ATP,
with this step we make a lot more
Respiration Overview
Making Sugar for
Energy
Photosynthesis
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Photosynthesis
 Photosynthesis
- process plants, some
bacteria, and some protists use energy from
sunlight to produce carbohydrates
Photosynthesis - Stages
 There
are two steps in the
photosynthetic pathway

• Produces energy needed for light independent
reactions
 Conversion
of sunlight as an energy source
into usable chemical energy is associated
with the actions of the green pigment
chlorophyll
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Light Reactions
During Light Reactions sunlight activates
chlorophyll
The activation of chlorophyll causes it to “grab” a
hold of a water particle and split it into hydrogen
and oxygen
Oxygen is released as waste
Hydrogen used to generate ATP
After hydrogen used, they AND ATP are sent to
the light-independent reactions
Quick Check
The Light In-dependent Reactions
• Uses energy from Light Reactions to assemble
Carbon Dioxide with hydrogen to make sugar
Photosynthesis - Step 1
 The
The Light Dependent Reactions
Photosynthesis - Step 2
 Light



in-dependant (dark) reactions
ATP, from light reactions, used as an energy
source
On membranes of inner chloroplast are
assembly line series of proteins for
production of sugar
Sugar (glucose) assembled from carbon
dioxide from air + hydrogen from water of
light reactions
• It takes 6 carbon dioxide + 6 water molecules to
make one sugar molecule
In Summation
 Why
do you think it can be said that the light
reactions DRIVE the dark reactions?
 If the sun ceased to exist at this moment,
would the dark reactions stop at the same
rate? Explain
 Explain the function of the mitochondria and
the chloroplast.
 Why is it important to have folded inner
membranes in the mitochondria and
chloroplast?
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