Download Cells and Energy Cellular Respiration Chapter 2 Lesson 4 Part 1

Cells and Energy
Cellular Respiration
Chapter 2 Lesson 4 Part 1
Cells and Energy
• How does a cell obtain energy?
• How do some cells make food
molecules?
Cells and Energy
Cellular Respiration
Cellular Respiration
is a series of chemical reactions
that convert the energy in food
molecules into a usable form of
energy called ATP
the breaking down of an
energy source by cells to
obtain usable energy
Sugar (glucose) is
the most common
energy source in
cellular respiration.
(some can use fats,
oils, proteins, etc.)
Cellular respiration
requires many enzymes.
Enzymes are catalysts
(substances which help
to change other
substances without
being permanently
changed themselves).
2 types of cellular
respiration


aerobic – requiring
oxygen
anaerobic – not
requiring oxygen
(some bacteria and
fungi)
Most cells carry on aerobic respiration.
Aerobic Cellular Respiration
First few steps for breaking
down glucose takes place in
the cytoplasm and it is
called glycolysis.
Most takes place in the
mitochondrion (called
reactions in the
mitochondria).
Cellular Respiration
Essentially cellular respiration takes
place in three parts:
1. Glycolysis
2. Krebs Cycle (or The Citric Acid
Cycle)
3. Electron Transport
Glycolysis
the first step in cellular respiration, is a
process by which glucose is broken down
into smaller
molecules.
It occurs in the
cytoplasm.
Glycolysis literally means "splitting sugars."
Cellular Respiration
Glycolysis
produces some
ATP molecules
and uses
energy from
other ATP
molecules.
Aerobic Cellular Respiration
• The second step of cellular respiration
requires oxygen and occurs in the
mitochondria of eukaryotic cells.
• The smaller molecules made from glucose
during glycolysis are broken down.
• Large amounts of ATP—usable energy—
are produced. Cells use ATP to power all
cellular processes.
Reactions in the Mitochondria
Aerobic Cellular Respiration
glucose + oxygen --->
ATP
+ carbon dioxide + water
Anaerobic Cellular Respiration
Some cells exist in
environments that do not have
oxygen available.
Many bacteria in the lower
layers of swamps, lakes, or the
ocean do not have oxygen.
Other cells which operate
best with a supply of oxygen
can occasionally operate
without oxygen.
Types of anaerobic
cellular respiration
(usually named by the
products that are produced
from the glucose)
Alcoholic fermentation
 Lactic acid fermentation

Fermentation
Fermentation
is a reaction
that eukaryotic and prokaryotic
cells use to obtain energy from
food when oxygen levels are
low.
Fermentation occurs in a cell’s
cytoplasm, not in mitochondria.
Alcoholic fermentation
anaerobic cellular
respiration that produces
alcohol and carbon dioxide
from glucose
example:
yeast in
bread dough
Lactic acid fermentation
a type of anaerobic
cellular respiration that
produces lactic acid from
glucose
examples: yogurt, cottage
cheese,buttermilk,sauerkraut,
human muscle cells
Fermentation