Download CHAPTER 4, SECTION 2: CELL ENERGY

CHAPTER 4, SECTION 2:
CELL
ENERGY
FROM SUN TO CELL
All cells need energy to live,
grow & reproduce.
Plant cells-energy from sun
Animal cells-energy from
food
FROM SUN TO CELL
 Nearly all energy that fuels life
comes from the sun!
 Photosynthesis: process in which
plants capture energy from the
sun & change it into food.
 Supplies plants w/energy &
animals that eat plants w/energy.
PHOTOSYNTHESIS
 Pigments-molecules that absorb light energy.
 Chlorophyll-main pigment used in photosynthesis; gives
plants green color; found in chloroplasts.
 Plants use energy captured by chlorophyll to change
carbon dioxide and water into food.
 Food in form of glucose (simple sugar). Carbohydrate!
 Plants make glucose, convert sun’s energy into a form of
energy that can be stored.
 Energy in glucose is used by plant’s cells.
 Also produces oxygen.
GETTING ENERGY FROM
FOOD
 Animal cells----cellular respiration or
fermentation
 Cellular respiration---uses oxygen to
break down food. Releases more
energy from a given food than
fermentation.
 Fermentation—process in which cells
can get energy without using oxygen.
CELLULAR
RESPIRATION
 Respiration means “breathing”.
 Cellular respiration different from breathing!
How?
 Breathing supplies oxygen needed for cellular
respiration.
 Breathing also removes carbon dioxide, waste
product of cellular respiration.
 Cellular respiration is a chemical process that
occurs in cells.
CELLULAR
RESPIRATION
 Food (glucose) is broken down into carbon dioxide
and water, and energy is released.
 Animals---most of energy released maintains body
temperature.
 Some energy used to form adenosine triphosphate
(ATP), which supplies energy that fuels cell
activities.
 Takes place in cell membrane (prokaryotes) and
mitochondria (eukaryotes).
FERMENTATION
 A way cells get energy from food without
oxygen.
 Burning sensation in legs after physical
activity?
 When muscle cells can’t get oxygen needed for
cellular respiration, they use fermentation to
get energy.
 Produces lactic acid, buildup contributes to
muscle fatigue and causes a burning sensation.
 Happens in animal cells, fungi and bacteria.
FERMENTATION
 Another type occurs in some types of
bacteria and yeast.
 Yeast forms carbon dioxide during
fermentation.
 Bubbles of gas causes dough to rise
and leave small holes in bread after it’s
baked!