Cells and Energy
Biology
Chapter 4
Amazing Energy
• How do you get energy
to do all the things you
do?
• FOOD, cells get energy
from food
Remember
• Cells are the building blocks of life
All Living Things Need Energy
• How do you use energy?
– Talking, writing, playing, even sleeping
• Energy is the ability to do work and cause
change.
Review
• All organisms are made up of more that one
cell.
• Cells are the building blocks of life
• Cells carry out all life functions
• They can move, reproduce, use energy, grow,
and respond to the environment
• Cells use energy
Energy
• There are many forms
– Sunlight
– Food
– Chemical
Food
• Once you eat something it is broken down into
molecules
• Some molecules are in the form of sugar
• These sugar molecules are absorbed by your
cells
• Sugar molecules contain energy
• Cells transfer energy to make a special
compound, ATP
ATP
• ATP is a form of Chemical Energy.
• The energy in ATP can be used by a cell to
carry out life processes
• Cells breakdown ATP quickly
• ATP breaks down ADP
• Formula:
– ATP -> ADP + P + energy
How Materials Enter and Leave Cells
• Cells need certain
materials to absorb
energy
• They also need to get
rid of waste
Osmosis
• A cell is made up of
mostly water and
dissolved substances.
• Water can move in and
out of a cell membrane
• This diffusion is called
osmosis
• The direction the water
moves depends on
where there is a higher
concentration
Osmosis in Plant Cells
• When a plant cell has
little or no water the
plant droops
• When water is received
it swells and stands
straight
Passive Transport
• The diffusion of certain
molecules through the
cell membrane occur
passively, or without
help
Active Transport
• Energy is used to move
materials across the
membrane
• Molecules of certain
substances move
through the cell
membrane from an
area that is less
crowded to an area that
is more crowded
• This happens in the
roots of plants
• Active transport is also
used to move waste out
of the cell
Cellular Respiration
• Most things need two
things to survive: Food
and oxygen
• Food breaks down into
sugar molecules
• Mitochondria in cells
use oxygen to release
energy
• Energy in sugar
molecules is converted
into usable energy
• ATP
Cellular Respiration
• The process by which
cells release energy
from food
• This takes place in the
mitochondria of the cell
• Cellular respiration
releases energy
• Water and carbon
dioxide are also
produced in the process
• Carbon dioxide is gas
Check Your Understanding
1. What do cells need in order to carry out life
functions?
2. What is diffusion?
3. Where in the cell does cellular respiration
take place?
Photosynthesis
• Animals eat other
organisms to get food
• Plants make their own
food using carbon
dioxide, water, and
energy from sunlight
• Photosynthesis
Chlorophyll
• Chloroplast is only in
plant cells. It converts
sunlight into food and
energy
• Chlorophyll is inside of
chloroplast, its aids in
absorbing energy from
the sun
• Carbon dioxide gas ->
plant cell
• Water -> cell membrane
in roots
• Sunlight -> energy
(chlorophyll)
• Water + Carbon
dioxide= Plant Food
• This “plant food” is a
type of sugar
• The sugar is stored until
it is needed for cellular
respiration
Photosynthesis
• Light energy + water +
carbon dioxide ->
oxygen + sugar
• Oxygen is made as a
“byproduct”
– It passes out of the plant
cell and into air
• After the plant cells
made their own food
they continue cellular
respiration like animal
cells
• Mitochondria uses
oxygen to release
energy in food
molecules and form ATP
Cellular Respiration and
Photosynthesis
• Cellular Respiration
• Photosynthesis
• Oxygen + sugar -> ATP
• Light energy + water +
energy + water + carbon
carbon dioxide ->
dioxide
oxygen + sugar
• Cellular respiration uses
oxygen and sugar to
release energy
• Water and carbon
dioxide are given off as
byproducts
• Photosynthesis uses
energy, carbon dioxide,
and water to make
oxygen and sugar
Check for Understanding
1. What three things are needed by plant cells
during photosynthesis?
2. Why do plants need to go through the
process of photosynthesis?
3. What two things are produced as a result of
photosynthesis?
LAB