Transcript Photosynthesis and Respiration

Unit 6:
Cell Processes and
Energy
Chemical Compounds in Cells
•Element- any substance that can’t be
broken down into simpler
substances.
- Ex: oxygen and nitrogen
•Compound- When two or more elements
combine chemically, they form a
compound.
- Ex: water and carbon dioxide
Chemical Compounds in Cells
•Watera) Made up of 2 hydrogen and 1 oxygen
atoms
b) Dissolves chemicals that cells need
c) Most chemical reactions in cells could
not take place withOUT water.
d) Helps cells keep their size and shape.
e) Helps maintain a stable temperature
(water temp changes slower than air
temp)
Chemical Compounds in Cells
•Organic compounds- contain carbon
•Inorganic compounds- do not contain
carbon
- Ex: water and salt
Carbohydrates
a) Organic compounds
b) energy-rich compound made of
carbon, hydrogen, and oxygen
c) Ex: starch and sugar, fruit, bread
d) Sugar + sugar = starch
e) Plant cells use starch to store energy,
used for short-term storage
f) Important components of cell parts
Ex: Cellulose in cell wall
Carbohydrates
Lipids
a) Ex: fats, oils, waxes
b) energy-rich compounds, made of
carbon, hydrogen, and oxygen
c) Contain more energy than carbs
d) Cells store energy, used for long-term
storage
e) Cell membranes are made of lipids
Proteins
a) Long organic molecules of carbon,
hydrogen, oxygen, nitrogen and
sometimes sulfur.
b) Ex: spider webs, fingernails,
feathers, meat, eggs, nuts
c) Make up cell organelles
d) Proteins called enzymes help chemical
reactions occur
e) Made of smaller molecules called
amino acids
f) The order of amino acid linkage
determines the protein’s identity
Nucleic Acids
a) Long organic molecules of carbon,
hydrogen, oxygen, nitrogen, and
phosphorus
b) Contain cells’ instructions for life
c) DNA (Deoxyribonucleic acid)–
carries genetic info., passed from
parent to offspring
d) RNA (ribonucleic acid)- important for
protein synthesis
Molecule Movement
•The cell membrane is semi-permeable
which means some things can pass
through it and others cannot
Molecule Movement
•Diffusion- the main way small molecules
move across the cell membrane.
a) Movement of molecules from high
to low concentration
b) Cause of diffusion- Molecules
bump into each other
c) Diffusion of oxygen- more oxygen
outside cells than in, so oxygen
moves from high to low
concentration and enters cells.
Molecule Movement
•Osmosis- The diffusion of water from
an area of high concentration to an
area of low concentration.
•Many cellular processes depend on
osmosis
Molecule Movement
•Osmosis- The movement of water to an
area of higher dissolved materials .
• Many cellular processes depend on
osmosis
Cell Transport
a) Passive transport- movement of dissolved
materials through a cell membrane without
using the cell’s energy.
-Ex: Diffusion and osmosis
b) Active transport- movement of dissolved
materials through a cell membrane using the
cell’s energy.
Ex: engulfing
c) Engulfing- cell wraps around a particle and
engulfs it. Also called endocytosis.
Cell Transport
d) Why are cells so small?
- Smaller cells= more surface area for
movement of molecules. Less
distance for cytoplasm to span.
e) Cells are small so they can be efficient!
Cellular Energy
•Every living thing needs energy
•The sun is the source of energy for most
living things
•Photosynthesis
a) Photo- light
b) synthesis- to put together
c) Nearly all living things obtain
energy either directly or indirectly
from the energy of sunlight
captured during photosynthesis
d) Autotroph- makes its own food
e) Heterotroph- obtain food by eating
other organisms
Sources of Energy
• Nearly all living things obtain energy either
directly or indirectly from the energy of
sunlight captured during photosynthesis.
Photosynthesis- Stage 1
•Photosynthesis: Stage 1- Capturing the
energy in sunlight
a) Happens in chloroplasts in leaves
b) Pigments- colored chemical compounds
that absorb light. Gives leaves their
green color
c) Cholorphyll- the main pigment in
chloroplasts
d) See figure on pages 88-89
Photosynthesis- Stage 2
•Photosynthesis: Stage 2- Using energy to
make food
a) Cells need water (absorbed by
roots from soil)
b) Cells need carbon dioxide (enters
leaves from air)
c) Stomata- opening in leaves,
allows carbon dioxide and
oxygen to move in to and out of
leaves
d) Happens inside chloroplasts,
water and CO2 undergo
chemical reactions
Photosynthesis- Stage 2
•Photosynthesis: Stage 2- Using energy to
make food
e) Reactions are powered by energy
from the first stage
f) Plants produce sugar with the
formula C6H12O6
g) Oxygen is produced and exits
through stomata
sunlight
6CO2 + 6H2O  C6H12O6 + 6O2
Carbon Dioxide + Water

Sugar + Oxygen
The Two Stages of Photosynthesis
• During photosynthesis, plants and some
other organisms use energy from the
sun to convert carbon dioxide and water
into oxygen and sugars.
Cellular Respiration
•Cellular Respiration- animal cells break down
sugar and obtain energy
a) Your cells store energy until you
need it
•Respiration: Stage 1
a) Happens in cytoplasm
b) sugar is broken up into smaller
molecules
c) oxygen is not involved (Anaerobic)
d) Releases a small amount of energy
Cellular Respiration
•Respiration: Stage 2
a) Happens in mitochondria
b) Small molecules from step one
are broken down even further
c) Requires oxygen (aerobic)
d) Releases LOTS of energy
e) See page 92
C6H12O6 + 6O2  6CO2 + 6H2O
Sugar + Oxygen  Carbon Dioxide + Water
Two Stages of Respiration
• During respiration, cells break down simple
food molecules such as sugar and release the
energy they contain.
Photosynthesis and Respiration
• You can think of photosynthesis and
respiration as opposite processes.
Fermentation
a) Energy-releasing process that DOES NOT
require oxygen
b) Energy released is much less than that
during cell. resp.
c) Happens in environments that lack oxygen
Alcoholic Fermentation
d) Alcoholic Fermentation
- Happens in yeast and single-celled
organisms
- Releases alcohol
- Also releases carbon dioxide and energy
- Used to make bread and beer
Lactic Acid Fermentation
e) Lactic Acid Fermentation
- Happens in your muscles
- Produces lactic acid
- Makes your muscles
sore
- Happens when muscle
cells use up
oxygen faster
than it can be
replaced