Transcript Ways to Gain Energy

Warmup 10/12/16
How do plants get energy? What do you know?
Objective
To learn how both animal
and plant cells get their
energy.
Tonight’s Homework
p 80: 1-3
p 85: 2, 3, 8
Notes on Cellular Energy and Respiration
Ways to Gain Energy
Cells have to use energy all the time. Even if
they’re just ‘sitting there’.
If a cell stops using energy, it is dead.
Every time a cell does something, it uses
energy. Even to build fats and carbs for later
use.
So what are the ways that cells use energy?
Notes on Cellular Energy and Respiration
Energy use is broken into two types:
Autotrophs – “Auto” means “self”, “troph”
means “nourishment”.
These types of organisms generate their own
food. These are mainly plants and algae.
Notes on Cellular Energy and Respiration
Energy use is broken into two types:
Heterotrophs – “Hetero” means “other”, “troph”
means “nourishment”.
These types of organisms have to get their food
from something else. This includes anything
that eats plants or animals for food.
Notes on Cellular Energy and Respiration
Photosynthesis
So how do plants get their own energy?
From the sun! But how do we know?
Notes on Cellular Energy and Respiration
Photosynthesis
So how do plants get their own energy?
From the sun! But how do we know?
Back in the 1600s, scientists thought that plants
got their energy from the soil.
A scientist named Van Helmont did a ton of
experiments and found that plants got almost
none of their energy that way.
Notes on Cellular Energy and Respiration
In 1772, a scientist named Joseph Priestly did
some experiments where he put a plant in a jar
and others in the dark.
After many experiments, he found that plants
needed fresh air and light to properly grow.
Notes on Cellular Energy and Respiration
After a lot of work by a scientist named Dr.
Melvin Calvin, we now know the chemical
process:
CO2 + H2O + light  C6H12O6 + O2
Notes on Cellular Energy and Respiration
Chlorophyll
So how do plants do this exactly?
Chlorophyll has the special property of being
able to absorb light.
There are actually 4
kinds of chlorophyll
and each can absorb
light of a slightly
different type.
They reflect green light, so that’s what we see.
Notes on Cellular Energy and Respiration
Conditions for Photosynthesis
Photosynthesis doesn’t happen all the time. A
plant needs to meet a few certain conditions for
photosynthesis.
- Sufficient light of the right type.
If there isn’t enough light, or if the light is
all green, a plant can’t absorb it.
- Carbon dioxide.
Our reaction showed that plants need to
take in CO2 for the reaction to work.
- Temperature
If it is too hot or too cold, photosynthesis
fails!
Notes on Cellular Energy and Respiration
Cellular Respiration
So how do things like people and animals get
energy?
We do what’s called “cellular respiration”.
“Respiration” sounds like “breathing” but in this
case it isn’t.
Respiration is just when a cell breaks down
energy into ATP so it can function.
Respiration comes in two forms.
Notes on Cellular Energy and Respiration
Aerobic
“Aerobic” has a root of “aero” which means “air.”
When most cells break down energy, they do a
reaction that requires oxygen.
2ATP + C6H12O6 + O2  CO2 + H2O + 4ATP
You’ll notice that this is the same as
photosynthesis but backwards. This takes the
energy that plants store and breaks it back
down.
Notes on Cellular Energy and Respiration
This energy (C6H1206) is a simple sugar called
“glucose”, and the process of breaking it down is
called “glycolysis”.
Notes on Cellular Energy and Respiration
Anaerobic
If a cell doesn’t have any oxygen, it has to
make energy through an anaerobic process.
This is way less efficient than glycolysis but
helps your cells when they need extra energy.
In this form, your body uses a simple acid to
break down the glucose. This can sometimes
produce other acids.
Notes on Cellular Energy and Respiration
For example, when you exercise and “feel the
burn”, your muscles aren’t getting enough
oxygen, so they do anaerobic respiration and
make lactic acid, which burns.
Exit Question
What’s the difference between aerobic and anaerobic
respiration?
a) Aerobic uses oxygen, anaerobic does not
b) Anaerobic uses oxygen, aerobic does not
c) Aerobic makes energy, anaerobic does not
d) Anaerobic makes energy, aerobic does not
e) There is no difference
f) Not enough information