Bioenergetics

Bioenergetics

The study of energy flow (energy transformations) into and within living systems

Bioenergetics

Occurs wherever chemical conversions can take place Cytoplasm Plastids Mitochondria

Cytoplasmic bioenergetics

Simple reactions can occur yielding small amounts of energy

Plastids

Many types: Leucoplasts

store starch

Chromoplasts store pigments

Chloroplasts store chlorophyll

chloroplast

stroma

grana (thylakoids)

Plastids – What are they?

Pro = EarlyChromo = ColorChloro = GreenLeuco = WhiteAmylo = Starch

Where are the chloroplasts in a leaf?

In the mesophyll!

Key features of leaves

Cuticle – waxy covering Mesophyll – two middle layers

of cells, mostly contain chloroplasts

Xylem and Phloem – Water and sugar transport tubes

Stomata – air openings Guard cells – open and close stomata

Guard cells open and close stomata

Sometimes H2O is lost, must be replaced by roots

Transpiration - H2O diffusion out of plants

Gas Exchange

CO2 enters through the stomata

O2 exits through the stomata

CO2 and O2 diffuse throughout the leaf

CO2 diffuses into the chloroplast for photosynthesis

Chloroplasts

Contain Thylakoids (flattened sacs) Have pigments in their membranes

Grana - Stack of thylakoids Stroma - Fluid inside

chloroplast

chloroplast

stroma

grana (thylakoids)

Pigments

Chlorophyll Found in chloroplasts Green pigment

Two forms - a and b Absorb blue and red

light, reflect green/yellow

Pigments

Accessory pigments Found in the

Chromoplasts Absorb and reflect other

colors Can only be seen in the

fall of the year

Why do leaves change color in the fall?

Photosynthesis

General Equation

CO2 + H2O --> C6H12O6 + O2

Major Steps1. Absorb light energy§ Convert light energy into chemical energy§ Store chemical energy in sugars

Initial Reactants

H2O enters the plant through the roots

CO2 diffuses into the leaf through the stomates

Guard cells open and close through the day to regulate homeostasis

Absorb Light Energy

In the chloroplast, pigments are embedded in the thylakoid membrane

Pigments have photosystems Different wavelengths of

light stimulate the movement of electrons

Convert light energy into chemical energy

Movement of electrons generates ATP

Store chemical

energy in sugars

CO2 diffuses into the stroma of the chloroplast

Here, it gets converted into glucose using the chemical energy generated into ATP

End products

Glucose Oxygen (by-product)

Diffuses out of the leaf at the stomates

General Energy Transformations

Light Energy Chemical Energy Chemical Energy

Sunlight ATP Glucose

All organisms must obtain and transform energy for their life processes.

Animals Plants Fungi Protists Bacteria

How do organisms make energy?

Photosynthesis makes energy for the purpose of making glucose

ALL organisms use Respiration to make additional energy

Why Respiration?

Movement Transport in cells Maintenance Nervous Signals Biosynthesis

Respiration

Release of energy by breaking down glucose

1 Glucose = 38 ATPs!!!!!!

General Equation

C6H12O6 + O2 --> H2O + CO2 + ATP

Life has options…

Aerobic - Uses Oxygen! Animals Plants

Anaerobic - Little or no oxygen! Some animals Yeast Bacteria

Major Steps of Aerobic Respiration

Glycolysis Kreb’s Cycle Electron Transport Chain

Glycolysis

Simple step in the cytoplasm Makes 2 ATPs! Glucose is cut in half! Yields two Pyruvate molecules

(3 carbons each)

Kreb’s Cycle

Occurs inside the mitochondria Pyruvate molecules get broken into CO2

and H+ Makes 2 more ATPs!

Electron Transport Chain

Occurs on the cristae (membrane) of the mitochondria

H+ transfer excess energy to ATP synthase

Excess H+ + O2 H2O

O2 is the final electron

acceptor!

ATP Synthase

Enzyme responsible for: ADP to ATP and O2 to H2O

Cellular Respiration

Electron transportchain and oxidativephosphorylation

Chemical energy

Chemical energy (high-energy electrons)

GlucosePyruvicacid

Glycolysis

Mitochondrialcristae

Cytosolof cell

Via oxidativephosphorylation

H2O

Mitochondrion

Krebscycle

CO2

CO2

ATPATPATP

Can you function without O2?

Glycolysis yields 2 ATP Glycolysis does not require Oxygen

Yes you can!! You just get a little bit of energy

The Role of ATP

In cells, ATP is used for: Movement Transport in cells Maintenance Nervous Signals Biosynthesis

Chemical Energy and ATP

Most cell processes use ATP for energy Do you get energy from eating sugar?

Yes? No?

All cells use ATP

ATP is a molecule that transfers energy How is ATP like money in your wallet?

ATP is used to: Build molecules Move materials

Structure of ATP

Energy is released when a phosphate group is removed from the molecule

ATP = Adenosine TRI-phosphate

ATP

When the third P is removed, energy is released

Unstable and easily removed for energy

ATP = ADP + P ADP = Adenosine DI-

phosphate

ATP and ADP

Questions

Where are molecules from food involved in the cycle of ADP to ATP?

Describe the relationship between energy stored in food and ATP.

How many ATP?

Carbohydrates offer easy ATP Carbs are not stored in the body

One glucose = 38 ATP molecules!

Proteins about the same as Carbs Not typically used for energy but to build

more proteins

Fats (lipids) offer the most ATP One triglyceride = 146 ATP molecules

How do plants eat?

They make their own food

Plants absorb energy from the sun and make sugars to break down for ATP

Chemosynthesis

Some species of bacteria use chemicals to make food

They break the food down for ATP

Solar Energy?

Calculators, homes and cars use energy from sunlight

Energy for people comes from ATP ATP comes from the breakdown of

sugars How are sugars made?

Photosynthetic organisms

Producers – organisms that produce the source of chemical energy for themselves and for other organisms Plants Bacteria Protists

Basic Food Chains

Animals eat plants = consumers Animals that eat other animals, bacteria

and fungi that decompose organisms Wolf eats rabbit, rabbits tissues supply

energy to wolf, tissues were built from plants, which made the sugars and other carbon-based molecules

Photosynthesis

Plant cells use sunlight energy to make organic compounds

Directly or indirectly, the energy for almost all organisms begins as sunlight

Sunlight and Radiant Energy

Ultraviolet Microwaves Visible light or Radio waves?

Plants absorb visible light

Where does it occur?

In the leaves!

Fermentation

When you undergo heavy exercise, you force your muscles to use fermentation!

Large amounts of Oxygen for Aerobic Respiration cannot be stored in cells

Cells need energy, so they choose the alternate route!

Anaerobic Respiration

Two types Lactic Acid Fermentation

Yeast and bacteria, your muscles Alcoholic Fermentation

Without fermentation, glycolysis would not continue

Fermentation recycles the molecules that allow glycolysis to continue

Fermentation

A build-up of lactic acid?

That must burn! It does until you recovery breath,

this is why your body breathes hard for several minutes after you stop exercising

You are making up for the oxygen loss

The replenishment of oxygen allows the cells to remove the excess lactic acid

Food Diary

Write down all of the foods you ate in the last 24 hours

Now, cross out…

Lactic Acid Fermentation

What would life be like without: Cheese, bread and yogurt?

Bacteria and Mold Convert milk into cheese Make yogurt go sour

Alcoholic Fermentation

Some yeast and plants Begins at the same point of lactic acid

fermentation Used to produce

Bread, beer and wine

Microbes in our Digestive System?

Bacteria in your digestive tract rely on fermentation

Without them we would not fully digest food They allow us to absorb more nutrients from

food

All cells need chemical energy.

Processes that make food include: Photosynthesis Chemosynthesis

Processes that make energy include: Respiration (two types) Fermentation (two types)