A. chloroplast B. photosynthesis C. cellular respiration D. glucose E. fermentation F. chemical energy G. mitochondria ____ 1. To stay alive, a cell must be able to release the ____________ that is stored in a molecule's bonds. ____ 2. ____________ is the process by which plants produce glucose and oxygen. ____ 3. A major energy source for most cells is a sugar molecule called ____________. ____ 4. Cells use oxygen to release the energy in glucose during ____________. ____ 5. Cellular respiration takes place in a cell's ____________. ____ 6. If a muscle cell does not have enough oxygen, it can still release energy through the process of ____________.

1. F. chemical energy A. chloroplast B. photosynthesis C. cellular respiration D. glucose E. fermentation F. chemical energy 2. B. photosynthesis 3. D. glucose 4. C. cellular respiration 5. G. mitochondria G. mitochondria 6. E. fermentation ____ 1. To stay alive, a cell must be able to release the ____________ that is stored in a molecule's bonds. ____ 2. ____________ is the process by which plants produce glucose and oxygen. ____ 3. A major energy source for most cells is a sugar molecule called ____________. ____ 4. Cells use oxygen to release the energy in glucose during ____________. ____ 5. Cellular respiration takes place in a cell's ____________. ____ 6. If a muscle cell does not have enough oxygen, it can still release energy through the process of ____________.

Time 12:00am 1:00 am 2:00 am 3:00 am 4:00 am CO2 (ppm) 900 912 930 948 955

Chapter 2: How Cells Function 2.1: Chemical reactions take place inside cells

2.2: Cells capture and release energy

2.3: Materials move across the cell’s membranes

Have already learned: -the cell is the basic unit of all living things -Plant cells and animal cells have similarities and differences Will learn: -why cells need energy -How energy is captured and stored -How plants and animals get energy

All cells need energy

• • • Animal cells, plant cells, bacteria cells, unicellular organisms: ALL need energy – Animals get it from food – Plants get it from the sun Type of energy = chemical energy!

– Cells must release the chemical energy stored in bonds (between atoms) in order to stay alive Cells release chemical energy from glucose (sugar molecule)

All cells need energy

• • • Muscle cells  – release chemical energy from glucose to move legs  • More running, more glucose needed Energy from?

– food!

For plants: – Sunlight + water + CO 2 glucose + O 2 

• •

Some cells capture light

Source of ALL energy?

–

Ultimately…the SUN!

Photosynthesis – process that plants cells use: – Energy from sunlight into chemical energy – Takes place in plant cells that have chloroplasts • Chloroplasts contain chlorophyll • Chlorophyll absorbs light 1.

Starting materials: carbon dioxide (air) + water (soil) 2.

3.

The process: Materials enter chloroplasts + energy (sunlight)  The products: Glucose and Oxygen!

Some glucose is linked together • to build large carbohydrates: stored as starch

energy

All cells release energy

• • Glucose and other sugars are “cell food” – Glucose is stored as glycogen or starch • Must be broken down to use as energy • Break the bonds of sugar – release energy!

Two ways: – Respiration • Requires oxygen • Release more usable energy than fermentation – Fermentation • Does not require oxygen

Cellular Respiration

• • 1.

2.

3.

Think: reverse of photosynthesis …occurs in mitochondria ( chloroplasts ) – Starting materials: oxygen and sugar • USE oxygen to RELEASE energy stored in sugars, such as glucose Gain oxygen and sugars – The process: Glucose in cytoplasm is broken down into smaller molecules, releasing some energy – Molecules move to mitochondria and oxygen enters cell (and moves to mitochondria) – The smaller molecules are further broken down • Hydrogen released (combines with oxygen to make water) – The products Energy, carbon dioxide, water ( starting products of … ) Some of this energy is transferred to other molecules, so is released as heat

• • •

Fermentation

Cells releasing energy withOUT oxygen When cells first break glucose into smaller molecules, a small amount of energy is released – With oxygen…cellular respiration would continue in the mitochondria – Without oxygen…fermentation continues in the cytoplasm Two types: Alcoholic and Lactic Acid Fermentation – Both start with small molecules made from sugars – Next reactions occur producing either alcohol and carbon dioxide OR lactic acid – In both, a small amount of energy is then released

Fermentation

• Examples: – Bread: mix flour, milk, and sugar, with a microorganism yeast • Without oxygen, yeast converts the sugar into alcohol and carbon dioxide (CO 2 ) – bubbles of CO 2 gas form in the dough causing it to rise…alcohol evaporates, the yeast is killed, and CO 2 makes the bread spongy – Yogurt, cheese, sourdough bread • Lactic acid bacteria convert the sugars found in milk – Sourdough bread: acidity changes  sour flavor – Yogurt and cheese: milk partially solidifies: creamy texture of yogurt…if fermentation continues  cheese

Energy and exercise

• Some cells (and organisms) can release energy using either cellular respiration or fermentation – – At rest, muscle cells store both energy and oxygen During exercise all the energy and oxygen may be used up • Fermentation is then used to break down the sugars – Less energy than with cellular respiration – Waste product: lactic acid = burns!

• • Breath hard to replace used oxygen Muscles stop hurting and build back up oxygen and energy levels

• • http://www.cambridgestudents.org.uk/subjec tpages/biology/igcsebiology/igcsebiologysimul ations Grow a plant