Warm-up

• So, you just put some new plants in the garden.

• What do these plants need to grow?

Unit 4Energy in a Cell

Learning Intention: Understand how the cell transforms energy into

useable forms

Organisms need energy for…

• Movement• Active transport• Digestion• Excrete waste• Breathing/respiration• Make new cells• Reproduction

Energy in the cell

• ATP, Adenosine triphosphate– Adenosine molecule with 3 phosphates

How is ATP formed and used for energy?

• ATP acts like a charged battery. • Cell recycle the ATP they use for work– When ATP is broken down to form ADP, energy is

released for use by the cell– ADP, adenosine diphosphate is like a drained

battery• BUT, it can be re-charged!!!!

Relocation of electrons transfers energy!!!!

• Electron transfers are called oxidation-reduction reactions, or redox reactions.

Review Page 223 in the (B) Textbook.

Where do organisms get energy?The Food Chain

What are autotrophs and heterotrophs?

• Autotrophs-organisms that can make their own food (producer)

• Heterotrophs- organisms that can’t make their own food (consumer)

• Autotrophs: “self” “feeders” They make their organic molecules from inorganic raw material. Producers of the biosphere– Photoautotrophs: Organisms that can use energy from light to drive the synthesis of organic molecules– Chemoautotrophs: Use energy from chemical to drive synthesis of organic molecules

What is Photosynthesis?

Photo=Light Synthesis=to make• The process which takes place in plants

where glucose and oxygen are made from sunlight

What is the photosynthesis equation?

6 H2O+ 6 CO2 + sunlight sunlight --> C6H12O6 + 6 O2

Water Carbon dioxide Glucose Oxygen

Where is the site of photosynthesis?

• Chloroplasts in leaf cells

Pigments in chloroplasts trap the energy in sunlight

Light Receptors:– Chlorophyll a- Directly involved in the light reaction– Accessory Pigments- chlorophyll b, carotenoids, xanthophyll. Absorb the wavelengths that are reflected from Chlorophyll a

Why do most plants look green?

2 parts of photosynthesis• Light Dependent Reaction• Light Independent Reaction– Also called the Calvin Cycle

Journal: What molecules are reactants for each reaction? What molecules are products of each reaction?

What happens in the light dependent reactions of photosynthesis?

1. Light excites electrons (ZAP & Wohoo!!!)2. Electrons are then moved down an

electron transport chain. (Chuga – Chuga)3. Energy from the electrons is used to

recharge ATP and NADPH (BAM!)– H2O is split to replace lost electrons forming 02

Photosystems harvest energy from light to charge ADP and NADP+

What happens during the Light Independent Reactions/ Calvin Cycle?

• Energy stored in ATP and NADPH is used to attach carbon atoms from CO2 to form organic compounds– Glucose, amino acids, and lipids– Glucose, a monosaccharide, is combined to form

what polymers– Amino acids are combined to form what polymers?

**AP Bio

Where do the light independent reactions take place?

• The Stroma

Anatomy of a Leaf• Cuticle-outer waxy layer of leaf• Epidermis-upper and lower layer• Mesophyll-middle layer of leaf-chloroplasts• Vein-Tubes for transport of food and water• Stoma-opening in the lower epidermis where gases pass

through• Guard Cells-Surround the stoma and regulate the opening and

closing of the stoma

How does photosynthesis in a plant work?

• CO2 + H2O + sunlight (reactants)• CO2 enters the plant through the stoma in the leaves• H2O rises to the leaves through veins after being

absorbed• Sunlight diffuses through the cuticle and epidermis

into mesophyll cells.• H2O+CO2+sunlight ---> C6H12O6+O2

Journal: What limits Photosynthesis?

• Having enough CO2

• Having enough H2O, may lose it through the process of transpiration, water vapor exits the leaf through the stoma

• Having enough sunlight

How do plants deal with sunlight as a limiting factor?

• Plants grow large leaves• Plants grow toward light

How do plants deal with water as a limiting factor?

• Small leaves• Stomata on the ventral or bottom surface of

the leaf• A cuticle or waxy layer on the leaves• Stomata only open at night

How do plants deal with CO2 as limiting factor?

• This usually isn’t a limiting factor except under water

• Stomata open lots

What is the function of the:

• Stomata= allow gases to go in and out of the leaf

• Guard cells= regulate opening and closing of stomata

• Veins= carry food and water through plant• Cuticle= decrease water loss• Mesophyll cells= carry out photosynthesis• Epidermis cells= protect leaf

The General Equation

6CO2 + 6H20 Light C6H12O6 + 6O2