Unit 4 Cell Metabolism Metabolism A process that

Unit 4: Cell Metabolism

• Metabolism = A process that involves using energy to build or break down molecules • Photosynthesis and cellular respiration involve making and breaking energy-rich molecules

Obtaining Nutrients: 2 Strategies • Autotrophs (self feeders)= make their own food from “inorganic” substances and energy Ex: Plants, algae, certain bacteria • Heterotrophs (different feeders)= obtain their nutrients by feeding on other organisms Ex: Animals and Fungi

Photosynthesis • Happens in: autotrophs • Goal: Converting light energy into chemical energy (glucose) • Glucose: carbohydrate monomer C 6 H 12 O 6

Photosynthesis Equation Reactants Products carbon dioxide + water + light glucose + oxygen CO 2 + H 20 + C 6 H 12 O 6 + O 2

Cellular Respiration (Autotrophs AND Heterotrophs) • Happens in: autotrophs AND heterotrophs • Goal: converting chemical energy (glucose) into USABLE energy (ATP) • ATP = adenosine triphosphate

Why ATP? • ATP is a USABLE form of energy for the cell • Energy is released from ATP by breaking the bonds between phosphate groups Bond Breaks Here!

Cellular Respiration Equation Reactants Products Glucose + oxygen Energy + Carbon Dioxide + Water C 6 H 12 O 6 + O 2 ATP + CO 2 + H 20

Comparing Photosynthesis and Respiration CO 2 + H 20 + Energy (Light) C 6 H 12 O 6 + O 2 C 6 H 12 O 6 + 02 Energy (ATP) + CO 2 + H 20 IMPORTANT COMPARISON!: the reactants of one reaction are the products of the other reaction!

Photosynthesis!

Where on the plant does photosynthesis take place? • LEAVES of plants • Very large leaves (Ex: Rain Forest Leaves) are used to capture A LOT of sunlight • Pores at the bottom of leaves (stomata) take in carbon dioxide and release oxygen

Photosynthesis Summary • Takes place in the chloroplasts (in leaf cells)! • 2 Main Processes: 1) Light Reactions 2) Dark Reactions (AKA calvin cycle or light -independent reactions)

Chloroplast Structure • Thylakoids are stacked to form grana • Light Reactions take place in the thylakoid membrane • Dark Reactions take place in the stroma

Part 1: Light Reactions • Purpose: 1) absorb light 2) produce oxygen 3) transfer sun energy to electrons • Requires a green pigment called chlorophyll to absorb sunlight • Where: thylakoid membrane

What happens to the electrons energized by sunlight? • Join with a molecule called NADP+ (an electron carrier) • Sunlight splits water into hydrogen and oxygen

Summary of Light Reactions Start With: Sunlight, water, NADP+ End with: Oxygen, NADPH, ATP

So how do we get ATP? • Sunlight hits clusters of pigment called Photosystems I and II • This excites electrons and joins them with protein carriers and finally NADP+ • ATP is created when protons flow through an enzyme called ATP synthase Explanation continued on next slide…

Part 2: Dark Reactions/Calvin Cycle • Purpose: produce glucose from CO 2 • Uses electrons from NADPH and energy from ATP (broken back into ADP and P) • Does not require light • Where: stroma

Summary of Dark Reactions (Calvin Cycle) Start With: CO 2 , NADPH, and ATP End with: Glucose and NADP+

Notice that the products of the light reactions are used in the dark reactions!

Factors Affecting the Rate (Speed) of Photosynthesis 1. Intensity of light 2. Concentration of carbon dioxide 3. Temperature.

Thought Question • Why do scientists believe that bacteria with photosynthetic abilities were some of the first organisms on Earth?

Organism of the Day • Golden Eagle

• These birds have been measured in captivity at a wingspan of 9. 7 ft and a weight of 27 pounds. • They can additionally be found in tundra, shrublands, coniferous forests with openings and steppe, prairies and other regional grassland habitats. • These organisms are carnivorous.

• Typical prey weight usually is around 10 pounds.

How powerful are they? http: //www. youtube. com/watch? v=Vkl. Ts. Tid_I • 0 -1 min 15 sec and at 4 min 10 sec mark

Sugar Glider

“Sugars” • Marsupials – They have a pouch like a kangaroo • Webbed from the arms to the legs to create wing-like appendages • Jump from tree top to tree top which is where they got their name • This is the exotic version of the flying squirrel

They originally hail from Australia, Indonesia and New Guinea, and live in forests. http: //www. youtube. com/watch? v=yq. SGJz. Siz 5 s