Photosynthesis Photosynthesis Photosynthesis is the way that plants

Photosynthesis

Photosynthesis • Photosynthesis is the way that plants make food from sunlight – You take in food which is digested and then transferred to cells for use by mitochondria – Plants can’t “eat” so they make food which is then transferred to the mitochondria – Mitochondria then transform the “food energy” into chemical energy

Photosynthesis Raw Materials 6 CO 2 + 6 H 2 O Carbon dioxide Water

Photosynthesis Source of Energy sunlight

Photosynthesis Necessary Catalyst Chlorophyll

Photosynthesis → Produces

Photosynthesis Products C 6 H 12 O 6 + 6 O 2 Oxygen Carbohydrate (glucose sugar) (to breathe)

Photosynthesis 6 molecules of carbon dioxide gas from the atmosphere and 6 molecules of water from the environment will react with sunlight in the presence of chlorophyll to form a molecule of nutrient glucose sugar and release 6 molecules of oxygen gas into the atmosphere OR

Photosynthesis 6 CO 2 + 6 H 2 O + light energy → C 6 H 12 O 6 + 6 O 2 Carbon dioxide Water Carbohydrate Oxygen

Photosynthesis Say it in sentence form!

Photosynthesis ______ + ____ → _______ + ____ Carbon dioxide Water Carbohydrate Oxygen

Photosynthesis Some bacteria

Photosynthesis Some protists Some bacteria

Photosynthesis Most plants

Photosynthesis • Autotroph: organism that makes its own food (photosynthesis or chemosynthesis) • Heterotroph: organism that must consume food

Epidermis Mesophyll (site of Chloroplasts And Photosynthesis) Guard cells Epidermis Vein Stoma

Photosynthesis • Epidermis: water-proof covering of the surface of the leaf

Photosynthesis • Stoma: Opening in the leaves – water exits – O 2 exits – CO 2 enters

Photosynthesis • Stoma: Opening in the leaves – water exits – O 2 exits – CO 2 enters Transpiration

Photosynthesis • Mesophyll: central layer of cells – contains chloroplast-rich cells – site where most photosynthesis occurs

Photosynthesis

Photosynthesis • 2 sets of reactions:

Photosynthesis

Photosynthesis • 2 sets of reactions: – LIGHT DEPENDENT REACTIONS

Photosynthesis • 2 sets of reactions: – LIGHT DEPENDENT REACTIONS – LIGHT INDEPENDENT REACTIONS (Calvin cycle)

Light Dependent Reactions • Thylakoids contain pigments (molecules that absorb light)

Light Dependent Reactions • Thylakoids contain pigments – chlorophyll a • absorbs red and blue light • reflects green light

Light Dependent Reactions • Thylakoids contain pigments – carotenoids • absorb blue • reflect red and yellow light

Light Dependent Reactions • Thylakoids contain pigments – absorb sunlight energy – give up energized electrons

Light Dependent Reactions • ATP and NADPH are produced to be used in the next step of photosynthesis: the Calvin cycle (Light Independent Reactions) • Requires input of light energy and a water molecule • Oxygen is produced and released as a byproduct

Light Dependent Reactions Electron acceptor Ele ctr on 2 e- Tra ns 2 e- Ele c tro n Sy Tra ste ns m por t po rt S ys te m 2 e- NADPH + H+ Water molecule is split 2 H+ Oxygen is + released as a by-product O NADP+ + 2 H+ H 2 O 2 e- Light Energy is removed from the electrons as they move down the ETC. The energy is used to convert ADP to ATP Photosystem II ADP + Pi + Energy → ATP and NADPH leave thylakoid and enter stroma to be used in the Calvin cycle

Light Independent Reactions (Calvin cycle)

Calvin cycle • Uses ATP and NADPH produced in the light-dependent reactions • Also uses CO 2 taken in through stoma • Requires no sunlight; occurs around the clock • Produces carbohydrate which is used by mitochondria in respiration

Photosynthesis

Photosynthesis 6 molecules of carbon dioxide gas from the atmosphere and 6 molecules of water from the environment will react with sunlight in the presence of chlorophyll to form a molecule of nutrient glucose sugar and release 6 molecules of oxygen gas into the atmosphere OR

Photosynthesis 6 CO 2 + 6 H 2 O + light energy → C 6 H 12 O 6 + 6 O 2 Carbon dioxide Water Carbohydrate Oxygen