Bio 4: Photosynthesis Flashcards Preview

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Flashcards in Bio 4: Photosynthesis Deck (17):
1

Autotrophs

Organisms that use light or chemical energy and inorganic molecules to synthesise complex organic molecules.

2

Heterotrophs

Organisms that ingest and digest complex organic molecules releasing chemical potential energy stored in them.

3

Chloroplasts

+Disc shaped
+2-10um long
+Double membrane
+Intermembrane space 10-20nm wide
+Folded into lamellae (stack: granum)
+Stroma - fluid filled matrix
+Thylakoids

4

Photosynthetic pigments

Molecules that absorb light energy. Each pigment absorbs a range of wavelengths in the visible region and has its own distinct peak of absorption.

5

Chlorophyll

Magnesium iron in it
Chlorophyll a has two forms - 680 and 700
680 is in PSII, 680nm
700 is in PSI, 700nm
a absorbs blue light

6

Carotenoids

Carotene - orange
Xanthophyll - yellow

7

Light dependent stage

In the thylakoid membrane

8

Water (in LDS)

+ source of hydrogen ions for chemiosmosis
+ source of electrons

9

Photophosphorylation

Making of ATP from ADP and P in the presence of light.

10

Electron carriers

Molecules that transfer electrons.

11

Electron acceptors

Chemicals that accept electrons from another compound. They are reduced while acting as oxidising agents.

12

Cyclic photophosphorylation

+Only PSI
+No redNADP made
+No photolysis of water
+Small amount of ATP made

13

Non-cyclic photophosphorylation

+PSI & PSII
+ATP is made
+Photolysis of water
+redNADP is made

14

Light independent stage

Takes place in the stroma, also called the Calvin cycle. carbon dioxide is fixed and used to build complex organic molecules.

15

Calvin Cycle

CO2 combines with RuBP, makes GP
GP is reduced and phosphorylated making TP (+ NADP and ADP + P)
TP is phosphorylated
5/6 TP becomes RuBP

16

Light intensity

+More electrons for photophosphorylation
+Therefore more ATP and redNADP
+More GP is reduced to TP
(High TP and RuBP, low GP)

17

Temperature

+Above 25C oxygenase activity increases more than carboxylase
+Photorespiration exceeds photosynthesis
+ATP and redNADP are wasted
+Very high also damages proteins