Ch 10 - Photosynthesis Flashcards by Alaina Imro

Photosynthesis

Conversion of the kinetic energy of light to potential energy in the covalent bonds of organic compounds

How well did you know this?

Not at all

Perfectly

What is made from the energy of light?

Glucose

How well did you know this?

Not at all

Perfectly

Autotroph

An organism that obtains food molecules without eating other organisms or substances derived from them

“Producers of the biosphere”

Plants

How well did you know this?

Not at all

Perfectly

Photoautotroph

Use the energy of sunlight to make organic molecules from water and CO2

How well did you know this?

Not at all

Perfectly

Heterotroph

Organism that obtains organic food by eating other organisms or their by products

“Consumers of the biosphere”

Animals

How well did you know this?

Not at all

Perfectly

Major site of photosynthesis in plants

Leaves - chloroplasts

How well did you know this?

Not at all

Perfectly

2 phases of photosynthesis

1) the light reactions

2) the Calvin cycle

How well did you know this?

Not at all

Perfectly

Pigment molecules embedded in thylakoid membranes

Chlorophylls & accessory pigments (carotenoids)

How well did you know this?

Not at all

Perfectly

Light absorbed by chlorophylls

Red & blue

How well did you know this?

Not at all

Perfectly

Light transmitted by chlorophylls

Green

How well did you know this?

Not at all

Perfectly

Chlorophyll a

Main photosynthetic pigment

CH3

How well did you know this?

Not at all

Perfectly

Chlorophyll b

Accessory pigment
Absorbs additional wavelengths & broadens the spectrum for photosynthesis
CHO

How well did you know this?

Not at all

Perfectly

Porphyrin ring

Light absorbing “head” of molecule

Mg atom in center of molecule

How well did you know this?

Not at all

Perfectly

Phytol tail

Interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts

How well did you know this?

Not at all

Perfectly

Carotenoids

Family of orange & yellow pigments found in photosynthetic organisms

Present in carrots, tomatoes, squash and green leaves

Absorb blue-violet, transmit orange

Absorb excessive light that would damage chlorophyll

Antioxidants w many health benefits

How well did you know this?

Not at all

Perfectly

Carotene

General category of carotenoids

Present in yellow vegetables

How well did you know this?

Not at all

Perfectly

Xanthophylls

Present in green vegetables

General category of carotenoids

How well did you know this?

Not at all

Perfectly

Beta-carotene

Essential nutrient the body converts to vitamin A
Present in orange carrots, sweet potatoes, and squash
Type of carotenoid

How well did you know this?

Not at all

Perfectly

Lutein

Type of carotenoid
Exists in dark green kale, broccoli, yellow egg yolk, and bell peppers
May counteract decline in cognitive function

Lycopene

Type of carotenoid

Exists in red tomatoes, watermelon, apricots, grapefruit and papaya

Zeaxanthin

Type of carotenoid

Protects against cataracts and macular degeneration

Anthocyanins

Compounds responsible for reds, pinks, purples, and blues in plants
Peak absorbance = 500nm
Attractants/repellants
Absorb UV-B light and protect DNA
Protect photosynthetic apparatus from too much light

Betanin

Prominent red pigment in beets
Betacyanin
Glycosylated compounds - betalains

Photosystem

Assemblage of chlorophylls and accessory pigments

Reaction center

Pair of chlorophyll molecules Where energy is transferred to chlorophylls Electrons are ejected wants the gain so much energy

Primary electron acceptor

Captures ejected electrons

Electron transport chain

Made up of electron carriers in the thylakoid membrane | Transport of electrons results in production of ATP and NADPH

Photosystem I

Absorbs maximally at 700nm | RC in chlorophyll a = P700

Photosystem II

Absorbs maximally at 680 P680 Responsible for large increase in atmospheric O2 that occurred 2.5 billion years ago

Step 1 in linear electron flow

Photons strike pigment molecules embedded in thylakoid membranes Energy passed to P680 - excites electrons

Step 2 in linear electron flow

Excited electron is transferred to the primary electron acceptor

Step 3

Electrons leaving P680 are replaced w electrons from water | Water = ultimate donor of electrons

Step 4

Electrons pass thru electron transport chain to PS I

Step 5

As electrons flow through electron chain, hydrogen ions are pumped from stroma into thylakoid space

Step 6

Light is absorbed at PS I, energized electrons are captured by electron acceptor These electrons are replaced by electrons passed from PS II thru electron transport chain

Step 7

Electrons are passed from primary electron acceptor of PS I to protein ferredoxin

Step 8

Electrons are transferred from ferredoxin to NADP+ to reduce it to NADPH Reaction takes a H+ ion from the stroma: NADP+ + 2e- + H+ --> NADPH (electrically neutral) Electrons at PS I aren't used to make ATP, they're passed on to NADP+

NADP+

Ultimate acceptor of electrons

Chemiosmosis

Mechanism used by chloroplasts to generate ATP Redox reactions of electron transport chains Generates an H+ gradient across a membrane H+ ions are pumped from stroma into thylakoid space As H+ ions flow back into stroma thru ATP synthase, ATP is made from ADP & Pi

The Calvin cycle

ATP and NADPH made in light reactions are used to power the conversion of CO2 to glucose Takes place in the stroma

3 steps of the Calvin cycle

1) carbon fixation 2) reduction (synthesis of G3P) 3) regeneration of RuBP

Carbon fixation

Yields 12 PGA CO2 is captured from the atmosphere and incorporated into an organic compound Creates an unstable 6-C compound that immediately splits into 2 --> 2 PGA's (3-C compound)

Reduction of PGA

Yields 12 G3P's | Using the energy of 1 ATP and 1 NADPH, each PGA molecule is converted to a molecule of G3P

Regeneration of RuBP

Yields 6 RuBP and 1 glucose | Some G3P is used to make glucose, the rest is used to regenerate RuBP

Net reaction of Calvin cycle

6 CO2 --> 1 glucose | Everything gets multiplied by 6