NCSU BIO 183 Lisa Parks Exam 2

autorophs

are able to produce their own organic molecules through photosynthesis

heterotrophs

live on organic compunds produced by other organisms

Cellular respiration

extraction of energy from organic molecules, series of reactions

Reactions in cellular respiration

Oxidation and dehydrogenations

Oxidation

loss of electrons

Dehydrogenatations

lost electrons are accompanied by hydrogen

NAD+

an electron carrier, accepts 2 electrons and 1 proton becomes NADH

aerobic respiration

final electron receptor is oxygen (O2

anaerobic respiration

final electron acceptor is an inorganic molecule (not O2)

fermentation

final electron acceptor is an organic molecule

Aerobic Respiration equation

C6H12O6 + 6O2 —> 6CO2 + 6H2O

Cell are able to make ATP by

substrate-level phosphorylation

oxidative phosphorylation

Substrate-level phosphorylation

transferring a phosphate directly to ADP from another molecule (Krebs Cycle) (Glycolsis)

Oxidative phosphorylation

use of ATP synthase and energy derived from a proton (H+) gradient to make ATP (ETC)

Oxidation of Glucose stages

Glycolysis

Pyruvate oxidation

Krebs cycle

electron transport chain and chemiosmosis

Glycolysis

converts glucose to pyruvate

Glycolysis characteristics

10 step biochemical pathway

occurs in cytoplasms

2 molecules of pyruvate are formed

net production of 2 ATP molecules by substrate-level phosphorylation

2 NADH produced by the reduction of NAD+

Products of Pyruvate Oxidation

per 1 pyruvate molecule

1 CO2

1 NADH

1 acetyl-CoA

Acetyl-CoA

consists of 2 carbons from pyruvate attached to coenzyme A

Pyruvate dehydrogenase

catalyzes the reaction in mitochondira

Krebs Cycle

oxidizes the acetyl group from pyruvate

Krebs Cycle characteristics

occurs in the matrix of the mitochondria

biochemical pathway of 9 steps

Krebs Cycle products per 1 molecule CoA

release 2 molecules of CO2

reduce 3 NAD+ to 3 NADH

reduce 1 FAD (electron carrier) to FADH2

produce 1 ATP

regenerate oxaloacetate

Electron Transport Chain

series of protein complexes and molecules within the inner mitochondrial membrane that transfer high-energy electrons from electron donors to electron acceptors, generating a proton gradient across the membrane. This gradient is then used by ATP synthase to produce ATP, the cell's primary energy source.

Energy Yield of Respiration

theoretical energy yields

38 ATP per glucose for bacteria

36 ATP per glucose for eukaryotes

actual energy yield - 30 ATP per glucose for eukaryotes

Oxidation without O2

Fermentation

• ethanol fermentation

• lactic acid fermentation

Fermentation

reduces organic molecules in order to regenerate NAD+

Ethanol Fermentation

occurs in yeast, CO2, ethanol, and NAD+ are produced

Lactic acid fermentation

occurs in animal cells (especially muscles)

electrons are transferred from NADH to pyruvate to produce lactic acid

Photosynthesis equation

6CO2 + 12 H2O —> C6H12O6 + 6H2O + 6O2

Photosynthesis is divided into

• light-dependent reactions

• carbon fixation reactions

Light-Dependent Reactions

capture energy from sunlight

make ATP and reduce NADP+ to NADPH

Carbon Fixation reactions

use ATP and NADPH to synthesize organic molecules from CO2

Chloroplast components

thylakoid memebrane

grana

stroma

chlorophyll

Thylakoid membrane

internal membrane arranged in flattened sac

contain chlorophyll and other pigments

Grana

stacks of thylakoid membranes

Stroma

semiliquid substance surrounding thylakoid membranes

Pigments

molecules that absorb visible light

Absorption spectrum

the range and efficiency of photons it is capable of absorbing

Chlorophyll a

primary photosynthetic pigment in plants and cyanobacteria

absorbs violet-blue and red light

Accessory Pigments

secondary pigments absorbing light wavelengths other than those absorbed by chlorophyll a

Chlorophyll b

increases the range of light wavelengths that can be used in photosynthesis

Carotenoids

acts as antioxidants or photoprotectors

Light-dependent reactions stages

Primary photoevent

charge separation

electron transport

chemiosmosis

Primary Photoevent

a photon of light is captured by a pigment molecule

Charge Separation

energy is transferred to the reaction center; an excited electron is transferred to an acceptor molecule

Noncyclic photophosphorylation

Photosystem I

Photosystem II

Photosystem II

acts first

accessory pigments shuttle energy to the P680 reaction center

excited electrons from P680 are transferred to electron carriers similar to ETC

electron lost from P680 is replaced by an electron released from the splitting of water

Photosystem I

receives energy from an antenna complex

energy is shuttled to P700 reaction center

excited electron is transferred to a membrane-bound electron carrier

electrons are used to reduce NADP+ to NADPH

electrons lost from P700 are replaced from the b6-f complexA

ATP production via chemiosmosis in Light-Dependent Reactions

ATP synthases is embedded in the thylakoid membrane

protons have accumulated in the thylakoid space

protons move into the stroma only through ATP synthase

ATP is produced from ADP + Pi

(Photosynthesis) To build carbs, cells need

Energy

• ATP from light-dependent reactions

Reduction Potential

• NADPH from photosystem I

Calvin cycle characteristics

biochemical pathway that allows from carbon fixation

occurs in the stroma

uses ATP and NADPH as energy sources

incorporates CO2 into organic molecules

Carbon fixation

the incorporation of CO2 into organic molecules

• occurs in the first step of the Calvin cycle

Calvin Cycle phases

Carbon fixation

• RuBP + CO2 —> 2 molecules PGA

Reduction

• PGA is reduced to G3P

Regeneration of RuBP

• G3P is used to regenerate RuBP

Energy need for Calvin Cycle

18 ATP molecules

12 NADPH molecules

Carbon Fixation equation

ribulose-bis-phosphate + CO2 —> 2(PGA)

5 carbons 1 Carbon 3 carbons

• catalyzed by rubisco

Rubisco enzymatic activities

carboxylation

photorespiration

Carboxylation

the addition of CO2 to RuBP

• favored under normal conditions

Photorespiration

the oxidation of RuBP by the addition of O2

Communication between cells require

ligand

receptor protein

Ligand

the signaling molecule

Receptor protein

binds the ligand

• may be on the plasma membrane or within the cell

Direct contact

molecules on the surface of one cell are recognized by receptors on the adjacent cell

Paracrine signaling

signal released from a cell has an effect on neighboring cells

Endocrine signaling

hormones released from a cell affect other cells throughout the body

Phosphorylation

a common way to change the activity of a protein

Protein kinase

an enzyme that adds a phosphate to a protein

Phosphatase

an enzyme that removes a phosphate from a protein

Steroid hormones

have a non-polar, lipid-soluble structure

cross the plasma membrane to a steroid receptor

usually affect regulation of gene expression

3 subclasses of membrane receptors

channel linked receptors

enezymatic receptors

G protein-coupled receptor

Channel linked receptors

ion channel that opens in response to a ligand

Enzymatic receptors

receptor is an enzyme that is activated by the ligand

G-protein

protein bound to GTP

G-protein-coupled receptors (GPCRs)

receptors bound to G proteins

• G protein is a switch turned on by the receptor

• G-protein then activates an effector protein (usually an enzyme)

Second messenger

effector protein produces, generates the cellular response to the original signal

Adenylyl Cyclase

produces cAMP as a second messenger

Depolarization

cell membrane less polarized, less negative relative to surrounding solution

Hyperpolarization

cell membrane more polarized, more negative

Phototropism

growth in response to light

Gravitropism

response of a plant to the gravitation field of the Earth

Glycolysis Substrate

1 molecule glucose (6C)

Glycolysis End products

2 molecules pyruvate (3C each)

2 net ATP

2 NADH

Glycolysis occurs in

cytoplasm

Pyruvate Conversion Substrate

2 molecules pyruvate (3C each)

Pyruvate Conversion End products

2 molecules acetyl CoA (2C each)

2 CO2

2 NADH

mitochondrial matrix

Pyruvate conversion occurs in

Krebs Cycle Substrate

2 molecule acetyl CoA (2C each)

Kreb Cycle End products

4 CO2

2 ATP

6 NADH

2 FADPH2

Krebs Cycle occurs in

mitochondrial matrix

ETC substrate

10 NADH and 2 FADH2

ETC end products

30-34 ATP (34 = ideal)

ETC occurs in

inner mitochondrial membrane

Maximum ATP from cell respiration

36-38 ATP

ATP Synthase

enzyme that synthesizes ATPin the mitochondrial inner membrane