bio exam 3

What process do all energy come from protons of?

Light

Photosynthesis formula

6H2O + 6CO2 + sunlight --> C6H12O6 + 6O2

Photosynthesis is the most important ___________ process.

Endergonic

Photosynthesis moves from ____________ reactants to _____________ products.

Inorganic to Organic

What do both the product and reactants of photosynthesis have?

H2O or water

What are chloroplasts?

Photosynthetic organelle; Thylakoids contain light-absorbing pigments.

Where are chlorophyll molecules found in the chloroplasts?

Thylakoid membranes

What parts of the chloroplast does photosynthesis happen in?

Stroma, Thylakoid, and Thylakoid space

Definition of stroma

Liquid surrounding thylakoids.

What is the first step of photosynthesis?

Energy is extracted from protons of light (part of light reactions).

What happens when light is absorbed?

An electron is boosted to a higher energy level/get excited.

What is split during the light reactions?

Water is split and O2 is released.

What products are produced during the light reactions?

ATP and NADPH

What is the second step of photosynthesis?

Calvin Cycle

What does the Calvin Cycle do with CO2?

Attaches it to an organic molecule (carbon fixation).

What is carbon fixation?

The capture of CO2 into an organic molecule.

What is rubisco?

An enzyme that catalyzes the fixation of carbon dioxide in the Calvin cycle.

What are the products of the Calvin Cycle?

G3P, ADP, Pi, NAD+, and sugar.

What is the relationship between 2 G3Ps?

They equal 1 sugar molecule.

Why does the Calvin cycle depend on the light reactions?

It cannot convert light into energy.

Where does the energy used to produce ATP in the light reactions come from?

The movement of H+ throughout a membrane.

What is photophosphorylation?

The production of ATP by chemiosmosis during the light reactions of photosynthesis.

What is chemiosmosis?

The movement of ions across a semipermeable membrane, down their electrochemical gradient.

Light can be absorbed by ___________.

Photopigments.

Which wavelengths of light can chlorophyll absorb?

All wavelengths except green.

What happens to green light?

It is reflected.

Where are pigments located?

In a protein complex called the Photosystem.

Where can the photosystem be found?

Embedded in the thylakoid membrane.

What is chlorophyll a?

The primary pigment that converts light energy to chemical energy.

What are chlorophyll b and carotenoids?

Accessory pigments.

What trait does chlorophyll b have in relation to chlorophyll a?

Chlorophyll b has a higher wavelength than chlorophyll a.

What is the only light-dependent step in the photosystem?

The transfer of light energy to pigment molecules.

What happens to the 'special pair' of chlorophyll a molecules when they get excited?

They become excited.

What occurs during a transfer of electrons in the photosystem?

Electrons transfer from chlorophyll a to the primary electron acceptor.

How do electrons enter the photosystem?

Through the splitting of water/H2O.

What must be replaced during this process?

Electrons must be replaced with the primary pair.

What happens if electrons are not replaced?

The process will stop.

What kind of gradient is created when electrons move through the electron transport chain?

Proton (H+) gradient.

What is produced during photosystem 2?

ATP.

How many photosystems are there?

2, Photosystem I and Photosystem II.

Which photosystem comes first?

Photosystem II.

What are the products at the end of Photosystem 1?

NADPH.

Where do ATP and NADPH from the photosystems move to?

The Calvin Cycle.

What does the Calvin Cycle reduce CO2 using?

ATP and high energy electrons from NADPH.

What is the first phase of the Calvin cycle?

Carbon fixation.

What occurs during carbon fixation?

Inorganic CO2 is converted to an organic compound.

What is the second stage of the Calvin cycle?

Reduction.

What happens during reduction?

6 ATP invested to make 6 ADP, 1,3-bisphosphoglycerate is converted to six G3P.

What is the third stage of the Calvin cycle?

Regeneration of RuBP.

What does G3P do in the regeneration of RuBP?

G3P is used to regenerate RuBP.

How many ATP, NADPH, and CO2 are needed to produce 1 molecule of G3P?

9 ATP, 6 NADPH, 3 CO2.

What happens when a leaf gets hot?

Water leaves through stomata.

What happens when the stomata closes?

O2 builds up inside the leaves and CO2 cannot enter leaves.

What is photorespiration?

Rubisco fixes O2 instead of CO2.

What are the steps of photorespiration?

1. Stomata close, plant runs out of CO2. 2) Rubisco adds O2. 3) Unstable product breaks down to CO2.

What allows a plant without light to live?

Stored energy in the form of sugar or starch.

What is G3P used for?

Production of sucrose, cellulose, glucose, and starch.

Where does the Calvin cycle occur?

In the stroma.

What is an autotroph?

An organism that makes its own food.

What is a heterotroph?

An organism that cannot make its own food; a consumer.

What type of processes are metabolic pathways typically?

Redox processes.

In photosynthesis, what molecule is oxidized and what is reduced?

Water is oxidized and carbon dioxide is reduced.

What is cell communication?

The process through which cells detect and respond to environmental signals.

All cells respond to __________ in their environment.

Changes.

What are the steps of cell signaling?

Reception, transduction, response.

What happens during reception?

A signaling molecule binds to a receptor.

What occurs during transduction?

Signal pathway, molecules change shape.

What happens during the response?

The cellular response is activated.

What depends on which combination of signals a cell receives?

What a cell does.

What are the four responses we discussed?

Cells survive, divide, differentiate, and die.

Which cell signaling response can lead to cancer?

Division.

What happens during differentiation?

A cell takes on adult characteristics and carries out normal functions.

What is the central dogma?

Transcription and translation; DNA → RNA → protein.

What is gene expression?

Production of the protein of a particular gene.

What are transcription and translation?

Both processes of gene expression.

What proteins are required for transcription?

Transcription factors that regulate transcription.

What might a cellular response involve?

Production of a particular protein.

What does a growth factor do?

Stimulates growth and division of cells.

What is a ligand?

A molecule that binds specifically to the receptor site of another molecule.

What does a heart muscle ligand do?

Decreases the rate and force of contraction.

What does a salivary gland cell ligand do?

Stimulates saliva secretion.

Responses to ligands may be _______ in different cells.

Different.

What are the two types of signaling molecules?

Hydrophilic and hydrophobic.

What can hydrophobic molecules do?

Diffuse through the membrane.

Cell-surface receptors are ___________ molecules.

Hydrophilic.

Intracellular receptors are ___________ molecules.

Hydrophobic.

What are the two main types of local signaling?

Paracrine and synaptic signaling.

What is paracrine signaling?

Secreting cell diffuses locally and triggers response in neighboring cells.

What is synaptic signaling?

A nerve cell releases neurotransmitters into a synapse, stimulating the target cell.

What is long-distance signaling called?

Endocrine signaling - hormonal.

How does endocrine signaling work?

Secreted molecules diffuse into the bloodstream and trigger responses in target cells anywhere in the body.

Hormones can be __________ or ___________.

Proteins or steroids.

What are the four kinds of receptors?

Ligand-gated ion channels, G protein-coupled receptors, receptor tyrosine kinases, intracellular receptors.

What are ligand-gated ion channels?

Membrane ion channels operated by the binding of specific molecules.

What are G protein-coupled receptors?

Special class of membrane receptors with an associated GTP binding protein.

What are the three G protein subunits?

Alpha, Beta, Gamma.

What are receptor tyrosine kinases?

Membrane receptors that attach phosphates to tyrosines creating a dimer.

What is a dimer?

Two monomers bonded together.

What are intracellular receptors?

Receptors located inside the cell rather than on its cell membrane.

What does GTP do?

Is similar to ATP and is used to make ATP or power work in the cell.