bio quiz 11, 12, ATP

What is ATP composed of?

ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups.

How is energy released from ATP?

when the terminal phosphate bond is broken by hydrolysis.

What creates potential energy in ATP?

Repulsion between the negative charges of the three phosphate groups creates a lot of potential energy, likened to a compressed spring.

What types of cellular work are powered by ATP hydrolysis?

mechanical, transport, and chemical processes

What is phosphorylation in the context of ATP?

the transfer of a phosphate group, typically used to power endergonic reactions.

What is a phosphorylated intermediate?

a recipient molecule that is more reactive (less stable, with more free energy) than the original molecule.

What effect does ATP hydrolysis have on proteins?

causes a change in protein shape and binding ability.

How is ATP regenerated?

by the addition of a phosphate group to adenosine diphosphate (ADP).

Where does the free energy needed to phosphorylate ADP come from?

exergonic breakdown reactions (catabolism).

What is the ATP cycle?

involves the shuttling of inorganic phosphate and energy, coupling energy-yielding processes to energy-consuming ones.

Metabolism

totality of an organism's chemical reactions

Metabolic pathway

In this, a specific molecule is altered in a series of steps to produce a product.

Catabolic pathways

release energy by breaking down complex molecules into simpler compounds.

Anabolic pathways

consume energy to build complex molecules from simpler ones.

Downhill reactions

Catabolic pathways are described as this.

Uphill reactions

Anabolic pathways are described as this

Bioenergetics

the study of how energy flows through living organisms.

Energy

the capacity to cause change, can be used to do work—move matter against opposing forces, such as gravity and friction.

Kinetic energy

energy associated with motion.

Thermal energy

kinetic energy associated with random movement of atoms or molecules.

Heat

Thermal energy in transfer from one object to another

Potential energy

energy that matter possesses because of its location or structure.

Chemical energy

potential energy available for release in a chemical reaction.

Example of chemical energy

Complex molecules, such as glucose, are high in chemical energy because energy is released as they are broken down to simpler products.

Thermodynamics

the study of energy transformations in a collection of matter.

System

In thermodynamics, refers to the matter being studied.

Surroundings

In thermodynamics, refers to the universe.

Isolated system

cannot exchange energy or matter with its surroundings.

Closed system

heat can transfer but energy cannot.

Open system

can exchange energy and matter with its surroundings.

First law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

Energy of the universe

constant

Second Law of Thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

Entropy

A measure of molecular disorder, or randomness.

Spontaneous Processes

Processes that occur without energy input; they can happen quickly or slowly.

Nonspontaneous Processes

Processes that decrease entropy and require an input of energy.

Gibbs Free Energy (G)

The portion of a system's energy that can do work when temperature and pressure are uniform throughout the system.

Change in Free Energy (ΔG)

Indicates whether a reaction is spontaneous or not.

Exergonic Reaction

A chemical reaction that proceeds with a net release of free energy to the surroundings.

Endergonic Reaction

A chemical reaction that absorbs free energy from the surroundings.

Equilibrium

The point at which forward and reverse reactions occur at the same rate, describing a state of maximum stability.

Free Energy Change Equation

ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is temperature in Kelvin, and ΔS is the change in entropy.

Free Energy and Stability

Free energy can be thought of as a measure of a system's stability; unstable systems (higher G) tend to become more stable (lower G).

Energy Flow in Ecosystems

Energy flows into ecosystems as light and exists as heat.

Spontaneous Process and Work

A process is spontaneous and can perform work only when it is moving toward equilibrium.

Thermal Energy Loss

For every energy transfer or transformation, some energy is converted to thermal energy and lost as heat.

Processes Increasing Entropy

Can occur spontaneously.

Processes Decreasing Entropy

Are nonspontaneous and require an input of energy.

Endomembrane System

consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and plasma membrane, which are either continuous or connected via transfer by vesicles.

Endoplasmic Reticulum (ER)

accounts for more than half of the total membrane in many eukaryotic cells and is continuous with the nuclear envelope.

Smooth ER

synthesizes lipids (including oils, phospholipids, & steroids), metabolizes carbohydrates, detoxifies drugs and poisons, and stores calcium ions.

Rough ER

has bound ribosomes, which secrete glycoproteins and distributes transport vesicles, serving as a membrane factory for all-bound proteins synthesized in it.

Golgi Apparatus

consists of flattened membranous sacs called cisternae, modifies products of ER, manufactures macromolecules, and sorts and packages materials for transport.

Lysosomes

membrane-bound sacs of hydrolytic enzymes that an animal cell uses to digest macromolecules, working best at acidic pH.

Vacuoles

large vesicles derived from the ER and Golgi apparatus that perform a variety of functions, including food vacuoles formed by phagocytosis.

Contractile Vacuoles

found in many freshwater protists, pump excess water out of cells.

Central Vacuoles

found in many mature plant cells, contain a solution called sap and play a major role in plant growth.

Mitochondria

the sites of cellular respiration, the metabolic process that uses oxygen to generate ATP, and are found in nearly all eukaryotic cells.

Chloroplasts

found in plants and algae, the sites of photosynthesis and contain the green pigment chlorophyll as well as enzymes for sugar production.

Chloroplast

One of a group of plant organelles called plastids.

Thylakoids

Membranous sacs stacked to form granum within chloroplasts.

Stroma

The internal fluid of chloroplasts containing DNA, ribosomes, and enzymes.

Plastids

A group of plant organelles, including chloroplasts and others.

Endosymbiont Theory

Suggests that an early ancestor of eukaryotes engulfed a non-photosynthetic prokaryotic cell, leading to the evolution of mitochondria and chloroplasts.

Peroxisomes

Specialized metabolic compartments bounded by a single membrane that contain enzymes to remove hydrogen atoms and form hydrogen peroxide (H2O2).

Compartmentalization

The separation of enzymes that produce hydrogen peroxide and those that dispose of it to prevent damage to cellular components.

Cytoskeleton

A network of fibers extending throughout the cytoplasm that organizes the cell's structures and activities.

Microtubules

Cytoskeletal structures that shape the cell, guide movement of organelles, and separate chromosomes during cell division.

Microfilaments

A network that helps support the cell's shape and forms a cortex just inside the plasma membrane.

Intermediate filaments

More permanent cytoskeleton fixtures that support cell shape and fix organelles in place.

Cell Wall

An extracellular structure that distinguishes plant cells from animal cells, providing protection and maintaining shape.

Primary cell wall

The relatively thin and flexible wall secreted first in plant cells.

Middle lamella

A thin layer between primary walls containing polysaccharides called pectins.

Secondary cell wall

An additional layer added between the plasma membrane and the primary cell wall in some cells.

Glyoxysomes

Peroxisomes in seeds that convert fatty acids to sugar to feed seedlings.

ATP

A molecule that serves as the energy currency of the cell, produced by mitochondria.