Ch5 and ch 28 bio II

Potential energy

Energy stored in the location or structure of matter; chemical energy is a form of potential energy

Kinetic energy

The energy of motion.

Hypotonic

A solution with a lower solute concentration than the solution it is compared with. Water tends to move into the cell.

Isotonic

Solutions with equal solute concentrations; water moves in and out at equal rates, with no net movement.

EA (activation energy)

The energy needed to start a chemical reaction. Enzymes lower the activation energy.

Phagocytosis

A type of endocytosis in which a cell engulfs a large particle by wrapping its membrane around it, forming a vacuole

Pinocytosis

A type of endocytosis often called “cell drinking”; the cell takes in droplets of extracellular fluid in small vesicles

What is the First Law of Thermodynamics

Energy can change form, but it cannot be created or destroyed

What is the Second Law of Thermodynamics

Energy transfers or transformations increase disorder (entropy), and some energy is lost as heat

Where do living things convert potential chemical energy to kinetic energy

In cells, energy from food is transferred into ATP during cellular respiration. ATP then powers cellular work, including movement and transport

What are animals dependent on for their true source of energy? (Hint: it’s not ATP)

sun, it helps there food

What will happen to a cell if it cannot make ATP

It will not have the usable energy needed to carry out cellular work, such as chemical reactions, transport, and movement. Its functions will fail and it may die

How does energy coupling work

An energy-releasing (exergonic) process helps form ATP. ATP then transfers energy, often by transferring a phosphate group, to power an energy-requiring (endergonic) process.

Compare and contrast endergonic and exergonic reactions. Know examples of each

Exergonic reactions release energy; cellular respiration is an example. Endergonic reactions require an energy input and produce products with more potential energy; building molecules is an example. Both are chemical reactions in the cell.

What are enzymes made of

proteins

Why is the shape of an enzyme so important

Its active site has a specific shape that fits its substrate. If the shape changes, the substrate may no longer fit and the enzyme may not work properly

What is the function of an enzyme

An enzyme is a catalyst that speeds up a chemical reaction by lowering the activation energy. It is not used up by the reaction

Compare and contrast competitive and noncompetitive inhibitors. Explain the structural relationship of enzyme, substrate, and active site

The substrate fits into the enzyme’s active site, where the reaction occurs. A competitive inhibitor blocks the active site and prevents the substrate from binding. A noncompetitive inhibitor binds somewhere else on the enzyme and changes its shape, so the active site no longer fits the substrate.

How does an enzyme perform its function

The specific substrate binds to the enzyme’s active site. The enzyme adjusts around it (induced fit), helping bonds break or placing molecules in a position that helps the reaction occur. Products are released, and the enzyme can be used again

Where are enzymes for the cell’s use made

ribosome

What are cofactors

Inorganic, non-protein helpers needed by some enzymes. zinc, iron, and copper. hemoglobin (iron)

What are coenzymes

Organic, non-protein helpers needed by some enzymes. vitamins

How does the plasma membrane determine what passes through it

The plasma membrane is selectively permeable. Its phospholipid bilayer allows some small nonpolar molecules to pass, while membrane transport proteins allow specific ions or molecules to cross. The types and numbers of transport proteins affect what can pass.

How does signal transduction occur

A signaling molecule binds to a receptor protein in the membrane. The receptor relays the message by activating other molecules inside the cell, creating a signaling pathway

List and describe the different types of passive transport

Diffusion: particles move from an area of higher concentration to lower concentration. Osmosis: water diffuses across a selectively permeable membrane. Facilitated diffusion: specific substances move down their concentration gradients through membrane transport proteins. These processes do not require the cell to use energy.

Why is facilitated diffusion passive transport

Substances move down their concentration gradients through transport proteins, so the cell does not need to spend energy

List and describe the different types of active transport

Active transport uses energy (usually ATP) and transport proteins to move substances across the membrane. Exocytosis moves large materials out of the cell when a vesicle fuses with the membrane. Endocytosis brings large materials into the cell in vesicles; it includes phagocytosis (engulfing particles), pinocytosis (taking in fluid), and receptor-mediated endocytosis (taking in specific substances using receptors).

What must occur before the sodium-potassium pump will work? Explain this process

ATP supplies energy for active transport by transferring a phosphate group to a transport protein. This phosphorylation changes the protein’s shape so it can move a substance across the membrane

What terms can be used for hypertonic, hypotonic, and isotonic conditions for both plants and animals

Hypotonic: animal cells take in water and may lyse (burst); plant cells become turgid. Isotonic: animal cells remain normal; plant cells become flaccid. Hypertonic: animal cells lose water and shrivel; plant cells lose water and become plasmolyzed (the membrane pulls away from the cell wall).

What happens when we drink salt water

would cause dehydration

What organ plays a major role in osmoregulation

kidneys?

Explain what is happening with the liver cell if the person has hypercholesterolemia

excessively high cholesterol levels in the blood. Faulty receptor-mediated endocytosis in liver cell membranes prevents the liver cells from removing excess cholesterol from the blood.

Neuron

Functional nerve cell specialized for carrying signals

Dendrites

Branched extensions that receive signals and convey them toward the cell body

Cell body

Region of the neuron containing the nucleus

Axon

Extension that transmits signals to other cells

Myelin sheath

Insulating covering around segments of an axon

Nodes of ranvier

Gaps between myelin-covered axon segments

Synaptic terminals

Axon endings involved in communicating with another cell

Resting potential

Voltage across the membrane of a neuron at rest

Ion concentration gradient

Difference in ion concentrations across a membrane

Threshold

Level of stimulation needed to trigger an action potential

Action potential

Rapid change in membrane voltage that rises and returns toward resting potential

Depolarization

Phase in which Na+ entry makes the interior more positive

Repolarization

Phase in which K+ exit makes the interior more negative

All-or-none

Principle that a full action potential occurs once threshold is reached

Synapse

Junction where a neuron communicates with another cell

Synaptic cleft

Gap crossed by neurotransmitters at a chemical synapse

Neurotransmitter

Chemical signal released by a sending neuron

Receptor

Specific molecule on a receiving cell that binds a neurotransmitter

Excitatory signal

Input that moves the receiving cell closer to firing threshold

Inhibitory signal

Input that moves the receiving cell farther from firing threshold

Reuptake

Removal of a neurotransmitter by uptake into the sending neuron

What are the major parts of a neuron, and how does information travel through it

Dendrites receive signals and carry information toward the cell body; the axon transmits signals toward synaptic terminals and other cells

What roles do the myelin sheath and nodes of Ranvier play

Myelin insulates segments of the axon and supports effective signal conduction; nodes of Ranvier are gaps between myelin segments

What is the resting potential, and why does it exist

It is the electrical voltage across the membrane of a resting neuron, with the inner surface relatively negative compared with the outer surface, arising from ion concentration gradients

How does a stimulus begin an action potential

A stimulus changes membrane permeability and voltage. If threshold is reached, voltage-gated Na+ channels open and an action potential is triggered

What happens to Na+ and membrane voltage during depolarization

Na+ enters through opened Na+ channels, making the inside of the neuron more positive

What happens to Na+ channels, K+ channels, and membrane voltage during repolarization

Na+ channels close/inactivate while K+ channels open; K+ exits, making the inside more negative. Slowly closing K+ channels can cause a brief to undershoot

What does it mean that an action potential is all-or-none

Once threshold is reached, a full action potential occurs; its strength does not increase with stronger stimulation.

How does a neuron communicate the strength of a stimulus

By changing the frequency of action potentials, not the amplitude of each action potential

How does an action potential move along an axon

It is self-propagated as a one-way chain reaction of local electrical events along the axon.

How do electrical and chemical synapses differ

Electrical synapses transmit electrical signals directly between cells; chemical synapses use released neurotransmitters that cross a synaptic cleft and bind to receptors

Describe the steps of transmission at a chemical synapse

An action potential arrives at a synaptic terminal; vesicles release neurotransmitters; neurotransmitters cross the cleft and bind to receptors; ion channels may open, changing the receiving cell's voltage; neurotransmitters are removed by reuptake, breakdown, or diffusion

How do excitatory and inhibitory signals influence whether a neuron fires

Excitatory signals move membrane potential closer to threshold; inhibitory signals move it farther from threshold. Their combined effects determine whether an action potential occurs

What are the roles of acetylcholine, serotonin, dopamine, and norepinephrine in the notes

Acetylcholine is released by motor neurons to activate skeletal muscles; serotonin and dopamine affect sleep, mood, attention, and learning; norepinephrine is described as an excitatory neurotransmitter and also a hormone

What does it mean for a receiving neuron to have a specific neurotransmitter receptor

Only cells with the appropriate receptor can respond to that neurotransmitter

How do SSRIs affect neurotransmitter signaling

They inhibit serotonin reuptake, allowing serotonin to remain in the synaptic cleft longer

four things on or in the plasma membrane

• Phospholipids – Form the main bilayer of the membrane.

• Proteins – Help transport substances and communicate with other cells.

• Cholesterol – Helps maintain membrane stability and fluidity.

• Carbohydrates – Help cells recognize and identify each other.