Biol 101: Chapter 5 - The Working Cell

Plasma membrane

Physical isolation, regulation of exchange with the environment, communication with the environment, and structural support.

Extracellular fluid (ECF)

Found outside the cell.

Cytosol

Found inside the cell.

Phospholipids

The organic molecule mainly composed in the plasma membrane.

Cholesterol

Stabilizes the membrane fluidity and adds flexibility.

Bilayer

2 layers.

Hydrophilic part of a phospholipid

The heads.

Hydrophobic part of a phospholipid

The tail.

Fluid mosaic

Describes plasma membranes as flexible and made up of many different molecules.

Organization of phospholipids in a plasma membrane

Hydrophilic heads facing toward the water, hydrophobic tails facing away from the water.

Functions of membrane proteins

Transport, structural, recognition, and cell signaling.

Membrane permeability

The ease with which substances can cross the cell membrane.

Impermeable membrane

Nothing passes through.

Freely permeable membrane

Anything can pass through.

Selectively permeable membrane

Some things can pass, others can't.

Substances that can easily pass through cell membranes

Small, hydrophobic, polar, and uncharged molecules.

Ions and plasma membrane

No, ions cannot pass freely through the plasma membrane.

Large polar molecule like glucose

No, it cannot pass through the membrane.

Protein transport carrier

Required to carry glucose into the cell.

Diffusion

Substances move from high concentration to low concentration.

Equilibrium in diffusion

There is an equal concentration on both sides of the membrane.

Energy requirement for diffusion

No, energy is not needed for diffusion.

Protein channels for diffusion

No, protein channels are not needed for diffusion.

Gases that can easily move into or out of cells

Carbon dioxide and oxygen.

Osmosis

Movement of water from high concentration to low concentration.

Water movement

Water moves from High concentration to Low concentration.

Solvent

In a solution, the solvent is the substance that dissolves the solute.

Hypertonic

Net water flow out of the cell.

Hypotonic

Net gain of water into the cell.

Isotonic

No net gain or loss of water.

Water movement in hypertonic vs hypotonic

If the inside of the cell is hypertonic and the extracellular fluid is hypotonic, water moves into the cell.

Water movement in isotonic

If the inside of the cell is isotonic to the extracellular fluid, there will be no movement of water.

Red blood cell in hypertonic solution

If you put a red blood cell in salt water (a hypertonic solution), it will shrink.

Red blood cell in hypotonic solution

If you put a red blood cell in pure water (a hypotonic solution), it will burst.

Red blood cell in isotonic solution

If you put a red blood cell in isotonic solution, there will be no net movement of water.

Facilitated diffusion

Facilitated diffusion does not require energy.

Protein channel in facilitated diffusion

Yes, a protein channel is required for facilitated diffusion.

Concentration in facilitated diffusion

In facilitated diffusion, the substance moves from High concentration to Low concentration.

Active transport

Active transport requires energy.

Energy requirement for active transport

Yes, ATP energy is required for active transport.

Protein channel in active transport

Yes, a protein channel is required for active transport.

Concentration in active transport

In active transport, the substance is being pumped from Low concentration to High concentration.

Energy molecule for active transport

ATP is the energy molecule required for active transport.

Endocytosis

Movement into the cell.

Phagocytosis

Phagocytosis moves food into the cell.

Pinocytosis

Pinocytosis moves fluid into the cell.

Exocytosis

Exocytosis is the ejection of material from the cell.

Energy definition

Energy is the capacity to cause change.

Potential energy of wood

A block of wood is an example of potential energy.

Kinetic energy of a photon

A photon is an example of kinetic energy.

Kinetic energy of heat

Heat is an example of kinetic energy.

Potential energy of food

Food is an example of potential energy.

Mechanical energy

Mechanical energy is used for motion in animals.

First law of thermodynamics

Energy can neither be created nor destroyed, but can be transferred or transformed; the total amount of energy in the universe is constant.

Second law of thermodynamics

When energy is transformed from one type into another, there is always a loss of usable energy, usually in the form of heat.

Entropy

Entropy is a measure of disorder or randomness in a system.

Energy source for Earth

The sun

Autotrophs

Convert sunlight to chemical energy (glucose)

Producers

Plants that make the energy for everything else in the biosphere

Consumers

Animals that eat plants

Decomposers

Fungi and bacteria that break down heterotrophs

Metabolism

All the chemical reactions in a cell

Anabolism

Building things

Catabolism

Breaking things down

Hydrolysis

Happens in catabolism

Dehydration synthesis

Happens in anabolism

Energy consumption in reactions

Anabolism consumes energy

Energy release in reactions

Catabolism releases energy

OIL

Oxidation is loss

RIG

Reduction is gain

Oxidation and reduction agents

Hydrogen, electrons, and energy

Tracking oxidation and reduction

Follow the flow of molecules

NAD → NADH

Reduction

Fe2+ → Fe3+

Oxidation

NADPH → NADP+

Oxidation

Cell respiration

C6H12O6 → 6CO2 Oxidation

Photosynthesis

6CO2 → C6H12O6 Reduction

Catalyst

Proteins that can speed up reactions

Enzymes

Lower the energy of activation of a chemical reaction

Active site

Where the substrate binds the enzyme

Substrate

The thing the enzyme works on

Induced fit

When the enzyme changes shape to hug the substrate

Inhibitor

Stopping the enzyme from doing its job

Competitive inhibition

Inhibitor binds at the active site

Non-competitive inhibition

Inhibitor binds to the enzyme at the active site or elsewhere

Effect of non-competitive inhibition

Changes the shape of the active site

Useful form of chemical energy

ATP (Adenosine triphosphate)

Structure of ATP

Adenosine with 3 phosphate groups attached

Functions of ATP

Provides the energy for work; immediate source of energy for cellular work

ADP-ATP energy transfer cycle

ATP is broken down to ADP, then ADP and phosphate are reused to rebuild ATP

Process creating ATP from glucose

Cell respiration