Exam 2 BIO

Plasma Membrane

The thin, flexible membrane that surrounds a cell and controls what enters and leaves the cells. made of a phospholipid bilayer with proteins.

Selectively Permeable

allows for some substances to pass through a membrane while preventing others from passing through

amphipathic molecule

a molecule that has both a hydrophilic part and a hydrophobic part. ex-phospholipids in the plasma membrane

Fluid Mosaic Model

model that describes the plasma membrane as a flexible layer of phospholipids with proteins and other molecules embedded within it. The lipids and many proteins can move sideways, making the membrane fluid and dynamic

Glycoprotein

A protein with a carbohydrate (sugar) attached to it. found on the cell membrane and helps with cell recognition, communication and attachment

Glycolipid

a lipid with a carbohydrate attached to it. found on the cell membrane and helps with cell recognition and communication

Peripheral proteins

proteins that are loosely attached to the surface of the plasma membrane rather than embedded inside it. helps with cell signaling, support and communication

Integral proteins

Proteins that are embedded in the plasma membrane, often extending through the entire phospholipid bilayer. helps with transport, communication and cell recognition

Transport proteins

membrane proteins that help move substances across the plasma membrane, such as ions, water and molecules. includes channel proteins and carrier proteins

Receptor proteins

Proteins on the cell membrane that receive signals from outside the cell and help trigger a specific response inside the cell

Passive Transport

The movement of substances across a cell membrane without the use of cellular energy (ATP), usually from an area of high concentration to one of low concentration.

Diffusion

movement of molecules from an area of high concentration to low concentration until they become evenly distributed. does not require cellular energy (ATP)

Osmosis

movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration. doesn’t require ATP

Hypertonic

A solution with a higher concentration of solutes than the cell. water moves out of the cell, causing the cell to shrink

hypotonic

a solution with less solute than the cell. Water moves into the cell

Isotonic

A state of equal concentration, pressure and tension within a cell and its solution

Lyse

the breaking down, rupture or destruction of a cells outer membrane.

Turgid

A cell that is firm due to high internal fluid pressure (watered, green leaf)

Flaccid

a cell or tissue that is limp due to lack of internal fluid pressure. (wilted leaf)

aquaporin

a specialized channel protein embedded in a cell membrane that allows water molecules to flow rapidly into and out of the cell while blocking other substances.

Active transport

the process of moving molecules across a cell membrane against their concentration gradient, moving from an area of low concentration to high concentration.

Endocytosis

Where a cell takes in Substances from outside the cell by surrounding them its cell membrane and forming a vesicle

Exocytosis

The process where a cell removes substances by transporting them in a vesicle that fuses with the cell membrane and releases the contents outside the cell

Facilitated diffusion

The movement of substances across the cell membrane from high concentration to low concentration using membrane proteins without using ATP

Signal transduction pathway

A series of steps in which a cell receives an external signal and converts it into a specific response inside the cell

Paracrine signaling

A type of cell signaling where a cell releases chemical signals that affect nearby cells

Endocrine signaling

A type of cell signaling where hormones are released into the bloodstream and travel to distant target cells

Ligand

a molecule that Binds to a specific receptor on or inside a cell and triggers a response

What is the plasma membrane? Where is it found? What cells? What are the major functions?

The plasma membrane is a thin, flexible barrier made mainly of phospholipid bilayer and proteins that surround a cell. It is found around the outside of every cell, separating the inside of the cell from its environment. All cells have a plasma membrane, Including Prokaryotic cells, And eukaryotic cells. It controls what enters and leaves the cell, Protects and separates the cell's interior, Allows cells to communicate through receptors, And helps maintain homeostasis.

What is the composition of the plasma membrane?

The PM Is mainly made of Phospholipids, Proteins, cholesterol and carbohydrates.

What is meant by the fluid mosaic model?

The model that describes the plasma membrane as a flexible phospholipid bilayer with proteins and other molecules moving within it.

What influences membrane fluidity

Temperature Higher temperature equals more fluid, Lower temperature equals less fluid. Fatty acid tails, More unsaturated tails equal more fluid, More saturated tails equal less fluid. Cholesterol, Help stabilize fluidity, prevents the membrane from becoming too rigid when cold and too fluid when warm.

What two types of proteins are found associated with membranes

Integral proteins, embedded within the membrane often spanning the entire bilayer. Peripheral proteins, attached to the surface of the membrane but not embedded in the bilayer.

What role do carbohydrates play in membrane function

Cell recognition, help cells identify each other. Cell to cell communication, help cells interact. Cell adhesion, help cells attach to other cells.

What is meant by the term selectively permeable membrane

A membrane that allows some substances to pass through while blocking others

What types of molecules can easily cross the plasma membrane? What which types can't? What is the role of transport proteins?

Small nonpolar molecules such as oxygen and carbon dioxide can cross the plasma membrane. Ions at large or polar molecules such as glucose and amino acids cannot easily cross. Transport proteins help substances that cannot easily cross the membrane move into or out of the cell These include channel proteins and carrier proteins.

What is the difference between passive and active transport

Passive transport moves substances across the cell membrane without using ATP. Molecules generally move from an area of high concentration to low concentration. Active transport requires ATP can move substances against the concentration gradient, from low concentration to high concentration.

What is meant by osmosis

Osmosis is the movement of water across a selectively permeable membrane from an area of lower solute concentration (more water) to an area of higher solute concentration (less water).

Be able to identify hypertonic, hypotonic, an isotonic solutions. How do they relate to osmosis

Hypertonic, More outside of the cell, water moves out, the cell shrinks. Hypotonic less solute outside the cell, water moves into, The cell swells and may burst. Isotonic, equal solute concentrations inside and out, water moves both ways equally, the cell stays about the same size. In this process water is moved through osmosis.

What are the effects of tonicity of solutions on animal and plant cells

Plant cells have a cell wall which help keep them from bursting in a hypotonic solution. Animal cells do not.

What does turgid flaccid and lyse mean

Turgid, firm and swollen with water. Flaccid Limp or Soft because the cell does not have enough water pressure. Lyse, burst open. An animal cell can do this if too much water enters it.

What is meant by facilitated transport

When Substances move across the cell membrane with the help of transport proteins. It is a type of Passive transport so it does not require ATP. Molecules move from high concentration to low concentration

What is a Aquaporin

A special channel protein in the cell membrane that allows water to move quickly into or out of the cell

What is meant by active transport

The movement of substances across the cell membrane that requires ATP. One main example of active transport is the sodium-potassium pump

Identify and distinguish between exocytosis and endocytosis as bulk flow on items into and out of the cell

Both are forms of active transport used to move large amounts of material across the cell membrane. Endocytosis, The cell membrane surrounds material and forms a vesicle to bring it inside. Exocytosis, A vesicle joins with the cell membrane and releases its contents outside the cell.

What is the signal transduction pathway

The process a cell uses to receive a signal and respond to it

What are the 4 types of signaling

Direct contact signaling, cells touch to communicate. Paracrine signaling, signals travel to nearby cells. Synaptic signaling, neurons released from neurotransmitters across a synapse to a target cell. Endocrine signaling, hormones travel through the bloodstream to distant target cells.

Know the three stages of cell signaling and what each does

Reception, The cell receives The signal when a signaling molecule (Ligand) Binds to a receptor. Transduction, the signal is relayed through the cell, often through a series of proteins or other molecules. Response, the cell reacts to the signal, such as turning a gene on or off, releasing a substance, or changing its activity.

What is a ligand and what does it do

A ligand is a signaling molecule that binds to a specific receptor and triggers a response inside the cell

What are two types of responses to cell signals

Change in gene expression, the signal causes certain genes to be turned on or off affecting which proteins are made. Change in cell activity, the The signal changes the activity of proteins or enzymes already in the cell.

Metabolism

All of the chemical reactions that happen inside a cell or organisms to keep it alive

Catabolic pathways

Metabolic pathways that breakdown large, complex molecules into smaller molecules, releasing energy

Anabolic pathways

Metabolic pathways that build larger, complex molecules from smaller molecules and require energy

Kinetic energy

The energy an object has because it is moving

Potential energy Stored energy due to an object's position, structure, or chemical bonds

Stored energy due to an object's position, structure, or chemical bonds

Chemical energy

A type of potential energy stored in the chemical bonds of molecules

1st Law of Thermodynamics

Energy cannot be created or destroyed, it can only be transferred or transformed from one form to another

2nd Law of thermodynamics

Whenever energy is transferred or transformed some energy becomes less useful, often being released as heat, and entropy increases

Entropy

The measure of disorder or randomness in a system, or more precisely, how dispersed energy is

Exergonic reaction

A chemical reaction that releases free energy

Endergonic reaction

A chemical reaction that requires an input of energy to occur

Energy coupling

When a cell uses the energy released by an exergonic reaction to power and endergonic reaction

ATP

The cell's main energy carrying molecule. It stores usable energy that cells can use to perform work

Enzyme

A protein that acts as a biological catalyst, meaning it speeds up a chemical reaction without being used up

Activation energy

The minimum amount of energy needed to start a chemical reaction

Substrate

The molecule that binds to an enzyme and is changed during a chemical reaction

Active site

The specific area on an enzyme were the substrate binds and the chemical reaction occurs

Cofactors

Non protein substances that help enzymes carry out chemical reactions

Competitive inhibition

When an inhibitor competes with the substrate for the enzymes active site, reducing enzyme activity

Non competitive inhibition

Occurs when an inhibitor binds somewhere other than the active site and changes the enzyme's function, slowing or stopping the reaction

allosteric regulation

Controls enzyme activity when a molecule binds to an allosteric site and changes the enzyme's shape or function

Denaturation

When a protein or enzyme loses its normal shape causing it to lose its function

What are metabolic pathways

A series of enzyme controlled chemical reactions that occur step by step in a cell

What is the difference between catabolic and anabolic pathways

Catalog pathways breakdown large molecules into smaller ones and release energy. Anabolic pathways build larger molecules from smaller ones and require energy.

While you living organisms obey the second law of Thermo dynamics

They obeyed the second law of Thermodynamics because every energy transformation releases some energy as heat increasing the overall entropy of the surroundings

No differences between spontaneous and non spontaneous processes with respect to energy

Spontaneous processes can occur without continuous input of energy and have a decrease in free energy These are exergonic. Non spontaneous processes require an input of energy to occur and have increase in free energy these are endergonic

Know the differences between systems high versus low in free energy

High free energy equals more usable energy and less stable. Low free energy equals less usable energy and more stable

What does ATP stand for? What is it? How made? How used by cells?

Stands for Adenosine Triphosphate. It is made by adding a phosphate to ADP using energy from food. When ATP loses a phosphate, energy is released for cellular work

What is meant by hydrolysis of ATP

ATP hydrolysis is the breakdown of ATP using water, producing ADP and phosphate and releasing energy for cellular work

What is meant by the term phosphorylated

Phosphorylation is the addition of a phosphate group to a molecule

How is the energy of ATP coupled in a cell

ATP couples energy to cellular work by hydrolysis and transferring a phosphate group to another molecule, providing energy to drive energy requiring reactions

How's ATP regenerated in a cell

ATP is regenerated when energy is used to add a phosphate group to ADP, forming ATP

Do enzymes change free energy

Enzymes lower activation energy but do not change the free energy of our reaction

What is meant by specificity

Enzymes specificity means that an enzyme binds to and acts on a specific substrate because of the shape and chemical properties of its active site

What are the major properties of enzymes

Enzymes are specific biological catalysts that lower activation energy, speed up reactions, are reusable, and do not change the reactions free energy

What is a cofactor? Why are vitamins and minerals important

a cofactor is a non protein substance that helps an enzyme function. Vitamins and minerals are important because many act as cofactors or coenzymes needed for enzyme activity

What is feedback inhibition

Feedback inhibition occurs when the end product of a metabolic pathway inhibits an enzyme earlier in the pathway, stopping or slowing further production

Cellular respiration

The process cells used to breakdown glucose and make ATP

Fermentation

A process that allows cells to keep making a small amount of ATP when oxygen is unavailable. This is called an anaerobic process. It occurs in the cytoplasm and allows glycolysis to continue by regenerating NAD+

redox reaction

A redox reaction is a reaction in which one substance loses electrons (oxidation), And another gains electrons (reduction)

NADH

An electron carrier that transports high energy electrons to the electron transport chain, where their energy is used to produce ATP.

Electron transport chain

The electron transport chain uses high energy electrons from NADH and FADH 2 to create A hydrogen ion gradient that powers ATP synthase to produce ATP. Oxygen is the final electron acceptor

Glycolysis

The first step of cellular respiration. It occurs in the cytoplasm and does not require oxygen. During glycolysis, one glucose molecule (6 carbons) is split into two pyruvate molecules (3 Carbons each), producing a net of 2 ATP and 2 NADH

Citric acid cycle

A stage of cellular respiration that occurs in the mitochondrial matrix. The citric acid cycle breaks down acetyl-CoA, releases CO2, and produces ATP, NADH, and FADH2 for cellular respiration.

Oxidative Phosphorylation

The stage of cellular respiration were most ATP is produced. It occurs in the inner mitochondrial membrane and includes the electron transport chain and Chemiosmosis.

Pyruvate

A 3 carbon product of glycolysis that can be converted into acetyl-CoA For cellular respiration.

Acetyl-CoA

Acetyl-CoA Is the two carbon molecule formed from pyruvate that enters the citric acid cycle

Oxaloacetate

A 4 carbon molecule that combines with acetyl-CoA Begin the citric acid cycle and is regenerated at the end.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for ATP production

ATP synthase

An enzyme in the inner mitochondrial membrane that makes ATP. Uses the flow of hydrogen ions to produce ATP from ADP and phosphate.