Biology Exam 2

Metabolism

The totality of an oragnism’s chemical reactions

An organism’s ___ transforms matter and energy

Metabolism

What is required to link Amino Acids together

Energy

Metabolic Pathway

Thousands of biochemical reactions that require energy transformations

Each step of a metabolic pathway is

A separate chemical reaction catalyzed by a specific enzyme

What are the two types of metabolic pathways required to maintain the cell’s energy balance?

Catabolic and Anabolic

Catabolic Pathways

Carbs, Lipids, Proteins; Break down complex molecules (food) into simpler ones; releases energy

Anabolic Pathways

Occurs in the body, it uses small molecules to build other substances, requires energy

Example of Catabolic Pathways

Cellular Respiration

Examples of Anabolic Pathways

Photosynthesis, Gluconeogenesis

Energy

The capacity to cause to change

Bioenergetics

Study of energy flow through a living system

Potential Energy

Energy matter has because of its structure

Kinetic Energy

Movement of objects

Free Energy

Available energy to do work

Gibb’s Free Energy (G)

The free energy change of a reaction; informs whether reaction is spontaneous or nonspontaneous

Spontaneous Change

Addition of external energy is not required, free energy decreases and the stability of a system increases, G is negative

Exergonic Reaction

Energy is exiting the system, spontaneous, G is negative

Endergonic Reaction

Energy is entering the system, reaction absorbs free energy from its surroundings, non spontaneous, G is positive

Activation Energy

The initial energy required for a reaction to start

What is the main source of activation energy in the cell?

Heat Energy obtained from the surroundings of the sistem

Heat Energy causes reactants to become

Contorted and unstable

Light Energy

For of electromagnetic energy (radiation)

Radiation

Composed of photons (packets of energy)

Electromagnetic Spectrum

The entire range of electromagnetic energy

Closed System

Isolated from its surroundings; reactions eventually reach equilibrium; G=0

Open System

Energy and matter can be transferred between the system and surroundings

What prevents equilibrium in organisms?

The constant flow of food in and waste out

1st Law of Thermodynamics

Energy cannot be created or destroyed. Energy can be transferred and transformed.

2nd Law of Thermodynamics

Spontaneous changes that do not require outside energy increase the disorder of the universe

Which has the greater entropy a liquid or solid state?

Liquid

When does entropy increase?

When a substance is broken down into parts, as temperature increases

What does entropy increase in (unit)?

rxns. where product molecules are greater in number than the reactant molecules

Entropy

Measure of unusable energy in a closed system, randomness, disorder

ATP

Cell’s primary energy transport, powers cellular work by coupling endergonic and exergonic reactions.

ATP Structure

Composed of an adenosine backbone and 3 phosphate groups attached

Breakdown of ATP is what

ADP with the release of energy

When is energy from ATP released

When a phosphate bond is broken

How does ATP drive endergonic reactions

phosphorylation, transferring a phosphate to other molecules

Phosphorylation

Transferring a phosphate to other molecules

Energy Coupling

The transfer of energy from catabolism to anabolism or from exergonic to endergonic

Enzyme

A Catalytic protein

Catalyst

Agent that speeds up a reaction without being consumed or permanently changed

Activation Barrier

Energetic hurdle that reaction must get over

The lower the activation barrier, the ___ the reaction can occur

faster

Enzyme Steps

The substrate moves toward the enzyme’s active site, chemical reaction is triggered, enzyme releases product.

What can affect an enzymes activity?

Temperature and pH, cofactors and regulatory molecules, local conditions

Why is enzyme activity regulated?

To help cells control their environment and meet their specific needs.

3 primary ways to regulate enzymes

Enzyme Activity Cofactors

Non-protein enzyme components (metals, NAD+)

Regulatory Molecules

Positive or negative regulation

Competitive Inhibitors

Similar shape to the substrate, compete for the active site

Noncompetitive Inhibitors

Bind to enzyme at different location (allosteric site, not active), causes a slower reaction rate

Disulfiram

Rx Drug, competitive inhibitor of aldehyde oxidase, causing build up of acetaldehyde and nausea and vomiting.

Cyanide

Compound that acts as a noncompetitive inhibitor, inner membrane protein in the mitochondria.

Allosteric Site

A special binding location on a protein or enzyme that is separate from the main active site

Nearly all cases of noncompetitive inhibition are ____ regulation

Allosteric

Feedback Inhibition

The end product of the metabolic pathway shuts down the pathway. Important regulator in cells

Within the cell, enzymes may be:

Grouped into complexes, incorporated into membranes, contained inside organelles

Membranes

A collage of different proteins embedded in the fluid matrix of the lipid bilayer

Plasma Membrane

The boundary that separates the living cell from its nonliving surroundsing

Selective Permeability

Allows some substances to cross more easily than others

What membrane is selectively permeable

Plasma Membrane

Functions of the Plasma Membrane

manages what enters and exits; receives external signals and initiates cellular response

Fluid Mosaic Model

States that a membrane is a fluid structure with a mosaic of various proteins in embedded in it

Cellular membranes are ___ ___ of lipids and proteins

Fluid mosaic

Phospholipids (membrane)

Main fabric of the plasma membrane; amphipathic;

Sterols (membrane)

Important for the fluidity of the plasma membrane

Squalene

Precursor for sterols and Hopanoids

Temperature’s Affect in the Nembrane

Affects movement “rate/speed” and distance of phospholipids

Cold Membrane

Close, restricting small molecules

Warm Membrane

Gaps, large holes

Fatty Acid Composition in the membrane

Fatty Acid Hydrophobic Tails

Saturated Fatty Acids in the Membrane

Less fluid because they are straight and tightly packed

Unsaturated Fatty Acids in the Membrane

More fluid because there are kinks creating space

Cholesterol in the Membrane

Creates space between phospholipids; random distribution.

Low temps of Cholesterol

Increases amount and fluidity

High temps of Cholesterol

Decreases amount and fluidity

Proteins in the Cell Membrane

2nd major component of membranes

What membrane does every single cell have?

Plasma Membrane

What is necessary to receive extra cellular signals from the environment?

Receptors in the plasma membrane

Functions of proteins in membranes

Transport, Reception, Enzymes, Binding and Adhesion

Integral Proteins

Integrated completely into the bilayer, amphipathic in nature

Why are Integral Proteins Amphipathic in nature?

Their shape and presence of amino acids

What determines how Integral proteins are arranged?

Locations and number of these regions

Peripheral Proteins

Occur only on the surfaces, enzymes or structural attatchment

What will always be the hardest thing to move across the membrane

Ions (need proteins)

Where are carbohydrates located in the plasma membrane?

On the exterior surface

Glycoproteins

Carbohydrate bound to a membrane protein

Glycolipids

Carbohydrate bound to a phospholipid

What are the functions of carbohydrates in the plasma membrane?

Cell to Cell recognition and attachment

What is this?

Alpha-helix protein

What is this?

Glycoprotein

What is this?

Glycolipid

What is this?

Peripheral Protein

What is this?

Integral protein

What is this?

Channel Protein

Viral Recptor

Glycoprotein that attaches to host cell

CD4

Cell adhesion molecule that functions to keep other immune cells close by when an immune response is generated