BIO 1001 latoya paul exam 2

Cell common features

plasma membrane, cytoplasm, DNA as hereditary blueprint, RNA to copy the genetic blueprint and guide construction of protiens

Energy

capacity to do work, available in bonds of molecules, potential and kinetic

work

the transfer of energy to an object by using a force that causes it to move

potential energy

stored energy, includes chemical energy.

kinetic energy

energy of movement, radiant

under the right conditions, ___ and ___ energy can be interconverted

potential, kinetic

first law of thermodynamics or the law of conservation of energy.

energy can neither be created nor destroyed, within closed or isolated systems, total amount is unchanged

second law of thermodynamics

energy conversion proceeds from more useful to less useful forms, not 100% efficient, when potential energy of gas is converted to move a car. lost has heat.

Entropy

whenever energy is used, complexity and organized are lost, same number of atoms but overall increase in simple product molecule, energy must be added to the system to restore order.

living things use the continuous influx of ______ from the sun to create low-entropy condition of life.

light energy

in creating _____ in the form of sunlight, the sun also produces vast entropy as heat.

kinetic energy

chemical reaction

process that breaks and forms the chemical bonds that hold atoms together.

chemical reactions convert one combination of molecules, ___ into different molecules, ___

reactants, products

all ___ transfer energy and release some heat.

chemical reactions

exergonic chemical reaction

products contain less energy than original reactants. overall release of energy

endergonic chemical reaction

products contain more energy than reactants, net input of energy

all chemical reactions require an initial energy input ( ___ ) to get started

activation energy

the ______ charged charged electron shells of atoms repel one another and inhibit bond formation

negatively

molecules need to be moving with sufficient ___ speed to overcome electronic repulsion and react

collision

increasing the ___ will increase kinetic energy and thus, the rate reaction

temperature

most organisms are powered by the exergonic breakdown of ___

glucose.

energy in glucose cannot be use ___

directly

it must first be transferred to ____ molecules.

energy-carrier

energy carrier molecules

high-energy molecules synthesized at the site of an exergonic reaction, where they capture some of the released energy.

energy carrier molecules capture and release energy only ___ cells. these molecules can ferry energy through cell membrane.

within

energy carrier molecules are not used for _____ energy storage.

long-term

Adenosine Triphosphate (ATP)

most common energy carrier, nucleotide composed of nitrogenous base adenine, ribose, and three phosphate groups. provides energy to drive various endergonic reactions.

ATP synthesis

Energy from exergonic reactions (such as sugar breakdown) is used to combine lower-energy molecules of Pi with adenosine diphosphate (ADP)

in atp synthesis there is a net input of energy; therefore, it is ___

endergonic

ATP breakdown

Energy in high-energy phosphate bonds is liberated, regenerating ADP and Pi. There is a net output of energy; therefore, it is exergonic. Used to drive endergonic reactions throughout the cell

in some exergonic reactions, some energy is transferred to ___.

electrons

the energetic electrons, are captured by ___.

electron carriers

electron carriers donate high-energy electrons to other molecules, often involved in pathways that generate ___

ATP

coupled reactions

An exergonic reaction provides energy needed to drive an endergonic reaction, using energy carriers as intermediaries

Exergonic and endergonic portions of coupled reactions often occur in ___ within a cell, hence the need for energy carriers

different places

Catalysts

speed the rate of reaction by reducing its activation energy, are neither used up nor permanently altered

Enzymes

highly specific biological catalysts. Both exergonic and endergonic reactions are catalyzed by enzymes

each enzyme has a pocket -___- into which the reactant molecules -___- can enter

the active site, substrates

what sequence and folding pattern give shape and charge to an enzyme's active site?

amino acid

amino acids determine which substrates can enter, only in specific ___

orientations

when amino acids orientate, distort, and reconfigure substrates enzymes encourage substrates to ___

react

___ or synthesis usually occurs in many small steps, each catalyzed by a different enzyme.

breakdown

each ____ lowers the activation energy for its particular reaction, allowing the reaction to occur readily at body temperature.

enzyme

Metabolism

sum of all chemical reactions inside a cell

metabolic pathway

sequence of linked metabolic reactions, starting reactant molecule is converted, via an enzyme, into an intermediary, which is converted, via another enzyme, to a second intermediary, and so on until an end product is produced

photosynthesis and glucose breakdown are examples of?

metabolic pathways

different metabolic pathways often involve some of the same ___.

molecules

thousands of metabolic pathways are directly or indirectly ___.

interconnected

what is influenced by the concentration of enzymes, substrate, or both?

reaction rate

what must regulate when and at what rate reactions occur, even when concentrations fluctuate?

living cells

what are codes for enzymes may be turned on or off?

genes

enzymes may be synthesized in what form?

inactive

substrates may be inhibited from what?

binding

substrates (sometimes end products) may ____ or inhibit enzymes.

activate

For a given amount of enzyme, as _____ levels increase, the ____ rate will increase until the active sites of all the enzyme molecules are being continuously occupied by new substrate molecules

substrate, reaction

in which ways are metabolic pathways controlled?

control of enzyme synthesis, which regulates availability, control of enzyme activity.

gene that ____ for specific enzymes are turned on and off according to the cell's changing needs.

code

when there is an increase in substrates may be triggered causing what to happen?

glucose enters bloodstream

when some enzymes are synthesized only during specific life stage, what happens?

lactase production in infancy

some enzymes are synthesized in what form?

inactive

when are activation of enzymes needed?

stomach acid transforms inactive pepsin, intestinal enzyme activates inactive trypsin.

competitive inhibition

A substance other than enzyme's normal substrate binds to the enzyme's active site, competing directly with the normal substrate

an ____ molecule binds temporarily to the enzyme.

inhibitor

noncompetitive inhibition

A molecule binds to a site other than the active site, causing the active site to change shape.

Allosteric inhibition is one form

allosteric regulation

Enzyme is either activated or inhibited by a substance binding briefly and reversibly to a site other than the active site

Allosteric inhibition

Form of noncompetitive inhibition. Allosteric regulator binds to enzyme; inactivating

Allosteric activation

Allosteric regulator binds to enzyme; activating

Feedback inhibition

Activity of an enzyme near the beginning of a metabolic pathway is inhibited by end product

Metabolic pathway stops producing the end product when product concentration reaches optimal level

Thermostat-like

Some ____ are competitive or noncompetitive inhibitors

poisons

Nerve gases and insecticides permanently block the active site (competitively inhibit) of ___.

acetylcholinesterase

Acetylcholine builds up, overstimulating muscles and causing ___.

paralysis

Arsenic, mercury, lead, and potassium cyanide act as ___ inhibitors

noncompetitive

Many drugs are ___ inhibitors

competitive

Penicillin inhibits enzyme needed to ___ bacterial cell walls

synthesize

Statins inhibit in ____ cholesterol-synthesizing pathway

enzyme

Aspirin and ibuprofen inhibit enzyme involved in ___,____,____

swelling, pain, and fever

Many anticancer drugs inhibit enzymes required to duplicate ____ (in actively dividing cells of patient as well)

DNA

Environmental conditions influence ___.

enzyme activity

Three-dimensional structure of an enzyme is sensitive to____ and temperature

pH

When outside the proper range, the enzyme becomes ___

denatured

Loss of exact three-dimensional structure is required for proper_____

functioning

what (refrigeration, freezing, salt) slows enzyme-catalyzed reactions that allow bacteria and fungi to grow and reproduce?

Preservation

All the membranes of a cell have a similar basic structure

Proteins suspended in or attached to phospholipid bilayer

Otherwise, membranes differ among tissue types and environments

Membranes function in ___, regulation of substances and reactions, communication, and attachments within and between cells

isolation

Fluid mosaic model

Molecules in a fluid flow past one another

Phospholipid bilayer

Various biological molecules, some embedded, some attached, form a patchwork

Glycolipids, glycoproteins, recognition proteins, enzymes, transport proteins, receptor proteins, anchoring proteins, cholesterol

Phospholipid

Polar (hydrophilic) "head"

Two nonpolar (hydrophobic) fatty acid "tails"

what surrounds all cells, even in multicellular eukaryotes?

Water

Weakly salty ___ surrounds animal cells

interstitial fluid

In water, phospholipids spontaneously arrange into a ___.

phospholipid bilayer

___ heads form hydrogen bonds with water molecules

Hydrophilic

Hydrophobic tails cluster___

within

At body temperature, phospholipids shift about rapidly therefore...

Phospholipids are not bonded together

Fluidity of the membranes

Allows shock absorption, membranes to merge, for cell shape change

Cholesterol and saturation of fatty acids help stabilize membranes which ...

Reduce fluidity at higher temperatures

Increase fluidity at lower temperatures

what does Cholesterol reduces permeability do?

Gives cell greater control over substances entering and leaving

Hydrophobic molecules can readily diffuse through the ___ bilayer

phospholipid

Many molecules used by cells are hydrophilic

therefore...

Cannot move through nonpolar, hydrophobic fatty acid tails

Movement of these molecules relies on the mosaic of membrane-associated proteins

Five major categories of membrane proteins:

Enzymes

Recognition proteins

Transport proteins

Receptor proteins

Connection proteins

Glycoproteins (glyco, "sweet")

Membrane proteins that bear carbohydrate groups from the outer member surface