Cell Biology Exam 1

What are cells made of?

Macromolecules

What drives what the cell can do?

Macromolecules

What are the four basic combinations of atoms?

Macromolecules

What are the small organic building blocks of the cell?

Sugars, fatty acids, amino acids, nucleotides

What are the four macromolecules?

Carbohydrates, lipids, proteins, nucleic acids

What are the structures of nucleotides?

Nitrogenous base, sugar, and phosphate group

Does DNA or RNA use thymine?

DNA

Does DNA or RNA use uracil?

RNA

Does adenine or guanine have three bonds?

Guanine

What is the basic structure of amino acids?

Amino group, carbon, carboxyl group

Why do proteins have so many different functions?

They have so many different structures

What do you look for to recognize a peptide bond?

C = O

What are the levels of folding to create functional proteins?

Disulfide bonds, hydrogen bonds, ionic bonds, and Van der Waals and hydrophobic interactions

What are lipids made up of?

Hydrophilic head and couple of hydrophobic fatty acid tails

What is the hydrophilic head of a lipid made up of?

Polar group, phosphate, glycerol

What causes variability in the lipid/phospholipid billayer?

Variability in the polar head group

What is energy?

The capacity to cause specific physical or chemical changes

Where do phototrophs get their energy from?

Light

What are the different kinds of biological work?

Synthetic, mechanical, concentration, electrical, heat production, bioluminescence

What is an example of synthetic work?

Photosynthesis

What is an example of mechanical work?

The contraction of a weight lifter’s muscles

What is an example of concentration work?

The accumulation of molecules in a cell

What is an example of electrical work?

The membrane potential of a plant cell

What is an example of heat production?

Shivering in the cold

What is an example of bioluminescence?

The courtship of fireflies

What is synthetic work?

Work of making something

What is mechanical work?

Physical movement of something

What is concentration work?

Accumulation of things

What is electrical work?

Focus on charge aspect of an ion

What is lost in the flow of energy?

Heat losses

How does energy flow?

One way; it doesn’t cycle

What membranes will be relatively stiff?

Contain mostly phospolipids with no double bonds

What does the amphipathic nature of fatty acid-containing phospholipids do?

Drives the formation of a bilayer which serves to isolate water and hydrophilic molecules on either side

What are the functions of carbohydrates?

Energy storage, structural stability, binding sites for proteins

What does a positive change in entropy favor?

The progress of a reaction from reactants to products

What process involves an increase in entropy of the system?

Combustion of paper

What is the storage of glucose molecules by linking them together in the form of glycogen an example of?

Synthetic work

What is entropy?

The measure of disorder or inability to do work in a system

What is enthalpy?

The measure of total heat content in a system

What is activation energy?

The minimum amount of energy reactants must contain before collisions between them will be successful in giving rise to products

What does a catalyst do?

Lowers energy required for activation

What is the active site?

The location on an ezyme where substrates bind and the catalysis occurs

What is a reversible inhibitor?

Inhibitors that binds in a noncovalent matter, has free and bound forms

What is an irreversible inhibitor?

Inhibitor that binds covalently to the enzyme and is usually toxic to cell

What is substrate-level regulation?

Controlling the concentration of substrate available to the enzyme

What is allosteric regulation?

Molecule other than substrate or immediate product regulates the enzyme

What is covalent modification?

Addition or removal of a functional group/amino acid sequence to an enzyme that affects its conformation and ability to bind substrate

What does covalent modification of phosphate groups do?

Regulates enzyme activity

What do kinases do?

Add phosphate groups

What do phosphotases do?

Dephosphorolate

What are proenzymes?

Enzyme precursors, can become functional enzymes

When is a chemical reaction spontaneous?

When the standard free energy change is negative

When is a chemical reaction not spontaneous?

When the standard free energy change is positive

What kind of work is a sodium/potassium pump an example of?

Concentration work

What happens when Delta G = 0 in a chemical reaction?

Reactants and products are at equilibrium, no work can be done, no energy is required

Why is the steady state vital to life possible?

The cell continually takes up energy from the environment

What is the difference between how matter and energy flow through the biosphere?

Matter flows in cycles, whereas energy flows in one direction

When cells maintain themselves in a steady state, which is vital to life, where are most of their reactions?

Far from thermodynamic equilibrium

What does it mean to make a polymer?

Taking individual building blocks and sticking them together like legos

What is special about polymers?

Like legos, they can be taken off and added to other places

What is hydrophobicity?

The way molecules behave or react to water

How does hydrophobicity affect molecules?

It gives molecular machines options for building

What do molecules that do not interact well with water tend to do?

Cluster together and exclude both water and molecules that DO interact well with water

What is a group with three phosphate groups called?

Triphosphate

What does a prime (1’, 2’) symbol signal to look at?

The sugar instead of the nitrogenous base

What is a phosphodiester?

A link between nucleotides, usually connected to a phosphate group

What are the two chains of DNA brought together by?

Hydrogen bonding between nitrogenous bases

How are DNA strands arranged?

Antiparallel to each other

What do Purines always bond with?

Pyrimidine

What is the backbone structure of all amino acids?

Amino group - carbon - carboxyl group

Where does variation in amino acids come from?

Changes in the R group

Which macromolecules have the most diversity in structures and therefore functions?

Proteins

What is the strongest kind of bond, according to biology?

Covalent

What is usually the strongest bond?

Ionic

What tweaks the structure of a protein?

Hydrogen bonds breaking and forming

What is the point to hydrogen bonds tweaking the structure of proteins?

Enables it to bind to something or let go of something

What is the primary structure of proteins?

Sequence of amino acids

What is the secondary structure of proteins?

Folded basic predictable structures of the amino acid sequence

What is the tertiary structure of proteins?

Secondary structures that have been more folded into itself

What do fatty acid tails heavily rely on to exclude water from the interior of the membrane?

Hydrophobicity

What determines fluidity in the phospholipid bilayer?

The structure of fatty acids

What is the variability in lipids caused by?

Variability in the polar head group

What characteristic in the fatty acid tail causes the membrane to be more fluid?

More double bonds or kinks

What are the pieces of polysaccharides called?

Monosaccharides

What does it mean if the Delta H (change in heat) is positive?

The reaction is endothermic, it takes in heat

What does it mean if the Delta H (change in heat) is negative?

The reaction is exothermic, it releases heat to its surroundings

How are cells harnessing energy from one reaction to power another?

By constantly coupling reactions together

When a reaction is exergonic, what is the released energy used for?

To make ATP

What is a substrate?

The reactant or material being converted in a reaction

What do the enzyme oxidoreductases do?

Catalyzes oxidation-reduction reactions, moves/removes whole hydrogen

What do the enzyme transferases do?

Moves functional group from one molecule to another

What do the enzyme hydrolases do?

Use water to break bonds

What do the enzyme lyases do?

Remove or add a group from/to molecules, but isn’t necessarily a transfer

What do the enzyme isomerases do?

Rearrange bonds within a molecule

What do the enzyme ligases do?

Join two molecules together

How does temperature affect the kinetic energy of molecules?

It affects how well the protein can fold into different conformations

Which substrate binding model is more strongly supported by evidence?

Induced-fit model

What is the lock-and-key model of substrate binding?

The shape of the substrate and the conformation of the active site are complementary to each other

What is the induced-fit model for substrate binding?

The enzyme undergoes a change when binding to the substrate, BECOMING complementary after binding

How does a competitive inhibitor work?

It binds to the active site, blocking the substrate and making no product