Cell Biology Flashcards

According to the seven common criteria for life, what distinguishes living matter from nonliving matter regarding energy?

The ability to transform energy and matter

The flow of genetic information from DNA to RNA to protein known as ___

central dogma

What is the specific ratio of length to thickness for a typical nerve cell’s axon?

10,000: 1

Which fundamental chemical units are used to build every cell’s protein across all organisms?

The same 20 amino acids

How does the second law of thermodynamics define the spontaneous direction of change in an isolated system?

Systems change toward arrangements that are most probable and have greater disorder

In thermodynamic terms, what does “disorder” represent in a living space or system?

More possible arrangements of components and fewer constraints

Why do living cells bit defy the second law of thermodynamics despite building internal order?

They release heat into their surroundings, increasing the environment’s entropy more than the internal order decreases it

What is the most disordered form of energy that is lost to the surroundings during cellular reactions?

heat

The first law of thermodynamics states that energy can be converted from one form to another, but it cannot be ___

created or destroyed

The amount of “useful energy” in a system that is avaliable to do work

free energy (G)

Under what condition can an energetically unfavorable reaction with a positive in change of free energy

If it coupled to a second reaction with a negative change in free energy large enough that the net Delta g is negative

Under what condition can an energetically unfavorable reaction with a positive Delta G proceed in a cell?

If it is coupled to a second reaction with a negative Delta G large enough that the Delta G is negative

How do enzymes influence the activation energy barrier of a chemical reaction?

Enzymes lower the activation energy barrier to speed up reactions that are already energetically favorable

What is the standard free-energy change for the combustion of glucose in oxygen?

-2880kJ/mole

What keeps molecules in the cytosol in constant rapid motion, allowing enzymes to explore efficiently by diffusion?

heat energy (Brownian motion)

How many substrate molecules can a typical enzyme capture and process per second?

About 1000 molecules

Photosynthesis uses the energy of sunlight to produce sugars from atmospheric

CO2

In the carbon cycle, what process restores carbon to the atmosphere as CO2 from living organisms?

Cell respiration

In a redox reaction, the term _____ refers to any reaction in which electrons are removed from an atom

Oxidation

How does the oxidation state of carbon change as it forms polar covalent bonds with oxygen or chlorine?

Carbon acquires a partial positive and is said to be oxidized

In organic molecules, what simple metric can be used to track the progression of reduction?

Counting the number of C-H bonds (more bonds equal more reduction)

Why is Delta G more useful than Delta G for comparing the relative energetics of different metabolic reactions?

Delta g is independent of concentration and reflects the intrinsic characters of reacting molecules under ideal conditions

At chemical equilibrium, what is the value of the free-energy change Delta G?

0

What is the relationship between the equil constant K and Delta G at 37 degrees celscius

Delta G= -5.94logK

How much of a change in Delta G is required to shift the equilibrium constant K by a factor of 10 at 37 degrees celsicus?

5.94kJ/mole

What is the equilibrium constant K for the reaction A +B →AB expressed in terms of concentrations?

K= [AB]/ ([A][B])

Catabolism

Metabolic pathways that break down food molecules into smaller units, yielding useful energy and building blocks

In the synthesis of biological polymers, which type of reaction is energetically favorable: condensation or hydrolysis?

hydrolysis

How does a cell capture energy from the oxidation of a food molecule for later use in biosynthesis?

By storing it as chemical-bond energy in activated carriers

Which activated carrier is the most widely used ‘energy currency’ in cells?

ATP

Which group is carried by the activated carrier Acetyl CoA?

acetyl group

Activated carriers like NADH, NADPH, and FADH2 primarily transport which two components?

electrons and hydrogens

What defines a “high-energy” bond, such as phosphoanhydride bonds in ATP?

a bond that releases a large amount of free energy when broken by hydrolysis

What is the standard free-energy change (Delta G) for the hydrolysis of ATP to ADP?

-30.5kJ/mole

In the two-step energy-coupled synthesis of A-B, what occurs during the “activation” step?

Energy from ATP converts A-OH into a higher energy intermediate (A-O_PO3) via phosphoryl transfer

What likely origin explains why many of today’s activated carriers contain nucleotide portions?

They may have originated in an earlier RNA world to facilitate binding to RNA-based catalysts (ribozymes)

Protein family

A group of proteins whose members share similar amino acid sequences, 3D structures, and biological functions

Which member of the serine protease family specifically cleaves after large aromatic residues?

Chymotrypsin

Where are the identical antigen-binding sites located on a Y-shaped antibody molecule?

at the meeting point of a heavy chain and a light variable domain

What structural component of an antibody allows for the generation of billions of distinct binding sites?

protruding hyper variable loops of varying length and sequence

Which specific chemical bond holds the heavy and light chains of an antibody together?

disulfide bonds

When carbon is converted from methane to CO2, is it undergoing progressive oxidation or reduction?

progressive oxidation

If the reaction X → Y has a positive delta G, it is described as an __ reaction

energetically unfavorable

Why is the Delta G of ATP hydrolysis inside cells much more negative than its delta G of -30.5kj/mole?

BC the ratio of ATP to the products ADP and phosphate is kept very high in the cell

The condensation reaction joining two molecules releases a molecule of ___, while hydrolysis consumes one

Water

Which digestive enzyme in the serine protease family is specialized for cleaving after positively charged residues?

trypsin

What is the primary role of S- adenosylmethionine as an activated carrier?

carrying a methyl group

The frequency of collisions between enzymes and substrates depends primarily on their ___

concentrations

How do linear enzyme-catalyzed pathways contribute to cellular metabolism?

they interlink to form a complex web of reactions that convert starting materials into final products needed for survival

if the equilibrium constant K for a reaction is 10², what is the intrinsic delta G at 37 degrees celsicus?

-11.9kJ/mole

In terms of electron shift, why is the carbon in a C-H bond considered reduced?

The carbon nucleus holds more than its share of electrons, acquiring a partial negative charge

The spontaneous tendency toward disorder in the universe is an everyday experience that requires ___ to reverse

energy input

What term describes the complex, stepwise breakdown of food molecules to harvest energy?

Cell respiration

Why are spontaneous reactions not necessarily rapid reactions?

They may still face a high activation energy barrier that prevents them from occurrinh quickly without a catalyst

Which activated carrier is responsible for transporting a carboxyl group?

carboxylated biotin

In Y→ X reaction, if [X]/[Y] at equilibrium is greater than 1, is the delta g positive or negative?

negative

Which functional domain does a nerve cell use to carry electrical signals over long distances?

the axon

The collective term for all chemical reactions needed for a cell to survive, grow, and reproduce is __

metabolism

What is the resulting product of the ‘condensation’ step in energy-coupled biosynthesis?

The final product A-B

What physical constraint limits conventional light microscopy to a resolution of approx 200 nm?

The fundamental resolution limit is dictated by the wavelength of visible length used for imaging

Compare the primary structural difference between a simple microscope and a compound microscope regarding their lens systems

A simple microscope utilizes a single convex lens, whereas a compound microscope uses two or more lenses (objective and ocular)

Why are zebrafish considered a superior vertebrate model for developmental studies compared to mice?

zebrafish undergo external and transparent development, whereas mouse embryos develop internally

in the context of cell culture models, what is a significant limitation when compared to whole-organism models?

they lack the complex tissue context and systemic interactions found in multicellular organisms

Why is the eukaryote Y east specifically favored as a single-celled model in molecular biology?

it is powerful for studying the cell cycle and intracellular trafficking due to its rapid growth and eukaryotic organization