Bio and chem blitz bin

Why does 3d have a higher energy than 4s?

The 4s orbital is actually lower in energy than the 3d orbital due to effective nuclear charge and the distribution of electrons in the orbitals.

What is an orbital

An orbital is a quantum mechanical description of a region of space around the nucleus where there is a high probability (approximately 95%) of finding an electron.

How does the difference in atomic radius affect elements across a period and down a group?

Trend across a period: atomic radius decreases due to increased nuclear charge with constant shielding. Trend down a group: atomic radius increases due to electron shielding and additional electron shells.

Explain why chromium and copper do not fit the expected trend for electronic configuration.

Chromium (Cr) achieves a half-filled 3d subshell, while copper (Cu) achieves a fully-filled 3d subshell, which are both more stable configurations.

What are the two types of ionization used in a mass spectrometer and how do they differ?

Electron Impact (EI) Ionization: High-energy electrons ionize sample molecules by knocking off electrons. Electrospray Ionization (ESI): The sample is dissolved and pushed through a high-voltage needle, creating ions by protonation.

When would you use different ionization methods in mass spectrometry?

Electron Impact: used for elements and low molecular weight compounds; causes fragmentation. Electrospray Ionization: used for high molecular weight biological molecules; prevents fragmentation.

Describe how a time-of-flight mass spectrometer works.

Ions are accelerated by an electric field and travel to a detector. The time taken to travel a known distance allows calculation of each ion's mass based on their time of flight.

What is ionic bonding?

Ionic bonding is the strong electrostatic attraction between oppositely charged ions (cations and anions) in a giant ionic lattice, resulting from the transfer of electrons.

What are the secondary, tertiary, and quaternary structures of amino acids?

Secondary structure: local folding into specific shapes via hydrogen bonds between amino acid groups. Tertiary structure: 3D shape formed by interactions between R groups. Quaternary structure: assembly of multiple polypeptide chains or non-protein groups into a functional complex.

Describe the structure of hemoglobin.

Hemoglobin is a globular protein composed of two alpha and two beta globin chains, each attached to a heme group, allowing it to bind and transport oxygen.

State the main differences between globular and fibrous proteins.

Shape: globular is spherical, fibrous is elongated. Role: globular is physiological, fibrous is structural. Solubility: globular is generally soluble, fibrous is mostly insoluble. Sequence: globular is irregular, fibrous is repetitive. Stability: globular proteins are less stable, fibrous proteins are more stable.

Explain how the structure of glycogen is related to its function.

Glycogen's branched structure allows compact storage and provides multiple ends for rapid hydrolysis, facilitating glucose release for ATP production in respiration.

Explain how the arrangement of cellulose molecules in plant cell walls relates to their functions.

Cellulose molecules form straight chains that align parallel, providing structural support to plant cell walls with reduced hydrolysis at their ends.

What are triglycerides?

Triglycerides are non-polar, hydrophobic macromolecules formed by the condensation reaction between one glycerol molecule and three fatty acid molecules.

Describe the structure of a phospholipid bilayer.

A phospholipid bilayer consists of two layers of amphipathic phospholipids, with hydrophilic phosphate heads facing outward and hydrophobic tails inward, creating a semi-permeable membrane.

Explain how the structure of collagen molecules enables their function as fibers.

Collagen consists of repeating glycine amino acids, promoting hydrogen bonding between chains, which grants tensile strength and structural integrity as a fibrous protein.

Why are certain organelles not visible using a light microscope?

The resolution of a light microscope is insufficient due to the long wavelength of light, limiting the ability to visualize smaller organelles.

Explain how Km and Vmax indicate enzyme affinity for a substrate.

Two enzymes can exhibit the same Vmax; a lower Km indicates a higher affinity for the substrate, meaning the enzyme reaches half of Vmax at a lower substrate concentration.

What is the difference between reversible and irreversible inhibitors?

Reversible inhibitors temporarily bind to the active site via weak interactions. In contrast, irreversible inhibitors form strong covalent bonds, permanently inactivating the enzyme.

Differentiate between competitive and non-competitive inhibitors.

Competitive inhibitors bind to the active site, competing with the substrate, while non-competitive inhibitors bind to allosteric sites, altering the enzyme's shape and reducing its activity.

What is the primary structure of a protein?

The primary structure refers to the specific linear sequence of amino acids in a polypeptide chain, determining the protein's overall structure and function.

What are Van der Waals forces?

Van der Waals forces are weak intermolecular attractions arising from temporary or permanent dipoles in molecules, crucial for biological interactions.

Explain how temporary induced dipoles work.

Temporary induced dipoles occur when the random motion of electrons creates a temporary charge imbalance, inducing a similar imbalance in adjacent molecules, leading to attractive forces.

Describe permanent dipole-dipole interactions.

Permanent dipole-dipole interactions arise between polar molecules with fixed unequal electron distribution due to electronegativity differences, resulting in attractions between partially charged regions.

How do hydrogen bonds work?

Hydrogen bonds are strong intermolecular attractions formed between a delta-positive hydrogen atom covalently bonded to an electronegative atom and the lone pair of another nearby electronegative atom.

What is the ideal gas law and its equation?

The Ideal Gas Law describes the behavior of ideal gases via the equation $PV = nRT$, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.

State metric conversions for microscopy.

1 mm = 1000 µm; 1 µm = 1000 nm.

What is the formula for magnification?

Magnification is calculated using the formula: ext{magnification} = rac{ ext{image size}}{ ext{actual size}}.

Identify the rough endoplasmic reticulum and its functions.

The rough endoplasmic reticulum (RER) is involved in protein synthesis and transport, distinguished by the presence of 80S ribosomes on its surface.

Identify the Golgi body and describe its functions.

The Golgi apparatus modifies proteins received from the RER, sorts them for various destinations, forms secretory vesicles, and produces lysosomes containing hydrolytic enzymes.

Differentiate between 80S and 70S ribosomes.

80S ribosomes are larger, found in eukaryotic cells. 70S ribosomes are smaller, found in prokaryotes and organelles such as mitochondria.

What are lysosomes and their functions?

Lysosomes are vesicles produced by the Golgi apparatus containing digestive enzymes; they break down nutrients, bacteria, and debris and are involved in apoptosis.

What is plasmodesmata and its function?

Plasmodesmata are narrow cytoplasmic threads that connect adjacent plant cells, facilitating intercellular communication and transport.

Outline key structural features of a prokaryotic cell as found in a typical bacterium.

Prokaryotic cells are unicellular, generally range from 1-5 µm in diameter, possess peptidoglycan cell walls, have circular DNA, contain 70S ribosomes, and lack organelles with double membranes.

Describe the structure of viruses.

Viruses consist of nucleic acid (DNA or RNA) encased in a protein coat, known as a capsid, and may also have a lipid envelope.

What is the nucleolus and its function?

The nucleolus is a non-membrane bound structure within the nucleus where ribosomal RNA (rRNA) is synthesized and assembled into ribosome components.

Explain the enthalpy change of a reaction (ΔHr).

The enthalpy change, ΔHr, represents the heat change during a reaction at constant pressure, defined for a particular reaction as the difference in enthalpy between products and reactants.

Explain the enthalpy change of formation (ΔHf).

ΔHf is defined as the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

What is the enthalpy of combustion (∆Hc)?

∆Hc is the enthalpy change that occurs when one mole of a substance is completely burned in excess oxygen under standard conditions.

Explain the enthalpy change of neutralization (∆Hn).

∆Hn is the enthalpy change that occurs when one mole of water is produced from the reaction of an acid with an alkali under standard conditions.

Define Hess' law.

Hess' law states that the total enthalpy change during a chemical reaction is the same regardless of the route taken, as long as initial and final states are the same.

What is a ligand?

A ligand is any molecule that binds specifically to a receptor site on another molecule, mediating biological responses.

Explain the process of cell signaling.

Cell signaling involves the secretion of specific chemicals (ligands) from cells, their transport to target cells, and the binding of ligands to cell surface receptors, initiating a response.

What do phospholipids do?

Phospholipids are essential components of cell membranes, forming bilayers that provide structural integrity and a barrier to the passage of substances.

What is the role of cholesterol in the cell membrane?

Cholesterol maintains membrane fluidity by preventing the packing of phospholipids, allowing for flexibility and stability at varying temperatures.

What is simple diffusion?

Simple diffusion is the process by which solutes move from an area of high concentration to an area of low concentration across a semi-permeable membrane without the involvement of energy.

What is facilitated diffusion?

Facilitated diffusion is the passive movement of molecules across a cell membrane via specific carrier proteins, without requiring energy input.

What is active transport?

Active transport is the process of moving ions or molecules against their concentration gradient, requiring ATP and specific transport proteins to assist.

What is osmosis?

Osmosis is the diffusion of water molecules across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Describe endocytosis and exocytosis.

Endocytosis is the process by which cells engulf external substances, forming intracellular vesicles. Exocytosis is the fusion of these vesicles with the plasma membrane to release their contents outside the cell.

What is dynamic equilibrium?

Dynamic equilibrium refers to a state in a closed system where the rates of forward and reverse reactions occur at the same rate, resulting in no net change.

What is a closed system, and what is its purpose?

A closed system is a thermodynamic system that can exchange energy but not matter with its surroundings, allowing for the study of energy interactions without mass transfer.

Describe the arrangements of glycoproteins, glycolipids, and cholesterol in cell surface membranes.

Glycoproteins and glycolipids are located on the outer surface of the membrane, facilitating cell recognition. Cholesterol molecules intersperse among phospholipid tails, enhancing membrane stability.

What are the equations for Kc?

The equilibrium constant Kc is expressed as K_c = rac{[C]^c[D]^d}{[A]^a[B]^b}, where [C], [D], [A], and [B] are the molar concentrations of the respective substances.

If Kc is less than 1, what does this indicate?

If Kc < 1, the equilibrium position favors the reactants, indicating a higher concentration of reactants compared to products; the backward reaction is favored.

If Kc is greater than 1, what does this indicate?

If Kc > 1, the equilibrium position favors the products, indicating a higher concentration of products compared to reactants; the forward reaction is favored.

What to consider when adding/subtracting using ICE tables?

When using ICE tables, ensure that changes to concentrations or pressures account for the stoichiometric coefficients of the balanced chemical equation.

What is Le Chatelier's principle used for?

Le Chatelier's principle is used to predict how changes in concentration, temperature, or pressure will affect the position of equilibrium in a reversible reaction.

Describe DNA.

DNA is composed of nucleotides, each consisting of a phosphate group, a sugar, and nitrogenous bases (adenine, thymine, guanine, and cytosine). The sequence of these bases encodes genetic information.

Describe histones.

Histones are proteins that facilitate the winding of eukaryotic DNA into structural units called nucleosomes, aiding in the organization and compaction of genetic material.

Describe sister chromatids.

Sister chromatids are identical copies of a single chromosome connected by a centromere, formed during DNA replication preceding cell division.

Describe a centromere.

The centromere is the constricted region of a chromosome where spindle fibers attach during cell division, facilitating the separation of sister chromatids.

Describe telomeres.

Telomeres are repetitive DNA sequences at the ends of eukaryotic chromosomes, produced by the enzyme telomerase, that protect genetic information during replication.

What occurs during interphase?

During interphase, the cell undergoes growth and DNA replication, preparing for mitosis and ensuring that each daughter cell receives a complete set of chromosomes.

What occurs during mitosis? (5 phases)

Mitosis consists of five phases: interphase (preparation), prophase (chromosome condensation), metaphase (chromosome alignment), anaphase (chromatid separation), and telophase (nuclear reformation), followed by cytokinesis.

What happens during cytokinesis?

Cytokinesis is the process of cellular division in which the cytoplasm is physically divided, resulting in the formation of two genetically identical daughter cells.

What is this an example of?

An example of effective versus non-effective collisions in a reaction, distinguishing between collisions that result in a reaction and those that do not.

What is covalent bonding?

Covalent bonding is the strong electrostatic attraction between shared pairs of electrons and the nuclei of the bonded atoms, forming stable compounds.

What is metallic bonding?

Metallic bonding is characterized by the attraction between a lattice of positive metal ions (cations) and a sea of delocalized electrons, resulting in electrical conductivity.

What is the main role of telomeres?

The primary role of telomeres is to protect important genetic information from being lost during DNA replication

What is the Brønsted-Lowry theory of acids and bases?

The Brønsted-Lowry theory defines acids as proton donors and bases as proton acceptors.

What are the conditions needed for the conatct process (5)

1. Catalyst: Vanadium(V) oxide (V_2O_5)

2. Temperature: 450^{\circ}C

3. Pressure: 2 \text{ atm} (or 1-2 \text{ atm})

4. Yield: 98\%

5. Equation: 2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)

What are the conditions needed for the Haber process

1. Catalyst: Iron (with potassium hydroxide promoter)

2. Temperature: 450^{\circ}C

3. Pressure: 200 \text{ atm}

4. Yield: \approx 15\% (Ammonia is recycled to reach 98\% total)

5. Equation: N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \quad \Delta H = -92 \text{ kJ mol}^{-1}

What is Activation energy

the minimum energy required for a collision to be effective

What is this and what does it describe?

A graphical representation of the change in pH of a solution (the analyte) as a specific volume of a reagent (the titrant) is added from a burette. It illustrates the progress of an acid-base neutralization, identifying the equivalence point and the buffer region.

How does pressure and concentration effect rate of reaction? (2)

There is a higher frequency of successful collision for both, because

Pressure - Less volume thus higher chances of colliding

Concentration - More frequency of particles to create successful collisions