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 the structures(that you are most likely to forget) inside of mitochondria called?

Cristae (singular: Crista): These are the actual folds of the inner membrane. More folds = more surface area = more ATP production.

Matrix: The semi-rigid, gel-like interior. It contains the enzymes for the Link Reaction and the Krebs Cycle, plus mitochondrial DNA and 70S ribosomes.

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: $ext{magnification} = \frac{ ext{image size}}{ ext{actual size}}$.

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 $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$, 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

What are the advantages of immobizing enzymes in alginate? (3)

Product Purity: The enzyme doesn't mix with the product, so no expensive downstream processing (separation) is needed.

2 Reusability: Beads can be recovered and used for many batches, making the process cost-effective.

3 Enhanced Stability: The alginate matrix protects the enzyme from denaturation, allowing it to function at higher temperatures or more extreme pH levels.

What are immobilized enzymes?

These are enzymes that are physically attached to, or trapped within, an insoluble, inert material. This prevents them from moving freely in the reaction mixture while still allowing them to catalyze reactions.

What are the main roles of stem cells?

Growth and Development

In embryos, stem cells are the "building blocks." They differentiate into every tissue type (e.g., nerve, muscle, blood) to form a complex organism from a single zygote.

Tissue Repair and Replacement

In adults, stem cells (found in specific "niches" like bone marrow) divide to replace damaged or dead cells. This maintains the integrity of tissues that have a high turnover rate, such as skin or blood.

What is this?

Boltzmann distribution.

What is the trend in ionisation energy across the period in period 3?

General Trend: First ionisation energy INCREASES across Period 3.

Explain the change in melting point across the group

Across Period 3, the melting point rises sharply from Na to Si, peaks at Si, and then drops significantly for P, S, Cl, and Ar.

What is a nucleotide and describe the structure of nucleotides

A monomer of nucleic acids made of 3 components:

1 Pentose Sugar: 5-carbon sugar (Deoxyribose in DNA, Ribose in RNA).

2 Phosphate Group: Acidic, negative charge. Attached to Carbon 5 (5').

3 Nitrogenous Base: Attached to Carbon 1 (1').

Purines (2 rings): Adenine (A), Guanine (G)

Pyrimidines (1 ring): Cytosine (C), Thymine (T) / Uracil (U)

How are the two strands of a DNA molecule anti-parallel? (4)

The two polynucleotide strands run in opposite directions parallel to each other.

One strand runs in the 5' to 3' direction, while the opposite strand runs in the 3' to 5' direction.

The 5' (five-prime) end terminates with a phosphate group attached to carbon-5 of the deoxyribose sugar.

The 3' (three-prime) end terminates with a hydroxyl (-OH) group attached to carbon-3 of the deoxyribose sugar.

Outline the mechanism of semi-conservative DNA replication. (5)

Flashcard Back

1 Unwinding: DNA helicase breaks hydrogen bonds between complementary base pairs to separate the strands and expose the templates.

2 Pairing: Free activated nucleotides align via complementary base pairing (A to T, C to G) and form new hydrogen bonds with the template.

3 Elongation (5' \rightarrow 3'): DNA polymerase catalyzes condensation reactions to form phosphodiester bonds between adjacent nucleotides, moving strictly in the 5' to 3' direction.

4 Continuous vs. Discontinuous: * Leading strand is synthesized continuously toward the replication fork.

Lagging strand is synthesized discontinuously away from the fork, creating Okazaki fragments.

5 Joining: DNA ligase joins the Okazaki fragments by forming phosphodiester bonds to complete the lagging strand backbone.

What does DNA polymerase do?

DNA polymerase synthesizes a new DNA strand by catalyzing the formation of phosphodiester bonds between aligned complementary nucleotides in a 5' to 3' direction via condensation reactions.

What does DNA ligase do?

It Seals nicks in the sugar-phosphate backbone by catalyzing the formation of phosphodiester bonds to join adjacent, pre-existing DNA fragments together (such as Okazaki fragments on the lagging strand).

How does the lagging an leading strand differ?

The leading strand is synthesized continuously toward the replication fork in the 5' to 3' direction, whereas the lagging strand is synthesized discontinuously away from the fork in short Okazaki fragments that must be joined by DNA ligase.

Short, single-stranded polynucleotide chain that contains ribose sugar instead of deoxyribose, uracil (U) instead of thymine, and carries the genetic code from the DNA in the nucleus to a ribosome for protein synthesis.

What is disproportanation

A reaction in which the same element is simultaneously oxidized and reduced.

How does magnesium oxide react with cold water? hot steam? (2)

With Cold Water: The reaction happens slowly (especially with \text{MgO}). It forms a metal hydroxide suspension.

With Hot Steam: The reaction is initially much faster due to the higher thermal energy. However, group 2 metal hydroxides undergo thermal decomposition at high temperatures. If the steam is hot enough, the hydroxide decomposes right back into the oxide and water vapor.

How does sodium oxide react to cold water? hot steam?

The Reaction with cold water: The reaction between sodium oxide and cold water is highly exothermic and occurs vigorously.

The Reaction with cold water: Sodium oxide reacts VIOLENTLY with hot water.

How to balance disproportionatation reactions? (5)

1. SPLIT & BALANCE ATOMS:

• Red: Cl₂ → 2Cl⁻ (0 to -1)

• Ox: Cl₂ + 6H₂O → 2ClO₃⁻ + 12H⁺ (0 to +5)

2. BALANCE CHARGES (e⁻):

• Red: Cl₂ + 2e⁻ → 2Cl⁻ [x5 to get 10e⁻]

• Ox: Cl₂ + 6H₂O → 2ClO₃⁻ + 12H⁺ + 10e⁻

3. COMBINE & CANCEL:

• 6Cl₂ + 6H₂O → 10Cl⁻ + 2ClO₃⁻ + 12H⁺

4. ALKALINE FIX (+12OH⁻ to both sides):

• 6Cl₂ + 12OH⁻ → 10Cl⁻ + 2ClO₃⁻ + 6H₂O

5. SIMPLIFY RATIO (÷2):

👉 3Cl₂ + 6OH⁻ → 5Cl⁻ + ClO₃⁻ + 3H₂O 👈

How is a polypeptide coded for?

It is coded by a gene, which is a specific sequence of nucleotides called a triplet when 3 bases are in a set, which forms a codon.

The codon codes for 1 amino acid

Which molecule has the codon, and which has the anticodon?

mRNA has the CODON. * What it is: A triplet of bases that carries the genetic code from the DNA to the ribosome.

tRNA has the ANTICODON. * What it is: A triplet of bases that is complementary to the mRNA codon and carries a specific amino acid.

What is transcription?

Definition: The process where a specific DNA gene sequence is copied into a complementary mRNA molecule.

Location: Occurs in the nucleus (of eukaryotes).

Key Mechanism: RNA polymerase separates DNA strands and pairs free RNA nucleotides against the antisense strand template

What is translation?

Definition: The process where the mRNA base sequence is decoded by a ribosome to synthesize a specific polypeptide chain.

Location: Occurs in the cytoplasm (at a ribosome).

Key Mechanism: tRNA molecules bring specific amino acids; tRNA anticodons bind to complementary mRNA codons. Peptide bonds form between adjacent amino acids.

What the heck are exons and introns?

Introns = Non-coding sections of DNA/RNA. They do not code for amino acids and are "interfering."

Exons = Coding sections of DNA/RNA. They are "expressed" to code for the amino acid sequence of a polypeptide

In a DNA molecule, what do you call the strand used in transcription? The other one is called?

The template strand and the other one is the non-transcribed strand