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

What is an orbital

An orbital is a region of space around the nucleus where there is a high probability (usually about 95%) of finding an electron.

Explain why chromium and copper does not fit the trend for electronic configuration

To achieve a half-filled 3d subshell (for Cr)" or "a fully-filled 3d subshell (for Cu).

What are two types of ionizations for a mass spectrometer and how do they differ

Electron Impact (EI) Ionization - How it works: High-energy electrons are fired from an "electron gun" (a heated filament) at the sample. These incoming electrons knock an electron out of the sample atoms or molecules.

Electrospray Ionization (ESI) - • How it works: The sample is dissolved in a solvent and pushed through a fine, pressurized needle that is connected to a high-voltage power supply. As the droplets emerge, they gain a proton (H^+) from the solvent.

when would you use different ionisation in a mass spec

Electron impact - Used for elements and low M_r compounds; causes fragmentation.

Electospray ionization - Used for high M_r biological molecules; prevents fragmentation

describe how a time of flight mass spec works

Ions of different Atomic mass numbers are accelerated by an electric field and each hit a detector to calculate the time of flight of each ion, which is used to calculate the mass

What is IONIC bonding

Ionic bonding is the strong electrostatic attraction between oppositely charged ions (cations and anions) in a giant ionic lattice.

What is a secondary, tetiary and quarternery structure of an amino acid?

Secondary - The local folding of the polypeptide chain into specific shapes, held together by hydrogen bonds between the NH group of one amino acid and the C=O group of another.

Tetiary - The further folding of the secondary structure into a specific, complex three-dimensional shape, determined by interactions between the R groups (side chains).

Quaternary - The association of two or more polypeptide chains (and sometimes non-protein prosthetic groups) into one functional unit.

Describe the strucure of haemoglobin

A globular protein made up of disulfide bonds and 2 a-globin chains and 2 b-globin chains each with its own haem group

state the main differences between globular and fibrous protiens (5)

Shape - globular is generally spherical and fibrous is long and thin

Primary role -Globular is physiological and fibrous is stuctural

Solubility- globular generally soluble and fibrous most are insoluble

Amino acid sequence - globular generally irregular and unvaried and fibrous is repetitive and organized

Stability - globular proteins are relatively unstable, fibrous proteins are stable and physically tough

explain how the structure of glycogen is related to its function (4)

● Branched → compact / fit more molecules in small area

● Branched → more ends for faster hydrolysis → release glucose for respiration to

make ATP for energy release

● Large, insoluble polysaccharide molecule → can't leave cell / cross cell membrane

● Insoluble in water → water potential of cell not affected (no osmotic effect)

Explain how the arrangement of cellulose molecules in plant cell walls are related to their functions

Cellulose has only 2 free ends for reduced hydrolosis

Straight chain formation to align with cell walls - gives support

structure of a pospholipid bi layer

A phospholipid bilayer is a universal component of all cell membranes, consisting of two layers of amphipathic phospholipids. It is arranged such that the hydrophilic phosphate heads point outward toward the aqueous environment, while the hydrophobic hydrocarbon tails point inward, creating a non-polar central core.

Explain how the stucture of collagen molecule makes it suitable to form a collagen fibres (3)

Every third amino acid in the chain is Glycine.

Thanks to Glycine, Hydrogen bonds form between the peptide groups of different chains. This "zips" the three strands together, providing immense pulling (tensile) strength.

Collagen is a fibrous protien

Explain, why these organelles are not visible using a light microscope.

The resolution is not high enough

The wavelength of light is too long

Explain how the KM or Vmax indicates the affinity the enzyme and has for the substrate bind

Two enzymes can have have the exact same Vmax as another but if one has a lower Km then its substrate affinity will be higher than the other.

Difference between reversible inhibitors and irreversible inhibitors

Reversible form weak bonds with the active sight and stay by the active site temporarily

Irreversible form string bonds with the active sight and permanently stay there causing all enzyme activity to stop.

Difference between competitive inhibitors and non competitive inhibitors

Competitive - Bind to active sight, makes up all the Vmax of normal substrate and similar in shape to substrate

Non competitive - Bind to the allosteric sight which alters the shape of the active site, causing it to have a much higher KM but lower Vmax (half) than a competitive inhibitor

What is a primary stucture of a protein

They are the specific sequence of amino acids in a polypeptide chain

What are Van der Waals forces?

Van der Waals forces are the weak intermolecular forces (forces between molecules) that arise from the attraction between temporary or permanent electric dipoles.

How do temporary induced dipoles work?

Temporary Induced dipole-dipole interactions : These occur when the random movement of electrons in an atom or molecule creates a temporary imbalance of charge, which then "induces" a matching imbalance in a neighboring molecule.

How do Permanent dipole-dipole interactions work

Permanent dipole-dipole : These occur between polar molecules that have a fixed, lopsided distribution of electrons due to differences in electronegativity (like in HCl). The permanent delta+ end of one molecule is attracted to the permanent delta- end of another.

How do Hydrogen bonds work?

Hydrogen bonds - Hydrogen Bonding is a strong intermolecular force of attraction between a delta+ hydrogen atom (which is covalently bonded to a highly electronegative atom: N, O, or F) and the lone pair of electrons on a neighboring highly electronegative atom (N, O, or F).

What is the ideal gas law and what is the equation used to calculate it?

The Ideal Gas Law is the equation of state for a theoretical gas composed of many randomly moving point particles that are not subject to interparticle interactions.

Equation - PV = nRT

Metric conversions for microscopy.

1mm =1000µm

1µm = 1000nm

Formula for magnification

magnification = image size/actual size

Identify the rough endoplasmic reticulum and understand their functions

rough : Primary Function: Protein synthesis and transport. (contains 80s ribosomes)

Smooth : Lipid metabolism, Carbohydrate metabolism, Detoxification (in the liver), calcium storage

Identify Golgi body and describe its functions

• Modification of Proteins: The Golgi receives proteins from the RER via transport vesicles. It modifies these proteins by adding or removing carbohydrate chains, often turning them into glycoproteins.

• "Sorting and Packaging": It acts like a warehouse. It tags proteins with "molecular labels" (like phosphate groups) to ensure they are sent to the correct location (e.g., to the cell surface membrane for secretion, to lysosomes, or back to the ER).

• Formation of Secretory Vesicles: Once processed and tagged, the proteins are packed into Golgi vesicles that bud off the trans-face (the exit side) of the Golgi. These vesicles move along the cytoskeleton to the plasma membrane for exocytosis.

• Lysosome Production: The Golgi is responsible for producing lysosomes, which contain hydrolytic enzymes (lysozymes) used for breaking down foreign matter or old organelles.

Difference between 80s and 70s ribosomes

80s: Larger, Found in the cytoplasm and attached to the RER of Eukaryotic cells.

Composed of a 60S large subunit and a 40S small subunit.

70s: Found in Prokaryotes, as well as within mitochondria and chloroplasts.

Composed of a 50S large subunit and a 30S small subunit.

What are lysosomes and what are their functions?

vesicles produced by Golgi that contain digestive enzymes with a low pH due to their function: --used to break down nutrients/bacteria/cell debris

-in apoptosis, lysosomes release their contents into the cell, activating a mechanism inside the cell to cause its death

What is the plasmodesmata and what is it's function?

a narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells and allows communication between them.

Outline key structural features of a prokaryotic cell as found in

a typical bacterium (6)

- unicellular

- generally 1-5 µm diameter

- peptidoglycan cell walls

- circular DNA

- 70S ribosomes

- absence of organelles surrounded by double membranes

Describe the structure of viruses

All viruses contain nucleic acid, either DNA or RNA (but not both), and a protein coat, which encases the nucleic acid

What is the nucleolus and its function?

The nucleolus is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis.

explain the enthalpy change of a reaction (ΔHr)

The enthalpy change that occurs when equation quantities of substances react under standard conditions, with all reactants and products in their standard states.

explain enthalpy change of formation, (ΔHf)

Definition: The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states, under standard conditions.

What is Enthalpy of combustion (∆Hc)

The enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions, with all reactants and products in their standard states.

Excess Oxygen: You must state it is burned in oxygen.

Enthalpy change of neutralization

Definition: The enthalpy change when solutions of an acid and an alkali react together under standard conditions to produce one mole of water.

Define Hess' law

total enthalpy change for a chemical reaction is independent of the route by which the chemical change occurs, provided the initial and final states (including temperature and pressure) are the same.

What is a ligand?

any molecule that binds specifically to a receptor site of another molecule

Explain the process of cell signalling(3)

•

secretion of specific chemicals (ligands) from cells

•

transport of ligands to target cells

•

binding of ligands to cell surface receptors on target cells

What do phospholipids do?

Phospholipids are essential for the structure of the cell membrane

What does cholesterol do in the cell membrane?

maintains fluidity

What is simple diffusion?

movement of a solute from an area of high concentration to an area of low concentration

What is facilitated diffusion?

The passive movement of a particle across a cell membrane via a carrier protein. (ATP required)

What is active transport?

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

What is osmosis?

diffusion of water across a selectively permeable membrane

Describe endocytosis and exocytosis.

•Endocytosis is an invagination in the surface of a cell that forms intracellular membrane bound vesicles;

•exocytosis occurs on the opposite side of the cell with fusion of the vesicle to the membrane and release of the vesicles' contents.

What is dynamic equilibrium?

Equilibrium in a closed system where the reactions occur at exactly the same rate in each direction

What is an enclosed system and what is its purpose?

A closed system (often referred to as an enclosed system in general contexts) is a thermodynamic system where energy can be exchanged with the surroundings, but matter cannot.

Describe the arrangements of glycoprotein and glycolipids and cholesterol in cell surface membranes

Glycoproteins and Glycolipids - They are found exclusively on the external surface of the cell surface membrane (the extra-cellular side).

Cholesterol - Cholesterol molecules are tucked between the fatty acid tails of the phospholipids.

What are the equations for Kc

Kc = [C]c+[D]d/[A]a=[B]b

If Kc is less than 1

- The position of equilibrium favours the left hand side of the reaction, i.e. there is a greater amount of reactants compared to products and the backward reaction is favoured

- Reactants more stable than products

If Kc is greater than 1

- The position of equilibrium favours the right hand side of the reaction, i.e. there is a greater amount of products compared to reactants and the forward reaction is favoured

- Products more stable than reactants

ICE tables what to add/subtract

Make sure you are watching coefficients when adding/subtracting......Everything must be proportinal

What is Le Chatelier's principle used for?

To work out how changing external conditions such as temperature and pressure affect the position of equilibrium

Describe DNA

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code.

Describe histones

winding proteins. (Histones serve as winding points for the eukaryotic DNA.)

Describe sister chromatids

Sister chromatids are two identical copies of a single chromosome that are connected by a centromere.

Describe a centromere

It is the ball in the middle where spindle fibers attach to chromatids during cell division. These fibers attach via multiprotein complexes called kinetochores.

Describe telomeres

- repeated DNA sequence on the ends of eukaryotic chromosomes

- produced by telomerase

What occurs during interphase?

cell growth and duplication of the chromosomes