Biology: Cell & Molecular Biology Practice Flashcards

A high-yield vocabulary review of biology concepts including biochemistry, cell structure, metabolism, and cell division based on the OATBooster lecture notes.

Electronegativity

The ability of an atom to attract shared electrons within a bond; high electronegativity indicates the atom pulls electrons closer to itself.

Ionic Bond

A complete transfer of electrons from one atom to another between atoms with very different electronegativities, existing between ions.

Covalent Bond

A bond where electrons are shared between atoms with similar electronegativities; can be single, double, or triple bonds.

Nonpolar Bond

The equal sharing of electrons due to highly similar electronegativity.

Polar Bond

The unequal sharing of electrons due to slightly different electronegativity, leading to the formation of a dipole.

Hydrogen Bond ($H$-Bond)

A weak bond requiring a hydrogen covalently bonded to a highly electronegative atom ($F$, $O$, or $N$), which is then attracted to another highly electronegative atom.

Van der Waals Interactions

Weak, temporary attractions between atoms or molecules in close proximity due to transient, uneven distribution of electrons.

Cohesion

The attraction between like molecules, such as $H_2O$; high cohesion in water produces high surface tension.

Adhesion

The attraction between unlike substances, such as water and non-water substances.

Capillary Action

The ability of a liquid to flow without external forces, explained by adhesion and cohesion; helps water flow upward in plants during transpiration.

Fat Soluble Vitamins

Vitamins that are deposited in body fat, including Vitamin $A$ (pigment/epithelial maintenance), Vitamin $D$ (calcium absorption), Vitamin $E$ (antioxidant), and Vitamin $K$ (blood clotting).

Water Soluble Vitamins

Vitamins not stored in the body and excreted in urine, including Vitamin $B$ (coenzymes or precursors) and Vitamin $C$ (collagen synthesis).

Dehydration Synthesis

The process by which monomers combine to form polymers, producing an $H_2O$ molecule.

Hydrolysis

The process by which an $H_2O$ molecule is used to break polymer linkages.

Polysaccharides

Long chains of monosaccharides; includes Starch (energy in plants), Glycogen (energy in animals), Cellulose (plant cell walls), and Chitin (fungi cell walls/arthropod exoskeletons).

Amphipathic

A molecule containing both hydrophilic (polar) and hydrophobic (nonpolar) properties, such as a phospholipid.

Steroids

Lipids characterized by four joined hydrocarbon rings; examples include steroid hormones, cholesterol, Vitamin $D$, and bile acids.

Porphyrins

Structures with 4 joined pyrrole rings and a central metal atom, such as Chlorophyll ($Mg$) and Hemoglobin ($Fe$).

Peptide bonds

The linkage type between amino acids in a protein's primary structure.

Primary structure

The linear sequence of amino acids connected by peptide bonds, determined by translated mRNA codons.

Secondary structure

The 3D shape ($\text{alpha helix}$ and $\text{beta sheet}$) resulting from hydrogen bonding between amino and carboxyl groups of adjacent amino acids.

Tertiary structure

The 3D structure due to interactions between amino acid $R$ groups, including hydrogen bonds, ionic bonds, hydrophobic effect, disulfide bonds, and Van der Waals forces.

Quaternary structure

A 3D structure arising from multiple protein subunits joining together.

Purines

Nucleotides with double ring nitrogen bases: Adenine ($A$) and Guanine ($G$).

Pyrimidines

Nucleotides with single ring nitrogen bases: Cytosine ($C$), Uracil ($U$), and Thymine ($T$).

Chargaff’s Rule

The number of purines is always equal to the number of pyrimidines ($A + G = T + C$).

Nucleolus

The region inside the nucleus where ribosomal RNA ($rRNA$) is made and ribosomal subunits are formed.

Rough ER (RER)

Synthesizes and modifies proteins before export; studded with ribosomes and capable of post-translational modifications like glycosylation.

Smooth ER (SER)

Synthesizes lipids and steroid hormones for export; functions in breakdown of toxins in liver cells and stores $Ca^{2+}$ in muscle cells.

Golgi Apparatus

A series of flattened sacs (cisternae) that sort, modify, and transport proteins and lipids; has a cis end (accepting) and trans end (exporting).

Peroxisomes

Organelles that break down toxic substances and fatty acids; they produce and break down $H_2O_2$ using the enzyme catalase.

Microfilaments

Cytoskeleton components composed of intertwined actin strands involved in cell motility, muscle contraction, and the cleavage furrow.

Microtubules

Hollow tubes made of tubulin polymers that provide support, motility (cilia, flagella), and intracellular transport network.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts were once independent prokaryotes that formed a symbiotic relationship with a larger cell.

Selective permeability

The property of the cell membrane that allows only certain substances to cross without the assistance of transport proteins.

Facilitated diffusion

Passive transport across the cell membrane from higher to lower concentration using membrane proteins.

Primary active transport

The movement of substances against their concentration gradient using energy from $ATP$ directly.

Secondary active transport

Using energy from a different electrochemical gradient to move substances against their concentration gradient; includes antiporters and symporters.

Gram Negative Bacteria

Bacteria with a thin peptidoglycan layer between an outer and inner membrane, staining pink; contain lipopolysaccharides (LPS) which act as endotoxins.

Gram Positive Bacteria

Bacteria with a thick peptidoglycan layer surrounding an inner membrane, staining purple.

Gibbs Free Energy Formula

$\Delta G = \Delta H - T\Delta S$; where $\Delta G < 0$ is spontaneous/exergonic and $\Delta G > 0$ is non-spontaneous/endergonic.

Zymogens (proenzymes)

An inactive precursor form of an enzyme that is activated or cleaved by specific conditions or molecules.

$$V_{max}$$

The maximum rate of a reaction, limited by enzyme saturation.

$K_m$ (Michaelis Constant)

The concentration of substrate at $\frac{1}{2} V_{max}$; inversely proportional to substrate binding affinity.

Competitive Inhibition

Inhibition where the inhibitor reversibly binds to the active site; increases $K_m$ but leaves $V_{max}$ unaffected.

Non-Competitive Inhibition

Inhibition where the inhibitor binds to an allosteric site, decreasing $V_{max}$ while leaving $K_m$ unaffected.

Glycolysis

The anaerobic breakdown of glucose into 2 pyruvate, 2 $ATP$, and 2 $NADH$ in the cytosol.

Phosphofructokinase (PFK)

The enzyme in Step 3 of glycolysis that converts fructose 6-phosphate to fructose 1,6-bisphosphate; the key irreversible regulatory step.

Pyruvate decarboxylation

The conversion of pyruvate into acetyl CoA in the mitochondrial matrix when oxygen is present, yielding $NADH$ and $CO_2$.

Citric Acid Cycle (CAC)

A cycle in the mitochondrial matrix that produces 1 $ATP$, 3 $NADH$, and 1 $FADH_2$ per cycle (twice per glucose molecule).

Oxidative Phosphorylation

The process of producing $ATP$ using energy from electron flow through the ETC and the proton-motive force via $ATP$ synthase.

Alcohol fermentation

Anaerobic process converting pyruvate to acetaldehyde and then to ethanol to regenerate $NAD^+$; acetaldehyde is the final electron acceptor.

Lactic acid fermentation

Anaerobic process in muscles, fungi, and bacteria converting pyruvate to lactate to regenerate $NAD^+$.

Beta-oxidation

The breakdown of fatty acid chains in the mitochondrial matrix to produce acetyl CoA, $NADH$, and $FADH_2$.

Photolysis

The splitting of water by light in Photosystem II to provide electrons, protons ($H^+$), and oxygen.

RuBisCo

The enzyme that combines $CO_2$ and $RuBP$ in the Calvin cycle; the most abundant enzyme on Earth but can also bind oxygen in photorespiration.

C4 Photosynthesis

A method to prevent photorespiration by physically separating light and dark reactions, moving the Calvin cycle to bundle-sheath cells.

CAM Photosynthesis

A method to minimize water loss by temporal separation, opening stomata only at night to fix $CO_2$ as malic acid.

Karyotyping

The process of visualizing a cell's chromosomes using a microscope, performed during metaphase to identify abnormalities.

Synapsis

The process during Prophase I of meiosis where homologous chromosomes pair up to form tetrads.

Crossing over

The exchange of chromosome segments between homologous chromosomes at chiasmata during Prophase I, increasing genetic variation.

Interphase

The stage of the cell cycle (G1, S, G2) during which cells grow and replicate DNA but are not actively dividing.

p53 gene

An important tumor suppressor gene that regulates cell division; mutations lead to uncontrolled division and tumor formation.