Cell Biology Review

Vocabulary flashcards for cell biology exam review.

Genomic Equivalence

The concept that all cells in a multicellular organism contain the same genetic information.

Cell Division and Cellular Differentiation

Cell division produces new cells, differentiation involves cells acquiring specialized functions and gene expression profiles. Once a cell differentiates, its ability to divide may be limited or restricted.

Differential Gene Expression

Cellular differentiation depends on differential gene expression. Different sets of genes are turned on or off in different cell types which leads to the production of specific proteins that define cell function and identity.

pKa

The pH at which half of the amino acid's ionizable groups are protonated.

Henderson-Hasselbalch equation

pH=pKa+log([A−][HA]) This relates pH, pKa, and the ratio of deprotonated to protonated forms, allowing quantitative estimation of protonation states at different pH values.

Polypeptide

A linear chain of amino acids.

Protein

One or more polypeptides folded into a functional 3D structure.

Protein Domain

A distinct functional and/or structural unit within a protein.

Homolog

Proteins related by evolutionary descent, sharing sequence and structural similarities.

Protein Quality Control and Ubiquitin-Proteasome System

Misfolded or damaged proteins are tagged with ubiquitin; proteasomes then degrade these proteins, maintaining cellular health.

Competitive Enzyme Regulation

Inhibitor binds active site, raises Km, Vmax unchanged.

Non-Competitive Enzyme Regulation

Inhibitor binds elsewhere, Vmax decreases, Km unchanged.

Vmax

Maximum rate of enzyme activity.

Km

Substrate concentration at half Vmax.

Transition Temperature (Tm)

Temperature at which membranes shift from rigid to fluid.

Integral Membrane Proteins

Span membrane.

Peripheral Membrane Proteins

Attached to surface.

Lipid-Anchored Membrane Proteins

Covalently attached to lipids.

Facilitated Diffusion

Carrier or channel proteins assist movement down gradients.

Transport Proteins

Undergo conformational changes; channels form pores.

Gradient-Driven Pumps

Use existing gradients (e.g., Na+/glucose symporter).

ATP-Driven Pumps

Hydrolyze ATP to move substances against gradients (e.g., Na+/K+ pump).

Na+/K+ Transporter

Enzyme that uses ATP to pump 3 Na+ out and 2 K+ in, crucial for maintaining ion gradients and cell volume.

Glycolysis

Converts glucose into pyruvate, producing ATP, NADH, and FADH2 for energy transfer.

Core Cis-Elements (TATA Box)

Located upstream of the gene; binds transcription factors to initiate transcription.

General Transcription Factors

Form pre-initiation complex, recruit RNA polymerase II, and start transcription.

Regulatory Elements and Trans Factors

Modulate transcription; transcription factors bind these elements to regulate gene activity.

Alternative Splicing

Different exons included/excluded, affecting function and evolution.

Aminoacyl-tRNA Synthetases

Attach amino acids to tRNAs, enabling translation.

Signal Sequences

Sequences direct proteins to specific locations (e.g., nucleus, mitochondria, secretion).

ER Signal Recognition Particle (SRP)

Binds signal sequences; halts translation until ribosome docks on ER.

Mannose-6-Phosphate Tagging

Targets enzymes to lysosomes; involves phosphorylation of mannose residues.

Receptor-Mediated Endocytosis

Receptors bind ligands, cluster in coated pits, invaginate, and form vesicles; mutations impair uptake.

Microtubules

Vesicle transport, cell shape.

Microfilaments

Muscle contraction, cell motility.

Intermediate Filaments

Structural support.

MTOC Organization

Centrosome nucleates microtubules, establishing polarity; critical for mitosis.

Kinesin

Moves toward plus-end (outward).

Dynein

Moves toward minus-end (inward).

Myosin

Interacts with actin, involved in muscle contraction

G1 Phase

Cell growth, prep for DNA synthesis.

S Phase

DNA replication.

G2 Phase

Prep for mitosis.

M Phase

Mitosis and cytokinesis.

G1/S Checkpoint

Assess DNA damage.

G2/M Checkpoint

Ensures DNA replication completeness.

Cyclins

Bind CDKs, activating them; levels fluctuate during the cycle, controlling progression.

DNA Damage Checkpoint

Activated by DNA lesions; halts cycle, activates repair pathways.

Principles of Cell Signaling

Signal detection, transduction, response, and regulation.

Endocrine

Long-range signaling type.

Pathway Mutations/Drugs

Activating pathways or cause constant activation, affecting cell growth.

Oncogenes

Gain-of-function mutations promote growth.

Tumor Suppressors

Loss-of-function mutations remove growth restraints.