MCB150 Flashcard Set for Exam Review

A comprehensive set of flashcards for MCB150 exam review, covering key cellular and molecular biology concepts.

γ-tubulin

The protein that forms the scaffold for microtubule nucleation at the centrosome.

Kinesin

The primary motor protein moving vesicles toward the microtubule plus end.

Taxol

A drug that stabilizes microtubules by binding them directly.

9 triplet microtubule arrangement

The microtubule arrangement in a centriole.

9+2 arrangement

The microtubule arrangement in the axoneme, consisting of 9 doublets and 2 central singlets.

Prometaphase

The phase of mitosis that involves nuclear envelope breakdown.

Kinesins and dyneins

The proteins that drive spindle elongation during anaphase B.

Basal body

The structure that anchors minus ends of microtubules in cilia.

Actin and myosin II

The cytoskeletal components that make up the contractile ring in cytokinesis.

Nuclear Localization Signal (NLS)

The presence of this signal determines whether a protein enters the nucleus.

Nuclear Export Signal (NES)

Used by exportins for the selective export of proteins from the nucleus.

Lack of an NLS

What keeps cytoplasmic proteins out of the nucleus.

Mitochondrial targeting sequence

The signal that directs a protein for import into mitochondria.

Free ribosomes in the cytoplasm

The location where most mitochondrial proteins are synthesized.

Chaperonins

Proteins that maintain precursor proteins in an unfolded state during mitochondrial import.

Endocrine signaling

The type of signaling that involves a molecule traveling through the bloodstream.

Juxtacrine signaling

A type of signaling that involves cells touching each other.

Dissociation constant (Kd)

A value that measures receptor-ligand binding affinity.

High affinity

What a low Kd indicates about a ligand-receptor interaction.

Gα

The protein that exchanges GDP for GTP and activates downstream signaling when a ligand binds to a GPCR.

Adenylyl cyclase

The enzyme that synthesizes cAMP from ATP.

Phosphodiesterase

The enzyme that degrades cAMP.

IP3 and DAG

The second messengers released by cleavage of PIP2.

Enzyme-linked receptor (tyrosine kinase)

The type of receptor involved in the EGF (Epidermal Growth Factor) pathway.

Cytochrome c

The major signaling molecule that triggers apoptosis through the intrinsic pathway.

Apoptosome

The complex that activates caspase-9 in intrinsic apoptosis.

Caspases

Protease enzymes that cleave specific substrates to dismantle the cell during apoptosis.

Bcl-2 proteins

Proteins that prevent intrinsic apoptosis by stabilizing mitochondrial membranes.

Initiator caspases (like caspase-8)

What the death-inducing signaling complex (DISC) activates.

Fas ligand

It binds death receptors to trigger the extrinsic apoptosis pathway.

RNA interference (RNAi)

Gene silencing by small non-coding RNAs like siRNAs and miRNAs.

RISC complex

A complex that guides siRNA or miRNA to target mRNA for silencing.

Long non-coding RNA (lncRNA)

The type of ncRNA that scaffolds the assembly of chromatin modifiers.

PRC2 (Polycomb Repressive Complex 2)

What HOTAIR recruits to repress transcription.

miRNA

A molecule that inhibits gene expression by base-pairing to mRNA.

Cas9 protein

The protein that creates double-stranded breaks in DNA in CRISPR systems.

crRNA

The small RNA that works as a guide for Cas9 in CRISPR.

tracrRNA

The secondary RNA molecule that stabilizes Cas9/crRNA complexes.

Spindle assembly checkpoint

What prevents anaphase if a kinetochore fails to attach to a microtubule during mitosis.

Activation of separase enzyme

What triggers the separation of sister chromatids at the metaphase-anaphase transition.

Centromeres

The DNA regions that differ from kinetochores, which are protein complexes.

Astral microtubules

The microtubules that anchor the spindle poles to the cell cortex during mitosis.

Phosphorylation of nuclear lamins

What initiates disassembly of the nuclear envelope in mitosis.

Metaphase

The phase of mitosis in which chromosomes align at the metaphase plate.

Late prophase

The phase of mitosis when the mitotic spindle first becomes fully formed.

Centrosome

The structure that organizes microtubules during mitosis.

Primary messengers

Extracellular signals in comparison to secondary messengers, which are intracellular.

IP3

The second messenger that triggers calcium release from the ER.

Phosphorylation

The process that amplifies a signal inside a cell by one kinase activating many targets.

Activation of cyclin-dependent kinases (CDKs)

The event that initiates G1-S transition in the eukaryotic cell cycle.