Gene Control & Cell Differentiation – Lecture Overview

Vocabulary flashcards summarizing key terms and definitions from the lecture on gene control, cell differentiation, and mechanisms of gene expression regulation.

Cell Differentiation

Process by which cells become specialized by expressing different sets of RNAs and proteins without altering their DNA sequence.

Housekeeping Genes

Genes whose products (e.g., actin, DNA polymerase) are expressed in virtually all cell types because they perform essential cellular functions.

Cell-Type-Specific Gene Expression

Production of RNAs or proteins (e.g., hemoglobin in red blood cells) that are abundant in one specialized cell type and virtually absent in others.

Nuclear Transplantation (Frog Experiment)

Classic experiment showing that a nucleus from a differentiated frog skin cell can direct development of a normal tadpole when placed in an enucleated egg, proving DNA sequence is retained.

Dedifferentiation in Plants

Ability of differentiated plant cells in culture to revert to a pluripotent state and regenerate an entire adult plant.

Somatic Cell Nuclear Transfer (Animal Cloning)

Technique where a nucleus from an adult differentiated cell is transferred into an enucleated egg to produce a genetically identical clone (e.g., cloned calves).

RNA-seq

High-throughput sequencing method that quantifies and maps RNA molecules, revealing gene expression levels across the genome.

mRNA Expression Spectrum

Complete set of mRNAs present in a cell; can be used to identify cell type and discover previously unrecognized subtypes.

Single-Cell mRNA Sequencing

Technique that profiles transcripts in individual cells, enabling classification of cell subtypes (e.g., seven neuron subtypes in mouse brain).

Two-Dimensional Gel Electrophoresis

Protein separation method based on size and isoelectric point, visualizing differences in protein expression between tissues.

External Signal–Induced Gene Expression

Alteration of a cell’s transcription pattern in response to extracellular cues, such as glucocorticoid hormones modulating liver gene expression.

Glucocorticoids

Hormones released during starvation or exercise that signal liver cells to increase energy production and induce enzymes like tyrosine aminotransferase.

Transcriptional Control

Regulation of gene expression by controlling when and how often a gene is transcribed; primary control point for most genes.

RNA-Processing Control

Regulation achieved by controlling splicing and other processing events of RNA transcripts.

RNA Transport and Localization Control

Selective export of mature mRNAs from nucleus and their positioning within the cytoplasm to influence translation.

Translational Control

Regulation of gene expression by selecting which cytoplasmic mRNAs are translated by ribosomes.

mRNA Degradation Control

Selective stabilization or destruction of specific mRNA molecules, affecting their availability for translation.

Protein Degradation Control

Regulation of protein levels by selective destruction of proteins in response to signals or cell-cycle stage.

Protein Activity Control

Post-translational regulation that activates, inactivates, localizes, or modifies proteins (e.g., phosphorylation, ubiquitylation).

Gene Expression Pathway

Multi-step route from DNA to active protein, including transcription, RNA processing, mRNA export, translation, and post-translational events.

Housekeeping vs. Specialized Proteins

Contrast between widely expressed proteins necessary for basic cell function and proteins expressed only in specific cell types for specialized tasks.

Gene Control Hierarchy

Concept that gene expression can be regulated at multiple sequential steps, with transcription initiation providing the most energy-efficient control.