Cytology Exam 2 Vocabulary

Comprehensive vocabulary flashcards generated from Cytology Exam 2 lecture notes covering resting membrane potential, cytoplasm components, organelles, cellular extensions, cell division, and protein synthesis.

Resting Membrane Potential (RMP)

The electrical potential energy produced by the separation of oppositely charged particles across the plasma membrane in all cells, ranging from $-50\,mV$ to $-100\,mV$.

Voltage

The difference in electrical charge between two points, occurring only at the membrane surface.

Na+-K+ Pump

An active transport mechanism that maintains RMP by continuously ejecting $3\,Na^+$ out of the cell and bringing $2\,K^+$ back inside.

Cytoplasm

All cellular material located between the plasma membrane and the nucleus, composed of cytosol, inclusions, and organelles.

Cytosol

The gel-like solution of cytoplasm made up of water and soluble molecules such as proteins, salts, and sugars.

Inclusions

Insoluble molecules in the cytoplasm that vary with cell type, such as glycogen granules, pigments, lipid droplets, vacuoles, and crystals.

Organelles

Metabolic machinery structures of the cell, each with specialized functions, categorized as either membranous or nonmembranous.

Nucleus

The largest organelle that contains the genetic library of blueprints for the synthesis of nearly all cellular proteins.

Nuclear Envelope

A double membrane barrier enclosing the nucleoplasm with nuclear pores that allow substances to pass into and out of the nucleus.

Nucleolus

A dark-staining spherical body within the nucleus involved in ribosomal RNA (rRNA) synthesis.

Chromatin

Uncoiled DNA that serves as the cell's genetic material, which condenses to form chromosomes.

Mitochondria

Double-membrane enclosed organelles known as the power plant of cells because they produce ATP via aerobic cellular respiration and replicate via fission.

Rough Endoplasmic Reticulum

A series of parallel, flattened membranous tubes studded with ribosomes that serves as the site of protein synthesis.

Smooth Endoplasmic Reticulum

A network of continuous looped tubules lacking ribosomes that functions in lipid synthesis and detoxification.

Golgi Apparatus

Stacked and flattened membranous sacs that modify, concentrate, and package proteins and lipids received from the rough ER.

Peroxisomes

Membranous sacs containing powerful detoxifying substances that neutralize toxins and participate in fatty acid breakdown and synthesis.

Lysosomes

Spherical membranous bags containing digestive enzymes that digest ingested bacteria, viruses, and toxins, and degrade nonfunctional organelles.

Ribosomes

Nonmembranous organelles composed of protein and rRNA that serve as the site of protein synthesis, existing as free or membrane-bound forms.

Cytoskeleton

An extensive network of microtubules and microfilaments that acts as the cell's bones, ligaments, and muscle for component movement.

Centrioles

A pair of barrel-shaped organelles involved in cell division, controlling the cytoskeleton, and forming the basis of cilia and flagella.

Cilia

Hair-like, motile surface extensions that work together in a sweeping motion to move substances across cell surfaces in one direction.

Flagella

Longer cellular extensions that propel the whole cell, found in humans exclusively on sperm cells.

Microvilli

Minute, fingerlike extensions of the plasma membrane that project from selected cell surfaces to increase surface area for absorption.

Mitosis

The division of the nucleus in which duplicated DNA is distributed to new daughter cells across four stages: prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm resulting in the creation of two new cells.

Gene

A segment of DNA containing a specific sequence of nucleotides that holds the code for one polypeptide.

Exons

The parts of a gene that actually code for amino acids.

Introns

Noncoding segments of DNA interspersed amongst exons within a gene.

Messenger RNA (mRNA)

Single-stranded RNA copied from the DNA template strand during transcription that carries the codon sequence for protein synthesis.

Ribosomal RNA (rRNA)

A structural component of ribosomes that, along with tRNA, assists in translating mRNA messages into polypeptides.

Transfer RNA (tRNA)

Carrier molecule for amino acids containing a specific anticodon triplet that complementary base-pairs with an mRNA codon.

Transcription

The process of transferring genetic code held in a DNA gene base sequence into a complementary base sequence of mRNA.

Promoter

A special gene sequence that acts as the starting point for transcription where RNA polymerase binds.

RNA Polymerase

An enzyme that separates DNA strands and synthesizes mRNA matching the DNA template sequence.

Spliceosomes

Special protein complexes that remove noncoding introns from pre-mRNA, joining exon coding regions together.

Translation

The step of protein synthesis where the nucleic acid base sequence of mRNA is translated into an amino acid sequence.

Codon

A complementary three-base sequence on mRNA representing one of $64$ possible triplets for amino acids or stop signals.

Anticodon

A three-base sequence on tRNA that determines which specific amino acid is bound and pairs with a matching mRNA codon.

Aminoacyl Site (A site)

The binding site on a ribosome for incoming aminoacyl-tRNA.

Peptidyl Site (P site)

The binding site on a ribosome for tRNA linked to the growing polypeptide chain.

Exit Site (E site)

The binding site on a ribosome for outgoing tRNA to leave the ribosome.