Cell Biology, Transport, Organelles, and DNA Replication Vocabulary

A complete collection of vocabulary flashcards covering plasma membrane structure and transport, cell organelles, nuclear structures, DNA replication mechanisms, RNA synthesis, and stages of the cell cycle based on lecture notes.

Phospholipid Bilayer

The structural backbone of the plasma membrane, arranged with hydrophilic heads facing outward and hydrophobic tails facing inward, allowing nonpolar compounds to cross easily.

Integral Proteins

Plasma membrane proteins that function as receptors and form ion channels that allow polar compounds to cross the membrane.

Peripheral Proteins

Plasma membrane proteins that function as enzymes, alter cell shape, anchor the plasma membrane, and link cells together.

Cholesterol

A lipid component embedded in the plasma membrane that functions to stabilize its structure.

Glycocalyx

A cell-surface layer composed of glycoproteins and glycolipids that helps cells stick together and enables cell-cell recognition.

Microvilli

Tiny folds of the plasma membrane that function to increase the surface area of the cell.

Tight Junctions

Specialized membrane junctions where proteins fuse adjacent cell membranes together to make the tissue impermeable.

Desmosomes

Protein connections between cells that allow mechanical tension to be distributed throughout the tissue.

Gap Junctions

Transmembrane channels between adjacent cells (such as cardiac muscle cells) that allow direct chemical and electrical communication.

Passive Transport

Movement of substances across the plasma membrane that does not require $ATP$ but requires a gradient to move compounds from high to low concentration.

Gradient

A difference in physical or chemical properties between two adjacent areas, such as concentration, pressure, partial pressure, or electrical potential.

Simple Diffusion

A type of passive transport where small, nonpolar molecules pass directly through the phospholipid bilayer down their concentration gradient.

Facilitated Diffusion

A type of passive transport where polar compounds and electrolytes move across the membrane through ion channels or transport proteins.

Osmosis

The passive movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Isotonic

A condition where two solutions have equal solute concentrations, resulting in no net movement of water across the membrane.

Hypertonic

A solution with a higher concentration of solutes relative to another solution, causing water to move into it from a hypotonic solution.

Hypotonic

A solution with a lower concentration of solutes relative to another solution, causing water to leave it and enter a hypertonic solution.

Crenation

The shrinkage of a cell that occurs when water leaves the intracellular fluid and enters a hypertonic extracellular fluid.

Solute Pumping

An active transport process that uses carrier proteins and $ATP$ to move compounds across the plasma membrane against their concentration gradient.

Sodium-Potassium Pump

A specific solute pump that uses $ATP$ to move $3$ sodium ions out of the cell and $2$ potassium ions into the cell.

Exocytosis

An active transport process where a cell packages compounds into a vesicle, which fuses with the plasma membrane to release contents outside the cell.

Phagocytosis

A form of endocytosis commonly referred to as cell eating, where a cell engulfs solid particles.

Pinocytosis

A form of endocytosis commonly referred to as cell drinking, where a cell engulfs extracellular fluid droplets.

Receptor-Mediated Endocytosis

A targeted form of endocytosis where specific cell-surface receptors bind and import required compounds into the cell.

Mitochondria

Membrane-bound organelles responsible for cellular $ATP$ production.

Ribosomes

Cellular structures composed of RNA and proteins that carry out protein synthesis.

Rough Endoplasmic Reticulum (RER)

An organelle studded with ribosomes that modifies, folds, and packages proteins synthesized by those attached ribosomes.

Smooth Endoplasmic Reticulum (SER)

An organelle involved in lipid metabolism and the detoxification of drugs and alcohol.

Golgi Apparatus

An organelle that receives proteins from the RER, then sorts, modifies, repackages, and exports them.

Lysosomes

Membrane-bound sacs containing digestive enzymes that destroy pathogens and worn-out organelles.

Peroxisomes

Membrane-bound sacs containing oxidase enzymes that use oxygen to neutralize toxins and free radicals.

Centrioles

Organelles that organize the mitotic spindle during cell division and form the structural bases of cilia and flagella.

Microtubules

Cytoskeletal elements that form the mitotic spindle, maintain cell shape, and support organelles.

Intermediate Filaments

Cytoskeletal proteins that provide tensile strength to protect the cell from mechanical stress.

Microfilaments

Cytoskeletal proteins involved in cell movement and muscle contraction.

Nuclear Pores

Openings in the nuclear membrane that allow large molecules, such as RNA and proteins, to pass between the nucleus and cytoplasm.

Nucleoli

Organelles located within the nucleus responsible for assembling ribosomes.

Chromatin

The uncoiled form of genetic material consisting of DNA loosely wrapped around histone proteins, allowing easy access to genes.

Chromosomes

Tightly coiled and supercoiled structures of DNA wrapped around histones, formed to protect genetic material during mitosis ($46$ total arranged in $23$ pairs in humans).

Gene

A specific segment of DNA that contains the instructions required to code for a protein.

Genetic Code

The complete set of genomic instructions necessary for producing all the proteins required by the body.

Sister Chromatids

Two identical strands of DNA joined together at a central region called the centromere.

Nucleotide

The monomeric subunit of DNA consisting of a phosphate group, a deoxyribose sugar, and a nitrogenous base.

Complementary Base Pairing

The specific bonding rule in DNA where adenine bonds exclusively to thymine and guanine bonds exclusively to cytosine via hydrogen bonds.

Semiconservative Replication

The mechanism of DNA replication in which each newly formed DNA double helix contains one original parent strand and one newly synthesized strand.

Helicase

The enzyme that unwinds the double-stranded DNA molecule and breaks hydrogen bonds between nitrogenous bases to separate the template strands.

DNA Polymerase

The enzyme responsible for building new DNA strands complementary to template strands, synthesizing exclusively in the $5'$ to $3'$ direction.

DNA Ligase

The enzyme that connects Okazaki fragments together on the lagging strand to form a continuous DNA strand.

Leading Strand

The newly synthesized DNA strand that is built continuously in the $5'$ to $3'$ direction toward the advancing replication fork.

Lagging Strand

The newly synthesized DNA strand built discontinuously in the direction away from the replication fork as short Okazaki fragments.

Okazaki Fragments

Short segments of newly synthesized DNA produced on the lagging strand during replication.

DNA Replication Fork

The Y-shaped region where template strands are separated by helicase to allow DNA polymerase to build leading and lagging strands.

mRNA

Messenger RNA; a transcript copy of a gene whose nucleotide sequence is translated into a protein at the ribosome.

rRNA

Ribosomal RNA; the functional RNA component that forms part of the ribosome's physical structure.

tRNA

Transfer RNA; RNA molecules that transport specific amino acids to the ribosome during protein translation.

Transcription

The nuclear process where an mRNA copy of a DNA gene sequence is synthesized.

Translation

The cytoplasmic process where ribosomes decode the mRNA sequence to build a specific protein.

G1 Phase

The subphase of interphase characterized by rapid cell growth and active protein synthesis.

S Phase

The subphase of interphase during which DNA replication occurs alongside cell growth.

G2 Phase

The subphase of interphase focused on growth, protein synthesis, centriole replication, and final preparation for mitosis.

Early Prophase

The initial stage of prophase where chromatin supercoils into visible chromosomes, and centrioles connected by microtubules begin moving to opposite poles to form the mitotic spindle.

Late Prophase

The stage of prophase where the nuclear membrane breaks down and kinetochore microtubules attach to the centromeres of sister chromatids.

Metaphase

The mitotic phase where chromosomes align along the equator (metaphase plate) of the cell.

Anaphase

The mitotic phase where centromeres split, kinetochore microtubules recoil, and sister chromatids are pulled apart to opposite poles of the cell.

Telophase

The final mitotic phase where identical sets of chromosomes uncoil at opposite ends of the cell, nuclear membranes reform around them, and the mitotic spindle breaks down.