Membrane Transport and Cell Cycle Vocabulary

A comprehensive set of vocabulary flashcards covering membrane transport, osmosis, tonicity, vesicular transport, and the cell cycle, based on the provided lecture notes.

Passive transport

Movement of substances down their concentration gradient without energy input; includes diffusion, osmosis, and facilitated diffusion.

Concentration gradient

Difference in the amount of substance from one area to another; drives movement from high to low concentration.

Simple diffusion

Passive movement of lipid-soluble or small molecules across the membrane down their gradient without transport proteins.

Osmosis

Diffusion of water across a semipermeable membrane down its own concentration gradient.

Osmotic pressure

The pulling force exerted by solutes in solution that draws water toward the solution with higher solute concentration.

Hydrostatic pressure

Pushing pressure due to fluid volume; the force exerted by a fluid against its container.

Tonicity

Relative osmotic pressure between two solutions; described as isotonic, hypertonic, or hypotonic.

Isotonic

Two solutions with the same tonicity; no net water movement between them.

Hypertonic

A solution with higher osmotic pressure than another, causing water to move out of cells.

Hypotonic

A solution with lower osmotic pressure than another, causing water to move into cells.

Hemolysis

Bursting of red blood cells due to a hypotonic solution.

Cremation (crenation in cells)

Shriveling of red blood cells due to a hypertonic solution.

Facilitated diffusion

Passive transport that uses carrier proteins or channels to move substances down their gradient.

Carrier protein

Protein that assists specific molecules to cross the membrane down their concentration gradient.

Aquaporin

Channel protein that facilitates water passage across the cell membrane.

Primary active transport

Active transport that uses direct input of ATP to move substances against their gradient (e.g., Na+/K+ pump).

Sodium-potassium pump

Primary active transporter that moves 3 Na+ out and 2 K+ in, using ATP to maintain gradients.

Secondary active transport

Active transport that uses energy stored in an ion gradient (indirectly from ATP) to move another substance against its gradient.

Cotransport (symport)

Secondary active transport where two substances move in the same direction.

Countertransport (antiport)

Secondary active transport where two substances move in opposite directions.

Vesicular transport

Bulk transport using vesicles; always requires ATP and is independent of concentration gradients.

Exocytosis

Vesicles fuse with the plasma membrane to secrete contents outside the cell.

Endocytosis

Process of bringing material into the cell via vesicles.

Pinocytosis

Cell drinking; endocytosis of fluids and dissolved substances.

Phagocytosis

Cell eating; endocytosis of large particles or cells.

Receptor-mediated endocytosis

Endocytosis initiated when ligands bind to specific cell-surface receptors, triggering vesicle formation with clathrin.

Clathrin

Protein that forms a coated pit/vesicle during receptor-mediated endocytosis.

Interphase

Cell cycle phase when the cell grows and DNA is replicated (G1, S, G2; includes G0 in some cells).

G0 phase

A non-dividing or permanently non-proliferative state; some cells stay here permanently (e.g., neurons).

G1 phase

First gap; cell growth and normal metabolic activity, checks for division readiness.

S phase

DNA synthesis/replication phase; each chromosome is copied (semi-conservative).

G2 phase

Second gap; final preparations for mitosis, ensuring components are ready.

M phase

Mitosis and cytokinesis; division of the cell into two daughter cells.

Mitosis

Division of the nucleus and distribution of chromosomes into two daughter nuclei; consists of prophase, metaphase, anaphase, and telophase.

Prophase

Chromosomes condense, nucleolus disappears, nuclear envelope breaks down, and the spindle apparatus forms.

Metaphase

Chromosomes align along the metaphase (equatorial) plate in the center of the cell.

Anaphase

Sister chromatids separate and are pulled toward opposite poles; cell elongates.

Telophase

Nuclei reform around separated chromosomes; chromosomes de-condense; spindle disassembles.

Cytokinesis

Division of the cytoplasm, resulting in two separate daughter cells; often involves a cleavage furrow.

Sister chromatids

Two identical copies of a chromosome held together at the centromere prior to separation.

Centromere

Region of a chromosome where sister chromatids attach and spindle fibers connect during mitosis.

Kinetochore

Protein structure at the centromere where microtubules attach during mitosis.

Centriole

Organelles that organize the spindle apparatus during cell division (in centrosomes).

Centrosome

Region containing a pair of centrioles; organizes spindle fibers for mitosis.

DNA helicase

Enzyme that unwinds the DNA double helix at replication forks.

DNA polymerase

Enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template.

Okazaki fragments

Short fragments of DNA synthesized on the lagging strand during replication.

DNA ligase

Enzyme that joins Okazaki fragments and seals nicks in the DNA backbone.

Semiconservative replication

Each new DNA molecule contains one old strand and one new strand.

Replication fork

Region where the DNA double helix is unwound and replication occurs.

Primase

Enzyme that synthesizes RNA primers to start DNA synthesis.

RNA primer

Short RNA sequence that provides a starting point for DNA synthesis.

Leading strand

New DNA strand synthesized continuously toward the replication fork (5' to 3').

Lagging strand

New DNA strand synthesized discontinuously away from the replication fork as Okazaki fragments.

DNA polymerase I

Enzyme that replaces RNA primers with DNA and helps join fragments on the lagging strand.

Normal saline

0.9% NaCl solution used intravenously to approximate isotonicity with blood.

Isotonic to blood

A solution that has the same tonicity as blood, preventing net water movement into/out of cells.

Metaphase plate

Imaginary plane where chromosomes align during metaphase.

Chromosome condensation

Process of compacting DNA into visible chromosomes for segregation.