Bio Lecture 9/11

Vocabulary flashcards covering key terms and definitions from lecture notes on diffusion, osmosis, endomembrane system, organelles, and basic cellular energy processes.

Diffusion

The passive movement of particles from an area of high concentration to an area of lower concentration, driven by thermal energy; no cellular energy input required.

Simple diffusion

Diffusion of small, nonpolar or uncharged molecules across the phospholipid bilayer without the help of membrane proteins.

Concentration gradient

The difference in solute concentration between two regions that drives diffusion.

Thermal energy

The random kinetic energy of particles that powers diffusion and other spontaneous movements.

Osmosis

Diffusion of water across a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Free water

Water molecules not bound to solutes and free to move; availability depends on solute binding.

Hypotonic solution

A solution with lower solute concentration than the cell, causing water to move into the cell (plants tolerate swelling; animals may lyse).

Hypertonic solution

A solution with higher solute concentration than the cell, causing water to move out of the cell.

Isotonic

A solution with solute concentration equal to that of the cell, resulting in balanced water movement.

Turgor pressure

The pressure exerted by water-filled vacuoles against the plant cell wall, helping maintain rigidity.

Lysis

Bursting of a cell due to excessive water intake or membrane damage.

Endomembrane system

A network of membranes inside the cell (nucleus, ER, Golgi, lysosomes, vesicles, plasma membrane) that work together to synthesize, modify, and transport cellular materials.

Nucleus

Membrane-bound organelle that houses the cell’s genetic material.

Nuclear envelope

Double-membrane surrounding the nucleus with nuclear pores for transport.

Nuclear pores

Protein channels in the nuclear envelope that regulate traffic between the nucleus and cytoplasm.

Nucleolus

Dense region within the nucleus where rRNA is synthesized and ribosome assembly begins.

Chromatin

DNA wrapped around proteins inside the nucleus; becomes chromosomes during cell division.

Nucleoid

Region in prokaryotes where the circular chromosome is located; not membrane-bound.

Prokaryotic cell

Cell type (bacteria, archaea) lacking a membrane-bound nucleus and most organelles; DNA in a nucleoid.

Eukaryotic cell

Cell type with a membrane-bound nucleus and numerous membrane-bound organelles.

Plasma membrane

Phospholipid bilayer that encloses the cell and regulates traffic in and out.

Cytoplasm

Region inside the cell membrane excluding the nucleus; includes cytosol and all organelles.

Compartmentalization

Division of the cell interior into distinct compartments by membranes to enable specialized functions.

Vesicle

Small, membrane-bound sac used to transport materials within the cell.

Endoplasmic reticulum (ER)

A network of membranous tubules continuous with the nuclear envelope; site of protein and lipid synthesis.

Rough ER

ER region with bound ribosomes; synthesizes proteins destined for membranes, secretion, or lysosomes.

Smooth ER

ER region lacking ribosomes; synthesizes lipids and helps make membrane material.

Ribosome

Ribonucleoprotein complex that synthesizes proteins; can be free-floating or bound to the ER.

Free ribosome

Ribosomes suspended in cytoplasm that generally synthesize cytosolic or organelle-targeted proteins.

Bound ribosome

Ribosomes attached to the rough ER; synthesize proteins for membranes, secretion, or lysosomes.

Golgi apparatus

Stack of flattened membranes that modifies, sorts, and packages proteins and lipids for transport.

Cis face

Receiving side of the Golgi where vesicles from the ER fuse.

Trans face

Shipping side of the Golgi where vesicles bud off to destinations.

Cisterna

A single flattened Golgi sac; multiple cisternae make up the Golgi stack.

Lysosome

Organelle with digestive enzymes in an acidic lumen that break down macromolecules and ingested material.

Vacuole

Membrane-bound vesicle involved in storage and transport; central vacuole is prominent in plants.

Central vacuole

Large plant cell vacuole that stores water and helps maintain turgor pressure.

Plant cell wall

Rigid layer outside the plasma membrane in plants, providing structural support and protection.

Cytoskeleton

Network of protein filaments that gives the cell shape, supports organelles, and enables movement.

Microtubules

Hollow tubules of tubulin that provide tracks for vesicle transport and form the spindle.

Microfilaments

Actin filaments involved in cell shape changes and movement.

Mitochondria

Organelles that produce ATP via cellular respiration; contain multiple membranes and their own DNA.

Mitochondrial matrix

Internal fluid-filled space inside the inner mitochondrial membrane where the Krebs cycle occurs.

Intermembrane space

Space between the outer and inner mitochondrial membranes.

Chloroplast

Plant cell organelle where photosynthesis occurs; contains chlorophyll and a double membrane.

Thylakoid membranes

Flattened membrane-bound sacs inside chloroplasts where light-dependent reactions take place.

Stroma

Fluid surrounding the thylakoids in chloroplasts; site of the Calvin cycle.

Peroxisome

Organelle containing enzymes that break down hydrogen peroxide to water and oxygen; detoxifies reactive oxygen species.

Glycosylation

Addition of sugars to proteins, typically occurring in the Golgi apparatus, to aid folding and targeting.

Exocytosis

Process by which vesicles fuse with the plasma membrane to release contents outside the cell.

Endocytosis

Process by which the plasma membrane folds inward to form vesicles that ingest material from outside.

Food vacuole

Vesicle formed during endocytosis that contains ingested material to be digested.

DNA

Deoxyribonucleic acid; the genetic material stored in the nucleus of eukaryotic cells.

RNA

Ribonucleic acid; transcribed from DNA and used for protein synthesis.

Nucleic acids

Class of macromolecules (DNA and RNA) that store and express genetic information.

Nucleotides

Monomers of nucleic acids; consist of a nitrogenous base, a five-carbon sugar, and one to three phosphates.

Nucleoside

A nitrogenous base attached to a five-carbon sugar; lacks the phosphate group.

Deoxyribose

Five-carbon sugar in DNA lacking an oxygen on the 2' carbon.

Nucleoside monophosphate/diphosphate/triphosphate

Nucleotides with one, two, or three phosphate groups; ATP is a triphosphate.

ATP

Adenosine triphosphate; primary energy currency of the cell with high-energy phosphate bonds.

High-energy phosphate bonds

Phosphate-phosphate bonds in nucleoside triphosphates that release energy when broken.

Dehydration synthesis

Chemical reaction that links monomers into polymers with the release of water.

Nuclear envelope

The membrane surrounding the nucleus; is continuous with the endoplasmic reticulum.

Lumen

The interior space within a membrane-bound compartment, such as the ER lumen.

Vesicle trafficking

Movement of vesicles between organelles, often along cytoskeletal tracks, typically cis-to-trans.

Glycosylation (Golgi)

Addition of sugars to proteins in the Golgi apparatus, aiding in folding and targeting.

Chlorophyll

Green pigment in chloroplasts that captures light energy for photosynthesis.

Endomembrane system continuity

The outer nuclear membrane is continuous with the rough and smooth endoplasmic reticulum.

Endoplasmic reticulum lumen

The internal cavity of the ER where lipid and protein processing occurs.

Cisternae

Flattened sacs of the Golgi apparatus; a stack of cisternae constitutes the Golgi.

Cis-to-trans secretion

Directionality of Golgi processing from the cis (receiving) side to the trans (shipping) side.

Vesicle fusion

Merging of a vesicle with a target membrane to deliver its contents.