MCB Textbook Unit 1 Chapter 2--Parts of a Cell

plasma membrane

Selectively permeable barrier surrounding a cell.

receptors

Proteins that detect signals from the cell's environment.

transport proteins

Proteins that assist in moving molecules across the plasma membrane.

phospholipids

Molecules that make up the cell membrane; have hydrophobic and hydrophilic properties.

sterols

A type of lipid that varies by cell type; cholesterol is a common sterol in animal cells.

carbohydrates in plasma membrane

Attached to receptors outside the plasma membrane, playing a role in cell recognition.

Fluid Mosaic Model

Concept describing the plasma membrane as composed of various components that can move.

cytoplasm

Gel-like substance where many chemical reactions of the cell's metabolism occur.

ribosomes

Cellular structures made of ribosomal RNA and proteins, essential for protein synthesis.

free ribosomes

Ribosomes that synthesize proteins used within the cytoplasm.

membrane-bound ribosomes

Ribosomes that produce proteins designated for membranes or export from the cell.

centrifugation

Process of spinning cells or particles at high speeds to separate them based on weight.

prokaryotic ribosomes

Ribosomes with a sedimentation rate of 70s, composed of 50s and 30s subunits.

eukaryotic ribosomes

Ribosomes with a sedimentation rate of 80s, consisting of 50s and 40s subunits.

nuclear envelope

Double bilayer of phospholipids that encloses the nucleus.

nuclear lamina

A network of protein cables providing structural support to the nuclear envelope.

chromosomes

Bundled DNA structures for cell division.

chromatin

The less condensed form of DNA in a functioning cell.

nuclear pores

Protein structures that allow molecules to pass between the nucleus and cytoplasm.

small ribosomal subunit

Subunit of the ribosome that binds mRNA and tRNA for decoding genetic information.

large ribosomal subunit

Subunit of the ribosome containing the enzymatic center for forming peptide bonds.

nucleoli

Cellular structures within the nucleus where ribosomal subunits are assembled.

endomembrane system

A system of membranes including the endoplasmic reticulum and Golgi apparatus.

smooth endoplasmic reticulum

ER that synthesizes lipids like phospholipids.

rough endoplasmic reticulum

ER studded with ribosomes, involved in protein synthesis and processing.

Golgi apparatus

Organ system of membrane sacs for modifying, sorting, and packaging proteins.

cis face of Golgi

The receiving side of the Golgi apparatus, interfacing with the rough ER.

trans face of Golgi

The shipping side of the Golgi apparatus, where processed molecules exit.

glycosylation

The addition of sugar molecules to proteins or lipids for modification.

peroxisomes

Small organelles that break down fatty acids and detoxify substances.

glyoxisomes

Specialized peroxisomes in plants that convert stored oils to usable energy.

mitochondria

Organelles with two membranes that generate energy for the cell.

cristae

The folds of the inner membrane of mitochondria, increasing surface area for energy extraction.

intermembrane space

Space located between the outer and inner membranes of the mitochondria.

matrix (mitochondria)

Fluid inside the mitochondria where the citric acid cycle takes place.

thylakoids

Membrane sacs within chloroplasts involved in photosynthesis.

grana

Stacked thylakoids in chloroplasts, where light reactions occur.

stroma (chloroplasts)

The fluid surrounding thylakoids in chloroplasts.

cytoskeleton

Network of protein fibers that provide structural support and shape to the cell.

cilia

Short, hair-like structures that aid in cell movement or fluid movement over cell surfaces.

eukaryotic flagella

Long, whip-like structures used for motility in certain eukaryotic cells.

microfilaments

Protein filaments made of actin, crucial for muscle contraction and cell division.

microtubules

Cytoskeletal components made of tubulin, involved in cell division and intracellular transport.

intermediate filaments

Protein fibers providing mechanical support and strength to the cell.

motor proteins

Proteins that move along cytoskeletal filaments using energy from ATP.

myosin

Motor protein that interacts with actin filaments for muscle contraction.

dynein

Motor protein that moves along microtubules in cilia and flagella.

kinesin

Motor protein that transports cellular materials along microtubules.

extracellular matrix

Network surrounding cells that provides structural support and facilitates communication.

integrins

Membrane proteins that link the cytoskeleton to the extracellular matrix.

peptidoglycan

Complex carbohydrate forming the cell wall structure in some bacteria.

glycocalyx

Sticky layer of proteins and carbohydrates assisting bacterial adhesion and evasion of the immune system.

pili

Hair-like structures that allow bacteria to attach to surfaces and each other.

fimbriae

Similar to pili, these allow bacterial adherence to hosts or surfaces.

flagellin

Protein that makes up bacterial flagella, enabling movement.