Cell Structure and Transport: Nucleus, Membranes, and Organelles

Nucleus

Contains DNA in the form of chromatin or chromosomes.

Nucleolus

Produces ribosomes.

Plasma Membrane

Boundary & Protection; consists of a phospholipid bilayer, cholesterol for fluidity, protein channels/gates for transport, glycoproteins for cell recognition.

Fluid Mosaic Model

Describes the plasma membrane structure.

Tight Junctions

Zipper-like, leak proof connections found in the intestines.

Desmosomes

Anchors that prevent cells from separating; button-like structures found in skin.

Gap Junctions

Connexons channel communication; found in heart & embryonic cells.

Cytoplasm

Location of chemical reactions; contains organelles and nutrients.

Mitochondria

Site of cellular respiration; converts glucose and oxygen into ATP.

Cristae

Folds of the inner membrane of mitochondria; more folds increase surface area to volume ratio.

Ribosomes

Sites of protein synthesis made of 2 subunits of rRNA; can be free-floating or attached to the rough endoplasmic reticulum.

Endoplasmic Reticulum

Rough ER is involved in protein synthesis; Smooth ER is involved in lipid metabolism and detoxification of drugs.

Golgi Body

Modifies, packages, and sorts molecules made by the rough and smooth ER with the help of transport vesicles.

Lysosomes

Vesicles full of digestive enzymes to break down food molecules.

Peroxisomes

Vesicles full of oxidase enzymes to detox harmful molecules; convert DNA damaging free radicals to peroxide (H2O2).

Cytoskeleton

Provides internal support; consists of microfilaments, intermediate filaments, and microtubules.

Centrioles

Arrangement of microtubules used in moving chromosomes around during cell division; found in pairs.

Cilia

Little hairs made of microtubules; involved in movement, found in the respiratory tract, brain ventricles, and fallopian tubes.

Flagella

Long tail made of microtubules; involved in movement, found in sperm cells.

Microvilli

Tiny hairs, similar to cilia; increase surface area of the membrane for greater absorption, found in intestines.

Active Transport

Movement of molecules against their concentration gradient, requiring ATP.

Passive Transport

Movement of uncharged atoms/molecules (H2O, O2, CO2) through phospholipids from high to low concentration to achieve equilibrium.

Osmosis

In a solution, if there's less water, then there's more solutes and vice versa; cells in a hypotonic solution will expand, while cells in a hypertonic solution will shrink.