Human Anatomy Ch. 3

Pinocytosis

"cell drinking"

Phagocytosis

"cell eating"

Endoplasmic Reticulum

A network of intracellular membranes connected to the nuclear envelope, which surrounds the nucleus. There are two types of ER: rough and smooth

Nucleoli

A transient nuclear organelle that synthesizes ribosomal RNA. They also assemble the ribosomal subunits

Freely Permeable Membranes

Allow any substance to pass without difficulty

Peripheral Proteins

Are bound to the inner or outer surface of the membrane and are easily separated from it. Integral proteins greatly outnumber peripheral proteins

Centrioles

Are cylindrical structures composed of short microtubules. During cell division, the centrioles are associated with the formation of spindle fibers which move the strands of DNA to the poles

Integral Proteins

Are part of the membrane structure and cannot be removed without damaging or destroying the membrane. Most integral proteins pass all the way through the membrane one or more times and are therefore known as transmembrane proteins

Solutes

Are the dissolved particles in a solution

Genes

Are the functional units of heredity

Microtubules

Are the largest components of the cytoskeleton with diameters of 25 nm

Anchoring Proteins

Attach the plasma membrane to other structures and stabilize its position. Inside the cell, membrane proteins are bound to the cytoskeleton

Carrier Proteins

Bind solutes and transport them across the plasma membrane

Receptor Proteins

Bind to specific extracellular molecules called ligands

Ligand

Can be anything from a small ion like calcium, to a relatively large and complex hormone

Ribosomal RNA (rRNA)

Combines with already constructed proteins to form the ribosomes where polypeptides are synthesized

Golgi Apparatus

Composed of five to six flattened discs. Golgi apparatus renews or modifies the plasma membrane, modifies and packages secretions such as hormones or enzymes for release through exocytosis, and packages special enzymes within vesicles for use in the cytosol

Cytokinesis

Cytoplasmic division splits the cell in two. In animal cells cleavage furrow or "pinching in" causes the cytoplasmic division. This process begins as early as anaphase but continues through telophase. The completion of cytokinesis marks the end of cell division.

Transcription

DNA serves as a template for the formation of mRNA

Recognition Proteins

Detected by cells of the immune system. Enzymes in the plasma membranes may be integral or peripheral proteins

Passive Transport Processes

Do not require energy because particles are moving down the concentration gradient

Active Processes

Do require energy

Microvilli

Finger-shaped extensions of the plasma membrane. A core of microfilaments stiffens each microvillus and anchors it to the cytoskeleton. Microvilli greatly increase surface area of the cell and enhance its ability to absorb nutrients from the extracellular fluid

Rough ER (RER)

Functions as a combination workshop and shipping depot. The RER is the site where newly constructed proteins are chemically modified and packaged for export to the golgi apparatus

Cytoskeleton

Functions as the cell's skeleton. It provides and internal framework made of protein that gives the cytoplasm strength and flexibility. The cytoplasm of all cells includes microfilaments, intermediate filaments, and microtubules

Hypertonic

Higher solute concentration in the solution than in the cell

Cholesterols

Important lipid that helps to stabilize the relatively weak plasma membrane

Cytoplasm

Is a general term for the material located between the plasma membrane and the membrane surround the nucleus. A colloid with as consistency that varies between that of thin maple syrup and almost-set gelatin, cytoplasm contains many more proteins than does extracellular fluid.

Membranous Organelles

Isolated from the cytosol by a phospholipid membrane (just as the plasma membrane isolates the cytosol from the extracellular fluid). Includes: mitochondria, nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, and peroxisomes

Smooth ER (SER)

Lacks ribosomes; has numerous functions including synthesizing phospholipids and cholesterols, synthesizing steroid hormones, synthesizing and storing glycerides, synthesizing and storing glycogen

Glycocalyx

Layer of superficial membrane carbohydrates. The glycocalyx is important in cell recognition, binding to extracellular structures, and lubrication of the cell surface.

Cilia

Long slender extensions composed of microtubules which extend from the cell's surface for the purpose of propelling fluids or solids

Hypotonic

Lower solute concentration in the solution than in the cell

Endocytosis

Moving substances into the cell

Exocytosis

Moving substances out of the cell

Non-membranous Organelles

Not completely enclosed by membrane so that all of their components are in direct contact with the cytosol. Includes: cytoskeleton, centrioles, microvilli, cilia, flagella, and ribosomes

Impermeable Membranes

Nothing can pass through. Cells may be impermeable to specific substances, but no living cell has an impermeable membrane

Selectively Permeable Membranes

Permit the passage of some materials and prevent the passage of others

Ribosomes

Responsible for protein synthesis and are often attached to endoplasmic reticulum. The more protein a cell synthesizes the more ribosomes it has. A functional ribosome consists of two subunits, one small subunit and one large subunit

Isotonic

Same solute concentration in the solution than in the cell.

Plasma Membrane

Separates the cell contents, or cytoplasm, from the extracellular fluid

Nuclear Pores

Serve as passageways that permit chemical communication between the nucleus and the cytosol.

Active Transport

Similar to facilitated diffusion because it too requires carrier proteins however it differs in that it requires ATP and is not dependent on concentration gradients. Therefore, substances can be pumped into and out of the cell regardless of concentration gradients. Most common example is the sodium-potassium pump.

Facilitated Diffusion

Some molecules are too big to fit through the spaces between the phospholipids and therefore require an integral protein, also known as a carrier protein, to ferry them across the membrane. This type of transport is a carrier-mediated process but DOES NOT REQUIRE ATP

Peroxisomes

Special vesicle that breaks down organic compounds and neutralizes toxic compounds generated by the process. These vesicles contain degradative enzymes

Lysosomes

Special vesicles that provide an isolated environment for potentially dangerous chemical reactions. These vesicles contain digestive enzymes with a wide variety of functions

DNA

Stores the instructions for protein synthesis

Nuclear Envelope

Surrounds the nucleus and separates it from the cytoplasm. The nuclear envelope is a double membrane

Messenger RNA (mRNA)

Takes the coded message of a DNA strand out to the cytoplasm and ribosomes for constructing the polypeptides. The code is written in triplets called codons

Osmosis

The diffusion of water through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration

Cytosol

The fluid component of the cytoplasm, also called intracellular fluid; may contain inclusions of insoluble materials

Nucleoplasm

The fluid contents of the nucleus

Simple Diffusion

The movement of solutes through a selectively permeable membrane from an area of high solute concentration to an area of low solute concentration

Mitochondria

The powerhouses of the cell; responsible for ATP synthesis

Microfilaments

The smallest of the cytoskeleton elements, and are composed of the protein actin

Solvent

The substance that the solutes dissolve into

Intermediate Filaments

These are the strongest and most durable of the cytoskeleton elements

Transfer RNA (tRNA)

Transfers the amino acids to the ribosome for addition to the building polypeptide chain

Daughter Cells

Two daughter cells are produced and each daughter cell has the same number of chromosomes as the parent cell. The daughter cells are now in G1 of interphase and will begin growing and doing their everyday function

Anaphase (apart)

a. Chromatids get pulled apart. b. Single-stranded chromosomes migrate to opposite ends of the cell.

Prophase

a. Nuclear membrane breaks down. b. Double-stranded chromosomes condense and become visible. c. Spindle fibers form.

Telophase

a. Nuclear membrane reforms. b. Single-stranded chromosomes decondense and disappear. c. Spindle fibers break down

Metaphase (middle)

a. Spindle fibers attached to the kinetochore begin pulling on the chromosome. b. Double-stranded chromosomes line up in the middle of the cell called the metaphase plate.