Objectives Chapter Three

Interstitial fluid

cells are submersed (bathed) in this fluid 

Blood plasma

fluid of the blood

Cerebrospinal fluid

fluid surrounding nervous system organs

Extracellular fluids (body fluids)

Substances found outside cells-Interstitial fluid, blood plasma, cerebrospinal fluid

Plasma membrane (functions)

Defines boundaries, separates intracellular fluid (fluid inside the cell) from extracellular fluid (fluid outside the cell), plays important role in cellular activity

Six functions of plasma membrane proteins

Transport – Signal Transduction – Attachment – Intracellular Joining – Enzymatic Activity – Cell-Cell Recognition

Transport

An exchange of molecules (and their kinetic energy and momentum) across the boundary between adjacent layers of a fluid or across cell membranes.

Signal Transduction

the linkage of a mechanical, chemical, or electromagnetic stimulus to a specific cellular response 

Attachment

Maintains the shape of cell

Intracellular Joining

The function of membrane proteins in which membrane proteins of adjacent cells hook together, as in gap junctions or tight junctions.

Enzymatic Activity

A protein built into the membrane with an active site exposed.

Cell-Cell Recognition

the ability of a cell to distinguish one type of neighboring cell from another is crucial to the functioning of an organism carbohydrates are important for this

Tight junctions

Adjacent integral proteins fuse together forming impermeable junctions. Example location: epithelial cells of the lungs

Desmosomes

Thickened patches, known as plaques, hold cells together via linker proteins. Keratin filaments provide stability to the plaques. These types of junctions help prevent shearing forces and allow “give” between cells, reducing the possibility of tearing under tension.

Example location: skin

Gap junctions

Transmembrane proteins that form pores which allow small molecules to pass from cell to cell. Allows electrical signals to be passed quickly from one cell to the next cell.

Example locations: heart, brain

Selective permeability

refers to the cell membranes ability to differentiate between different types of molecules, only allowing some molecules through while blocking others. 

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Simple diffusion

Nonpolar lipid soluble (hydrophobic) substances diffuse directly through the phospholipid bilayer

Diffusion

Collisions between molecules in areas of high concentration cause them to be scattered into areas with less concentration

Facilitated Diffusion

Certain lipophilic molecules (e.g., glucose, amino acids, and ions) transported passively by either binding to protein carriers or moving through water-filled channels

Osmosis

a type of diffusion. Movement of a solvent (usually water) across a selectively permeable membrane either through aquaporins or the lipid bilayer. Occurs when water concentration is different on two sides of a membrane.

Primary Active Transport

Required energy directly from ATP hydrolysis. Energy from hydrolysis of ATP causes change in shape of transport protein.

Example: Sodium-Potassium Pump

Secondary Active Transport

Depends on the ion gradient that was created by the primary active transport system. Energy stored in gradients is used indirectly to drive transport of other solutes

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Filtration

the movement of material across a membrane as a result of hydrostatic pressure?

Osmolarity

measure of total concentration of solute particles

Tonicity

ability of a solution to change the shape or tone of cells by altering the cells’ internal water volume 

Exocytosis

an ATP requiring cell process by which large molecules are packaged in membrane bound vesicles which fuse with the cell membrane to expel the material into the extracellular fluid

Endocytosis

cellular process in which substances are brought into the cell

Transcytosis

transport into, across, and then out of cell

Vesicular trafficking

transport from one area or organelle in cell to another

Mitochondria

called the “power plant” of cells because they produce most of the cell's energy molecules (ATP) via aerobic (oxygen-requiring) cellular respiration. Contain their own DNA, RNA, ribosomes

Ribosomes

granules containing protein and rRNA. Site of protein synthesis. Free ribosomes synthesize soluble proteins that function in cytosol or other organelles. Membrane-bound ribosomes (forming rough ER) synthesize proteins to be incorporated into membranes, lysosomes, or exported from cell

Rough Endoplasmic Reticulum

external surface studded with ribosomes. Manufactures all secreted proteins, integral proteins and phospholipids. Assembled proteins move to ER interior, enclosed in vesicle, go to Golgi apparatus

Smooth Endoplasmic Reticulum

network of tubules continuous with rough ER. Its enzymes (integral proteins) function in absorption, synthesis, and transport of fats.Lipid metabolism; cholesterol and steroid-based hormone synthesis; making lipids of lipoproteins. Detoxification of drugs, some pesticides, carcinogenic chemicals. Storage and release of calcium

Golgi Apparatus

 Modifies, concentrates, and packages proteins and lipids from rough ER. Transport vessels from ER fuse with golgi apparatus; proteins modified, tagged for delivery, sorted, packaged in vesicles. Three types of vesicles bud from opposite side: 

Secretory vesicles (granules)

release export proteins by exocytosis

Lysosomes

Spherical membranous bags containing digestive enzymes (acid hydrolases) that bud off the golgi apparatus. "Safe" sites for intracellular digestion. Digest ingested bacteria, viruses, and toxins; Degrade nonfunctional organelles

Peroxisomes

bud off from the endoplasmic reticulum. Membranous sacs containing powerful oxidases and catalases. Detoxify harmful or toxic substances

Nuclear Envelope

Double-membrane barrier; encloses nucleoplasm. Outer layer is continuous with rough ER and bears ribosomes. Pores allow substances to pass; regulates transport of large molecules into and out of nucleus

Nucleolus

Dark-staining spherical bodies within the nucleus. Involved in rRNA synthesis and ribosome subunit assembly. Usually one or two per cell

Chromatin

Threadlike strands of DNA (30%), histone proteins (60%), and RNA (10%). Arranged in fundamental units called nucleosomes – DNA packaged around proteins called histones. Will condense into bars like bodies called chromosomes when cell starts to divide

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Interphase

the cell is not dividing. It is performing its normal cell functions. It is not part of mitosis

Early Prophase

the duplicated chromatin condenses into chromosomes. Spindle fibers begin to form but the nuclear membrane is still present so chromosomes are not yet on spindle microtubules

Late Prophase

the nuclear membrane disintegrates and chromosomes begin to attach to spindle microtubules

Metaphase

the chromosomes have lined up at a midline called the metaphase plate. There are still two copies of every single chromosome in the cell. Double the normal set

Anaphase

the duplicated chromosomes split, and one chromatid, one side of each X, moves to opposite poles along the spindle fibers. Each chromatid is a chromosome in a functioning, Interphase cell

Telophase

the chromosomes have completed their movement and two new nuclei form as the nuclear envelop surrounds each set of chromosomes

Translation

mRNA → protein 

Converts base sequence of nucleic acids into amino acid sequence of proteins. Each three-base sequence on mRNA represented by codon

Transcription

DNA → mRNA 

Transfers DNA gene base sequence to complementary base sequence of mRNA

Triplets

(three sequential DNA nitrogen bases) form a genetic library. Bases in DNA are A, G, T, and C. Each triplet specifies coding for number, kind, and order of amino acids in polypeptide

Codons

a sequence of three nucleotides which together form a unit of genetic code in a DNA or RNA molecule.

Anticodons

at other end (head) binds mRNA codon at ribosome by hydrogen bonds 

E.g., if codon = AUA, anticodon = UAU