Chapter 1 - Cellular Biology

Prokaryotes

contain no organelles, nuclear material is not encased, characterized by lack of distinct nucleus, single chromosome, lack histones

Eukaryotes

larger, extensive intracellular anatomy and organization that prokaryotes, include organelles, many chromosomes

Differentiation

stem cells get specialized to perform one kind of function (promoted by asymmetric cell division)

Eight chief cellular functions

movement, conductivity, metabolic absorption, secretion, excretion, respiration (absorbs oxygen), reproduction, communication

Nucleus

largest organelle, two membranes (nuclear envelope) with pits (nuclear pores) for chem messages, contains nucleolus, DNA, and DNA-binding protiens

Nucleolus

small dense structure composed largely of RNA

Nucleus function

cell division and control of genetic information (processing of RNA)

Cytoplasm

aqueous solution (cytosol) that fills the cytoplasmic matrix, one-half the volume of cell, contains enzymes and ribosomes, storage unit

Cell polarity

spatial differences in shape, structure, and function, depends on distribution

Ribosomes

RNA-protein complexes synthesized in the nucleolus, provide sites for cellular protein synthesis

Endoplasmic reticulum

extend throughout the outer nuclear membrane, synthesis, folding, and transport of protein and lipids for organelles (new sensing cellular stress)

Golgi complex

network of smooth membranes and vesicles processing and packaging proteins onto secretory vesicles to be brought to inter and extracellular places

Lysosomes

saclike structures, contain digestive enzymes (trash cans)

Peroxisomes

lysosome look alike but contain oxidative enzymes that produce hydrogen peroxide and detoxify

Mitochondria

metabolic machinery for cellular energy metabolism, enzymes of respiratory chain (inner membrane) generate most ATP, also has a role in osmotic regulation, pH control, calcium homeostasis, and cell signaling

Cytoskeleton

“bone and muscle” of cell, network of protein filaments, form cellular extensions, intermediate filaments bridge the cytoplasm form one cell junction to another

Lipid bilayer

composed of two apposing leaflets (made of phospholipids) and proteins, basic structure of cell membranes

Glycolipids and glycoproteins

carbohydrates that are chemically combined with lipids and proteins, mainly associated with plasma membranes

Caveolae

flask-shaped invaginations on outer surface of plasma membrane, storage site for signaling proteins

Lipids

each lipid molecule is said to be polar, or amphipathic (one part hydrophobic and one part hydrophilic)

Posttranslational modifications

alter the activity and function of proteins, pathogens interfere with the host’s PTMs

Membrane proteins

transmembrane proteins (both sides), monolayer, linked on either side (covalently attached to a lipid), attached by other proteins

Membrane protein removal

detergents (integral membrane proteins & peripheral membrane proteins)

Function of proteins in membrane

recognition and binding units (receptors), pores or transport channels, specific enzymes, cell surface markers, CAMs, catalysts of chemical reactions

Cell adhesion molecules (CAMs)

proteins that allow cells to hook together and form attachments of the cytoskeleton for maintaining cellular shape

Cell cortex

meshwork of proteins attached to the underside of the membrane, stabilizes plasma membrane

Proteostasis

state of cell balance of the process of protein synthesis, folding, and dehydration, made of ribosomes (makers); chaperones (helpers); and two protein breakdown systems or proteolytic systems (lysosomes and ubiquitin-proteasome system UPS)

Glycocalyx

carbohydrate coating protects the cell from mechanical damage

Carbohydrate membrane function

specific cell-to-cell recognition and adhesion

Cellular receptors

protein molecules on the plasma membrane, in cytoplasm, or in the nucleus that can recognize and bind with specific smaller molecules called ligands

Cell-to-cell adhesions

how cells come together to form tissues, cell adhesion molecules in the cell’s plasma membrane, the extracellular matrix, and specialized cell junctions

extracellular matrix

intricate meshwork of fibrous proteins embedded in a gel substance of carbohydrates

basement membrane

type of ECM, thin, tough, flexible, beneath epithelial cells

3 macromolecules in matrix

1) fibrous structural proteins w/ collagen and elastin 2) adhesive glycoproteins 3) proteoglycans and hyaluronic acid

Collagen

cable-like fibers or sheets that provide tensile strength or resistance to longitudinal stress

Elastin

rubber-like protein fiber stretches and recoils

Fibronectin

large glycoprotein promotes cell adhesion and cell anchorage

Fibroblasts

cells that secret the ECM

Cell junctions

specialized plasma membrane regions where cells interconnect

Adhering junctions

spot desmosomes, hemidesmosomes, belt desmosomes

Tight junction

impermeable junction that hold cells together, sealed in a way that molecules can not leak between

Gap junction

communication junction, mediates the passage of small molecules from cell to cell

Connexons

hemichannels that extend outward from each of the adjacent plasma membranes

Gating

calcium goes up and permeability at junctional complex goes down

Homeostasis

stable internal environment

Contact-dependent signaling

cells must be in close membrane-to-membrane contact

Paracrine signaling

cells secrete local chemical mediators that are taken up, destroyed, or immobilized

Autocrine signaling

cells produce signals they alone respond to

Hormonal signaling

endocrine cells secrete hormones travel through blood stream to produce response in other cells

Nerohormonal signalling

hormones released by neurosecretory neurons

Neurotransmitters

chemicals used to communicate directly with nurons

Signal transduction pathways

communication pathways or signaling cascades to respond to external stimuli

Anabolism

energy-using process of matabolism

Catabolism

energy-releasing process of metabolism

Phases of catabolism

digestion, glycolysis and oxidation, citric acid cycle, oxidative phosphorylation

Oxidative phoosphorylation

occurs in mitochondria creates ATP

Cytochromes

proteins that are carrier molecules of hydrogen ions (from the surface of the mitochondria)

Anaerobic glycolsis

how ATP is formed when there is no available oxygen

Membrane transport proteins

what most of the molecular transfer in and out of cells is dependent on

Passive transport

water and small molecules move easily through pores in the plasma membrane

Active transport

cell’s expenditure of metabolic energy to move molecules in and out of cell, requires pumps

Diffusion

movement of a solute molecule from an area of greater to lesser concentration

Filtration

movement of water and solutes through a membrane because of a difference in pressure pushing on one side of it

Hydrostatic pressure

mechanical force of water pushing against cellular membranes

Osmosis

movement of water down a concentration gradient through a semipermeable membrane

Osmolarity

concentration of molecules per volume of solution

Endocytosis

substance to be transfered is engulfed by a segment of plasma membrane

Pincocytosis

fluid and solute molecules are ingested through formation of small vesicles

Phagocytosis

large particles (like bacteria) are ingested through formation of large vesicles

Extracellular vesicles

released for normal and pathogenic condition originating from plasma membrane carry cargo to target cell and regulate functions

Exocytosis

membrane-bound vesicle carries macromolecules to the outer cell membrane

Cell polarization

inside of cell is more negatively charged than the outside

G1 Phase

period between M phase and start of DNA syntheses

S Phase

DNA synthesis in cell nucleus

G2 Phase

between completion of DNA synthesis and next phase in which RNA and protein synthesis occurs

M Phase

mitosis nuclear and cytoplasmic division: prophase, metaphase, anaphase, telophase (after is cytokinesis)

Mitogens

induce or stimulate mitosis

Growth factors

stimulate an increase in cell mass or cell growth

Survival factors

inhibit the programmed cell death

3 factors that maintain cellular organization

1) recognition and cell communication 2) selective cell-to-cell adhesion 3) memory

Nervous tissue

composed of neurons and receive and transmit electrical impulses rapidly across junctions called synapses

Epithelial tissue

covers most internal and external surfaces of the body

Connective tissue

binds various tissues and organs together, supporting them in their locations and serving as storage sites for nutrients

Muscle tissue

composed of long, thin, highly contractile cells or fibers

Simple Squamous Epithelium

lining of blood vessels leads to diffusion and filtration, lining of pulmonary alveoli (air sacs) leads to separation of blood from fluid in tissues, bowman’s capsule (kidney) where it filters substances from blood

Stratified Squamous Epithelium

epidermis of skin and linings of mouth, pharynx esophagus, and anus provide protection and secretion

Transitional Epithelium

linings of the urinary bladder and other hollow structures stretch, allowing expansion of the hollow organs

Simple Cuboidal Epithelium

Glands and parts of the kidney tubules and outer covering of the ovary secrete fluids

Simple Columnar Epithelium

ducts of many glands and lining of the digestive tract allow secretion and absorption form the stomach to the anus

Ciliated Simple Columnar Epithelium

Linings of the bronchi of lungs, nasal cavity, and oviducts allow secretion, absorption, and propulsion of fluids and particles

Stratified Columnar Epithelium

Lining of epiglottis, part of pharynx, anus, and male urethra provide protection

Pseudostratified Ciliated Columnar Epithelium

lining of large ducts of some glands, male urethra, respiratory passages, and eustachian tubes of ears transport substances

Loose or Areolar Tissue

attaches skin to underlying tissue; holds organs in place by filling space between them; supports blood vessels —- intracellular fluid transports nutrients and waste products

Dense Irregular Tissue

dermis layer of skin; acts as a protective barrier

Dense, Regular (White Fibrous) Tissue

forms strong tendons of muscle, ligaments of joints, some fibrous membranes, and fascia that surround organs and muscles

Elastic Tissue

lends strength and elasticity to walls of arteries, trachea, vocal cords, and other structures

Adipose Tissue

stores fat, which provides padding and protection

Cartilage

gives form, support, and flexibility to joints, trachea, nose, ear, vertebral disks, embryonic skeleton, and many internal structures

Bone

lends skeleton rigidity and strength

Special Connective Tissue: Plasma

serves as a matrix for blood cells