Chapter 3: Cell Form and Function Flashcards
Cell Shapes and Sizes:
Squamous: thin, flat, scaly (fried egg, nucleus as yoke) (line esophagus and epidermis)
Cuboidal: 4 sides same size, square (liver cells)
Columnar :taller than wide (inner lining of cells of stomach and intestine)
Polygonal: irregular angular sides with 4 or more sides.
Stellate: starlike shape (nerve cells)
Spheroidal: round or oval (egg cells and wbc)
Discoidal: Disk-shaped (RBC)
Fusiform: spindle-shaped (smooth muscle)
Fibrous: Long, slender, threadlike
Unit of measuring cells: micrometer
Cell Structure:
Plasma Membrane Cytoplasm Cytoskeleton Organelles Nucleus Inclusions Cytosol
Membrane Proteins
Transmembrane proteins pass through phospholipid bilayer. Hydrophilic regions on either side of membrane, and hydrophobic throughout membrane.
Peripheral Proteins: do not protrude into phospholipid but attach on to inner or outer face of membrane.
Functions: Receptors, Cell adhesion molecules, Second-messenger system, Enzymes, Carriers, Cell Identity markers, Channel proteins (leak channels=always open. Ligand-gated=chemical messengers. Voltage gated=electrical potential. Mechanically gated=physical stress of cell.)
Glycocalyx
“Identity tag” in all animal cells. Functions include: protection, immunity to infection, defense against cancer, transplant compatibility, cell adhesion, fertalization, embryonic development.
What is Microvilli?
Extension of plasma membrane to increase SA of cell. (brush border, fringe)
Developed in cells made especially for absorption; epithelial of kidney and intestines.
What is Microvilli?
Extension of plasma membrane to increase SA of cell. (brush border, fringe)
Developed in cells made especially for absorption; epithelial of kidney and intestines.
What is cilia?
Hair-like sensors 7-10 um long. Found in ear and kidney. Beat in waves across surface of epithelium to propel materials. (power and recovery stroke)
What are pseudopods?
cytoplasm filled extensions of cells. Locomotive for capturing particles.
Diffusion
Moving particles from a higher concentration to a lower concentration. Factors affecting Diffusion: Temperature Molecular weight Steepness of concentrate gradient Membrane SA Membrane permeability
Osmosis
Flow of water from one side of selectively permeable membrane to another (fluid balance).
Occurs in nonliving membranes and plasma membranes.
Water moves through membranes easiest through aquaporins.
Osmosis
Flow of water from one side of selectively permeable membrane to another (fluid balance).
Occurs in nonliving membranes and plasma membranes.
Water moves through membranes easiest through aquaporins.
What is tonicity?
Ability of solution to affect fluid volume and pressure in cell.
Hypertonic: higher number of solutes to water, causing cells to lose water and crenate.
Hypotonic: higher number of solutes that water, causing cell to swell and burst.
Isotonic: number of solutes are same as water, no change in cell shape.
Carrier Mediated Transport
Transport of molecules through membrane needing a carrier. Solute binds to carrier, changes shape, released on the other side.
Transport Maximum: when no more carriers are available.
1. Uniports: only carries one type of solute in 1 direction.
2. Symport: cotransports by carrying two or more solutes though membrane in same direction.
3. Antiport: 2 or more solutes in opposite directions by countertransport.
What are the 3 mechanisms or Carrier Mediated Transport?
- Facilitated Diffusion: transport of solute down concentration. Requires no energy, solute binds to carrier and is released inside the cell.
- Primary Active Transport: carrier moves solute of concentration gradient using ATP.
- Secondary Active transport: requires energy input. Na-K PUMPS: secondary active transport, regulation of cell volume, maintenance of membrane potential, heat production.
What is Vesicular Transport?
Moves large particles through membrane by vesicles.
Endocytosis: vesicles bringing matter into the cell. (Needs ATP)
1. Phagocytosis: “cell eating”, engulfs molecules by phagosome.
2. Pinocytosis: “cell drinking” taking in droplets of ECF containing molecules o=in use of cell (pinocytotic vesicles)
3. Receptor mediated endocytosis: receptors form a ‘pit’ in membrane to engulf molecules.
Exocytosis: Vesicles releasing material out of cell. (needs ATP)
What is a cytoskeleton?
Network of proteins and cylinders to structurally support a cell, hold shape, organize contents, direct movement within cell. Composed of:
Microfilaments: thin filaments made of actin protein form terminal web on cytoplasmic side of membrane.
Intermediates: thicker than micro. and made of keratin. Gives cell shape, resist stress.
Microtubules: cylinders of 13 parallel strands can protofilaments (long chain of tubulin). Hold organelles in place.
Nucleus
Largest organelle and only one clearly visible by microscope. Most cells have and nucleus, except for mature RBC (anuclear), and skeletal cells (multinuclear).
Enclosed in double membrane; nuclear envelope with nuclear pores to regulate traffic. Inside is fibrous zone; nuclear lamina to support, attach, and organize.
Nucleoplasm composed of chromatin and nucleoli where ribosomes are produced.
R & S Endoplasmic Reticulum:
Rough Endoplasmic Reticulum:
Cisterns parallel and flattened with ribosomes attached. Produces phospholipids and synthesizes proteins. Largest organelle in cells.
Smooth ER:
Synthesis steroids and detoxifies alcohol. (skeletal and cardiac muscle)
Ribosomes:
Small proteins and RNA found in nucleoli, cytosol, mitochondria, surface of RER and nuclear envelope.
Read coded genetic messages and assemble amino acids into proteins specified by code. Free ribosomes make protein.
What is the Golgi Complex:
System of cisterns that synthesis carbohydrates and put finishing touches on protein and glycoprotein synthesis. Receives proteins from RER, puts in to Golgi vesicles to migrate or become secretory vesicles.
What is a Lysosome?
Package of enzymes bound by membrane. Break down proteins, nucleic acids, carbs, phospholipids.
Cell Suicide.
What is Peroxisomes?
Contain different enzymes than lysosomes. Produces by ER and mitochondria. General function is to use O2 to oxidize organic molecules. Neutralize free radicals/
Proteasomes:
Protein disposal. Hollow, cylinder organelles.
What is Mitochondria?
Specialized in synthesizing ATP. Has folds called cristae and spaces between called matrix.
What is a centriole?
Assembly of microtubules in 9 groups. Plays a role in cell division and form bodies cillia and flagella.
