Chapter 3: Cell Form and Function

Question 1

Cell Shapes and Sizes:

Answer 1

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

Question 2

Cell Structure:

Answer 2

Plasma Membrane
Cytoplasm
Cytoskeleton
Organelles
Nucleus
Inclusions
Cytosol

Question 3

Membrane Proteins

Answer 3

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.)

Question 4

Glycocalyx

Answer 4

“Identity tag” in all animal cells. Functions include: protection, immunity to infection, defense against cancer, transplant compatibility, cell adhesion, fertalization, embryonic development.

Question 5

What is Microvilli?

Answer 5

Extension of plasma membrane to increase SA of cell. (brush border, fringe)
Developed in cells made especially for absorption; epithelial of kidney and intestines.

Question 5

What is Microvilli?

Answer 5

Extension of plasma membrane to increase SA of cell. (brush border, fringe)
Developed in cells made especially for absorption; epithelial of kidney and intestines.

Question 6

What is cilia?

Answer 6

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)

Question 7

What are pseudopods?

Answer 7

cytoplasm filled extensions of cells. Locomotive for capturing particles.

Question 8

Diffusion

Answer 8

Moving particles from a higher concentration to a lower concentration.
Factors affecting Diffusion:
Temperature
Molecular weight
Steepness of concentrate gradient
Membrane SA
Membrane permeability

Question 9

Osmosis

Answer 9

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.

Question 9

Osmosis

Answer 9

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.

Question 10

What is tonicity?

Answer 10

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.

Question 11

Carrier Mediated Transport

Answer 11

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.

Question 12

What are the 3 mechanisms or Carrier Mediated Transport?

Answer 12

1. Facilitated Diffusion: transport of solute down concentration. Requires no energy, solute binds to carrier and is released inside the cell.
2. Primary Active Transport: carrier moves solute of concentration gradient using ATP.
3. Secondary Active transport: requires energy input. Na-K PUMPS: secondary active transport, regulation of cell volume, maintenance of membrane potential, heat production.

Question 13

What is Vesicular Transport?

Answer 13

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)

Question 14

What is a cytoskeleton?

Answer 14

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.

Question 15

Nucleus

Answer 15

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.

Question 16

R & S Endoplasmic Reticulum:

Answer 16

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)

Question 17

Ribosomes:

Answer 17

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.

Question 18

What is the Golgi Complex:

Answer 18

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.

Question 19

What is a Lysosome?

Answer 19

Package of enzymes bound by membrane. Break down proteins, nucleic acids, carbs, phospholipids.
Cell Suicide.

Question 20

What is Peroxisomes?

Answer 20

Contain different enzymes than lysosomes. Produces by ER and mitochondria. General function is to use O2 to oxidize organic molecules. Neutralize free radicals/

Question 21

Proteasomes:

Answer 21

Protein disposal. Hollow, cylinder organelles.

Question 22

What is Mitochondria?

Answer 22

Specialized in synthesizing ATP. Has folds called cristae and spaces between called matrix.

Question 23

What is a centriole?

Answer 23

Assembly of microtubules in 9 groups. Plays a role in cell division and form bodies cillia and flagella.