Molecular Biology Ch 4

light microscope

visible light is passed through the specimen, and through the glass lens, which magnifies the image. Can resolve up to 0.2 um

scanning electron microscope (SEM)

distinguish the surface of the specimen.

transmission electron microscope (TEM)

offer details of the interior of the specimen. ultrastructure (internal details) are revealed.

magnification

ratio of object size to real size

resolution

minimum distance that 2 points are distinguishable from each other

Prokaryote cell

-bacteria and archea
-DNA concentrated in the nucleoid
-no membrane bound organelles
-small

eukaryote cell

-plants, animals, fungi, protists
-DNA is located in nucleus, a membrane bound organelle
-have membrane bound organelles
-bigger

similarities of prokaryotes and eukaryotes

-both have the semi-fluid substance cytosol
-all cells are chromosomes which carry genes/DNA
-all cells contain ribosomes (organelles that make protein)
-possess plasma membrane composed of phospholipid bilayer

Nucleus
(organelle)

-houses DNA. divided by a nuclear envelope (membrane bound)
-composed of: 1. double membrane composed of a phospholipid bilayer 2. chromosomes- compact units of DNA 3. nucleolus- DNA condenses here 4. Nuclear lamina-maintains shape 5. Nuclear matrix- carry out transportation and organization.
6. Pores-each composed of 8 subunits

Ribosomes
(organelle)

-not membrane bound, manufacture protein.
-made of RNA and protein, 2 subunits
-build protein in 2 cytoplasmic locales(outside/surrounding nucleus): 1. Free ribosome- suspended in cytosol, make proteins that function in cytosol. 2. Bound ribosome- attached to the outside of the endoplasmic reticulum, proteins bound to the membrane and are secreted out of the cell.
-free and bound ribosomes are interchangeable to meet the need.

Endomembrane system
(organelle)

-made up of phospholipid bilayer.
-composed of the following organelles:
1.nuclear envelope (not an organelle, but houses one)
2. endoplasmic reticulum
3. Golgi Apparatus
4. Lysosomes
5. Vacuoles
6. Plasma membrane

Endoplasmic reticulum (endomembrane system)

-accounts for 1/2 of the membrane in a cell.
-continuous w/ the nuclear envelope.
-two types: smooth and rough

Smooth Endoplasmic Reticulum

-lacks ribosomes on surface
-functions lipid synthesis
-metabolizes carbohydrates
-detoxifies drugs
-stores Ca2+ ions for muscle contractions

Rough Endoplasmic Reticulum

-has ribosomes bound to surface.
-make proteins that are bound to membrane/secreted
-path of a protein: 1. Protein is made by ribosome 2. Protein enters lumen via pore. 3. 2nd, 3rd, and 4th structure occurs, "native conformation" (opposite denaturation)-secreted proteins "glycoproteins" 4. Transport protein by transport vessicle

chromatin

DNA and protein packaging found in chromosomes

Golgi Apparatus
(endomembrane system)

-receives protein from the ER
-protein matures as it goes through the cisternae (cisternal maturation model)
-before exit a "zip code" is placed on each protein.

Lysosome
(endomembrane system)

-hydrolytic enzymes
-acidic environment
-hydrolyzes macromolecules
-performs intracellular digestion:phagocytosis (take in food)
-performs autophagy: recycling of organelles

Vacuoles
(endomembrane system)

-maintenence compartment
-function w/ lysosomes (i.e. food vacuoles).
-In animal cells: food vacuoles.
-In protists: contractile vacuoles maintain water concentration by removing excess water and salt (isotonic=concentration)
-In Plants: central vacuole enclosed by a membrane called a tonoblast. Solution inside is sap. Central vacuole deter. pigment and enlarges to store water.

mitochondria
(organelle)

-found in animals and plants
-converts energy into forms the cell can use, ATP (adenine triphosphate)
-membranes made of ribosomes
-within the mitochondrial matrix is mitochondrial DNA

chloroplast
(organelle)

-found in plants only
-converts light energy into chemical energy
-composed of an inner and outer membrane.
-features stacked structures within called granums. The individual components of the granums are called thylakoids.
-has its own ribosomes and DNA

peroxisome
(organelle)

-transfer H and O into hydrogen peroxide
-hydrogen peroxide is used to break down alcohols and fats, then is converted to water and O2 before it leaves the peroxisome (it is toxic outside the peroxisome)

cytoskeleton
(intracellular)

-network of fibers extending throughout the cytosol and cytoplasm.
-functions: mechanical support and maintain shape, provide anchorage for organelles, provides motility (invol. the interaction of the cytoskeleton w/ the motor protein-the dynein.)

microtubles
(fiber of cytoskeleton)

-found in the cytoplasm of all eukaryote cells.
-polymer made of tubulin subunits (alpha and beta tubulin)
-functions as a track which moves things along.
-grows from the centrosome. Centrisome consists of 2 barrel shaped centrioles.
-make cillia and flagella (locomotion). Cillia are shorter and more in number. Flagella are longer and fewer.

Microfilaments
(fiber of cytoskeleton)

-polymers made of actin
-tension bearing, functions muscle contraction, and involved w/ pseudopodia "fake feet" (found in amoeba)

Intermediate filaments
(fiber of cytoskeleton)

-polymer made of the Keratin family of protein.
-provides framework for cytoskeleton.

Extracellular components in plant cells

-surrounded by the cell wall, which offers protection, maintains shape, prevents water loss, and holds the plant up against gravity.
-Made of cellulose.
-llamela: glue that holds cells together, made of pectin.
-plasmodesmata: channels of communication b/w cells.

Extracellular components in animal cells

-extracellular matrix (ECM): outside the framework of the cell.
-4 major components of ECM: 1. collagen-glycoprotein which makes fibers outside the cell. 2. Proteoglycan-another network of glycoproteins that interact w/ collagen. 3. Fibronectin-glycoproteins tgat bind to proteins in the plasma membrane. 4. Integrins- proteins in the plasma membrane that bind to the fibronectin.

Intracellular junctions

-tight junctions prevent leakage.
-desmosomes: anchor junctions, rivets
-gap junctions: channels of communication

ultrastructure of cillia and flagella in relation to function

-composed of 9 pairs of microtubles surrounding a pair of microtubles (9+2 arrangement). Microtubles extend downward into the basal body, a common base composed of 9 triplets of microtubles.
-the microtubles are grouped in pairs, and they use ATP (adenine triphosphate produced by the mitochondria) in order to slide against each other and create a whip-like action for the function of locomotion.