Chapter 4 - Characteristics of Prokaryotic and Eukaryotic Cells Test 1

Eukaryotic Ribosomes

(May be free in the cytoplasm or attached to rough endoplasmic reticulum and the nucleus) -Structure: Not membrane-bound; made up of RNA and protein. - Size: 80s= 60s+40s. - Function: sites of protein synthesis (where amino acids are assembled into polypeptides)

Prokaryotic: Flagella

(Singular - flagellum) - Long, thin structures that extend outward from the surface of the envelope. - Function is Locomotion - bacteria with flagella are motile; flagella rotate to propel the bacterium

Eukaryotic: Cytoskeleton

- (Not found in prokaryotes) - Structure: network of filamentous protein structures. - Functions: Give the cell shape (support and rigidity) anchor the organelles; transport substances through the cell (cytoplasmic streaming), cytoplasmic streaming also enables some eukaryotes to move (formation of pseudopods); involved in cell division; involved in cell motility (flagella)

Eukaryotic: Plasma membrane

- Already described in prokaryotic plasma membrane; here difference are between prokaryotes and eukaryotes: 1. Proteins involved in electron transport chain and photosynthesis are not found in cell membrane, but are found in cytoplasmic organelles (mitochondria and chloroplast respectively)

Prokaryotic: Endospores

- Extremely hardy, resting (non-growing) structures that some bateria - They are able to withstand harsh environmental conditions. - Principally gram (+), produced through the process of sporulation when nutrients are exhausted; - when favorable conditions return, endospores germinate to produce new vegetative cells, which grow and reproduce; some of the endospore-producing bacteria are pathogenic to humans. Examples: Clostridium and Bacillus

Prokaryotic: Nucleoid

- Function: carriers hereditary information and controls the functions of the cells. - Most of a bacterium's DNA is arranged in a single circular molecule called a chromosome. - Some bacteria also contains smaller circular DNA molecules called plasmids.

Archaea

Composed of Pseudomeurin (false peptidoglycan) containing NAG and NAA sugars.

Prokaryotic: Pilli

- Short hairlike appendages; - All gram negative bacteria have pilli; - Function is to attach bacteria to their bacteria, other cells or other surfaces. - Sex pilli allow one bacterial cell to adhere to another (cells can actually exchange genetic material through the pilli - this is the closest bacteria get to sexual reproduction): Conjugation.

Prokaryotic: Glycocalyx

- Slimy pr gummy carbohydrate substance that becomes the outermost layer of the cell envelope. - A thick glycocalyx is often called a capsule. Functions: - Protection from drying out. - Helps a cell adhere to a surface where conditions are favorable for growth. -Provide proection against Phagocytosis (engulfment and destruction by cells such as white blood cells)

Facilitated Diffusion

- Small, polar molecules, like water and some ions (sodium, magnesium, potassium, calcium, chloride, bicarbonate) can diffuse through channel proteins. - Most biologically important molecules, however, are polar and are much larger than water (EX. glucose) and cannot fit through channel proteins. - Special selective carrier proteins are located in the membrane to transport molecules like glucose.

Eukaryotic: Cilia

Short, hairlike, motile cellular extensions that occur on the surfaces of certain cells; Ex: some protozoa like Paramecium (called cilates) use cilia for motility and feeding.

Eukaryotic Cell wal

1.Algae: made of cellulose 2. Plant Cells: made of cellulose 3. Fungi: in most made of chitin 4. Animal Cells: no cell wall. 5 Protozoans: no cell wall.

Peripheral Proteins

Usually attached to membrane surface

Mycobacteria

With mycolic acid (lipid). Example: Mycobacteria tuberculosis, M.leprae, Norcarida

Membrane bound organelles

-Eukaryotic cells have specializes membrane-bound organelles that carry out specific functions such as phtosynthesis (chloroplasts), ATP production (mitochondria), lipid and protein synthesis (ER, golgi complex), cellular digestion (lysosomes) and transport (vesicles).

Eukaryotic Chloroplasts

-Structure: Usually shown oval shaped; double membrane; contains chromatophores (or thylakoid) pigments for photosynthesis - Function: Involved in photosynthesis (ability to make food)

Amphitrichous

1 flagella on each end (Ex. S.Volutans)

Monotrichous

1 flagella on one end

Prokaryotic: Ribosomes

- Made up pf RNA and protein. - Function: Site of protein synthesis: prokaryotic ribosomes are smaller than eukaryotic ribosomes. - Size: 70s (complete structure) = 50s (large subunit) + 30s (smaller subunit)

Prokaryotic: Cytoplasm

- Matrix composed primarily of water (90%), proteins, other organic and inorganic substances.

Prokaryotic: Plasma or Cell membrane

- Membrane that encloses that cytoplasm of any cell. Function -To contain the cytoplasm and to transport and regulate what comes in and what goes out of the cell. (Selective permeability) - Contains enzymes for making ATP and/or chromatophores and other pigments for photosynthesis. Many prokaryotic cell membranes are similar to eukaryotic cell membranes. - Its structure is referred to as the fluid mosaic model, because the structure behaves more like a fluid than a solid. Contains: - Membrane lipids: Composed primarily of phospholipid molecules. -Membrane Proteins: Proteins float in the fluid lipid bilayer.

Endosymbiotic Theory

- Mitochondria and chloroplasts were once free-living prokaryotes. - Evidence for this includes their structure and functions: double membrane, circular DNA, 70 ribosomes, reproduction and protein synthesis on their own.

Euakryotic Nucleus

- Nuclear Envelope: double membrane with nuclear pores that surrounds the nucleus. - Chromosomes: genetic material composed of DNA and associated; chromosomes are linear. - Function: Carriers of the hereditary information, which exerts a continuing influence over the ongoing activities of the cell through protein synthesis" "control center of the cell" - Isolates the DNA in eukaryotic cells.

Eukaryotic Mitochondria

- Structure: Usually shown oval shaped; double membrane: smooth outer membrane and a folded inner membrane (folds provide more surface area for chemical reactions to take place) - Function: break down energy containing organic molecules (Ex. Carbohydrates) & repackage the energy into smaller units (ATP) that can be used by the cells; called the "Powerhouse" of the cell.

Vesicles

- Structure: membrane- bound sacs that could be pinched off pieces of golgi complex, E.R or cell membrane. - Function: Transport material within the cell and into and out of the cell. - Lysosomes: contains enzymes for breaking down proteins, lipids etc.(digestion within the cell) they fuse with other vesicle (such as phagocytic vesicles) to degrade or digest their contents.

Prokaryotic: Structure of Cells wall

- The chief component of peptidoglycan. - Composed of long chains of polysaccharides of NAM and NAG cross-linked by short proteins (peptides) - When linked together these chains create the single rigid mesh-like molecule that forms the bacterial wall (resembles a chain link fence)

Simple Diffusion through the cell membrane

- The lipid interior of the cell membrane is a barrier to simple diffusion; only some molecules can pass through this barrier; most polar molecules (polar molecules get "stuck" in the nonpolar fatty acid tails) - Small, nonpolar, lipid soluble molecules like fats, gases (carbon dioxide, oxygen) & small polar molecules (water, alcohol, urea) move easily through the cell membrane by simple diffusion.

Diffusion

- The net movement of particle from a greater concentration to a lower concentration to distribute the particles uniformly; it's a passive process - molecules will diffuse freely until an equilibrium is reached.

Active Types of Transport

- The net movement of particles from a lower concentration to a greater concentration to distribute the particles uniformly. - These processes use energy (ATP) - Example: Na+/K+ pump.

G (+)

- Thick peptidoglycan wall is many layers thick. - Teichoic proteins help to hold layers together. - Example: S.aurues

G (-)

- Thin peptidoglycan mesh in only one layer thick. - Outer membrane: composed of a bilayer membrane; the inner layer is composed of phospholipids; the outer layer is composed of lipopolysaccharides (LPS's), a compound that's not found in any other living organisms. Part of the LPS is hydrophobic, part is hydrophilic; most molecules are transported across the outer membrane and into the cell through proteins called porins. These compounds are endotoxins and are only released when the bacteria die and their cell walls are broken down. Endotoxins cause fever and dilate blood vessels (Drop in blood pressure results). Killing the bacteria may increase the concentrations of this toxin. - Examples: E.Coli, Salmonella, Shigella, Pseudomonas, Proteus, Neisseria gonorrhoeae.

Prokaryotic: Axial Filaments

Bundles of flagella form an Endoflagella, which wrap around the cell body between the cell wall and the outer membrane; found only in one type of bacteria called the spirochetes. Ex Letospira and Treponema (causes syphilis)

Mycoplasmas

Group of bacteria that lack a physical cell wall; not all bacteria have a cell wall

Eukaryotic: Flagella

In humans, the single, long, hairlike cellular extension that occurs in sperm cells; beat in waved (prokaryotic flagella rotate) some protozoans like the euglena use flagella for motility.

Integral proteins

Inserted in the bilayer; mainly involved in transport

Prokaryotic: Function of cell wall

Maintaining shape and withstanding osmotic pressure.

Eukaryotic: Glycocalyx

May exist outside the plasma membrane; composed of carbohydrate chains from glycoproteins and glycolipids in cell membrane.

Peritrichous

Multiple flagella all around (Ex E.coli)

Lophotrichous

Multiple flagella on one end

Eukaryotic: Endocytosis

Substances are imported into the cell' vesicles (sacs) are formed from the cell membrane, when solid material is imported into the cell, this type of endocytosis is specifically called phagocytosis ("cell-eating"). Example: A white blood cell engulfing a bacteria.