BIO220 Unit 2 (Ch 4, 5 & 6)

Prokaryotes vs. Eukaryotes differences

- Prokaryotes have no nucleus or membrane bound organelles

- Eukaryotes have a nucleus and membrane bound organelles

Prokaryotes and Eukaryotes similarities

DNA, cell membrane, ribosomes, cytoplasm

Prokaryote DNA

Contained in the cytoplasm (in the nucleoid region), organized into one chromosome, and exists in a ring

Eukaryote DNA

Organized into individual chromosomes

Cell division in prokaryotes

binary fission

Cell division in eukaryotes

mitosis

Ribosomes - prokaryotes vs eukaryotes

prokaryotes - smaller

eukaryotes - larger

flagella

whiplike tails found in one-celled organisms to aid in movement

Eukaryotic flagella

made of microtubules arranged in a 9+2 arrangement

Prokaryotic flagella

longer projections that propel the prokaryotic cell through its liquid environment

monotrichous flagella

single flagellum at one end

lophotrichous flagella

small bunches emerging from the same site

amphitrichous flagella

flagella at both ends of the cell

peritrichous flagella

dispersed over surface of cell; slowest

chemotaxis

Cell movement that occurs in response to chemical stimulus

photoaxis

movement of a cell toward light

glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication

Glycocalyx functions

-Inhibit killing by white blood cells by phagocytosis, contributing to pathogenicity

-Protect cells from dehydration and nutrient loss

-Attachment - formation of biofilms

Gram positive bacteria

thick cell wall composed primarily of peptidoglycan and cell membrane (1 major layer)

-retain crystal violet & stain purple

Gram negative bacteria

outer cell membrane, thin peptidoglycan layer, and cell membrane (2 major layers)

-lose crystal violet & stain red from safranin counterstain

Lipopolysaccharides & Lipoproteins (LPS)

•Lipid portion of the bacterial cell wall (endotoxin) may become toxic when released during infections caused by Gram - bacteria causing aches, fever, shock

Mycoplasmas

bacteria that naturally lack a cell wall

Plasmids

-Small circular, double-stranded DNA

-Free or integrated into the chromosome

-Not essential to bacterial growth and metabolism

-May encode antibiotic resistance, tolerance to toxic metals, enzymes, and toxins

Endospore

A thick-walled protective spore formed by some G+ bacterial cells and resists harsh conditions.

-when exposed to adverse environmental conditions; capable of high resistance and very long-term survival

Archaea (domain)

primitive, adapted to extreme habitats and modes of nutrition

"extremophiles"

Cytoplasm

A jellylike fluid (mostly water) inside the cell in which the organelles are suspended

Rough ER (Endoplasmic Reticulum)

Has ribosomes attached for protein synthesis

New proteins may be folded and packed for delivery

Smooth ER (Endoplasmic Reticulum)

synthesis and storage of lipids (including phospholipids)

Golgi

A system of membranes that modifies and packages proteins via vesicle for transport (shipping center)

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

plant cell - chloroplast

Found in plant cells

Capture energy from sunlight and use it to produce food for the cell

what type of cell is this?

plant cell

more square/angular shaped due to rigid cell walls

what type of cell is this?

animal cell

what type of cell is this?

bacterial cell

small, simple cell that does not contain organelles

Cell Wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Found in plant cells, fungi & most bacterial cells

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Ribosomes

site of protein synthesis

Lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell (like the cell's stomach)

Cilia

The hairlike projections on the outside of cells that move in a wavelike manner

Found only in Eukaryotic cells

heterotroph

An organism that cannot make its own food.

autotroph

An organism that makes its own food

Ex. plants & some protists are able to utilize photosynthesis to make their nutrition

Fungi - energy

heterotroph

Fungi - benefits

-Decomposers of dead plants and animals

-Sources of antibiotics, alcohol, organic acids, vitamins

-Used in making foods and in genetic studies

Fungal Infections

Most often found on skin (also hair, nails, etc.) and in the lungs

Protists - energy

heterotroph & autotroph (some are photosynthetic)

Helminths - energy

heterotroph

Microscopic fungi - two forms (morphologies)

yeast - round ovoid shape, asexual reproduction

hyphae (mold) - long filamentous fungi or molds

Dimorphic fungi

can change between yeast to hyphae forms and back

Helminths are

parasitic worms

Helminths - two major groups

1. flatworms - examples: tapeworms, flukes

2. roundworms (nematodes) - examples: pinworms

Helminths are acquired through what route?

-ingestion of larvae or eggs in food; from soil or water; some are carried by insect vectors

sarcodines

animal-like protists that move by changing shape, extending pseudopods (amoeba)

Detrimental example: infective amoeba (Entamoeba histolytica) cause amebic dysentery

Chaga's disease

caused by a pathogenic flagellate T. cruzi

obligate intracellular parasites

viruses cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses

Viruses can infect what?

all organisms (bacteria, fungi, algae, plants, animals, protozoa)

The host range of a virus is determined by

•How the molecules (spikes) on the surface of the virus match up with receptors on the surface of the cell(s) it infects.

capsid

Outer protein coat of a virus

What are the two main structural types of viruses?

1. helical

2. icosahedral

helical viruses

hollow, cylindrical capsid

Icosahedral viruses

Capsids forming 20 triangular faces and 12 corners.

enveloped virus

surrounded by envelope (additional structure outside the capsid)

naked (nonenveloped) virus

virus without an envelope

complex virus

A virus with a complicated structure, such as a bacteriophage.

bacteriophage

A virus that infects bacteria

viral genome types

Includes dsDNA, ssDNA, and dsRNA, ssRNA (know all 4)

General phases in animal virus multiplication cycle:

1. Adhesion - binding of virus to specific molecule on host cell

2. Penetration - genome enters host cell

3. Uncoating - the viral nucleic acid is released from the capsid

4. Synthesis - viral components are produced

5. Assembly - new viral particles are constructed

6. Release - assembled viruses are released by budding (exocytosis) or cell lysis

(know these in order)

Bacteriophage skip which multiplication step?

uncoating

viral methods of penetration (how they get into cells)

-Endocytosis - entire virus is engulfed and enclosed in a vacuole or vesicle

-Fusion - envelope merges directly with the cell membrane resulting in nucleocapsid's entry into cytoplasm

viral methods of releasing

•Assembled viruses leave host cell in one of two ways:

-Budding - exocytosis; nucleocapsid binds to membrane which pinches off and sheds the viruses gradually; cell is not immediately destroyed

-Lysis - nonenveloped and complex viruses released when cell dies and ruptures

transformation

•Some animal viruses enter host cell and permanently alter its genetic material resulting in cancer - transformation of the cell

Examples of mammalian viruses capable of causing transformation (cancer)

-HPV (human papilloma virus)

-Epstein-Barr virus - Burkitt's lymphoma

Lysogenic viruses

enter cell & integrate into the cell's DNA and multiply without immediately killing the cell

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