Lecture 3 Flashcards by Britney Hansard

How are prokaryotes different from eukaryotes?

lack of nucleus and histones

the makeup of their cell wall

lack of membrane-bound organelles

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What do all prokaryotic bacterial cells possess?

a cell membrane

cytoplasm

ribosomes

a cytoskeleton

one chromosome
May be a few in some prokaryotes

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What do most prokaryotic bacterial cells possess?

a cell wall

a glycocalyx

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What do some prokaryotic bacterial cells possess?

flagella, pili, and fimbriae

an outer membrane

plasmids

inclusions

endospores

intracellular membranes

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What is pleomorphism?

when cells of one species vary in shape and size caused by variations of the cell wall structure

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What are the 3 bacterial shapes?

Coccus (circular), Rod (rectangle with round edges), spiral

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What are flagella?

used for bacterial movement
360o rotation
Flagellar structure differs between Gram positive and Gram negative cells due to differences in cell wall structure

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What are the 4 flagellar arrangements?

Monotrichous
Lophotrichous
Amphitrichous
Peritrichous

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What is mono trichous?

single flagellum

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What is lophotrichous?

small bunches or tufts of flagella

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What is amphitrichous?

flagella at both poles of the cell

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What is peritrichous?

flagella dispersed randomly over the surface of the cell

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How do bacteria move?

in response to chemical signals

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What happens when a cell “runs”? (bacterial movement?)

smooth linear movement toward a stimulus

- positive

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What happens when a cell “tumbles”? (bacterial movement?)

flagellar rotation reverses, causing the cell to stop and change its course
negative

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What are fimbriae used for??

used for attachment

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What are pili used for?

used for attachment and genetic exchange during

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What is glycocaylx?

Sticky layer composed of polysaccharides (sugars), proteins or both
Varies in thickness, can be either a slime layer or capsule
Used to avoid phagocytosis, and for adhesion (biofilms)

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What is the capsule of a cell?

Bound more tightly to the cell, denser and thicker than a slime layer

What is the slime layer?

Loosely attached to cell surface
Attachment and prevents drying
Helps trap nutrients near the cell
Formation of biofilms
All bacteria have at least a very thin slime layer

Where is the cell envelope?

outside of the cytoplasm

What is the cell envelope composed of?

cell wall

cell membrane

outer membrane in some bacteria

What is a peptidoglycan cell wall?

Repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments
Present in most bacteria
Provides strength to resist rupturing (lysis) due to osmotic pressure

What are 3 characteristics of a gram positive cell?

Thick peptidoglycan

Teichoic acid, lipoteichoic acid

One membrane involved

What are 3 characteristics of a gram negative cell?

Thin peptidoglycan layer surrounded by two phospholipid membranes (outer membrane and cell membrane Lipopolysaccharide and porins in outer membrane Periplasmic space

Where is the only place an outer membrane is found?

Gram negative bacteria

What is the outer membrane composed of?

composed of bilayer of phopholipids inside and lipopolysaccharide (LPS) outside Pores

Where is only periplasm found?

gram negative bacteria

What is periplasm?

Extra cellular compartment Enzymes to break down nutrients Proteins to bind nutrients for transport

Who was the gram stain found by?

Hans Christian gram

What is the cell membrane?

A lipid bilayer with proteins embedded bacterial cell membranes contain primarily phospholipids (30%–40% of the membrane mass) and proteins (60%–70% of the membrane mass)

What does the cell membrane provide?

Provides a site for reactions | contains enzymes of respiration and ATP synthesis since prokaryotes lack mitochondria

What is a major action of the cell membrane?

A major action of the cell membrane is to regulate the passage of nutrients into and out of the cell – selectively permeable

What is the cytoplasm composed of?

70-80% water Soluble proteins, salts, carbohydrates Site of nearly all chemical reactions Contains the DNA in the nucleoid

Is the nucleoid membrane bound?

Where is bacterial DNA found?

Nucleiod

How does DNA exist in bacteria?

DNA of most bacteria exists in the form of a single circular bacterial chromosome

What does the prokaryotic ribosome do?

Translates mRNA into proteins

What is the cytoskeleton?

Peptidoglycan layer determines shape of many bacteria

What genuses are bacterial endospores found in?

Bacillus and Clostridium

Are bacterial endospores highly resistant?

yes

What are the 4 major divisions of prokaryotic bacteria based on cell wall structure?

1. Gracilicutes 2. Firmicutes 3. Tenericutes 4. Mendosicutes

What is gracilicutes?

gram-negative cell walls and thus are thin-skinned

What are firmicutes?

gram-positive cell walls that are thick and strong

What are tenericutes?

lack a cell wall and thus are soft

What are mendosicutes?

archaea with unusual cell walls

What is the percent of genes all bacteria share?

70 - 80