Microbiology Ch 4. 1-4.6

A cell wall and some form of glycocalyx are found in ___ bacterial cells

most

Three structures of bacterial cells are:

Cell Membrane, cytoplasm, ribosomes

Microbes act as a group when?

When assembled in a biofilm

Which of the following makes bacteria and archae different from eukaryotes?

They lack a nucleus

Size of bacterial cells;

1 um, (micrometer)

Interna structures of bacterial cells

Ribosomes, inclusions, Nucleoid

Common Shapes found in bacteria;

Coccus, rod and spirillum

Mycoplasmas are pleomorphic because they lack cell walls and thus display extreme variations in shape.

True

A complex grouping of cells arranged in a cubical packet of 8,16 or more is called

Sarcina

Choose prefixes that may be used to describe arrangements of bacilli

strepto and diplo

Planktonic bacteria:

Live as single cells, not in biofilm communities

In a stratified biofilm

Aerobes are found NEAR the surface while anaerobes are found near the bottom

A Palisades arrangement

formed when cells of a chain remain partially attached at the ends; folding into side by side rows

Planktonic

Bacteria that live as single cells

Biofilms are stratified meaning that

different microbes occupy spaces that best fit their environmental needs

Fimbriae, flagella and pill are all examples of (blank) structures found in some bacteria

External

Prefixes bacilli;

Diplo and Strepto

Planktonic bacteria

live as single cells, not in biofilm communities

Appendages that propel bacterial cells through aqueous include;

axial filaments and flagella

Appendages provide motility

-Flagellum

-Axial filaments

Biofilms correct statement

DNA Molecules may be present in biofilms as an attractant to more cells

External Structures in bacteria

Extrernal

+ ( chemotaxis)

To move towards a chemical attractant by flagellar motion

Flagellum causes a bacterial cell to swim or (blank) towards a stimulus, interrupted by clockwise rotation in which the cell (blank) and changes its course

run, tumbles

Phototaxis

Some photosynthesis bacteria move by flagellar motion in response to light during this time.

Match the letter on each cell type with the correct arrangement of the flagella on that cell

Nanowires

Very thin, long tubular extensions of the cytoplasmic membrane used by bacteria to transfer food between one another

Phototaxis

When bacteria move in response to a light source

Bacterial S layer

• S layer is rarely observed in cell grown in lab rich in medium

• S layer consists of thousands of copies of a single protein

Fimbriae Function:

Sticking to cells and other surfaces

Nanowires are used for (blank) between neighboring bacteria cells:

• Transferring amino acids

• Shuttling electrons

S layer surrounding bacterial cells is comprised of;

protein

Fimbria

Adhesion

Glycocalyx consists of;

Capsules and Slime layers

Cell Envelope;

cell wall, cytoplasmis membrane and the outer membrane

Cell wall in bacteria is composed of

peptidoglycan

Cell wall functions

• preventing destruction with changes in osmoric pressure

• maintaining the shape of the bacterium

Peptidoglycan is a component of the cell wall in;

bacteria

Teichoic and Lipochoic

Functions for cell wall maintenance and contribute to acidic charge on the cell surface

Teichoic and Lipochoic acids are (blank)

Polysaccharides embedded in the cell wall of gram positive bacteria

Mycolic acid functions

It reinforces the cell wall and makes the bacterium resistant to certain chemical and dyes

Which stain technique allows differentiation of mycobacterial cells

Acid-fast stain

Major structural component of the cell membrane are (blank)which form a bilayer and has 30-40% of membrane mass

Lipids

All bacteria possess a cell (blank) but not all bacteria possess a cell (blank)

membrane, wall

Which is a selective barrier between the internal and external contents of the cell?

Cell membrane

Components of cell membrane

• Proteins

• Lipids

Which of the following describes the primary function of cell membrane

Form a barrier between the internal and external content of the cell

Only gram (blank) possess an outer membrane

negative

Porins

Control access to the inside of the cell

Which cell structure is responsible for synthesizing protein

Ribosome

Organic and inorganic nutrients can be stored in bacterial cells in cytoplasmic (blank)

Inclusions

Density of the ribosome in bacteria is

70’s

Ribosomes are located where?

In the cytoplasm of bacteria

Plasmids

An extrachromosomal circular piece of DNA that contains genes not essential for cell growth

Metabolocally active and reproducing cells and nutritional shortages are metabollically inactive some bacteria produce

Vegetative cell and an endospore

Extremophiles

Methanogens

can convert CO2 and H2 into methane gas

3 advantages of endospores formation

• Highly resistant to radiation and heat

• More resistant to antimicrobial agents

• Provides protection in dry conditions

Halophiles

Archaea requre high salt concentrations in order to grow

Which group of archaea grow at very low temperatures

Psychrophiles

Gram stain steps in order;

1.) Crystal violet

2.) Gram’s Iodine

3.) Alcohol

4.) Safranin ( red-dye)