BIO 220: Lecture Exam #2: Chapter 3

cells

What are the structural units of all living things?

Robert Hooke; 1600

Who first observed plant cells with a crude microscope, and in what year?

Anton van Leeuwenhoek; animalcules

Who was the first person to discover living microbes, and what did he call them?

rainwater, his own feces, and teeth scrapings

From what sources did Anton van Leeuwenhoek observe the living microbes?

Matthias Schleiden studies plant tissues, and Theodor Scwhann studied animal tissues

Which two scientists contributed to the idea that all living things are composed of cells, and what tissues did each study?

Rudolf Virchow

Who proposed that cells only arise from other cells?

All organisms are composed of cells and cell products

What does the modern cell theory state about the composition of all organisms?

the cell

What is considered the simplest structural and functional unit of life?

activities of its cells

According to modern cell theory, what determines an organism’s structure and function?

from preexisting cells

Where do new cells come from, according to modern cell theory?

fundamental similarities

Do cells from different species have many differences or fundamental similarities?

prenucleus

What does the word “prokaryote” mean in Greek?

true nucleus

What does the word “eukaryote” mean in Greek?

nucleic acids, proteins, lipids, and carbohydrates

What chemical components are found in both prokaryotic and eukaryotic cells?

No, they use the same kinds of chemical reactions to metabolize food, build proteins, and store energy.

Do prokaryotic and eukaryotic cells use different types of chemical reactions for metabolism and energy?

cellular and acellular

What are the two main categories of microbes based on cellular structure?

bacteria and archaea

Which types of microbes are prokaryotic?

fungi, protozoa, algae, and helminths

Which types of microbes are eukaryotic?

not made of cells

What does “acellular” mean in the context of microbes?

viruses and bacteriophages

Which microbes are considered acellular?

as one circular chromosome, not enclosed in a membrane

How is the genetic material organized in prokaryotic cells?

no

Do prokaryotic cells have histones?

no

Do prokaryotic cells contain membrane-bound organelles?

peptidoglycan cell walls

What type of cell wall do prokaryotes typically have?

by binary fission

How do prokaryotic cells reproduce?

as multiple chromosomes enclosed by a nuclear membrane

How is the genetic material organized in eukaryotic cells?

Histones are proteins that DNA winds around (forming chromatin); they are found in eukaryotic cells

What are histones, and which type of cell has them?

yes, they have many

Do eukaryotic cells have membrane-bound organelles?

polysaccharide cell walls

What type of cell wall do eukaryotic cells typically have?

by mitosis

How do eukaryotic cells divide?

external, cell envelope, internal

What are the three main structural regions of a prokaryotic cell?

appendages: flagella, pili, fimbriae; glycocalyx: capsule, slime layer

What structures are included in the external components of a prokaryotic cell?

the protective outer layer of a prokaryotic cells composed of polysaccharide, protein, or both

What is the glycocalyx?

outer membrane (typically present in gram negative bacteria), cell wall, cell membrane

What are the components of the prokaryotic cell envelope?

cytoplasm, ribosomes, inclusions, nucleoid/chromosome, actin cytoskeleton, endospore

What are the internal structures of a prokaryotic cell?

cell membrane, cytoplasm, cytoskeleton, ribosomes, and one (or a few) chromosomes (DNA)

What structures are found in all bacterial cells?

cell wall and glycocalyx (a surface coating)

What structures are found in most, but not all, bacterial cells?

flagella, pili, fimbriae, outer membrane, plasmids, inclusions, and endospores

Which bacterial structures are only found in some bacterial cells?

glycocalyx

a coating or layer of molecules external to the cell wall. it serves protective, adhesive, and receptor functions. it may fit tightly or be very loose and diffuse.

bacterial chromosome or nucleoid

composed of condensed DNA molecules. DNA directs all genetics and heredity of the cell and codes for all proteins.

plasmid

double-stranded DNA circle containing extra genes

pilus

an elongate, hollow appendage used in transfers of DNA to other cells

ribosomes

tiny particle composed of protein and RNA that are the sites of protein synthesis

actin cytoskeleton

long fibers of proteins that encircle the cell just inside the cell membrane and contribute to the shape of the cell

flagellum

specialized appendage attached to the cell by a basal body that holds a long, rotating filament. the movement pushes the cell forward and provides motility.

fimbriae

fine, hair like bristles extending from the cell surface that help in adhesion to other cells and surfaces

inclusion/granule

stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed.

cell wall

a semirigid casing that provides structural support and shape for the cell

cell (cytoplasmic) membrane

a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool

outer membrane

extra membrane similar to cell membrane but also containing lipopoly saccharide. controls flow of materials, and portions of it are toxic to mammals when released.

endospore

dormant body formed within some bacteria that allows for their survival in adverse conditions

cytoplasm

water-based solution filling the entire cell

unicellular organisms

Do most prokaryotes exist as multicellular or unicellular organisms?

in colonies or biofilms

In what forms can prokaryotes sometimes organize themselves?

about 0.2-1.0 micrometers in width and 2-8 micrometers in length

What is the average size of a prokaryotic cell?

pleomorphism

What term describes variation in shape and size among cells of the same species?

variations in cell wall structure

What causes pleomorphism in prokaryotes?

Corynebacterium diphtheriae

Name one example of a pleomorphic bacterial species

Mycoplasma species

Which bacterial genus lacks a typical cell wall and is also pleomorphic?

it maintains one consistent shape (most bacteria)

What does it mean if a bacterium is monomorphic?

star-shaped (Stella) and square or rectangular shapes (Haloarcula)

What are some examples of unusual bacterial shapes?

according to their cell shape and arrangement

How are bacteria often described and categorized?

no, they can have variations in shape and size

Do rod-shaped bacteria all look the same?

coccus, rod/bacillus, vibrio, spirillum, spirochete, branching filaments

List some bacterial shapes.

the patterns or planes in which the cells divide and how they remain attached after division

What influences the arrangement of bacterial cells?

cocci

Which bacterial shape shows the greatest variety of cell arrangements?

single; example: Chlamydia trachomatis

What is a single cocci cell called? Give an example.

Diplococci; example: Neisseria meningitidis

What is the term for cocci arranged in pairs? Give an example.

tetrads; example: Micrococcus luteus

What is the name for cocci arranged in groups of four? Give an example.

clusters; called staphylococci; example: Staphylococcus epidermidis

What arrangement is described as clusters of cocci? Give an example.

Chains; called streptococci; examples: Lactococcus spp. and Streptococcus spp.

What is the term for cocci arranged in chains? Give examples.

single, pairs, tetrads, clusters, chains

List the cell arrangements.

because they divide only in the transverse plane

Why do bacilli have less variety in cell arrangement compared to cocci?

single (most bacilli are single)

What is the arrangement called when bacilli occur as single cells?

Diplobacilli; example: E. coli

What is the term for bacilli arranged in pairs? Give an example.

Streptobacilli; example: Bacillus megaterium

What do you call call bacilli arranged in chains? Give an example.

a short bacillus that nearly looks like a cocci

What is a coccobacillus?

Bordetella pertussis

Give an example of a coccobacillus species.

to propel (move) the bacteria

What is the main function of flagella in bacteria?

outside the cell wall

Where are bacterial flagella located?

long, filamentous appendages

How would you describe the structure of bacterial flagella?

they rotate 360 degrees

How do bacterial flagella move?

a protein hook

What connects the flagellum to the bacterial cell body?

by a basal body attached to the cell wall and membrane

How is the flagellum anchored to the cell?

two pairs (four rings total)

How many pairs of rings are found in the flagellar basal body of Gram-negative bacteria?

the outer two are anchored to the cell wall, and the inner two are anchored to the plasma membrane

Where are the rings in Gram-negative bacteria anchored?

only one pair (two rings total)

How many pairs of rings are found in the flagellar basal body of Gram-positive bacteria?

to the plasma membrane

Where is the basal body of Gram-positive flagella anchored?

monotrichous

What is the term for a bacterium with a single flagellum?

lophotrichous

What is the term for bacteria with flagella in small bunches or tufts at one end

amphitrichous

What do you call a bacterium with flagella at both poles of the cell?

petrichous

What is the arrangement called when flagella are spread all over the cell surface?

because it helps identify microbes

Why is bacterial motility important in the lab?

by observing movement through semisolid media or using a hanging drop slide

How is motility typically detected in the lab?

the bacteria are motile

What does it mean when cells move away from the line of inoculation in semisolid media?

yes, they can alter both speed and direction

Can bacteria change the speed and direction of flagellar movement?

when a bacterium moves in one direction for a period of time

What is a “run” or “swim” in bacterial movement?

abrupt, random changes in direction caused by reversal of flagellar rotation

What are “tumbles” in bacterial motility?

movement toward or away from a stimulus

What is taxis in bacteria?

movement in response to a chemical stimulus

What is chemotaxis?