Microbiology (EXAM 1)

Dr. Yang

1 micrometer

10^-6 meters

1 nanometer

10^-9 meters

Who was the first to publish the depiction of microorganisms using cork tissue?

Robert Hooke (1665)

Who was the father of microbiology?

Anton van Leeuwenhoek

When did Leeuwenhoek describe a single celled organism using what level of magnification??

1674; 300X

What is the theory of spontaneous generation?

the theory that microorganisms arise spontaneously from nonliving matter

Who tried to disprove spontaneous generation and who actually disproved it?

Francesco Redi and Pasteur

Explain Francesco Redi’s experiments

He did 3 separate experiments

1) left meat in an open container and saw that formation of maggots occurred in the meat

2) In a separate experiment, he cork sealed the container. No maggots formed.

3) Gauze covered the container and maggots formed on top of the gauze but not on the meat.

Explain Pasteur’s swan neck flask experiments

1) sterilized the liquid by extensive heating, and microbes are trapped and unable to pass through

2) when the same shaped-flask is tipped so dust is able to get into sterile liquid, the liquid putrefies

What are the 3 tenets of the modern cell theory?

1) All organisms are made of one or more cells

2) Cells are the fundamental units of organisms

3) all cells come from other cells (biogenesis)

What are the three categories of microbes?

Non-cellular

Cellular (prokaryotic)

Cellular (Eukaryotic)

What are the subcategories of non-cellular microbes?

\-viruses

\-viroids

\-prions

What are the subcategories of prokaryotes?

\-bacteria

\-archaea

T/F: Viruses are noncellular

True

What is the simplest kind of virus?

just nucleic acid with a protein coat

T/F: viruses can have DNA or RNA

True

T'/F: viruses can have additional structures like envelopes or tails

true

What are obligate intracellular parasites?

reliant on host mechanisms to replicate

between prokaryotes and eukaryotes, which has a nucleus?

eukaryotes

what size are prokaryotes?

\~10 micrometers

what is the size of eukaryotes?

10-100 micrometers

what is notable about archaea?

live in extreme environments

coccus

circle shape

bacillus

rod shaped

vibrio

slightly curved rod shape

coccobacillus

elongated circle

spirillum

spiral shapted

spirochete

coiled shape

Types of eukaryotic cells

1) fungi: act as decomposers

2) algae: photosynthetic

3) protozoa: unicellular organisms with animal-like characteristics

4) helminths: worms; eggs and juvenile stages are microscopic

T/F: all algae are eukaryotic

False

What is the definition of microbiology? what are the subfields?

the study of all different types of microorganisms

\-bacteriology

\-mycology

\-protozoology

\-protozoology

\-parasitology

\-virology

What is the endosymbiotic theory?

theory relating to the origin of mitochondria and chloroplasts

\-in order to form the mitochondria and chloroplasts, you need to have the nucleus and endo-membrane system

T/F: Mitochondria and chloroplasts have their own ribosomes that look more like bacteria DNA than eukaryotic DNA

true

What do most textbooks say are the first form of life?

microbes

whats the difference between classification and taxonomy?

classification: the practice of organizing organisms into different groups based on their shared characteristics

taxonomy: the classification, description, identification, and naming of living organisms

who is the father of taxonomy?

Carolus Linnaeus

Why is taxonomy today based on similarities within ribosomal RNA sequences?

1) all cells contain ribosomes

2) rRNA is slow to change

why do we use binomial nomenclature?

using the same name allows scientists to share information efficiently and accurately

Definition of resolution

ability of the lenses to distinguish two points a specific distance apart

\-dependent on wavelength of light used in the microscope

\-shorter wavelength = higher resolution

Put the following in order of magnification:

light microscopy

x-ray crystallography

human eye

transmission electron microscopy

scanning electron microscopy

Human eye

light microscopy

scanning electron microscopy

transmission electron microscopy

x-ray crystallography

What is bright field/light microscopy?

\-uses visible light as source of illumination

\- ocular magnification x objective magification

\- max resolving power: 0.2 micrometers

simple staining

one stain, single step

* methylene blue
* giesma stain

what are some differential staining methods?

staining and de-staining steps

* gram stain
* endospore stain
* acid-fast stain

What is phase-contrast microscopy?

type of microscopy where high-contrast images are made without staining

* you can view internal structures of living organisms

diffraction

scattering of light rays as they “touch” a specimen’s edge

what type of microscopy uses phase-contrast microscopy?

phase-contrast

What is fluorescent microscopy?

utilizes fluorescence and immunofluorescene

Fluorescence: ability of substances to absorb short wavelengths of light (UV) and emit a longer wavelength (visible)

immunoflourescence: utilizes antibodies to fluorescently label protein/organism of interest

* used to detect pathogens within clinical specimens
* identify particular molecules/structures within a cell

What is an electron microscope?

Uses short -wavelength electron beams to increase magnification and resolution

* used to examine really small objects (viruses/organelles)
* false color often added
* two main types of electron microscopy
* scanning
* transmission

what is scanning electron microscopy?

* forms images of specimen surfaces- coat specimens with metal which diffract electron
* 3D image

What is transmission electron microscopy?

* works like a light microscope, but with electron
* cross-sections
* specimens must be dehydrated and sliced ultrathin
* resolves objects up to 10 pm apart
* stain with heavy metals to increase contrast

What do ALL cells possess?

* cytoplasm
* 1+ chromosomes
* ribosomes

what defines a cell?

cell membrane

what are elements of a cell membrane?

phospholipid bilayer

glycoproteins

carbohydrates

lipids

cholesterol

pores/porin

what are some functions of proteins found on the membranes of a cell?

\-support for structures that protrude from the cell (flagella, pili)

\-signaling and communication

\-export of toxins and other virulence factors

\-transport of substances in/out of the cell across the membrane

\- establish concentration gradients for energy transfer

which plasma membrane component can be either found on its surface or embedded in the membrane structure?

proteins

T/F: Cell membranes are selectively permeable

true

What types of molecules are impermeable to the plasma membrane?

Large, uncharged polar molecules; like glucose and sucrose

Ions like H+, Na+, HCO3-, Ca 2+, Cl-, Mg2+, K+

Which molecules are freely permeable in a cell membrane?

hydrophobic molecules; like O2, CO2, and N2

what molecules are somewhat permeable in a membrane?

small, uncharged polar molecules; like H2O and glycerol

What is receptor-mediated endocytosis?

occurs when binding of proteins to receptors triggers the cell to pinch off a portion of the membrane and bring it inward into the cell.

What is phagocytosis?

eukaryotes can use their membranes to transport materials into and out of the cell

and the cell eats what is brought in through a vacuole

what are all the membrane bound organelles inside a eukaryotic cell?

\-nucleus

\-ER (smooth and rough)

\-Golgi

\-mitochondria

\-ribosomes

What is unique about the structure of the nucleus?

\-double membrane

\-nucleolus

\-nuclear pore complex

T/F: the outer membrane of the nucleus is continuous with the endoplasmic reticulum

True

what does the nuclear pore complex do?

its a very complicated structure that regulates synthesis and transport

what does the nucleolus do?

assists with ribosomal RNA synthesis

what does the golgi apparatus do?

modifies and directs proteins synthesized in the ER to their proper locations

What do lysosomes do?

they are derived from the Golgi and fuse with other vesicles (endosomes) to digest their contents

What is the big picture purpose of the endomembrane system?

to synthesize cell components and moves materials around the cell

What is the transmembrane domain?

the part of the domain embedded in the membrane

List the sequence of events involved in the incorporation of a proteinaceous molecule within a cell

include the following terms:

vesicle

ribosome

golgi

tagging

modification

ER

synthesis of proteins

1) synthesis of protein on the ribosome

2) modification in the endoplasmic reticulum

3) tagging in the Golgi Apparatus

4) distribution via vesicle

How does the mitochondria generate energy?

respiration

what are the structures of the mitochondria?

outer membrane, inner membrane, intermembrane space, matrix, cristae

what are the structures within the chloroplast?

outer membrane, inner membrane, granum, thylakoids, stroma

What are 2 advantages of membrane bound organelles?

compartmentalization + surface area

How does a membrane bound organelle become advantageous when concentrating and isolating enzymes/reactants in a smaller volume?

it increases the rate and efficiency of chemical reactions

T/F: membrane bound organelles are advantageous because they confine potentially harmful proteins and molecules

True

membrane bound organelles are great for respiration and photosynthesis, why?

increases the membrane surface area

Which cytoskeleton elements are dynamic, rapidly assemble and disassemble, and function as both movement and structure?

microtubules and microfilaments

which cytoskeleton has a structural role only, holds organelles in place?

intermediate filaments

What are microfilaments?

actin filaments (actin monomers/polymers)

helps form psuedopods, cytoplasmic streaming, forms cleavage furrow, and muscle contraction

What are intermediate filaments?

made with fibrous subunits

helps form the inside of the nuclear envelope and holds filaments of cells together

(keratin is an example)

what are microtubules?

tubes made of alpha and beta tubulin

13 sets of tubulin dimers

lays down tracks on the cell and motor proteins move materials on them

centrioles and mitotic spindle

help form flagella and cilia

What are the stages of cell growth?

G1, S, G2, mitotic phases

normal diploid cells have ____ copies of each chromosome

two

Mitosis creates two _____ ____________ cells

identical daughter

haploid cells have ____ copy of each chromosome

one

what generates genetic diversity?

recombination/crossing over

meiosis forms what?

4 unique gamete cells

between mitosis and meiosis, which is sexual and which is asexual reproduction?

mitosis=asexual

meiosis=sexual

where are genes found in bacteria?

nucleoids and plasmids

what are plasmids in bacteria?

small, circular double stranded DNA molecule

* extrachromosomal genetic element
* replicates independently of chromosomal DNA
* can be transferred from one bacterium to another

Explain binary fission of a bacterial cell

1. DNA replication
2. protein synthesis and expansion of cytoplasm causes cell to elongate


1. septum forms and the cell divides

what structure helps divide the circular DNA of bacteria?

replisomes

what is the bacterial cell wall?

a single, interlinked molecule that encloses the entire cell

what are the functions of the bacteria cell wall?

provides support and protection, determines cell shape, prevents cell lysis

what are bacterial cell walls made of?

peptidoglycan

where are peptidoglycan subunits made?

in the cytoplasm and transported outside the cell

what is peptidoglycan made of?

glycan sugars and peptides

what are two types of glycan sugars?

N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)