BIOL 2320 Lecture Test I Review

65 flashcards covering key concepts from the provided microbiology notes.

What is the Miasma Hypothesis?

An ancient belief that diseases are caused by bad air.

Which figure is known as the father of Western medicine and believed diseases came from the environment rather than supernatural causes?

Hippocrates.

Who was the first to observe microorganisms and with what instrument?

Antonie van Leeuwenhoek using microscopes he made.

What did Robert Koch prove about infections?

That specific microbes cause specific infections; identified bacteria causing anthrax, cholera, and TB.

What did Ignaz Semmelweis demonstrate regarding maternal mortality and infection?

That hand disinfection by medical personnel reduced infections and mortality in expecting mothers; contributed to germ theory.

What concept did Joseph Lister introduce?

Asepsis to prevent wound infections through sterile techniques.

What was Edward Jenner's major contribution to immunology?

The first vaccine for smallpox using cowpox.

Who was Onesimus and what did he introduce?

An enslaved West African man who introduced variolation to Boston in the early 1700s.

What categories of microorganisms can cause infectious diseases?

Bacteria, fungi, protozoa, parasitic worms, and viruses.

Who developed the first taxonomic system to organize organisms?

Carl Linnaeus.

List the eight levels of the taxonomic hierarchy in order from broadest to most specific.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

How should a scientific name be written?

Genus capitalized, species lowercase; italicized or underlined.

Name four methods used to identify microorganisms as listed in the notes.

DNA sequencing; autotrophic or heterotrophic classification; presence of nucleus and organelles; biochemical testing/staining.

What are the three tenets of the Cell Theory?

All living things are made of cells; the cell is the basic unit of life; all cells arise from pre-existing cells.

What are the four components all cells have as listed in the notes?

Plasma membrane, cytoplasm, DNA (genetic material).

What is a defining difference between prokaryotes and eukaryotes regarding nuclei?

Prokaryotes lack a true nucleus; eukaryotes have a nucleus.

What is the difference in ribosomes between prokaryotes and eukaryotes?

Prokaryotes have 70S ribosomes; eukaryotes have 80S ribosomes.

Do prokaryotes or eukaryotes have membrane-bound organelles?

Only eukaryotes have membrane-bound organelles.

What is the typical cell size range for prokaryotes versus eukaryotes?

Prokaryotes: about 1–10 μm; Eukaryotes: about 10–100 μm.

How do the chromosomes differ between prokaryotes and eukaryotes?

Prokaryotes have circular chromosomes (and may have plasmids); eukaryotes have linear chromosomes and may have organellar genomes.

What are the major differences between Gram-positive and Gram-negative cell walls?

Gram-positive: thick peptidoglycan, no outer membrane; Gram-negative: thin peptidoglycan with an outer membrane containing LPS.

In Gram staining, what colors do Gram-positive and Gram-negative bacteria appear?

Gram-positive: purple; Gram-negative: pink/red.

What is the function of fimbriae in bacteria?

Attachment to surfaces and other bacteria.

What is a capsule and its role in bacteria?

A polysaccharide layer attached to bacteria that helps prevent phagocytosis; associated with Streptococcus pneumoniae.

What is a slime layer (S layer)?

Loose extracellular material that can be shed from the bacterial surface under harsh conditions.

What are plasmids?

Small circular DNA molecules carrying genes such as antibiotic resistance.

What are teichoic acids and where are they found?

Components of the cell wall of Gram-positive bacteria.

What is the role of LPS (lipopolysaccharide)?

Part of the outer membrane of Gram-negative bacteria; can trigger a strong immune response.

What are the mycolic acids and which bacteria have them?

Fatty components of Mycobacteria cell walls that make bacteria harder to kill by immune cells.

What is an endospore?

A dormant, thick-walled cell formed by some Bacillus and Clostridium species to survive harsh conditions.

Describe the structure and function of the plasma membrane.

Phospholipid bilayer with embedded proteins; semipermeable barrier that controls what goes in and out of the cell.

Who disproved spontaneous generation and how did he do it?

Francesco Redi, by showing maggots come from fly eggs and not spontaneously.

What experiment did Louis Pasteur perform to disprove spontaneous generation?

Swan-necked flasks that allowed air but trapped microbes, showing life arises from existing organisms.

Who coined the term 'cell'?

Robert Hooke.

What does the Endosymbiotic Theory propose?

Mitochondria and chloroplasts evolved in eukaryotic cells through ancient symbiotic relationships with bacteria.

What evidence supports the Endosymbiotic Theory that mitochondria and chloroplasts have their own DNA?

They contain their own DNA.

What evidence shows mitochondria and chloroplasts have unique membranes?

They have their own membranes separate from the cell's plasma membrane.

How do mitochondria and chloroplasts divide?

They divide by binary fission, like bacteria.

What evidence suggests chloroplasts resemble cyanobacteria?

Chloroplasts resemble cyanobacteria in their photosynthetic capabilities.

What are the common shapes of bacteria and how are they arranged?

Cocci (spherical), Bacilli (rods), Streptococcus (chains), Staphylococcus (clusters).

What is the arrangement of Staphylococcus?

Clusters of cocci.

How does the bacterial cell wall protect bacteria in hypotonic environments?

It helps prevent lysis by providing rigid support.

What does isotonic mean in osmosis?

No net movement of water; equal water movement in and out.

Name the four phases of the microbial growth curve.

Lag, Exponential (Log), Stationary, Death.

What is a chemostat used for?

A large vessel that maintains bacteria in exponential growth by adding nutrients and removing culture.

Why are serial dilutions performed?

To determine the number of cells by obtaining countable concentrations.

Name three methods of bacterial cell division.

Binary fission, budding, fragmentation.

In thioglycolate tubes, where do obligate aerobes grow?

At the top.

In thioglycolate tubes, where do obligate anaerobes grow?

At the bottom.

How do facultative anaerobes grow in thioglycolate tubes?

Throughout the tube, with more growth at the top.

What is a microaerophile?

An organism that requires low levels of oxygen, growing in a thin band below the surface.

What is a neutrophile?

An organism that prefers neutral pH, around 7.

What is an acidophile?

An organism that grows at acidic pH (around 5.5).

What is an alkaliphile?

An organism that grows at alkaline pH (around 9–11).

Name the main temperature categories for microbes and their typical ranges.

Psychrophiles (cold, roughly -5 to 20 C), Mesophiles (moderate, roughly 15–45 C), Thermophiles (hot, roughly 45–80 C), Hyperthermophiles (very hot, up to ~105 C).

What is a genome?

The sum total of genetic material in an organism or pathogen.

How is bacterial DNA packaged differently from eukaryotic DNA?

Bacteria package DNA with DNA-binding proteins (no histones); eukaryotes package DNA around histone proteins.

How is DNA packaged in eukaryotes versus bacteria?

Eukaryotes wrap DNA around histones; bacteria use DNA-binding proteins and lack histones.

What are the basic components of a nucleotide?

Phosphate group, deoxyribose sugar, and a nitrogenous base (A, T, C, G).

What is the structure of DNA?

A double helix with two strands running in opposite directions, held together by hydrogen bonds.

What is the central dogma of molecular biology?

DNA is transcribed into RNA, which is translated into protein.

Name a key enzyme and its role in DNA replication: helicase.

Helicase unwinds and separates DNA strands at the origin of replication.

Name a key enzyme and its role in DNA replication: topoisomerase.

Topoisomerase prevents overwinding of DNA ahead of the replication fork.

Name a key enzyme and its role in DNA replication: ligase.

Ligase seals gaps between Okazaki fragments on the lagging strand.

What is the proofreading function of DNA polymerase?

It corrects incorrect bases during replication to reduce errors.

How can bacteria acquire new DNA?

Conjugation (via pilus), transduction (bacteriophage transfer), and transformation (uptake of environmental DNA).

What is a bacterial operon?

A group of genes with a common function transcribed together as a single mRNA.

What is a codon?

A sequence of three nucleotides in mRNA that codes for a specific amino acid.

What is the relationship between transcription and translation?

Transcription copies DNA into mRNA; translation uses mRNA to synthesize protein.

What is typically the start codon in translation and what does it code for?

AUG, which codes for methionine (start).

What indicates a stop codon in translation?

One of the stop codons (UAA, UAG, or UGA).