Microbio Exam 2 Review Ch 5, 6, 7

How big are viruses?

20 nm to 450 nm in diameter

How are viruses classified?

type of nucleic acid, presence of an envelope, shape, and size

What is dsdna and what viruses have it?

double stranded DNA wound together in a double helix, examples would be HPV or smallpox

What is ssdna and what viruses have it?

single stranded DNA instead of the traditional double strands, example would be Parvovirus B19

What is ssrna and what viruses have it?

positive sense single stranded rna that can act like mRNA and be directly translated into viral proteins by host cell’s ribosomes. Examples are Hepatitis A and polio

What is dsrna and what viruses have it?

double stranded rna wound in a double helix, examples are rotavirus and colorado tick fever virus

What are dermotropic viruses and what are examples?

viruses that have affinities for skin and subcutaneous tissues. Examples are chicken pox, shingles, measles, smallpox

What are neurotropic viruses and what are examples?

viruses that have affinities for brain and cns tissues. Examples are rabies, polio, West Nile virus

What are viscerotropic viruses and what are examples?

viruses that have affinities for internal organ tissues. Examples are AIDS and hepatitis A and B

What are pneumotropic viruses and what are examples?

viruses that have affinities for lungs and other respiratory structure tissues. Examples are influenza and common cold

What are the 5 steps of viral replication in animal viruses?

1. Adsorption

2. Penetration and Uncoating

3. Synthesis

4. Assembly

5. Release

What happens during adsorption for viruses?

the virus binds to receptors on the host cell, the first step of infection

What’s the difference between enveloped and naked viruses?

enveloped means the virus steals some of the host’s cell membrane when they leave, naked is they don’t have a cell membrane when they leave

Why are viral surface proteins/spikes important?

they are what attach to certain cells, so they determine the specificity of the virus

What are the different configurations of nucleic acids a virus can have?

they can be single stranded or double stranded and have either DNA or RNA, never both

What happens during penetration?

virus enters the host cell and releases its DNA or RNA

What happens during synthesis and how is it different for DNA and RNA viruses?

virus makes many duplicate copies of genetic material. In DNA viruses have replication in the nucleus and assembly in the cytoplasm, in RNA replication and assembly happens in the cytoplasm

What happens during assembly?

virus builds copies of itself using the building blocks (genetic material) from synthesis

What happens during release?

virus bursts out of the cell

How fast does the life cycle in animal viruses occur?

happens at different speeds for different viruses

What is cytopathic effect and what is an example?

when a virus damages a cell so the appearance under the microscope is changed, usually causing cell death. An example is syncytia which is the fusion of multiple cells causing cells to have multiple nuclei

What are lysogenic bacteriophage infections?

when the virus combines its DNA with bacteria and it doesn’t kill the host bacteria right away so the virus DNA can be copied when the bacteria undergoes cell division

What are lytic bacteriophage infections?

when the virus attaches to bacteria and makes it replicate a bunch more viruses and then release those viruses through bursting the bacteria cell, killing the host

What are the main purposes for cultivating viruses?

to study them, make vaccines, and isolate and identify them for clinical diagnosis

What are 3 ways to cultivate viruses?

cell culture, embryonic eggs, and live animals

What is in vivo vs in vitro?

in vivo is research that takes place in a living organism, in vitro is research that takes place in a controlled lab environment like a petri dish

Why are antiviral drugs more difficult to design that antibacterial drugs?

antibiotics don’t work on them and also since they replicate inside human host cells it’s hard to target the virus without also harming the human cells

What are 2 non cellular infectious agents besides viruses?

Viroids - singular stranded RNAs that have no protein coating that affect plants

Prions - misfolded proteins that cause neurodegenerative diseases

What are autotrophs?

organisms that produce their own food and energy from inorganic substances in the environment

What are photoautotrophs?

an autotroph that creates energy through photosynthesis, examples are plants or algae

What are chemoautotrophs?

an organism that gets energy from chemical compounds, examples are archaea and some bacteria

What are heterotrophs?

an organism that gains energy from consuming other organisms

What are photoheterotrophs?

organisms that use photosynthesis for cellular processes but consume organic compounds for energy and carbon, examples are some kinds of underwater bacteria

What are chemoheterotrophs?

organisms that gain their energy from chemical compounds and get their carbon from other living things, includes most animals

What is a saprobe and what is an example?

an organism that gains its energy from consuming dead or decaying organic matter, an example would be a lot of fungi and bacteria

What is a parasite and what is an example?

an organism that lives on or inside another organism and takes nourishment from it, examples are helminths and some protozoa

What is diffusion?

the movement of particles from an area of high concentration to low concentration

What is osmosis?

the movement of water molecules from high water concentration to low water concentration through a semi permeable membrane

What does isotonic mean?

equal concentration

What does hypertonic mean?

higher concentration of solute than water, causing cells to shrink

What does hypotonic mean?

higher concentration of water than solute, causing cells to swell up

What is passive transport and what are 2 examples?

movement of molecules across the cell membrane along the concentration gradient. This can be through simple diffusion (molecules go through the membrane without the use of a carrier protein) and facilitated diffusion (molecules go through membrane with the help of carrier proteins)

What is active transport and what is an example?

movement of molecules across the cell membrane against the concentration gradient. An example is the sodium-potassium pump where 3 molecules of sodium go out and 2 molecules of potassium go in and this process uses 1 ATP

What is a psychrophile?

organisms that survive in a extremely cold environment

What is a psychrotolerant?

organisms that can grow at 0 degrees celsius but is optimal at 20 degrees celsius

What is a mesophile?

organism that thrives between 20-45 degrees celsius

What is a thermophile?

thrives at higher than normal temps

What are obligate aerobes?

absolutely need oxygen to survive and grow, use oxygen as the final electron acceptor in aerobic respiration to generate ATP. Thrive in O2 that is 20% of atmosphere

What are microaerophiles?

need around 5% O2 environment to survive

What are facultative aerobes?

organisms that can thrive in high or low O2 environments

What are obligate anaerobes?

organisms that thrive with no O2

What are 4 environmental factors (besides temp and O2) that affect microbial growth?

pH, solute concentration, pressure, and radiation

What is mutualism?

symbiotic relationship where both organisms benefit

What is commensalism?

symbiotic relationship where one organism benefits and the other has no effect

What is parasitism?

symbiotic relationship where one organism benefits and the other is harmed

What are the 5 steps of cell division in bacteria?

1. Cell growth

2. Chromosome replication

3. Chromosomes move to opposite sides of the cell

4. Septum forms to divide the original cell into 2 daughter cells

5. Septum separates and new cells are made

What is doubling time and how fast is it?

how quick a cell can divide. Different times for different species, usually between 30-60 mins in the lab

What are the 4 phases of the bacterial growth curve?

lag, log(exponential), stationary, and death

What happens during the lag phase?

bacteria first gets inoculated and adapt to the conditions

What happens during the log (exponential) phase?

cells divide rapidly (exponential growth)

What happens during the stationary phase?

bacteria run out of nutrients to eat so growth rate declines rapidly

What happens during the death phase?

cells start dying instead of dividing

What is a quantitative method for analyzing bacterial growth?

plate counts, could be viable only or viable and nonviable using a spectrophotometer

What is a qualitative method for analyzing bacterial growth?

examinations under the microscope to see shape size or arrangement

What is metabolism?

all the reactions in an organism

What is catabolism?

breaking down of molecules

What is anabolism?

building up of molecules

What are constitutive enzymes?

60-80% of enzymes, continuously synthesized by the cell independent of environmental factors so they don’t need regulation

What are regulated enzymes?

if more substrate is added more enzyme will be produced and vice versa

What is competitive inhibition?

inhibitors physically block the active site leading to the substrate not being broken down

What is uncompetitive inhibition?

doesn’t block the active site, but it changes the active site shape so the substrate can’t be broken down

What are endergonic reactions?

reactions that use energy (anabolism)

What are exergonic reactions?

reactions that release energy (catabolism)

What is the chemical in which energy is stored and why is it good at storing energy?

ATP. The phosphate groups have lots of energy stored in them, and when you break it apart the energy all gets released

How do redox reactions relate to cellular energy transfer?

they transfer electrons and energy between molecules, powering cellular processes like ATP production

What are oxidoreductases?

an enzyme that catalyzes redox reactions by removing electrons from one substrate and adding them to another. Need cofactors like NAD or FAD for this process

Why are NAD and FAD needed for metabolism?

they’re electron carriers so they take high energy electrons and bring them to the electron transport chain to produce ATP

What are the 3 catabolic pathways that make ATP for the cell?

aerobic, anaerobic, fermentation

What happens in the aerobic pathway and how much ATP does it yield?

uses O2 in their metabolism and O2 is also the final electron acceptor. 36-38 ATP

What happens in the anaerobic pathway and how much ATP does it yield?

makes energy without O2 so O2 is NOT the final electron acceptor. 2-36 ATP

What is the fermentation pathway and how much ATP does it yield?

incomplete glycolysis so it ferments and uses organic molecules as final electron acceptor. 2 ATP

What happens during glycolysis?

6 carbon glucose converts to 2-3 carbon pyruvate, yields 2 ATP and 2 NADH

What happens during the Krebs cycle?

converts pyruvate to acetyl CoA, acetyl CoA is made into 6 carbon citrate, citrate is repeatedly oxidized and reduced to yield 2CO2, 3NADH, 1FADH2, and 1 ATP

What happens in the electron transport chain?

high energy electrons derived from NADH and FADH2 are passed down the line, losing more and more energy each time and generating ATP too until finally the molecule at the end (usually oxygen) accepts them

How are anaerobic and aerobic respiration different?

anaerobic doesn’t need oxygen and aerobic does, in anaerobic no O2 is needed to make ATP and O2 is not the final electron receptor, also anaerobic has less ATP produced

What are the steps of microbial fermentation?

an initial glycolysis stage where sugar is broken down into pyruvate, then a fermentation stage that converts pyruvate into alcohols or acids which produces ATP and regenerates NAD+

What are 3 things microbial fermentation can create?

lactic acid, vitamins, and CO2

How do viruses impact human infection and disease?

they’re the cause of many diseases and around 20% of cancers are caused by them

What are macronutrients vs micronutrients?

macronutrients are elements (CONHPS) required in large quantities for cell structure (carbs, proteins, lipids, DNA). micronutrients are elements that are needed in smaller amounts like zinc copper and manganese for enzyme function and cofactors

What is a halophile?

an organism that thrives in high salt concentration environments

What is synergism vs antagonism?

synergism is an interaction where the combined effect is greater than the sum of the individual effects. antagonism is an interaction where the combined effect is less than the sum of the individual effects. Think about it like synergism is 1+1=3 and antagonism is 1+1=0

What is an apoenzyme?

simple enzyme consisting of a protein alone, only activated when it’s bound to the appropriate cofactor or coenzyme

What is a holoenzyme?

complete and active enzyme that includes the protein (apoenzyme) and the metallic cofactor

What are cofactors?

inorganic element (metal) that helps the enzyme do their reaction

What are coenzymes?

organic molecules (vitamins) that help the enzyme do their reaction

What is a capsid?

the protein shell around the nucleic core of a virus

How is energy carried from catabolic to anabolic reactions?

high energy ATP bonds