exam 1

Question 1

Contrast the diversity and population density of microbes compared to other organisms

Answer 1

Lowest: sharks
Mammals
Reptiles
Birds
Beetles
Bacteria
Highest: viruses
Then: 
Lowest: Whooping cranes
Humans
Ants
Bacteria
Highest: Viruses
Then: 
Largest: rigbee(dog)
Cell phone
Bee
Flea
Hair
Human cell
Bacteria
Virus
Atom

Question 2

Recognize the role that microbes play in the biosphere

Answer 2

Play a vital role in anchoring the food web and bringing stability to the biosphere
Their absence would lead to disaster and collapse of the biosphere
Most species are benign therefore beneficial
Ex: yeast is important to food chain and tree burs help with nitrogen fixation
Can be good or bad
Cause influenza, zeka and norovirus
Important to ecosystem and food
Need microbes to survive

Question 3

Review the impact that microorganisms have had on human health during the course of history

Answer 3

Black plague, also known as the bubonic plague. It was caused by the bacterium Yersinia Pestis, which killed a great number in Europe due to the occurrence of importing and exporting
Influenza caused many young healthy men to be infected
West Nile River Virus, which attacked the United States.
Zika which is the new buzz virus which came to the United States
Coronavirus and it being easily transmissable and deadly

Question 4

Describe the function of components that make up the bacterial cell

Answer 4

Prokaryotes can be Gram Positive or Gram negative
Positive: They have a thick layer of peptidoglycan and only one plasma membrane, which help with substances going into and out of cells and has a purple color.
Negative: They have a thin layer of peptidoglycan, they have two plasma membranes. Top membrane which has LPS, which is an endotoxin and has a pinkish red color
Peptidoglycan are made up of NAM and NAG which are cross linking sugars.

Question 5

Compare and contrast cell structure between bacteria and eukaryotes the bacterial cells based on their morphological features

Answer 5

Eukaroytes: 
Various organlles 
compartmentalization
Dna in membrane
Mitosis
Dna with histones
More than one chromosome
Membrane bound organelles
Large ribosome
No cell wall
Prokaryotes:
Lack organization
No compartments/organelles
No dna in nucleus
No mitosis
No dna with histones
One chromosome
No membrane bound organelles
Smaller ribosome
Cell wall with peptidoglycan
SAME: plasma membrane, ribosomes, nucleus, cytoplasm, DNA, chromosome

Question 6

Diagram and label the cell wall and membrane(s) of both gram positive and gram
negative bacterial cells

Answer 6

gram positive= single cell wall, thick layer of peptidoglycan, teichoic does not touch membrane and leichoinic touches the membrane.

gram negative=double membrane with lps on outer membrane, single layer of peptidoglycan,

Question 7

Describe how bacterial cells divide

Answer 7

Bacterial cells divide using binary fission (meiosis) – they divide autonomously
DNA replicates
Chromosome separate
Septum forms
Parent cell divides into two progeny (cytokenesis)
Logarithmic growth
Allow for dif cell arrangement via plane of segregation

Question 8

Diagram and label a bacterial growth curve

Answer 8

1. Replicate autonomously
2. Lag phase upon initial entry into environement
3. Log phase where this is exponential growth until environment becomes limiting
4. Stationary phase
5. Decline and cell death if conditions become unfavorable

Question 9

Bacterial classificaiton

Answer 9

cocci=round
bacilli=rod
Shape and arrangement
membrane/cell wall organizaiton
G+ or g-
Accessories
Fimbriae-attach to surfaces
Flagella-motility. Can be single, multiple, or peritrichous (all over surface)
Capsule-has thick layer of polysaccharide adherence and evade immune system
Sex pilus-allow for dna movement from receptor to recipient
Growth conditions linked to metabolism
Temp, ph, o2, nutrients

Question 10

List various laboratory methods used to measure the growth of bacterial populations

Answer 10

Bacterial Culture which is plated on sample of media or the liquid broth and that is how they measure the oxygen levels
Aerobes: <3 Oxygen, they need it
Strict Anaerobes: Hate oxygen, can’t live with it
Facultative: Can and Can’t live, but prefer with
Microaerophiles: Only a little Oxygen (5%)
Areotolerant: Don’t care
Different Temperatures
Different pH
Internal Factors

Question 11

Recall the basic concepts of glycolysis and respiration and how they provide energy for the cell

Answer 11

Glycolysis - the cell takes sugar and converts it into pyruvate - this yields 2ATP
Pyruvate can go two ways

Fermentation - gets rid of it (no oxygen)
Citric Acid Cycle - to make MORE energy

-pyruvate in high levels can be toxic

Question 12

Classify bacteria based on the role of oxygen in their metabolism

Answer 12

Areboes: <3 Oxygen, they need it
Strict Anaerobes: Hate oxygen, can live with it
Facultative: Can and Can’t live, but prefer with
Microaerophiles: Only a little Oxygen (5%)
Areotolerant: Don’t care

Question 13

Recognize the range and diversity of food sources available to bacterial populations

Answer 13

look at flashcard before

Question 14

List various lab methods to characterize bacteria

Answer 14

• aspirated pus, swab, paper point
• clean sample
• smear (gram stain)
• culture (grow to purity in lab)
• agglutination test= pathogen must be in high enough concentration
• rapid identification still require isolation prior to characterization

Question 15

Apply the concepts of the central dogma of molecular biology to bacterial cells

Answer 15

LIVING ORGANISMS ARE A COLLECTION OF GENES EVOLVING TO ENSURE SURVIVAL

• Replication → transcription → translation
• DNA → RNA → Proteins
• DNA starts replication with DNA synthesis, then continues onto RNA transcription with RNA polymerase, this then continues onto translation of the protein – which includes tRNA and ribosomes to make amino acids.

Question 16

Contrast the structure of eukaryotic and prokaryotic genetic machinery including DNA structure and enzymes

Answer 16

Eukaryotic: DNA is organized and in the nucleus
-23 pairs of linear double stranded DNA chromosomes
-diploid
-3x10^9 bp
-25,000 proteins
Prokaryotic: The DNA is contained in nucleoid (non organized), circular chromosomes
-single,circular, double stranded DNA chromosome
-haploid
-5 million bp
-2000 proteins
-smaller scale than human cells
Phylogenetic Tree: Archaea, Eukaryotes, Bacteria

Question 17

Describe the ability of bacteria to respond to their environment by regulating gene
expression

Answer 17

-Operon is how bacteria regulate the expression of their genes
-They have so many genes, but can turn on and off specific genes when they want - epigenetics
Operons
RNA Polymerase - the enzyme that takes DNA to make RNA
Binds to the DNA at binding site (promoter)
Repressor binds to the operator - this blocks transcription of RNA polymerase
CAP Binding site - when CAP binds, this promotes the likelihood of RNA binding

Question 18

what sugar source does e coli prefer?

Answer 18

prefer glucose but not all environments have this

• must have another energy source (lactose)
• will only use if glucose is not around

Question 19

operon function

Answer 19

• operon allows e coli to convert lactose to energy by having 3 separate genes
• advatangeous for all 3 genes to be controlled at the same time

Question 20

operon defintion

Answer 20

region of genes in bacterial chromosome that are controlled through same regulatory network. they contain genes that are involved in the same biological process in bacterial cells

Question 21

operon component functions

Answer 21

cap site=promotes rna polymerase binding by binding cap
promoter=allows rna polymerase to bind
operator=binds repressor and presents rna polymerase from binding
lac y,z,a=functional bit that are protein machinery needed to use lactose as energy source (ZYA order)

Question 22

lacy

Answer 22

protein in cell membranes and transports lactose to cells

Question 23

lac z

Answer 23

enzyme that breaks down lactose into smaller sugars to be used in glycolysis

Question 24

lac a

Answer 24

enzyme with no known role yet

Question 25

lac repressor with no lactose

Answer 25

lac repressor binds to operator and prevent rna polymerase from binding

Question 26

lac repressor with lactose

Answer 26

- allolactose binds to repressor and makes repressor unbind to operator - rna polymerase binds to promoter and transcribe rna - rna used to make lac y,z, and a

Question 27

cap with low glucose

Answer 27

when glucose low, camp is produced. camp attaches to cap and allows it to bind to DNA. cap helps rna polymerase bind to promoter -high levels of transcription

Question 28

cap with high glucose

Answer 28

with glucose high, no camp is made, cap cannot bind dna without camp -transcription at low level

Question 29

Distinguish between the processes of transformation, transduction, and conjugation

Answer 29

Transformation: gathering genes from the environment, just by being in it. Uptake of naked DNA - active process + requires machinery. Only a small amount of DNA. Transduction: Mediated by bacteriophage (viruses) Types of Life Cycles Lytic phase - bacterial phage goes into the bacterial host cell and lysis the cell. Then releases viral progeny. Lysogeny phase - alternative life cycle, viral genome becomes a part of the bacterial host’s chromosome. Prophage is the process of the viral gene going into the host's chromosome Generalized - any fragment of bacterial chromosome transferred, just destroys cell, randomized chromosomes are in there Specialized - becomes a part of the cell and uses cell nutrition to make more of itself Conjugation: Sex pilus must be present to transfer genes through plasmids (mediated) A lot of DNA can be transfered. Plasmid mediated

Question 30

Match cell structure and machinery with the corresponding mechanism of genetic transfer

Answer 30

all involve recombination (homologous or non-homologous) involves physical exchange of dna. new genotype - horizontal transfer - differences in type of methods of uptake of DNA - unidirectional - donor to recipient - dna fragments

Question 31

what does not require recombination

Answer 31

plasmids - extra chromosomal genetic material - replicon - can be replicated independently of chromosome - small double stranded, circular DNA - multiple copies inside a cell - encode toxinsm resistant to antibiotics, heavy metals - conjugative or non-mobile - in all strains of bacteria tested

Question 32

Describe the impact gene exchange has on the diversity and adaptability of a bacterial population and how this relates to pathogenicity

Answer 32

Mutations can occur due to the survival of the fittest. Adaptability occurs in relation to the environment that the bacteria cells are surrounded in. Mutations can be neutral, advantageous or results in an inferior phenotype.

Question 33

Describe key features that allow bacteria to be pathogenic and cause disease

Answer 33

They are sticky, can invade, transmit, and toxic.

Question 34

Differentiate between opportunistic and exogenous bacterial pathogens

Answer 34

When normal flora is exposed to pathogens, it becomes an opportunistic pathogen. -exogenous bacterial pathogen comes from outside source and can cause disease in healthy ppl with normal immune diseases

Question 35

Illustrate the routes of infection (the 3I’s)

Answer 35

- Ingestion (eat it) by ingesting contaminated food or water. by not following proper protocol like hand washing, wearing gloves, or flushing lines. - inhalation (breathing it in) by breathing in infected particles from someones cough - inoculation (needle, mosquito) by fomite and touch infected surace and then touch face. accidental self injury with contaminated needle or sharps

Question 36

Recall the principles of diagnosis of infection and identification of pathogens

Answer 36

Exotoxin, endotoxin, mobility, characteristics, antibiotic resistance, ability to survive and mutate in different environments.

Question 37

List Koch’s Postulates

Answer 37

1. bacteria must be present in every case of disease 2. bacteria must be isolated from host with the disease and grown in pure culture 3. specific disease must be reproduced when a pure culture of bacteria is inoculated into a healthy susceptible host 4. bacteria must be recovered from experimentally infected host

Question 38

Explain the mechanism by which betalactam antibiotics work

Answer 38

Betalactam: Competitively binds transpeptidase that generates cross-links in the cell wall. Failure in cell wall causes cell death, usually by osmotic shock. Aerobic Gram positives and some anaerobic gram negatives

Question 39

Classify antibiotics into distinct groups based on their mechanism of action

Answer 39

Binds transpeptidase that generates cross-links in the cell wall (B-lactams) Pen V and Pen G Most narrow Amoxicillin and Ampicillin Broader range than Pen V and G Isoxazolyl Penicillins Broader than Amoxicillin and Ampicillin Clavulanic Acid No inherent antimicrobial activity B-lactam core that does not bind transpeptidases. Cephalosporins Large class of B-lactam derivatives. Carbapenems Late generation of B-lactams Considered drug of last resort Interfere with folic acid biosynthesis Sulphonamides Inhibit DNA gyrase or topoisomerase IV (replication) Quinolones Inhibits protein synthesis Tetracyclines and Clycyclcylines Doxycycline Tigecycline Lincosamides: binds to specific subunit of ribosome where it inhibits aminoacyl translocation (stop synthesis of proteins) Clindamycin Macrolides: binds to specific subunit of ribosome where it inhibits aminoacyl translocation (stop synthesis of proteins) Erythromycin Azithromycin Inhibits cell wall synthesis (sugar and protein) Vancomycin Drug of last resort Prodrug (inactive precursors) Metronidazoles: Converted by anaerobes into a toxin compound that binds DNA For anearobic bacteria and is not active Theu have enzyme that activates

Question 40

Describe how microorganisms can gain antibiotic resistance

Answer 40

Natural resistance Bacterium is inherently resistant Mutation Gene for target enzyme, transport pathway or prodrug activator altered by random mutation Acquired resistance( problem speeds up ) Horizontal gene transfer Generally within species Can be between species Digest it Produce an enzyme capable of digesting the drug ex. Penicillinase (b-lactamase) seen in Staphs ( break down beta lactam) Alter it’s target Modification of target enzyme ( Supposed to shut down MRSA has modified transpeptidase that does not bind b-lactam antibiotics (not effective ) Avoid it Reduce uptake into the cell Chloramphenicol Secrete it Tetracycline is transported out of the cell by an efflux pump

Question 41

Predict how the increased prevalence of antibiotic resistance can impact public health and treatment of bacterial infections

Answer 41

Can impact public health by bacterium not being sensitive to any antibiotics therefore humans becoming more ill because there will be no antibiotics to kill bacteria.