Lecture Quiz 4

Question 1

Operon

Answer 1

Set of genes transcribed as a single mRNA, under the control of one promoter. Transcription/Translation is simultaneous

Question 2

Where RNA polymerase sits down to do transcription. Produces mRNA.

Answer 2

Promoter

Question 3

Genes that code for proteins

Answer 3

Structural genes

Question 4

Regulate structural genes

Answer 4

Regulatory genes

Question 5

Genes that are always expressed (75%)

Answer 5

Constitutive genes

Question 6

Genes that are turned on/off as cells needs changed. Inducible/repressible operons.

Answer 6

Facultative genes

Question 7

Inducible operons

Answer 7

OFF by default, must be turned on. Activated by inducers.

Question 8

Lactose operon

Answer 8

In absence of lactose is OFF. Active repressor blocks RNA polymerase. In presence of lactones operon turns on. Lactose is the inducer. Genes get turned back off when lactose levels go down.

Question 9

Repressible operon

Answer 9

ON by default, must be turned off by co-repressors

Question 10

Tryptophan operon

Answer 10

When tryp levels are low the operon is ON, RNA polymerase is transcribing the DNA. As long as tryp levels stay low the operon will stay on.

When tryp levels are high the operon is turned off by the co-repressor.

Question 11

Transfer of DNA between cells of the same generation.

Answer 11

Horizontal gene transfer

Question 12

Methods of Horizontal gene transfer

Answer 12

1. Transformation
2. Transduction
3. Conjugation

Question 13

Uptake of nakedDNA from environment

Answer 13

Transformation.

Question 14

Property of cells that can naturally be transformed

Answer 14

Competency (vs. artificial competency)

Question 15

Gene transfer mediated by bacteriophages

Answer 15

Transduction

Question 16

Generalized Transduction

Answer 16

Lytic phage! Mistake during assembly leads to packaging of random DNA fragments from the host bacteria into the bacteriophage. This is then transferred to a new bacterial cell.

Question 17

Specialized Transduction

Answer 17

Lysogenic! Mistake int eh excision of a prophage from a host chromosome results in some bacterial DNA sticking on to viral DNA.

Question 18

Conjugation

Answer 18

F+ cell rells in an F- cell, each cell gets a copy of the other, now have 2 F+ cells that can make pili.

Question 19

Change in the nucleotide sequence of a gene

Answer 19

Mutation

Question 20

Types of mutation

Answer 20

• missense
• nonsense
• silent
• frameshift

Question 21

Causes of mutation

Answer 21

Spontaneous, Induced

Question 22

Spontaneous mutations

Answer 22

Due to unrepaired mistakes by replication enzymes.

Bacteria: 1 in 250 million
Virus: 1 in 250,000

Bacteriophage: ~2 mutations/genome
Influenza: ~1 mutation/genome

Question 23

Induced Mutations

Answer 23

Caused by external forces that increase the mutation rate. Chemical or physical agents that cause higher mutation rates than the spontaneous mutation rate.

Question 24

Thymine dimers

Answer 24

Caused by exposure to UV light, causes DNA molecule to be misshapen and interferes with DNA function. Two thymines form covalent bonds, prevents transcription/replication.

Question 25

UV mutation repair (2)

Answer 25

- Excision repair | - Light repair/photoreactivation: photolyase breaks bonds int eh thymine dimer. "undoes damage"

Question 26

Antigenic drift

Answer 26

Spontaneous mutations lead to minor changes in glycoproteins, so immune system recognition can be avoided. Increase in # of flu cases every ~2 years.

Question 27

Antigenic shift

Answer 27

During assembly an influenza virus that contains a new combination of two segments is put together. Very rare, but occasionally 2+ separate strains infect one host cell. New combo causes major genetic changes, usually associated with major outbreaks every ~10 years.

Question 28

Biotechnology

Answer 28

Use of biological system to make a product. Does not require genetically engineered organisms.

Question 29

Genetic Engineering

Answer 29

Intentional modification of genomes for practical purposes. Deliberate alteration of a genotype to change phenotype. Requires the use of biotechnology. GMOs, Insulin!

Question 30

DNA made from combining one or more sources into novel DNA molecules

Answer 30

Recombinant DNA

Question 31

Applications of biotechnology

Answer 31

1. Drugs/hormones 2. Vaccines 3. Genetic sequencing 4. Infection diagnosis 5. Industrial microbiology 6. Genomics (study of entire gene sequence of an organism) 7. Microbiomes (analysis of microbiological populations of an organism.)

Question 32

2 types of immunity

Answer 32

1. Innate: not dependent on antigens, immediate response, no memory, first/second line of defense 2. Adaptive: antigen dependent, lag between exposure and response, immunologic memory, third line of defense

Question 33

Defenses that do not target a specific pathogen.

Answer 33

Innate/nonspecific defenses

Question 34

Beneficial bacteria/microorganisms found in/on the body that promote overall health and help to stimulate the immune system. Produce conditions that do not promote the growth of harmful bacteria.

Answer 34

Normal microbiota

Question 35

Mechanical barriers

Answer 35

Peristalsis, urination, blinking, coughing, sneezing, vomiting

Question 36

Physical barriers

Answer 36

Skin, mucus, ciliated epithelium

Question 37

Chemical barriers

Answer 37

pH, lysozyme, lactoferrin, antimicrobial peptides, complement

Question 38

Enzyme that breaks down peptidoglycan, very effective against gram-positive bacteria

Answer 38

Lysozyme

Question 39

Compound that binds to free iron atoms, making iron unavailable to microbes as a cofactor.

Answer 39

Lactoferrin

Question 40

Small proteins that have antimicrobial properties. Many are cations, attracted to the negative charge of cells. Disrupt cell function

Answer 40

Antimicrobial peptides

Question 41

Types of antimicrobial peptides

Answer 41

1. Bacteriocins: resident microbiota 2. Cathelicidins, Defensins: macrophages, neutrophils 3. Dermicidins: sweat glands

Question 42

Complement

Answer 42

Set of >30 serum proteins. Membrane attack complex, opsonization.

Question 43

Membrane attack complex

Answer 43

Once activated complement proteins form a ring in the membrane of the target cell. Leads to cell lysis. G-neg bacteria, eukaryotic pathogens, enveloped viruses. Only pathogens surrounded by a membrane!

Question 44

Opsonization

Answer 44

Increased likelihood of phagocytosis. Non-host cell "tagged" for recognition. G-pos, G-neg, viruses, fungi, etc