Exam 3 - BIOL 250 Chaps 9, 12, and 13-14

What is horizontal gene transfer?

Transfer of DNA between organisms.

What are the 3 types of gene transfer?

Transformation, conjugation, transduction (TCT).

What is transformation?

Uptake of free DNA from the environment. (transformer)

What is conjugation?

DNA transfer trhough direct cell contact. (connection)

What is transduction?

DNA transfer via bacteriophage. (abduction)

What is generalized transduction?

Random bacterial DNA transferred

What is specialized transduction?

Specific genes transferred

What is recombination?

Integration of new DNA into genome

What is a virus?

Noncellular particle with DNA or RNA inside a capsid

Can viruses reproduce on their own?

No, they require a host

What is a virion?

The complete virus particle

Do viruses contain both DNA and RNA?

No, only one or the other

What is host range?

The organsims a virus can infect

What is tissue tropism?

Types of tissues a virus can infect

What is broad tissue tropism?

The virus can infect many different tissue types

What is narrow tissue tropism?

The virus can infect only one or a few specific tissue types

Why are antivirals hard to develop?

Few targets, high mutation rate, harm to host cells

What are the 5 steps of viral replication?

Attachment, penetration, replication, assembly, release. (APRAR)

Lytic Cycle

Immediate replication

Lysogenic Cycle

Integrates into host DNA

What is sterilization?

Killing all microbes, including spores and viruses

What is disinfection?

Removing some microbes from inaimate surfaces

What is antisepsis?

Removing microbes from living tissues

What is sanitation?

Reducing microbes to safe levels

What is bacteriostatic?

Static = stops growth

What is bactericidal?

Cidal = kills microbes.

What does an autoclave use?

High heat and pressure

What does filtration remove?

Bacteria, spores, fungi, but NOT viruses

Why is UV radiation limited?

It does not penetrate surfaces

What factors affect disinfectant effectiveness?

Population size, composition, concentration, time, organic matter

What is the human microbiome?

All bacteria, archaea, fungi, and protozoa that naturally inhabit the body

When does microbiome colonization begin?

At birth (and possibly before in utero)

What is bioburden?

The numbers of microbes in a specific body region

What are the 4 main microbiome regions?

Skin, mouth/nose, GI tract, intestines. (SMNGII)

Why is the skin hard for pathogens to colonize?

Variable conditions and existing microbiota provide protection against pathogen growth and colonization

Why does the eye have low microbial numbers?

Antimicrobial substances like lysozymes in tears

What is the mucociliary escalator?

Cilia + mucus system that removes microbes from lungs

What is the main defense of the stomach?

HIgh acidity (low pH)

Where is the highest mircobiota density in the body?

Intestines

What are transposable elements?

Mobile genetic elements that can move within a genome

What is the role of recombination in DNA repair?

It fixes damages DNA by using similar sequences as templates

What is a molecular clock?

A method that tracks evolutionary changes based on mutation rate

What is phylogeny?

The evolutionary relationships among organisms

What is a phylogenetic tree?

A diagram showing evolutionary relationships

What are the three domains of life?

Archaea, bacteria, and eukarya

What is natural selection?

The process where beneficial traits increase survival and reproduction

What is degenerative (reductive) selection?

Loss of genes over time as organisms adapt

What are homologous genes?

Genes that share a common ancestor

What are orthologs?

Homologous genes in different species with the same function

What are paralogs?

Genes within the same species that evolved new functions

What are analogous genes?

Genes with similar function but no common ancestor

What are immunomodulins?

Substances that modify or regulate the immune system

What does gnotobiotic mean?

Organisms with known or controlled microbiota

What is dysbiosis?

An imbalance in the microbiome

What are probiotics?

Live beneficial microbes

What are prebiotics?

Nutrients that feed beneficial microbes

What factors can change the microbiome?

Diet, lifestyle, antibiotics, environment

What is microbial antagonism?

Normal microbiota preventing pathogen colonization

What are the 5 steps of the viral replication cycle?

Attachment, penetration, replication, maturation, release

What happens during attachment (adsorption)?

The virus binds to a specific surface receptor on the host cell

What happens during penetration?

The viral genome enters the host cell

What happens during replication?

The host cell produces viral components in large amounts

What happens during maturation?

Viral parts assemble into complete virions

What happens during release?

Viruses exit the cell, often by lysis

What is burst size?

The number of viruses released from a single infected cell

What is the lytic cycle?

Immediate viral replication and destruction of the host cell

What is the lysogenic cycle?

Viral DNA integrates into the host genome and remains dormant

Which cycle is associated with generalized transduction?

Lytic cycle

Which cycle is associated with specialized transduction?

Lysogenic cycle

What is a surface receptor?

A host cell protein that viruses bind to for entry

What is a capsid?

Protein coat that surrounds the viral genome

What is an enveloped virus?

A virus with a membrane derived from the host cell

What is mode of transmission?

How a virus spreads between host

What is the Baltimore model?

Classification of viruses based on genome type and replication strategy

What is antigenic drift?

Small genetic mutations over time

What is antigenic shift (reassortment)?

Major genetic changes from mixing genome segments

What is a retrovirus?

An RNA virus that converts RNA into DNA

What is reverse transcriptase?

Enzyme that converts RNA into DNA

What are overlapping reading frames?

One DNA sequence codes for multiple proteins

What are the 5 categories of sterilization methods?

Wet heat, dry heat, filtration, radiation, chemicals

What factors affect antimicrobial effectiveness?

Population size, population type, concentration, exposure time, organic matter

What is MIC?

Minimum inhibitory concentration that stops microbial growth

What is MBC?

Minimum bactericidal concentration that kills microbes

What are synergistic drugs?

Drugs that work better together

What are antagonistic drugs?

Drugs that interfere with each other

What are the main antibiotic mechanisms of action?

Target cell wall, protein synthesis, DNA/RNA, or membrane

How do bacteria prevent intracellular accumulation of antibiotics?

Efflux pumps remove the drug

How do bacteria prevent antibiotic binding?

Alter the target site

How do bacteria dislodge antibiotics?

Enzymes modify or remove the drug

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