Bio final exam

Viruses

Considered non-cellular infectious agents.

Do not belong to any domain

Can infect almost any living thing

Basic Components of Viruses

1. Either DNA or RNA as a genetic core.

2. A tough protein coat/capsule.

DNA Viruses

Pox viruses.

Examples of DNA Viruses

Smallpox, Cowpox.

Examples of DNA Viruses

Herpesviruses.

Examples of DNA Viruses

Herpes, Chickenpox.

Examples of DNA Viruses

Hepadnaviruses.

Examples of DNA Viruses

Hepatitis B: liver disease.

RNA Viruses

Togaviruses.

Examples of RNA Viruses

Rubella (German measles).

RNA Viruses

Filoviruses.

Examples of RNA Viruses

Ebola, Marburg.

RNA Viruses

Retroviruses.

Examples of RNA Viruses

HIV: AIDS.

Viral Infection Process

Viruses cannot replicate themselves; they must infect a living cell to be reproduced.

Viral Infection Process

The infected cell does all the work and manufactures new viruses.

6 Steps in the Viral Infection Process

Viral Attachment: The virus attaches to the host cell.

6 Steps in the Viral Infection Process

Viral Penetration: Viral genetic material enters the host cell.

6 Steps in the Viral Infection Process

For HIV, it's RNA molecules that enter.

6 Steps in the Viral Infection Process

Herpes is a permanent infection because the virus invades nerve cells, and your immune system doesn't kill nerve cells.

Tissue effects

Warts: Skin.

Tissue effects

Influenza: Lungs.

Tissue effects

Herpes: Nerves.

6 Steps in the Viral Infection Process

DNA Formation: Viral genetic material is made into DNA.

6 Steps in the Viral Infection Process

For HIV: RNA → DNA via reverse transcriptase.

6 Steps in the Viral Infection Process

DNA viruses skip this step.

6 Steps in the Viral Infection Process

Viral DNA Incorporation: Viral DNA is incorporated into the host cell's DNA.

6 Steps in the Viral Infection Process

Infection can become permanent after this step.

6 Steps in the Viral Infection Process

Component Construction: The host cell makes parts to form new viruses.

6 Steps in the Viral Infection Process

Assembly & Release: Host cell assembles and releases new viruses.

6 Steps in the Viral Infection Process

Two release pathways: Budding - few viruses released; Lysis - large number released.

Influenza

Pathogen: RNA virus.

Influenza

Four types: A, B, C, D.

Influenza

Tissue affected: Lungs.

Influenza

20,000 deaths/year in U.S.

Influenza

Natural reservoir: Birds.

Influenza

Bird to person = Avian flu.

Influenza

Person to person = Regular flu.

Influenza

Swine play an important role in human infection.

Flu Shots

Why get them yearly?

Antigens

Substances that induce an immune response, often mutate making them unrecognizable to the body.

Viral reassortment

The process by which viruses exchange genetic material, creating new versions.

Flu shots

Vaccinations that contain multiple antigen versions to protect against influenza.

Influenza Virus Subtypes

Different strains of the influenza virus categorized by their hemagglutinin (H) and neuraminidase (N) proteins.

H5

A subtype of the influenza virus characterized by the hemagglutinin protein.

N1

A subtype of the influenza virus characterized by the neuraminidase protein.

Hand Washing

A crucial practice for inactivating influenza viruses, as they are easily deactivated.

Viral envelope

A lipid membrane surrounding a virus that can be broken down by soap and water.

Common Cold

An illness caused by over 200 viruses, primarily rhinoviruses, affecting the nasal membrane.

Rhinoviruses

The most common pathogens responsible for the majority of cold cases, accounting for 50%.

Sneezing

A method of spreading cold virus particles several meters through the air.

Evolution

A term often misunderstood, referring to the biological changes in organisms over time.

Evolutionary biology

The scientific study focusing on biological evolution.

Abiogenesis

The origin of life from non-living matter, occurring before any life existed.

Earth's age

Approximately 4.6 billion years.

Oldest life-containing rocks

Rocks estimated to be around 3.5 billion years old, containing evidence of early life.

Biological Evolution

The concept of evolution as understood by ancient Greek philosophers and later developed by scientists.

Lamarck

A scientist known for the idea of inheritance of acquired characteristics.

Malthus

An economist who noted that populations grow rapidly, leading to competition for resources.

Spontaneous Generation

The outdated belief that life can arise from non-living matter, exemplified by rotting meat attracting flies.

Louis Pasteur

A scientist who disproved spontaneous generation and established that cells arise from other cells.

Natural Selection

The mechanism driving evolution, where individuals best adapted to their environment survive and reproduce.

Charles Darwin

A naturalist who independently developed the theory of natural selection based on observations from HMS Beagle.

Alfred Wallace

A naturalist who contributed to the theory of evolution through natural selection.

Survival of the Fittest

A phrase describing the concept that individuals best adapted to their environment are more likely to survive and reproduce.

Genetic Variation

The differences in alleles among individuals in a population, crucial for natural selection.

Artificial Selection

The process of breeding organisms with desired traits, such as purebred dogs.

Directional Selection

A type of natural selection where allele frequencies shift in one direction due to specific environmental pressures.

Pesticide resistance

An example of directional selection where pests evolve to survive chemical treatments.

Antibiotic resistance

An example of directional selection where bacteria evolve to withstand antibiotic treatments.

Fruit Fly Experiment

Research by Isaac Lea demonstrating that species are not immutable and can evolve, as shown by fruit flies developing resistance.

Lifespan

~30 days

Starvation resistance

Evolved in 60 generations

Speciation

Interbreeding populations that are reproductively isolated

Geographical Isolation

Separated physically

Mechanical Isolation

Reproductive structures incompatible

Behavioral Isolation

Mating behavior differs

Temporal Isolation

Reproduce at different times

Ecological Isolation

Same area, different microhabitats

Polyploidy

Chromosome makeup changes → new species

Roots

Below ground, absorb water/nutrients, anchor plant

Taproot

Central, deep, e.g., carrot

Fibrous Roots

Shallow, widespread

Shoots

Above ground (stem, branches, leaves, flowers)

Surface-to-Volume Ratio

Surface area ÷ volume

Pollination

Transfer of pollen to female structure

Annuals

One growing season (e.g., corn, marigolds)

Biannuals

Two seasons (e.g., carrots)

Perennials

Grow year after year (e.g., campus plants)

Toxicodendron

Poison ivy, oak, sumac containing urushiol

Ecology

Interactions between organisms and environment

Population

Individuals of one species in a place/time

Rule of 72

Doubling time = 72 ÷ growth rate

Carnivores

Meat eaters

Herbivores

Vegetation eaters

Omnivores

Both meat and vegetation eaters

Commensalism

One benefits, other neutral (e.g., barnacles, remoras)

Mutualism

Both benefit (e.g., cleaner fish, ants/plants)

Predation

One eats another (e.g., lions)

Survivorship Curves

Type I: Large mammals; long life, high care