Viruses, Classification, and the Domains of Life

what are viruses made up of?

capsid (protein), nucleic acid (DNA or RNA)

what extra part do some viruses contain?

fatty membrane envelopes

name the 3 types of viruses?

round, rod, complex

give an example of a round virus

influenza, coronavirus, HIV

give an example of a rod virus

tobacco mosaic disease, tomato mosaic disease

give an example of a complex virus

bacteriophage

what is the function of a virus

replication = enter host cell, gets it to make copies, released and enter new host

what factors imply that viruses are living?

genetic material (DNA, RNA), protein, replicate (with host), heredity

what factors imply that viruses are non-living?

non cellular, do not respire, need host to replicate, no metabolism

describe why viruses are important economically/medically

1. gene transfer (genetic engineering) - vectors

2. control infection - bacteriophages infect and destroy bacteria

3. biological control - living things to control living things

describe the economic disadvantages of viruses

1. human disease - flu, cold, cold sores

2. plant disease - mosaic diseases

3. animal disease - rabies, bird flu, cow pox

why can viruses be a disadvantage to the economy?

economic losses - time off work, loss of crops, animal sickness, medical cost

what is classification?

arrangement of organisms based on similarities and differences

what is taxonomy?

study of classification

why is classification important?

simplifies the study of organisms, understand evolution, identifying relationships between organisms, awareness of variety of life

what was the oldest system of classification?

Aristotle - plants or animals, blood or non-blood

what system did Corolaus Linnaeus develop?

organisms become more related as they go down the scale, each group = taxon, binomical system = every organism has a Genus and Species name (eg Homo sapiens (humans))

what is a species?

group of organisms that can interbreed and produce fertile offspring

what changes in the classification system occurred in the 60’s?

kingdom taxon divided into 5 kingdowns - animal, plant, monera, protist, fungi

how do prokaryotes differentiate from eukaryotes?

Prokaryotes Eukaryotes

single celled multi celled

circle loop of DNA linear DNA threads

no nucleas + MBO’s nucleas + MBO’s

simple complex

what changes in the classification system occurred in the 70’s?

Carl Woese - monera kingdom divided into bacteria and archaea (6 kingdoms)

what changes in the classification system occurred in the 80’s-90’s?

Carl Woese - introduced new taxon above kingdom called = domain

3 domains = bacteria, archaea, eukaryotes

what are eukaryotes?

microscopic prokaryotes, live in extreme conditions (hot springs, lakes, soil, oceans)

what is phylogeny?

classification of organims based on evolutionary history

what is a phylogenetic tree

diagram that shows evolutionary relationships between organisms and species

what are the rules for phylogenetic trees?

time moves from left to right

horizontal line = branch

ancestor species - left

modern species - right

branch point = common ancestor

branch ends = extinction

how are unknown organisms classified?

drawings, graphs, keys (dichotomous = most common)

what is a dichotomous key?

series of questions with two choices each, based on things like colour, number of legs etc.

what new methods are used in classifying organisms?

studying the genome (DNA)

examining eDNA (environmental)

computer programmes - process bioinformatics