Biology Study Sheet - Viruses and Protists

This set of flashcards covers key vocabulary and concepts from the biology study sheet focused on viruses and protists.

Are viruses alive?

No, viruses are not living organisms as they cannot perform life functions independently.

Characteristics of Life that viruses fail

Cellular organization, metabolism, homeostasis, reproduction, heredity, response, growth & development, evolution.

Viral Structure

Includes a core (DNA or RNA), capsid (protein coat), receptor sites (attach to host), and sometimes an envelope (lipid layer).

Viral Shapes

Rod/filament (Ebola), spherical (HIV, flu), geometric (bacteriophage).

Size of viruses

Measured in nanometers (nm), typically ranging from 20-400 nm.

Lytic Cycle

A viral replication process where the virus attacks the host cell's machinery, leads to the production of new viral particles, and ultimately causes the host cell to lyse (burst), releasing the new viruses.

Lysogenic Cycle

Dormant viral cycle where viral DNA integrates into host DNA and can replicate during cell division. In this cycle, the virus remains inactive within the host, allowing it to be passed on to daughter cells without causing immediate damage. Activation can later trigger the lytic cycle.

Retrovirus

A type of virus that converts its RNA genome into DNA using reverse transcriptase.

Endosymbiotic Theory

Explains how eukaryotic cells originated from prokaryotes, specifically mitochondria and chloroplasts deriving from engulfed bacteria. Evidence is: Reproduce asexually, affected to certain antibitoics, and have their own ribosomes and circular DNA.

General characteristics of Kingdom Protista

Eukaryotic, mostly unicellular, aquatic, and reproduce asexually via binary fission.

Plant-like protists (Algae)

Autotrophs that contain chlorophyll and have cell walls; include phytoplankton and seaweed.

Animal-like protists

Heterotrophs classified by movement; types include pseudopods, flagellates, ciliates, and sporozoa.

Sporozoa

A group of non-motile parasites that reproduce with spores; example includes malaria.

Fungi-like protists

Multicellular heterotrophs that feed on dead matter and reproduce with spores.

Quick memorization tip for viruses

Viruses are not alive unless reproducing (lytic = burst cell, lysogenic = hidden).

Reverse transcriptors

converts RNA to DNA

Vaccines

Builds up an army of WBCs & antibodies to kill the living virus immediately before it can reproduce

HIV positive vs Aids

Aids is the disease that comes when HIV is active.

When HIV positive, Virus is in its LYSOGENIC CYCLE (dormant). Patient is not sick, but is a carrier of the virus. Can infect others. Patient has symptoms

Aids: night sweats, cold symptoms, diarrhea

• Disease begins when HIV enters the LYTIC CYCLE - WBCs are being destroyed

• Patient dies from other infections due to lack of immune system

  • E.g. pneumonia, cancer

Antibiotics

Attack bacterial cell walls causing the bacteria to die

Why we need new antibiotics

Bacteria evolve quickly - mutate:

• If one bacterium becomes resistant:

  • It can reproduce asexually very quickly to produce more

  • It can pass the resistance to other species through sexual reproduction.

Heterotrophs

Consume other organisms

Autotrophs

Create their own food