Prokaryotes and Viruses Bacteria, Archaea, and Viruses

BEFORE, you learned: Characteristics of Life: 3 Domains: 6 Kingdoms:

NOW, you will learn: Prokaryotes: Viruses The basic structure of bacteria Different types of archaea and bacteria Helpful/ harmful bacteria Viruses The basic structure of viruses How viruses multiply inside living cells Helpful/ harmful viruses

Prokaryotes “Pro” means before “Karyo” means seed… talking about the nucleus. So, Pro-karyo means before- seed or before the nucleus.

Prokaryotes Prokaryotes are microorganisms Very small organisms They reproduce through a process called binary fission Reproduction through division… 1 cell divides into 2 cells. 2 cells divide into 4 cells. 48, 816, 1632…

Basic Structure of Bacteria

Bacteria by Shape: Bacteria are often named after their shapes:

2 Types of Prokaryotes: Archaea Bacteria Can survive in the largest range of environments These can be very hot, very cold, or have too much of a single substance such as salt. Often named according to where they live… Simplest kind of life known on Earth All are composed of just one cell without a nucleus.

3 Types of Archaea Thermophiles Methanogens Halophiles They live in extreme heat or cold. “Thermo” = temperature, “philo” = love Thermo-phile = Temperature lover Their name comes from methane, the natural gas they produce. Live in the deep mud of swamps or in the guts of animals like a cow or termite. “methano” = methane, “gen” = produce Methano-gen = methane producers They live in very salty lakes and ponds. “halo” = salt, “philo” = love Halo-phile = salt lover

3 Roles of Bacteria in the Environment Parasites Producers Decomposers Organisms that harm their host. Thought of as “germs”… infections. Transform sunlight into food. Release oxygen gas, which animals need to breathe. Get energy by breaking down materials in decaying organisms. Help recycle materials in the environment.

Bacteria: Helpful and Harmful Break down materials to be used by other organisms. Cities use bacteria to break down sewage. Convert Nitrogen gas in the air into nitrogen compounds… able to be used by other organisms. Infections and diseases can cause harm to organisms by: Poisoning a body with chemicals it produces. Invade parts of the body multiplying in body tissues and dissolving cells.

Viruses Viruses are NON-LIVING because: Viruses do not grow or take in any energy once they are formed. Viruses can reproduce only by “taking over” a living cell and having that cell create copies of itself.

Viruses Structure Viruses are composed of genetic material surrounded by a protein coat called a capsid.

How do viruses infect cells? The next few slides we will look at an example virus, a bacteriophage. Bacteriophages infect and kill bacteria cells. They have been very well studied, so their method of infection is well understood.

5 steps of virus multiplication: Attachment: The virus attaches to the surface of the bacterium. Injection: The virus injects its DNA into the bacterium. Production: Host cell makes copies of viral DNA and proteins. Assembly: New viruses assemble from parts that have been created. Release: The cell bursts open releasing 100 or more new viruses.

Important Terms: Host Cell: Vaccine: The cells that viruses infect in order to make copies Vaccine: A small amount of weakened virus or bacteria that is used to stimulate the immune system

Viruses: Helpful and Harmful Scientists can use viruses to insert foreign genetic material into living cells. For example, the genetic material that allows some marine animals to glow can be inserted into tissue samples to help scientists study them. Host cells are often harmed when providing a living space for viruses: The virus uses the cell’s energy, materials, and processes. The virus often destroys host cells after making copies of itself