SBI3U - Unit 1 - Eubacteria

Bacteria

An individual prokaryotic cell or a single species that is in the domain Bacteria

Naming bacteria

A prefix that indicates how they aggregate, and a suffix that indicates its shape

Diplo-

The prefix used for bacteria that aggregate in pairs

Strepto-

The prefix used for bacteria that aggregate in chains

Staphylo-

The prefix used for bacteria that aggregate in clusters

-coccus

The suffix for a micro-organism whose overall morphology is spherical

-bacillus

The suffix for a micro-organism whose overall morphology is rod-shaped

-spirillum

The suffix for a micro-organism whose overall morphology is spiral-shaped

Autotrophic bacteria

Bacteria that produce their own food

Photosynthetic bacteria

Bacteria that use chemical energy to convert CO2 and water into carbohydrates

Cyanobacteria

Autotrophic bacteria that contain chlorophyll, are abundant in water, account for much of the atmospheric oxygen on Earth, and are believed to be the first photosynthesizing organisms

Chemosynthetic Bacteria

Bacteria that use chemical energy from inorganic molecules, such as hydrogen sulfide, to produce organic compounds

Heterotrophic Bacteria

Bacteria that consume other organisms for energy

Types of heterotrophic bacteria

Saprophytic and parasitic

Saprophytic Bacteria

Decomposers that feed on dead organic matter and act as agents of decay

Parasitic Bacteria

Bacteria that obtain food from living cells and fully depend on the host cells for nutrition

Aerobic Respiration

Oxygen is required to break down organic matter and produce energy

Obligate Aerobe

Bacteria that need oxygen and cannot survive without it

Anaerobic Respiration

Energy is produced by breaking down organic matter in the absence of oxygen

Obligate Anaerobe

Bacteria that cannot grow in the presence of oxygen

Facultative Bacteria

Bacteria that live in either anaerobic or aerobic conditions

Mesophile

An organism that lives in habitats characterized by moderate conditions

Bacteria reproduction

Binary fission, conjugation, transformation, and transduction

Binary Fission

The asexual form of reproduction used by most prokaryotes, in which a cell divides into two genetically identical daughter cells

How binary fission works

A cell will make a copy of its chromosome and it grows. When it reaches a certain size, it elongates and separates itself with a septum. This creates two identical daughter cells with a copy of the original DNA

Conjugation

A process in which there is a transfer of genetic material involving two cells

When conjugation occurs

This occurs in unfavourable conditions where new genetic combinations offer a better chance of survival

How conjugation works

One donor cell links to a recipient cell through a sex pilus, where it transfers genetic material

Transformation

The transmission of genetic material where a DNA segment is picked up by a living bacteria, which can now perform the function of the DNA

How transformation works

DNA contains genes. Bacteria can be given foreign DNA from another organism and make new proteins. In order for artificial transformation to work, the plasmid must be advantageous to the new cell, and selectable markers must be present to identify if the transformation works

Transduction

The transmission of genetic material when a virus infects one cell, and then another, which receives the new DNA

Plasmid

A small loop of DNA that is separate from the main chromosome, and contains different genes from the chromosome

Plasmid functions

They can join the chromosome or be transferred to another cell, making them an important part of genetic recombination

Endospore

A dormant bacterial cell able to survive for long periods during extreme conditions, such as heat, radiation, and toxic chemicals

Phases of bacterial growth

Lag phase, growth under favourable conditions, plateau at the carrying capacity, and death

Cause of the lag phase in bacterial growth

The bacteria must acclimatize

Cause for bacterial death after reaching the carrying capacity

There is a shortage of food and a build up of toxic waste

Glycocalyx

A protective layer on bacteria that exist as either a capsule or slime layer

Gram Stain

A stain that separates bacteria into Gram positive and Gram negative, based on the cell wall’s response to the stain

Gram-Positive

Bacteria that have a thick protein layer of peptidoglycan and stain purple

Gram-Negative

Bacteria that have a thin protein layer of peptidoglycan, a bilayered membrane, and stain pink

Bacteria that can degrade oil

In every ocean, there are bacteria that can degrade oil and emit CO2. Natural bacteria are so far the most efficient at this, as they are adapted to oil spills and the environment. Dead zones may result in deep water due to a lack of circulation of oxygen. However, it’s a very slow process to be cleaned