Notes for Bio 2- Bacteria

Microbe

A microscopic organism, including bacteria, archaea, eukarya, and viruses.

Estimated Microbial Diversity

Up to 99.99% of bacterial species may remain undiscovered, with only 30,000–40,000 identified.

Bacterial Diversity in Humans

Humans harbor about 500–1000 species of bacteria on their bodies, with the highest diversity found in the gut and skin.

High Surface Area-to-Volume Ratio

Allows small microbes to carry out essential life functions efficiently through diffusion.

Domains of Life

The three domains are Bacteria, Archaea, and Eukarya.

Cocci

Spherical shape of bacteria.

Bacilli

Rod-shaped bacteria.

Spirilla

Spiral-shaped bacteria.

Capsule

The outermost protective layer of a bacterial cell.

Cell Wall

Provides structural support and protection outside the plasma membrane.

Plasma Membrane

Regulates what enters and leaves the cytoplasm of a cell.

Plasmid

A small circular piece of DNA in bacteria, often carrying antibiotic resistance genes.

Pilus

Hair-like appendages involved in attachment and DNA transfer between bacteria.

Gram-Positive Bacteria

Bacteria with a thick glycoprotein layer exposed on the outside of the cell wall.

Gram-Negative Bacteria

Bacteria with a glycoprotein layer shielded by an additional outer membrane.

Conjugation

The transfer of DNA between bacteria via a physical connection.

Transduction

The process by which a virus transfers bacterial DNA from one bacterium to another.

Transformation

The uptake of DNA from the environment by a bacterium.

Impact of Bacteria on Digestion

Some bacteria, specifically intestinal archaea, assist in digesting tough food chemicals.

Human Microbiome

The community of microbes residing in and on the human body.

Microbial Cells vs. Human Cells

The human body contains about 68 trillion microbial cells, slightly more than human cells.

Independent Variable (IV)

The factor manipulated in an experiment, like the source of microbiome transplant.

Dependent Variable (DV)

The factor measured to see if it changes in response to the independent variable.

Stacked Bar Graphs

Used to show total quantities and their components, like cell types in the human body.

Side-by-Side Bar Graphs

Used to compare different independent categories or experimental results.

Pie Charts

Represent proportions of categories within a whole.

Behavioral Influence of Gut Microbes

Gut bacteria can affect behavior, appetite, and mood through neural signals.

Symbiotic Relationships

Mutually beneficial relationships between bacteria and humans.

Gas Production by Gut Microbes

Gut microbial activity during digestion can lead to gas production.

Causal Link

A direct relationship established between a change in microbial community and a behavior change.

Necessary Role of Microbial Transplants

Transplants help establish causation, rather than correlation, between microbiomes and behavior.

Mutation Rate in Bacteria

Bacteria generally exhibit a high mutation rate influenced by their smaller genome size.

Horizontal Gene Transfer

The process by which bacteria share genetic material with other bacteria.