Chapter 3 - Bacteria

Question 1

Composition of out body

Answer 1

In mothers womb we are 100% human cells

Now as a healthy adult, we are 10% human cells and 90% microbial by cell number

Question 2

Human-Microbiota Relationships: composition

Answer 2

In human population, the human microbiota composition varies depending on geographical location, climate, weather, age, gender, diet/nutrition and personal hygiene

But certain species while varying in abundance between individuals make regular appearances in human microbiota surveys

Question 3

Human-Microbiota Relationships: Development of the microbiota in infants

Answer 3

In healthy pregnancy, the fetal environment is sterile

Newborns are contaminated during and immediately after birth

Their microbiota changes as the infant grows: how microbiota develops

Their microbiota changes as the infant grows into a toddler, then young child, teenager, and adult

Question 4

Human-Microbiota Relationships:

Answer 4

Microbiota do not usually cause disease in healthy individuals

they are commensalists or mutualists with regards to the host

Question 5

Resident microbiota

Answer 5

are species that are life-long members of the body’s normal microbial community, but are not found everywhere (i
- some parts of the body remain sterile

Question 6

Transient microbiota

Answer 6

are just passing though –they are unable to remain in the body for extended periods of time due to:
COmpetition from resident microbes
- elimination by body system

Physical or chemical changes within the body that discourages the growth of transient microbes

Question 7

Mutualism

Answer 7

Interactions between 2 organisms in which both benefit

-MUTUALL

Question 8

Commensalism

Answer 8

Interaction between 2 organism in which one benefits but other is not harmed but also doesn’t benefit

Question 9

Parasitism

Answer 9

Interaction between 2 organism in which one benefits but other is harmed

Question 10

Microbiota and human relationship can be

Answer 10

Mutualism

commensalism

Question 11

Is your Microbiota Necessary?

Answer 11

The mouse model thing

Yes
Germ free mice have a very messed up immune system

Making germ free animal to see how it affects immune system and health

Another model is to treat with antibiotics
But still doesnt kill all bacterias

Question 12

What can Microbiota do for you

Answer 12

Microbial antagonism - make it difficult for pathogens to colonize and grow

• Out-compete for nutrients
• Changes in pH niche
• Occult favorable niches
• Produces inhibitory substances as a consequence of their metabolism
• eg bacteriocins that generate local antibiotic effectss
• can choose which bacteria to keep out

Question 13

What can Microbiota do for you :Gut brain axis

Answer 13

Stuff that occurs in the small intestines can be related to the brain though vagus nerve

Can improve mood

Question 14

What can Microbiota do for you: Nutritional benefits

Answer 14

Bacteria synthesizes vitamin K (for blood clotting) and vitamin B12

Converts steroids into the active form or a form that can be absorbed by the host

May break down food stuffs that are normally indigestible by host into compounds that can be digested

Conversion of bile acids (bile acids are important for digestion of fats, and transport/absorption of fat-soluble vitamins)

Question 15

What you can do for your microbiota!

Answer 15

The human body provides warmth, moisture, and a source of nutrients

The digestive tract is essentially a microbial fermentation chamber

Question 16

Human-Microbiota Relationships

Answer 16

Human body has many different environments - some are considered hostile

Certain members of the microbiota are only found in one anatomical location and never another
- eg they appear to exhibit a tissue preference for colonization

Each environment possess certain advantages and disadvantages and different microorganisms have adapted to certain regions of the body for their particular needs

Question 17

What environmental differences might you find in the human body?

Answer 17

Dry areas,
moist areas, areas with

high salt concentrations,

areas with low pH,

areas with low oxygen availability

Question 18

Is the microbiota always beneficial to the human?

Answer 18

no, microbiota CAN cause disease

Some microbiota can act as opportunistic pathogens when host is immunocompromised or weakened

Some microbiota can cause disease if they get into a different part of the body
- UTI, Ear infection

Some can cause secondary infection after antibiotic treatment of primary infection

Some can promote disease
- dental caries

Question 19

Social problems with the Microbiota

Answer 19

Some microbiota produce intestinal gas (CH4, H2S, CO2) as a by product of their metabolism

Some microbiota can cause body odor and morning breath