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BIO 111 MIDTERM > Microbes > Flashcards

Microbes Flashcards

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Biology 101 flashcards
1
Q

Why care about microbes?

A
  1. They make us sick
  2. they make us not sick ( bacteria in the gut microbiome help train our immune system and protect against pathogens)

3.They have been evolving for billions of years ( essential for all global nutrients cycles carbon, nitrogen, phosphorus)

  1. Continuing to evolve
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2
Q

Invisible world

A

Louis Pasteur(1870s): invisible microbes are responsible for fermentation, sepsis, and disease.

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3
Q

Social lives of bacteria: Symbiosis (living together)

A
  • Symbiosis has played a big role in the evolution of life on earth
  • Most plants and animals have microbiome: microbes living in and on them
  • Humans are 2% bacteria by mass
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4
Q

The rise of cyanobacteria

A

Banded iron formations consist of alternating layers of flint and iron oxide. They formed when the oxygen content of the atmosphere was high enough to oxidize ferrous to ferric iron.

This was the result of the evolution of oxygenic photosynthesis.

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5
Q

Levels of biological organization

A
  1. Individual cell
  2. Population
  3. Community
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6
Q
  1. Individual cell
A

Mechanism: Metabolism and replication

Process: requires continual input of energy and material to keep the cell out of thermodynamic equilibrium

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7
Q

2.Population

A

Mechanism: variation and evolution

Process: replication causes variation; reproduction causes competition. Which means fitness increase

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8
Q
  1. Community
A

Mechanism: Consumption and nutrient cycling

Process: Populations are linked by consumption. Must be in mass and energy balance at level of ecosystem.

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9
Q

The boundary of the cell is the plasma membrane:

A
  • The plasma membrane is a phospholipid bilayer
  • It separates life from the environment
  • Transport, signals, adhesion
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10
Q

The dual system of a cell

A
  • The membrane of the cell encloses two distinct biochemical systems:
  1. Metabolism
  2. Information
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11
Q
  1. Metabolism
A

The cell generates or harvests energy and channels it to synthesize new biomass, including the components responsible for metabolism. Without a membrane the products of metabolism would rapidly diffuse away from one another.

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12
Q
  1. Information
A

The cell stores the information necessary to synthesize the metabolic system. Without a membrane the information system could not be permanently linked to the metabolic system.

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13
Q

Growth leads to reproduction

A
  • Large cells are inefficient because volume increases faster than the surface area. Once the cell has grown to a certain size it divides to form 2 daughter cells. Both cells receive information and metabolic systems from the progenitor.
  • Reproduction involves the division of biomass and the replication of information
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14
Q

Growth and Reproduction

A
  • A more efficient metabolic system leads to more rapid growth and more rapid reproduction
  • If the information system is coupled with the metabolic system by being enclosed in the same membrane, the increased efficiency is heritable
  • The information that specifies a more efficient metabolic system will then itself be replicated more rapidly.
  • This is called evolution by natural selection
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15
Q

Plasmids

A

Small DNA molecules that occur in bacteria but are not essential for normal function:

  • They replicate at the same time as chromosome but daughter cells don’t always receive equal numbers
  • Some plasmids encode conjugation that results in plasmid transfer from a donor to a recipient via pilus
  • Plasmids may encode functions that benefit the host bacteria, but in some cases they are parasites
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16
Q

DNA replication follows the same basic scheme in prokaryotes and eukaryotes:

  • but differs in many important details
A
  • A protein ( DNA A ) recognizes origin of replication and unwinds DNA.
  • Origin-binding protein loads 2 helices onto DNA
  • ATP hydrolysis moves helicase along chromosome, driving a wedge between the strands and forcing
    them apart
  • An RNA primer is synthesized on the single stranded portion of DNA
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17
Q

Differential reproduction leads to

A

evolution by natural selection

18
Q

DNA

A
  • Information storage
  • nucleus and cytoplasm
19
Q

mRNA

A
  • Information retrieval
  • cytoplasm
  • ribosome
20
Q

Protein

A
  • product
  • cytoplasm
21
Q

ribosome

A

The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins

22
Q

The most important attributes of living organisms

A
  • genetic: self- replication and heritability
  • physiological: metabolism
23
Q

3 theories that explain the origin of life

A
  • special creation
    -panspermia
  • spontaneous generation
24
Q

Panspermia

A

a philosophical thought that life migrates naturally through space—states that the seeds of life exist all over the Universe and can be propagated through space from one location to another

25
Q

undirected panspermia

A

disperse microbes from planet to planet

26
Q

directed panspermia

A

deliberate seeding by aliens

27
Q

misdirected panspermia

A

galactic pollution by spacecraft

28
Q

spontaneous generation ( proved wrong)

A

archaic theory that utilized this process to explain the origin of life

29
Q

2 chemical processes need to happen for life to be possible:

A
  • growth
  • reproduction
30
Q

Growth

A

exergonic chemical reactions that release energy that is available for synthesizing organic molecules as the basis of metabolism

31
Q

Reproduction

A

separation of a fragment of the growing system itself capable of continued growth

32
Q

For life to evolve from prebiotic chemistry we need one more process:

A

Inheritance: reproduction gives rise to products that resemble their parents more closely than random members in the same population

33
Q

Two possible routes for origin of life:

A

genetic first
metabolism first

34
Q

Genetic first

A
  • RNA is replicated by rna polymers
  • RNA molecules can replicate without cells when they are provided with raw materials and a replicase
  • ## RNA can act as enzymes called ribozymes
35
Q

The evolution of metabolism

A
  1. Fermentation
  2. Respiration
    3.Photosynthesis
    4.Oxygenic photosynthesis
  3. Aerobic respiration
36
Q

LUCA

A

the last universal common ancestor

  • divided to give rise to 2 daughter cell:

one was the ancestor of all living bacteria
the other was the ancestor of living archea

37
Q

archaea

A

a group of micro-organisms that are similar to, but evolutionarily distinct from bacteria

38
Q

endosymbiotic theory

A
  • endosymbiosis is a special case of horizontal gene transfer involving an entire genome
  • Over time, some genes from the symbiont genome are transferred into the host genome
39
Q

What is a virus

A
  • tiny protein package a DNA or RNA genome
  • not considered a cell ( no cytoplasm, no ribosomes)
  • not capable of replication without a host cell
  • all forms of life are infected by viruses
  • all viruses use host resources ( nucleotides, amino acids) to build more copies of themselves
40
Q

Phage

A

is a virus that infects bacteria or achea

vector of horizontal gene transfer

41
Q

Coevolution

A
  • Defined as mutually imposed selective pressures
  • The evolution of one affects the other, and vice versa
  • Adaptation and counter adaptation
42
Q

First stage of infection

A

A phage must attach to a receptor protein on the bacterial surface

mutations in the receptor gene can confer resistance to the phage

phages are then under selection to bind to the mutated receptor

BIO 111 MIDTERM (3 decks)

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