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Summary microbiology
- Vak
- Microbiology
- Instelling
- Rijksuniversiteit Groningen (RuG)
This summary contains all the information from the lectures, I had a 7 last year.
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Voorbeeld 4 van de 67 pagina's
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Voorbeeld van de inhoud
MicrobiologyChapter 5 Poolman lecture 1:
• Replication: new copy of chromosome
• Transcription: DNA -> mRNA
• Translation: mRNA -> protein (= protein synthesis)
• Insertion: protein into membrane
• Folding: polypeptide -> native state (oorspronkelijke staat)
• Post-translational modification: chemical modification of protein (phosphorylation,
methylation, lipid attachment, …)
Microorganism are also called microbes.
Transertion: transcription, translation, insertion and folding of
membrane proteins occur simultaneously.
In the microbiology growth is defined as an increase in the
number of cells.
Binary fission: two cells (daughter cells) have arisen from one.
The partition that forms between dividing cells is called a
septum.
Generation time: the time that is required to form two cells from one cell (one generation). The time
is variable and depends on nutritional and genetic factors, and on temperature. In nature many
bacteria growth much slower than their maximum rates observed in the laboratory.
The growth time of bacteria generation times vary from 10 min to 10000 years. Clostridium
perfingens and Bivrio natriegens have optimal generation times of 10 min.
Budding Cell Division: this occurs in a few bacteria, these are cells that divide as a result of unequal
cell growth. In contrast to binary fission that yields two equivalent cells, budding division forms a
totally new daughter cell and the mother retaining her original identity.
➢ The formation of new cell wall material from a single point (polar growth). And not as by
binary fission throughout the whole cell.
➢ An advantage of polar growth is that more complex internal structures can be formed in
budding cells than in cells that divide by binary fission. Because large cytoplasmic structures,
such as internal membrane complexes, are not partitioned during the cell division process
and must be formed de nove in the developing bud.
➢ Some budding bacteria form cytoplasmic extensions such as stalks (Caulobacter), hyphae
(Hyphomicrobium), and appendages (Ancalomicrobium).
Planktonic growth: growth as suspension, can live in a liquid medium.
Sessile growth:
• attached to surface
• can develop into biofilms (a structured community of bacterial).
• microbial mats
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,Biofilms: is an attached polysaccharide matrix containing embedded bacterial cells. It begins with
the attachment of planktonic cells, this is followed by the production of a sticky matrix and further
growth. Biofilms have been implicated in difficult to treat infections of implanted medical devices.
Microbial mats: biofilms that form multilayered sheets with different organisms present in the
individual layers.
Exponential growth: the number of cells doubles in a constant time interval. When you show this in
logarithmic scale as a function of time, the points fall on a straight line. This shows that the cell
doubles in a constant time interval.
➢ You can read the generation time from a semilogarithmic graph.
Rekenvoorbeeld pagina 176/177 !
g = t/n (=doubling time, td) td=Ln2/D
• t is the duration of exponential growth (days/hours/minutes)
• n is the number of generations during the period of exponential growth
The instantaneous growth rate constant (K) expresses the rate at which the population is growing at
any instant (op elk moment). kN = dN/dt
An organism growing in an enclosed vessel, such as
a tube or flask (a batch culture). The growth curve
describes the four phases: lag, exponential, stationary
and death.
• The lag phase: growth begins only after a period of time. this may be brief or extended. It is
also observed when a microbial culture is transferred from a nutrient-rich culture medium to
one that is nutrient-poor. Than there is time needed for the synthesis of new enzymes and
metabolites.
• Stationary phase: when bacteria still keep growing it was in 48 h 4000 times the earth. This is
impossible. In this phase there is no net increase or decrease in cell number and thus the
growth rate of the population is zero. Some cells may even divide, but no net increase in cell
numbers because some dies.
• Death phase: the rate of cell death is much slower than the rate of exponential growth.
The four faces have meaning to cell population but not to the individuals.
Important of table 5.1 and slide 22 is that different microorganisms may have vastly different
nutritional requirements. Blz 182.
Liquid culture media are solidified (gestold) with agar
Solid media immobilize cells, allowing them to grow and form visible isolated masses called colonies.
Aseptic technique: a series of steps to prevent contamination (besmetting) during manipulations of
cultures and sterile culture media, both liquid and solid.. it is required for maintaining pure cultures.
Figure 5.12
Quantifying cells: Turbidimetry is the process of measuring the loss of intensity of transmitted light
due to the scattering effect of particles suspended in it. Door middel van turbidimetry kan de
hoeveelheid van een chemisch bestanddeel in een stof worden bepaald.
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,Chapter 1 Driessen lecture 1:
Microorganisms can’t be see with the human eye, they live in microbial communities.
Microorganisms are the tiny titans of the earth, they are the oldest form of life and the major
fraction of Earth’s biomass (~15%).
Culture: is a collection of cells that have been grown in or on a nutrient medium.
Medium: liquid/solid mixture containing all required nutrients.
Eukaryotic: plants and animals / Prokaryotic: bacteria and archaea.
Studying fundamental life processes:
• molecular biology and biochemistry
• genomics and molecular genetics
All cells have the following in common:
• cytoplasmic (cell) membrane: barrier that separates the inside of the cell from the outside
environment
• cytoplasm: aqueous mixture of macromolecules, small organics, ions, and ribosomes inside
cell
• ribosomes: protein-synthesizing structures
• cell wall: present in some microbes; confers structural strength
Genome: a cell's full complement of genes
Gene: segment of DNA that encodes a protein or an RNA molecule.
Eukaryotic DNA:
• linear chromosomes within nucleus
• much larger/more DNA (up to billions of base pairs)
prokaryotic DNA
• generally single circular chromosome that
aggregates to form the nucleoid region. ->
• may also have plasmids (extrachromosomal DNA)
that confer special properties
(e.g., antibiotic resistance). so not essential.
• small, compact (0.5–10 million base pairs)
In the figure are some form of metabolism by taking up nutrients from the environment and
transforming them into new cell materials and waste products shown.
Enzymes are required to carry out reactions that supply the
energy and precursors necessary for the biosynthesis of all
cell components. They are synthesized during gene
expression in the processes of transcription and translation.
All cells do transcription, translation and DNA replication.
Differentiation: formation of modified cells specialized for
growth, dispersal or survival, they make spores.
Spores have a very thick cell wall and can survive heat.
Horizontal gene transfer: prokaryotic cells exchange genes
with neighboring cells, same and different species.
Evolution: for example, the indiscriminate use of antibiotics
in human bacteria acquire new genes though the process of
3
, horizontal gene transfer and growth very fast. So there are
changing in genes.
• Earth is 4.6 billion years old
• First cells appeared between 3.8 and 4.3 billion
years ago
• The atmosphere was anoxic (no O2) until ~2.6 billion years ago, there was only N2, CO2 and
some other gasses.
➢ only anaerobic metabolisms
➢ first anoxygenic (non-oxygen-producing) phototrophs ~3.6 billion years ago
➢ cyanobacteria began slow process of oxygenating earth’s atmosphere ~ 2.6 billon
years ago
➢ plants and animals ~0.5 billion years ago
Domains: bacteria, archaea and eukarya. 60 genes are present in
cells of all domains so they all have a common ancestor, the
last universal common ancestor (LUCA).
• There are estimated 2 x 1030 microbial cells on Earth.
• Total amount of nitrogen and phosphorus within microbial
cells is nearly four times that in all plants and animal cells
combined.
• Extremophiles live in habitats too harsh for other life forms.
examples: hot springs, glaciers, high salt, high acidity/alkalinity,
high pressure.
• Ecosystem refers to all living organisms plus physical and
chemical constituents (bestanddelen) of their environment.
• Metabolic activities can change habitats and affect other
organisms. Like human activities release nutrients into the coastal
oceans, more microbial growth, more anoxic zones in the water, so
dead zones and mortality of fish and shellfish.
• Microbial ecology is the study of microbes in their natural environment.
• in humans, 1–10 microbial cells per human cell
Table 1.1
In the beginning of the twentieth century, the major causes of human death were infectious diseases
caused by bacterial and viral pathogens. Now children and the aged less deaths are causes by
microbial diseases. This is because now we have a combination of advances including our increased
understanding of disease process and the antibiotics.
Most microorganisms are beneficial and essential to human welfare.
Legumes are a diverse family of plants that include major crop species such as beans. They live in
close association with bacteria that form structures called nodules on their roots. In the nodules
bacteria convert N2 into NH3. And this is uses in fertilizer (kunstmest). So bacteria regulate nutrient
cycles.
Many aspects of agriculture depend on microbial activities
• nitrogen-fixing bacteria
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