Directional movement depends on the configuration of the flagella. Bacteria can move in response to a variety of environmental signals, including light (
phototaxis ), magnetic fields (
magnetotaxis ) using magnetosomes, and, most commonly, chemical gradients (
chemotaxis ). Purposeful movement toward a chemical attractant, like a food source, or away from a repellent, like a poisonous chemical, is achieved by increasing the length of
runs and decreasing the length of
tumbles . When running, flagella rotate in a counterclockwise direction, allowing the bacterial cell to move forward. In a peritrichous bacterium, the flagella are all bundled together in a very streamlined way (
[link] ), allowing for efficient movement. When tumbling, flagella are splayed out while rotating in a clockwise direction, creating a looping motion and preventing meaningful forward movement but reorienting the cell toward the direction of the attractant. When an attractant exists, runs and tumbles still occur; however, the length of runs is longer, while the length of the tumbles is reduced, allowing overall movement toward the higher concentration of the attractant. When no chemical gradient exists, the lengths of runs and tumbles are more equal, and overall movement is more random (
[link] ).
What is the peptidoglycan layer and how does it differ between gram-positive and gram-negative bacteria?
Compare and contrast monotrichous, amphitrichous, lophotrichous, and peritrichous flagella.
Key concepts and summary
Prokaryotic cells differ from eukaryotic cells in that their genetic material is contained in a
nucleoid rather than a membrane-bound nucleus. In addition, prokaryotic cells generally lack membrane-bound organelles.
Prokaryotic cells of the same species typically share a similar
cell morphology and
cellular arrangement .
Most prokaryotic cells have a
cell wall that helps the organism maintain cellular morphology and protects it against changes in osmotic pressure.
Outside of the nucleoid, prokaryotic cells may contain extrachromosomal DNA in
plasmids .
Prokaryotic
ribosomes that are found in the cytoplasm have a size of 70S.
Some prokaryotic cells have
inclusions that store nutrients or chemicals for other uses.
Some prokaryotic cells are able to form
endospores through
sporulation to survive in a dormant state when conditions are unfavorable. Endospores can
germinate , transforming back into
vegetative cells when conditions improve.
In prokaryotic cells, the
cell envelope includes a
plasma membrane and usually a cell wall.
Bacterial membranes are composed of phospholipids with integral or peripheral proteins. The fatty acid components of these phospholipids are ester-linked and are often used to identify specific types of bacteria. The proteins serve a variety of functions, including transport, cell-to-cell communication, and sensing environmental conditions. Archaeal membranes are distinct in that they are composed of fatty acids that are ether-linked to phospholipids.
Some molecules can move across the bacterial membrane by simple diffusion, but most large molecules must be actively transported through membrane structures using cellular energy.
Prokaryotic cell walls may be composed of
peptidoglycan (bacteria) or
pseudopeptidoglycan (archaea).
Gram-positive bacterial cells are characterized by a thick
peptidoglycan layer, whereas gram-negative bacterial cells are characterized by a thin peptidoglycan layer surrounded by an outer membrane.
Some prokaryotic cells produce
glycocalyx coatings, such as
capsules and
slime layers , that aid in attachment to surfaces and/or evasion of the host immune system.
Some prokaryotic cells have
fimbriae or
pili , filamentous appendages that aid in attachment to surfaces. Pili are also used in the transfer of genetic material between cells.
Some prokaryotic cells use one or more
flagella to move through water.
Peritrichous bacteria, which have numerous flagella, use
runs and
tumbles to move purposefully in the direction of a chemical attractant.
True/false
Bacteria have 80S ribosomes each composed of a 60S large subunit and a 40S small subunit.
What is the direction of water flow for a bacterial cell living in a hypotonic environment? How do cell walls help bacteria living in such environments?
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
ok
Shukri
how do you save a country economic situation when it's falling apart
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product
Abdureman
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