Explain the lac operon. How does it work when lactose is present and when lactose is not present. What about the presence of glucose?
Answer: The lac operon is an operon used to transport and metabolize lactose. In the presence of lactose, it functions as an inducer, it binds to the Lac I repressor protein and generate a conformational change that decreases its affinity for the operon region. Thus, the operon region is left free, the RNA polymerase can transcribe the structural genes.
Explanation:
An Operon is a group of structural genes whose expression is regulated by the same control elements and genes. The lac operon is an operon used to transport and metabolize lactose in Escherichia coli bacteria. Lactose is a disaccharide formed by the union of a glucose molecule and a galactose molecule (monomers). Upon breaking the glycosidic bond of lactose, both monomers are released and become available for use for energy. Remember that glucose is the main source of energy, and bacteria will always prefer to metabolize glucose rather than any other sugar, which they will only metabolize as an alternative energy source if glucose is not available.
The operon consists of several structural genes:
Lac z gene: encodes the enzyme β-galactosidase, which catalyzes the hydrolysis of lactose into glucose and galactose.Gene lac y: encodes the protein galactoside permease, for the transport of lactose into the bacterium.Promoter: region of DNA upstream of the above-mentioned genes that controls their expression, and where RNA polymerase binds to carry out gene transcription (synthesis of RNA from DNA that involves the expression of a gene).Operator: region of DNA located between the promoter and the beginning of the structural genes, which is recognized by the repressor protein Lac I.Repressor gene: encodes the Lac I repressor protein, which binds to the operator region and thus prevents transcription of genes under the control of this promoter. When the repressor is removed from the operator (in the presence of inducer which is lactose), RNA polymerase is ready to bind and start transcription.So, the lac operon is under a type of negative regulation, where genes can always be transcribed, except when the Lac I repressor protein is bound to the operator region. The promoter of the lac I gene is constitutive, so the Lac I protein is permanently expressed and remains bound to the operator, preventing the transcription of structural genes. That is, preventing the action of the lac operon in the absence of lactose. However, in the presence of lactose, it functions as an inducer of the operon. It is able to bind to the Lac I repressor protein and generate a conformational change that decreases its affinity for the operon region. Thus, the operon region is left free, the RNA polymerase can freely transcribe the structural genes, the enzyme β-galactosidase is synthesized which can degrade lactose to glucose plus galactose (and thus metabolize the lactose in the medium).
It should be clarified that in reality, the true inducing molecule of the lac operon is allolactose, an isomer of lactose obtained by a transglycosylation occasionally carried out by β-galactosidase. But usually to simplify terms, lactose is referred to as the inducer.
So, the lac operon is always inactive unless there is lactose in the medium. As mentioned, E. coli prefers glucose, so the lac operon will not be activated in the presence of lactose if glucose is present in the medium. If both glucose and lactose are present in the medium, the repressor is inactivated, so the operon is transcribed but at a basal (low) level due to the presence of glucose.
New world monkeys belong to the infraorder:
Group of answer choices
Catarrhini
Platyrrhini
Strepsirrhini
Tarsiiformes
Answer:
catarhini. hope helpful answer
Answer:
The answer for this question is that they belong to Platyrrhini
Explanation:
What are the processes that are occurring during interphase of the cell cycle.
Answer:
The cell is replicating its organelles and DNA. It's basically growing to prepare for mitosis.
Explanation:
What would be the reaction of sea anemone if a glass rod touch the tip of its tentacles?
Answer:
releasing venom from the skin
Is it true or false?????
Answer:
Explanation: true
Give any two examples for each. 1. Floating plants 2. Underwater plants 3. Fixed plants 4. Emergent plants 5. Insectivorous plants 6. Mangroves 7. Desert plants 8. Coniferous trees 9. Deciduous trees 10. Grass 11. Evergreen trees
Answer:
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Explanation:
awdawdawdadawdawdwaawdawdawdadawdawdwda
Please help meeee!!
Can you please give me an environmental risk or benefit for artificial selection?
Answer: i answered the first one you posted go check
Explanation:
A student constructs a Venn diagram to compare the organelles in plant and animal cells.
Venn Diagram of Plant and Animal Cells
Animal Only
Both
Plant Only
Which organelle should be listed under "Animal Only" in the diagram?
Organelle which is present in only plant cells are chloroplast, centrioles are present only in animal cells. The organelles present in both cells are ribosomes, nuclei, and mitochondria.
What are organelles?The cell parts are called cell organelles. There are both membrane-bound and non-membrane-bound organelles in these cell organelles, which are found within the cells and have distinct structures and functions. The direction and capability productively for the ordinary working of the cell.
Depending on whether or not they have a membrane, the various organelles that are found within the cell are divided into three groups. The types are double membranes, single membranes, and no membrane organelles.
Therefore, organelles perform biochemical functions.
Learn more about organelles, here:
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Describe the purpose of pasteurization.
Answer:
Here is some research:
The Purpose of Pasteurization
To increase milk safety for the consumer by destroying disease causing microorganisms (pathogens) that may be present in milk. To increase keeping the quality of milk products by destroying spoilage microorganisms and enzymes that contribute to the reduced quality and shelf life of milk.
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Can someone help me with this please.
what do you think are some human characteristics that reflect a common ancestry between non human primates and ourselves?
Explanation:
Primates are the mammalian order of organisms, having flexible hands and feet. These organisms have a developed brain and include organisms like lemurs, lorises, humans and apes. Humans are placental mammals, who have a highly developed brain.
Step 2 of 3
The evolutionary relationship between humans and non human primate can be studied based on the anatomical features and behavior that these two organisms share. The human characteristics that reflect a common ancestry between human and non-human primates are as follows:
1. The body hair are present on both the organisms.
2. Giving birth to young ones, after a long gestation period is common in both the organisms.
3. Different types of teeth which are incisor, canine, premolar and molars are present in both the organisms.
4. Both the organisms have the capability to regulate their thermal body temperature.
5. The brain size and capacity of both the organisms is large.
6. The capacity to learn and adapting to suitable behavior based on that is well present in both the organism.
Step 3 of 3
Chimpanzees are primates, belonging to the same ape family as humans. Chimpanzees are the closest living relative of humans. They are basically of two types, pan troglodytes and pan paniscus. Chimpanzee and humans are similar in following ways:
1. Brain volume of humans and chimpanzees is almost similar. Brain volume of human is 1350 ml (milliliter) while that of chimpanzee is 1370 ml.
2. Both humans and chimpanzees socialize among themselves.
3. According to scientific reports, humans and chimpanzees share about 95% similarity in DNA (Deoxyribonucleic acid).
The tissue layers of blood vessels from outer layer to inner layer are:
Answer:
The outermost layer is called the tunica adventitia.
The muscular middle layer is called the tunica media.
The innermost layer is called the tunica intima.
Explanation:
Answer:
tunica intima is the inner most tissue, tunica externa is he outermost layer of a blood vessel
Explanation:
Can you please help me with this question?
Answer:
B
Explanation:
Plz mark brainliest ;)
Answer:
Option B is the answer
The fact that _____ is electronegative gives a water molecule a partial positive side.
Answer:
Oxygen
Explanation:
In a molecule of water ie H20, Oxygen is more electronegative and hence attracts more electrons to itself making Hydrogen partially positive ♂️
Excess postexercise oxygen consumption (EPOC) is also known as oxygen debt.
a. True
b. False
Answer:
True.
Explanation:
Excessive postexercise oxygen consumption can also be called oxygen deficit. It occurs after an individual completes a physical activity. Physical effort does not allow oxygen consumption to be normalized as soon as the body comes to rest and for this reason, the body begins to breathe and demand oxygen more intensely. This moment is known as excessive postexercise oxygen consumption, or oxygen debit. The intensity of breathing at this time will depend on the physical effort made, the weight loss and the increase in total caloric expenditure.
describe the effect of temperature on transpiration rate
Answer:
Temperature affects the transpiration rate in two ways. Firstly, at warmer temperatures water molecules move faster, and the rate of evaporation from stomata is therefore much faster. Secondly, the water-holding capacity of warm air is greater than that of cold air.
Explanation:
I hope it helps you
Answer:
Temperature: Transpiration rates go up as the temperature goes up, especially during the growing season, when the air is warmer due to stronger sunlight and warmer air masses. Wind and air movement: Increasing movement of the air around a plant will result in a higher transpiration rate.
What are carbohydrates?
O Water is non-polar which is why other compounds will dissolve in it
O Macromolecules composed of amino acids
O Non-water soluble macromolecules with a high proportion of hydrocarbons
O Macromolecules composed of nucleotides
Answer:
O Non-water soluble macromolecules with a high proportion of hydrocarbons
Explanation:
Carbohydrates are one of the four biological molecules in nature (asides from proteins, nucleic acid, and lipids). Carbohydrates are a complex polymer consisting of several chains of carbon and hydrogen (hydrocarbons).
According to this question, carbohydrates are non-water soluble macromolecules with a high proportion of hydrocarbons.
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Answer:
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A(n) is a molecule, cell, or organ that directly carries out a response to a stimulus and restores homeostasis.
Answer:
Red blood cells and the heart causes response to stimuli
Like DNA, RNA follows base-pairing rules. Experiment to find which RNA _____________ on the right side of the Gizmo will successfully pair with the thymine at the top of the template strand of DNA.
Answer: Nucleotide; Adenine
Explanation: RNA Nucleotide contains bases of Thymine, Cytosine, Guanine and Uracil. The Uracil base in RNA, substitute the base Thymine in the DNA base and bonds with Adenine like as seen in DNA base pairing.
Thus, during DNA duplication, the thymine at the top of the template strand of DNA is replaced with Uracil and binds with Adenine.
what is photosynthesis .......?
Answer:
the process by which green plants turn carbon dioxide and water into food using energy from sunlight
Answer:
Explanation:
the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a by-product.
1. What is stimulus?
2. Define response.
3. What are tropic movements
4. What excretory products are produced in plants?
5. When do stomata open and close?
Answer:
1.someting that causes directly, development, interest.
2.an answer to somebody something
3.directional movement of particular part of a plant in response to environmental stimuli
4. carbon dioxide, oxygen
5. allow for the uptake of carbon dioxide anf to limit the loss of water due to evaporation
Comb jellies are:____.
A. Bilaterally symmetrical.
B. Similar to a cnidarian polyp.
C. Distinguished by eight bands of cilia.
D. Colonial animals.
E. Carnivores that use nematocysts to capture prey.
Answer:
C. Distinguished by eight bands of cilia.
Explanation:
Ctenophora, also known as comb jellies, represents a phylum of transparent, mostly pelagic, invertebrate marine animals that live around the world. This group characterized by eight rows of cilia (singular cilium) that are used for locomotion. Cilia are organelles and/or structures that extend from the surface of eukaryotic cells, which can be used to move the surrounding fluid, resulting in cell movement. This phylum is divided into two classes: Tentaculata (with tentacles) and Nuda (without tentacles).
The predatory bacterium Bdellovibrio bacteriovorus is able to penetrate a gram-negative bacterium that has a slimy cell covering. What is the correct sequence of structures penetrated by B. bacteriovorus on its way to the prey's cytoplasm
Answer:
The order of bacterial structures that the bacteria would penetrate would be:
Capsule.Lipopolysaccharide MembranepeptidoglycanPhospholipids Membrane.Explanation:
A parasite like B. bacteriovorus faces some challenges in getting into a bacterial cell. This is because these cells have devices and strategies to prevent the entry of parasites and ensure the survival of the bacteria. The first challenge would be to penetrate the bacterial capsule. The capsule is a structure that is located around many bacteria. This structure is rigid, with sharp edges and thick thickness, which protects the bacteria from external agents. If B. bacteriovorus manages to go beyond the capsule, it will find a membrane, also thick, composed mainly of lipopolysaccharides, which will also provide protection and try to prevent the entry of the parasite. If this membrane is crossed, B. bacteriovorus will face another layer called peptidoglycan. This layer establishes itself as a cell wall, being very difficult to break. Some bacteria present one more layer after peptidoglycan, which is a membrane made by Phospholipids, which is highly selective and difficult to break, but is more fragile than the previous layers. Only after overcoming all these structures, the parasite will have access to the bacterial cel
Why do plants store their food?
Explanation:
Storing the food helps them to use it in winter and survive because there is very little sunlight available and so they photosynthesis less. When they have extra food they store it in their seeds and when the seed grows it gets it's food from the plant until the plant is able to photosynthesis and produce its food.
Answer:
The main reasons being- survival, growth and reproduction
What is directly responsible for matter moving and changing in an animal's
body?
A. Water
B. Sun
C. Energy
D. Fuel
g the inability to metabolize phenylalanine is a recessive autosomal trait called PKU when A marries a woman at random from another town what is the probability that his first born will be affected by PKU
Answer:
The correct answer is - zero percent.
Explanation:
As it is known that PKU is a disease that takes place if one has wild type recessive rr only. It is given that A is normal heterozygous and if he marries normal women then
R r
R RR Rr
R RR Rr
so there will be 2 carriers and 2 unaffected but no affected.
Chó ăn xương, thế dạ dày của chúng tiêu hoá như thế nào?
Answer:
srd ghvj
Explanation:
Scientists have been studying the size of three populations in a river in Ireland. In this ecosystem, pike (a type of big fish), and perch eat snails. The data showed that all three populations were stable. Then the snail population increased suddenly. What will likely happen to the size of the perch population as a result? The size of the perch population will...
Options:
A. Stay the same. The size of it's consumer population did not change, so the number of deaths in the perch population did not change. There will be the same number of births and deaths in the perch population.
B. Decrease. The larger snail population will take more energy storage molecules from the ecosystem, leaving fewer available for the perch population. This will lead to more deaths than births in the perch population.
C. Increase. The larger snail population will provide more energy storage molecules for the perch population, so they will reproduce more. This will lead to more births than deaths in the perch population.
D. Increase. An increase in any population within an ecosystem will lead to an increase in the sizes of all other populations in the ecosystem.
Answer:
C. Increase. The larger snail population will provide more energy storage molecules for the perch population, so they will reproduce more. This will lead to more births than deaths in the perch population.
Explanation:
How and why does the epidermis produce new skin cells?
Answer:
About 95 percent of the skin cells in the epidermis are devoted to creating new skin cells in the lower two levels of the epidermis, which then cycle to the top layer to help form the stratum corneum. Eventually the dead cells of the stratum corneum flake off as new keratinocytes move up, and the cycle repeats itself.
Hope this answer is right!!