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3 years ago

Phospholipid bilayer

Biology

1 answer:

My name is Ann [436]3 years ago

4 0

Answer:

The cell membrane is the part of the cell made up of phospholipid bilayer.

Explanation:

The cell membrane is made up of two layers of phospholipids and hence these layers are known as the phospholipid bilayer. The tail of the phospholipids is made up of fatty acids and it is hidden on the inside of the structure. The heads made up of phosphate and glycerol face outwards. This structure makes the cell membrane ideal for the transport of molecules as they have both hydrophobic and hydrophilic regions.

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What is the significance of secondary growth in plants?

kipiarov [429]

The correct answer is A.
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3 years ago

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Need help asap <br> question 3 <br> - 20 points

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The amount of population change due to immigration or emigration

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3 years ago

Rank the following by size (1 is biggest, 5 is smallest):

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3 years ago

For this assignment you will complete an illustration(s) (by hand) of how the lac operon works. You should be sure to include de

Fantom [35]

<h2>Lac operon </h2>

Explanation:

Lac operon present in prokaryotic chromosomes whose product involves in transportation and catabolism of lactose

Lac operon consists of three structural genes called Lac Z,Lac Y and Lac A and a regulatory element(promoter and operator)
Lac I gene is present outside the Lac operon,act as regulatory gene and control the expression of Lac operon genes
Lac Z codes for β galactosidase which converts lactose into allolactose
Lac Y codes for Lac permease which act as a membrane transporter and transport lactose into the cells
Lac A codes for transacetylase which neutralize the toxic effects of lactose

Lac operon in absence of lactose

In absence of lactose Lac operon exists in switch off state
Lac I gene produces Lac repressor which binds to operator region and prevent binding of RNA Polymerase thus blocks transcription

Lac operon in presence of lactose

In presence of lactose Lac operon exists in switch on state
In presence of lactose few molecules of Lac operon enzyme catalyse conversion of lactose to allolactose
Allolactose act as an inducer,binds to the Lac repressor and induce conformational changes causing dissociation of Lac repressor from operator
In absence of Lac repressor RNA Polymerase binds to the promoter and starts transcription of genes which catabolize lactose

Lac promoter is a weak promoter and direct transcription of Lac operon genes in very low level in presence of lactose

For higher level expression of Lac operon genes,operon system require conversion of weak promoter to strong promoter which is always mediated by catabolite protein-cAMP complex(CAP-cAMP complex)
CAP cAMP complex binds to the upstream of promoter called CAP binding site and stimulate expression of Lac operon genes by facilitating binding of RNA Polymerase
Catabolite activator protein(CAP) or cAMP receptor protein(CRP) activate when cAMP binds
cAMP is a secondary messenger synthesized from ATP and act as co-activator of CRP
With respect to CAP cAMP complex Lac operon system is positively controlled
In prokaryotic cell cAMP is very low when glucose concentration is relatively high and vice versa
At high concentration of glucose the growth rate is maximum and lactose catabolism is repressed called catabolite repression

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3 years ago

Which best describes the process that the pest population has experienced due to this environmental change?

Murrr4er [49]

Answer;

Natural selection

Explanation;

-Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift.Genetic diversity allows the different organisms to have different physiological characteristics. Some of them provides them with genetic resistance, others don’t. The ones which are resistant survive the pesticide, others don’t ; this is known as natural selection.

-Those that are resistant will live longer and have a larger number of offspring (reproductive success). From one generation to another, there will be more and more resistant pests (because of their larger offspring), and less and less pests that are not resistant (because they tend to die young). If the selection process goes on, someday the pesticide will be useless (it will kill no pest).

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3 years ago

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