No one can see in total darkness. Fortunately, there’s almost always some light available. Even if it’s only dim starlight, that’s enough for your eyes to detect. What’s truly amazing is how little light is required for you to see.

Human eyes have two main features that help us see better in low light: the pupil’s ability to change size, and the eye’s two types of light-sensing cells.

Opening up to let in more light

Your pupils are the black areas at the front of your eyes that let light enter. They look black because the light that reaches them is absorbed inside the eyeball. It’s then converted by your brain into your perceptions of the world.

You’ve probably noticed that pupils can change size in response to light. Outside on a bright sunny day, your pupils become very small. This lets less light into the eye since there’s plenty available

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3 years ago

Bacteria and other microbes can be used to "clean up" an oil spill by breaking down oil into carbon dioxide and water. Two sampl

SVETLANKA909090 [29]

Answer:

Sample A

T= 21.3% and A= 21.3%

G=28.7% and C= 28.7%

SAMPLE B

T=28.7% and A= 28.7%

G= 21.3% and C= 21.3%

Sample A would have higher melting temperature

Explanation:

According to given information, sample A contains 21.3% thymine.

Percentage of adenine in sample A= 21.3% (Since adenine base pairs with thymine, so, adenine and thymine are present in equal amount in a double stranded DNA)

Total of A+T in sample A= 21.3 + 21.3 = 42.6%

G+ C content of sample A= 100-42.6= 57.4%

Percent G content of sample A = 57.4/2 = 28.7%

Percent C content of sample A = 28.7%

SAMPLE B:

According to the given information, sample B contains 28.7% thymine.

Therefore, percent of Adenine base in sample B= 28.7%

Total of A+T content in sample B= 28.7 + 28.7 = 57.4%

G + C content of the sample B = 100-57.4= 42.6%

Percent G content of the sample B= 42.6/2= 21.3%

Percent C content of sample B = 21.3%

There are three hydrogen bonds between a GC pair while there are only two hydrogen bonds between AT pair. The DNA content with higher GC content has higher melting temperature. Therefore, sample A would have higher melting temperature.

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3 years ago