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tresset_1 [31]
2 years ago
11

Which evidence suggests that several mass extinctions have occurred during Earth's history?

Biology
2 answers:
Tom [10]2 years ago
8 0

Answer:

OPTION (D)

Explanation:

jus took the unit test

Hitman42 [59]2 years ago
6 0

Answer:

Many fossils of organisms that are no longer living have been discovered.

Explanation:

Mass extinctions could be first identified because of the traces they left in the fossil record. In the strata, the lower, older rock layer shows a diversity of fossil life forms, and the younger lawyer above is depauperate if we compare.  

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DNA Polymerase helps copy a DNA molecule during the process of what?
PtichkaEL [24]
The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. During this process, DNA polymerase “reads” the existing DNA strands to create two new strands that match the existing ones.

Every time a cell divides, DNA polymerase is required to help duplicate the cell’s DNA, so that a copy of the original DNA molecule can be passed to each of the daughter cells. In this way, genetic information is transmitted from generation to generation.

Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form. This opens up or “unzips” the double stranded DNA to give two single strands of DNA that can be used as templates for replication.

DNA polymerase adds new free nucleotides to the 3’ end of the newly-forming strand, elongating it in a 5’ to 3’ direction. However, DNA polymerase cannot begin the formation of this new chain on its own and can only add nucleotides to a pre-existing 3'-OH group. A primer is therefore needed, at which nucleotides can be added. Primers are usually composed of RNA and DNA bases and the first two bases are always RNA. These primers are made by another enzyme called primase.

Although the function of DNA polymerase is highly accurate, a mistake is made for about one in every billion base pairs copied. The DNA is therefore “proofread” by DNA polymerase after it has been copied so that misplaced base pairs can be corrected. This preserves the integrity of the original DNA strand that is passed onto the daughter cells.



A surface representation of human DNA polymerase β (Pol β), a central enzyme in the base excision repair (BER) pathway. Image Credit: niehs.nih.gov

Structure of DNA polymerase

The structure of DNA polymerase is highly conserved, meaning their catalytic subunits vary very little from one species to another, irrespective of how their domains are structured. This highly conserved structure usually indicates that the cellular functions they perform are crucial and irreplaceable and therefore require rigid maintenance to ensure their evolutionary advantage.

7 0
3 years ago
Stress is the most common cause of (2 points)
bonufazy [111]

When stress becomes long-term and is not properly addressed, it can lead to a number of more serious health conditions, including depression. It's high blood pressure.

7 0
2 years ago
Read 2 more answers
This graph shows the harbor seal population in the gulf of Maine for a twenty year period. A population of seals with unlimited
NeX [460]

Answer:

Explanation:

This graph shows the harbor seal population in the gulf of Maine for a twenty year period. A population of seals with unlimited

resources will continue to grow exponentially as shown in the graph above. What are some density-dependent limiting factors that

would prevent continued exponential growth? Choose ALL that apply.

es )

5 0
2 years ago
The potential difference across a resting neuron in the human body is about 70 mv, and the current in it is approximately 200ua.
MrMuchimi

I = 200 ua

V = 70 mV

Power = ?

Formula: Power = IV

Solution:

Power = IV

= ( 200 x 10^-6 A ) x ( 70 x 10^-3 V )

Power = 1.4 x 10^-5 Watts

The power that the neuron release is 1.4 x 10^-5 Watts

5 0
3 years ago
Which two factors will increase the rate of a streams flow
Natali5045456 [20]

Answer: velocity and volume of water in the stream

Explanation:

3 0
3 years ago
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