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Biology
A Level

How does the Meselson and Stahl Experiment provide evidence for the semi conservative theory of DNA replication?

Before we start on the specifics of the experiment itself we need to understand how DNA replication occurs on a molecular level. DNA is made up of four different bases; A, C, G and T....

JD
Answered by Julia D. Biology tutor
26508 Views

How is mRNA produced in the nucleus of a cell?

Genes in DNA encode protein molecules. The first step of expressing a gene is transferring the information in DNA to a messenger RNA (mRNA) molecule, by a process called transcription. DNA Helicase unwind...

JT
Answered by Jamie T. Biology tutor
43944 Views

How does the body increase heart rate in response to exercise?

Heart rate is controlled by the AUTONOMIC nervous system. This is the branch of the nervous system which does NOT require voluntary thought and action, unlike the SOMATIC branch. This means it relies upon...

CC
Answered by Corey C. Biology tutor
26469 Views

Explain why maltose can only be broken down by the enzyme maltase.

The active site of an enzyme is complementary (meaning, it fits perfectly) to a substrate (in this can the substrate being maltose). Once the maltose and maltase combine to form the enzyme-substrate compl...

BP
Answered by Bradley P. Biology tutor
10218 Views

How does DNA replication occur?

DNA normally exists in the cell as a double-stranded structure, comprising of two complementary strands that are held together by hydrogen bonds.

DNA replication involves two main steps. Firstly, t...

KH
Answered by Katharine H. Biology tutor
12197 Views

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