Problem Analysis:
The image provided is a diagram of the process of transcription in molecular biology. Transcription is the first step in gene expression, where DNA is used as a template to synthesize RNA. The diagram shows the key components involved in this process, including DNA, RNA, and an enzyme called RNA polymerase.
The task asks us to:
1. Identify the missing molecule marked on the diagram.
2. Label it correctly using the options provided: adenine, guanine, cytosine, or thymine.
Step-by-Step Solution:
#### 1.
Understanding the Diagram:
- The diagram shows a section of DNA (double helix) with one strand being used as a template for RNA synthesis.
- RNA polymerase is shown binding to the DNA, indicating that transcription is occurring.
- A new RNA strand is being synthesized complementary to the template DNA strand.
- There is a labeled "missing nucleotide" in the RNA strand.
#### 2.
Key Concepts in Transcription:
- During transcription, RNA polymerase reads the template strand of DNA and synthesizes a complementary RNA strand.
- The base pairing rules for transcription are:
- DNA: A (adenine) pairs with T (thymine).
- DNA: T (thymine) pairs with A (adenine).
- DNA: G (guanine) pairs with C (cytosine).
- DNA: C (cytosine) pairs with G (guanine).
- In RNA, uracil (U) replaces thymine (T), so the base pairing in RNA is:
- RNA: A pairs with U.
- RNA: U pairs with A.
- RNA: G pairs with C.
- RNA: C pairs with G.
#### 3.
Identifying the Missing Nucleotide:
- The template DNA strand has a visible nucleotide labeled as "A" (adenine).
- According to the base pairing rules for transcription, adenine (A) in DNA pairs with uracil (U) in RNA.
- Therefore, the missing nucleotide in the RNA strand must be
uracil (U).
#### 4.
Labeling the Missing Nucleotide:
- The missing nucleotide is part of the RNA strand, and based on the base pairing rules, it must be
uracil (U).
Final Answer:
The missing nucleotide marked on the diagram is
uracil (U).
$$
\boxed{\text{uracil}}
$$
Parent Tip: Review the logic above to help your child master the concept of rna transcription worksheet.
