Science: DNA Structure and Protein Synthesis Worksheet

Question 1

Describe the overall shape of a DNA molecule and name the two main parts that make up each nucleotide.

Accepted Answer

A DNA molecule has the shape of a double helix. Each nucleotide contains a sugar-phosphate part and a nitrogenous base.

Question 2

Name the four nitrogenous bases found in DNA and identify which bases pair together.

Accepted Answer

The four nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine. Adenine pairs with thymine, and cytosine pairs with guanine.

Question 3

Explain why the sequence of bases in DNA is important to an organism.

Accepted Answer

The sequence of bases in DNA is important because it stores the genetic instructions for making proteins. Different base sequences lead to different proteins and traits.

Question 4

What is a gene, and where are genes located in a cell?

Accepted Answer

A gene is a segment of DNA that contains instructions for making a protein or functional RNA. In eukaryotic cells, genes are located on chromosomes in the nucleus.

Question 5

Compare DNA and RNA by giving two differences between them.

Accepted Answer

DNA contains deoxyribose sugar and uses thymine, while RNA contains ribose sugar and uses uracil. DNA is usually double-stranded, while RNA is usually single-stranded.

Question 6

What is transcription, and where does it occur in a eukaryotic cell?

Accepted Answer

Transcription is the process of making an RNA copy of a DNA sequence. In a eukaryotic cell, transcription occurs in the nucleus.

Question 7

During transcription, how does mRNA relate to the DNA template strand?

Accepted Answer

During transcription, mRNA is built as a complementary copy of the DNA template strand. RNA nucleotides pair with the DNA bases according to base-pairing rules, except RNA uses uracil instead of thymine.

Question 8

Write the mRNA sequence that would be transcribed from this DNA template strand: TAC GGA CTT

Accepted Answer

The mRNA sequence transcribed from the DNA template strand TAC GGA CTT is AUG CCU GAA.

Question 9

What is translation, and where does it occur in the cell?

Accepted Answer

Translation is the process in which the ribosome reads the mRNA sequence and assembles amino acids into a protein. Translation occurs at ribosomes in the cytoplasm.

Question 10

What is the role of tRNA in protein synthesis?

Accepted Answer

tRNA brings specific amino acids to the ribosome during translation. Each tRNA has an anticodon that matches an mRNA codon, helping place amino acids in the correct order.

Question 11

Define the term codon and explain its function in protein synthesis.

Accepted Answer

A codon is a sequence of three nucleotides on mRNA. Its function is to specify a particular amino acid or a start or stop signal during protein synthesis.

Question 12

An mRNA strand contains the codons AUG UUU GGC. Explain what these codons represent during translation.

Accepted Answer

These codons represent instructions for adding specific amino acids to a growing protein. AUG is the start codon and codes for methionine, UUU codes for phenylalanine, and GGC codes for glycine.

Question 13

What happens if a mutation changes one base in a DNA sequence?

Accepted Answer

If a mutation changes one base in a DNA sequence, it may change the mRNA codon and possibly alter the amino acid placed in the protein. This can have no effect, a small effect, or a major effect depending on the change.

Question 14

Explain why proteins are important in living organisms.

Accepted Answer

Proteins are important because they perform many jobs in living organisms, including acting as enzymes, providing structure, transporting materials, and helping cells communicate and function properly.

Question 15

Summarize the flow of genetic information from DNA to RNA to protein.

Accepted Answer

Genetic information flows from DNA to RNA to protein. DNA is transcribed into mRNA, and then mRNA is translated at the ribosome to build a protein from amino acids.

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Science: DNA Structure and Protein Synthesis

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