High School Biology : Understanding Transcription Regulation

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Transcription Regulation

All of the following statements about RNA are true EXCEPT __________.

Possible Answers:

RNA contains the carbohydrate ribose

RNA is most frequently a single-stranded molecule

adenine always pairs with uracil and cytosine always pairs with guanine in RNA

adenine always pairs with thymine and cytosine always pairs with guanine in RNA

RNA and DNA both have a sugar-phosphate backbone in their molecular structure

Correct answer:

adenine always pairs with thymine and cytosine always pairs with guanine in RNA

Explanation:

It is important to remember the base-pairing rules when discussing both DNA and RNA because they are the rules by which all of transcription and translation occur. In RNA, uracil takes the place of thymine, creating an A-D pair instead of an A-T pair. The structure of RNA is a single strand of alternating ribose and phosphate groups with nitrogenous bases attached to the ribose. One way that DNA and RNA differ is that DNA contains deoxyribose sugar while RNA contains the ribose sugar.

Example Question #4 : Transcription

Protein synthesis is the process by which proteins are made in cells. The proper order and location of the two main parts of protein synthesis are __________.

Possible Answers:

1) Translation in the nucleus 2) Transcription in the endoplasmic reticulum

1) Translation at the ribosome 2) Transcription in the nucleus

1) Transcription at the ribosome 2)Translation in the nucleus

1) Transcription in the cytoplasm 2) Translation in the nucleus

1) Transcription in the nucleus 2) Translation at the ribosome

Correct answer:

1) Transcription in the nucleus 2) Translation at the ribosome

Explanation:

Transcription must occur first because it is the process that copies the genetic code from the DNA, and it must occur in the nucleus because DNA is too large a molecule to leave the nucleus. Next comes translation, which is the reading of the "photocopied" code (mRNA) after it leaves the nucleus and connects with a ribosome. After this, the mRNA binds with ribosomes and is translated to create proteins.

Example Question #2 : Understanding Transcription Regulation

The tRNA holds the _________ which is the complimentary code of the __________ on the mRNA.

Possible Answers:

anticodon . . . codon

codon . . . anticodon

polypeptide . . . nucleic acid

protein . . . amino acid

transcription  . . . translation

Correct answer:

anticodon . . . codon

Explanation:

RNA is the key molecule involved in protein synthesis. During translation, the mRNA binds to a ribosome carrying a sequence of codons. The tRNA then binds to the ribosome/mRNA complex with the matching anticodon. The anticodon contains the three complimentary nucleotides to the codon.

Example Question #3 : Understanding Transcription Regulation

Prokaryotic transcription __________.

Possible Answers:

occurs in the cytoplasm

involves tRNA

occurs in the nucleus

is the same as eukaryotic transcription

occurs on ribosomes

Correct answer:

occurs in the cytoplasm

Explanation:

Prokaryotes do not have nuclei. It is translation, not transcription, that occurs on ribosomes. tRNA is the type of RNA that brings amino acids to the ribosome; again, translation is the process of protein synthesis from amino acids. There are many differences between eukaryotic and prokaryotic transcription! These differences are monumental in differentiating between eukaryotes and prokaryoes. For example, in eukaryotes, transcription occurs in the nucleus and involves mRNA processing—adding a 5' cap, adding a 3' poly-A tail, and splicing out introns; none of these things are true for prokaryotes.

Example Question #4 : Understanding Transcription Regulation

mRNA gets translated by the ribosome in sets of __________ nucleotides.

Possible Answers:

six

one

three

two

four

Correct answer:

three

Explanation:

The genetic code is based on codons, which are sets of three nucleotides. mRNA is read in the triplet code; each codon specifies for an amino acid. The genetic code is redundant (one amino acid may be coded for by multiple codons), but each codon only codes for one amino acid, or the stop codon.

Example Question #5 : Understanding Transcription Regulation

Which of these processes does not play a role in transcription regulation?

Possible Answers:

Ubiquitin

Chromatin remodeling complexes

Alternative splicing

DNA binding motifs and the associated proteins

Repressors

Correct answer:

Ubiquitin

Explanation:

Ubuiqitin is a protein synthesized to tag worn out or defective proteins for recycling. Since this would only eliminate proteins that have already been synthesized, it would be more of a translational regulation process. 

The other choices are common transcription regulators. Chromatin remodeling complexes are proteins that interact with the histones in chromatin. They are able to expand or condense the amount of coiling around histones and therefore allow greater or lesser access by transcription machinery to the DNA; thus, when the DNA is more tightly bound, it is less accessible and transcription is regulated. Our genes are broken into coding and non-coding sequences called exons and introns respectively. Alternative splicing is a process that alters the mRNA transcription product by selecting different combinations of exons to be joined together. This is an important process and allows the body to produce many more proteins than it normally would from the same quantity of genes. DNA binding motifs and their associated proteins are called transcription factors when interacting and they regulate transcription. They regulate by blocking a genes' promoter region (reduces the expression of that sequence) or they bond to the promoter to help the transcription machinery recognize that sequence and assemble itself (increases expression). Last, repressor proteins bond to promoter regions of genes they regulate. Often times the product of that gene is responsible for activating and inactivating that repressor. For example, a large quantity of a gene product can make it more likely for the repressor and that gene product (protein) to meet and join. This activity generally turns repressors on and transcription of that gene is reduced or stopped.

Example Question #6 : Understanding Transcription Regulation

Which of the following types of RNA forms ribosomes?

Possible Answers:

snRNA

mRNA

miRNA

tRNA

rRNA

Correct answer:

rRNA

Explanation:

rRNA forms ribosomes.

tRNA is transport RNA, it joins amino acids to ribosomes to assemble a protein molecule

SnRNA is small nuclear RNA, it splices pre-mRNA to form mRNA

miRNA is microRNA, which regulates gene transcription and translation

mRNA is messenger RNA, carries the genetic code for controlling the protein formed.

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