All High School Biology Resources
Example Questions
Example Question #1 : Understanding Transcription Regulation
All of the following statements about RNA are true EXCEPT __________.
adenine always pairs with uracil and cytosine always pairs with guanine in RNA
RNA contains the carbohydrate ribose
RNA is most frequently a single-stranded molecule
RNA and DNA both have a sugar-phosphate backbone in their molecular structure
adenine always pairs with thymine and cytosine always pairs with guanine in RNA
adenine always pairs with thymine and cytosine always pairs with guanine in RNA
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 #2 : Understanding Transcription Regulation
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 __________.
1) Transcription in the cytoplasm 2) Translation in the nucleus
1) Translation in the nucleus 2) Transcription in the endoplasmic reticulum
1) Transcription at the ribosome 2)Translation in the nucleus
1) Translation at the ribosome 2) Transcription in the nucleus
1) Transcription in the nucleus 2) Translation at the ribosome
1) Transcription in the nucleus 2) Translation at the ribosome
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 #1 : Understanding Transcription Regulation
The tRNA holds the _________ which is the complimentary code of the __________ on the mRNA.
anticodon . . . codon
polypeptide . . . nucleic acid
transcription . . . translation
codon . . . anticodon
protein . . . amino acid
anticodon . . . codon
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 #11 : Transcription
Prokaryotic transcription __________.
involves tRNA
occurs in the cytoplasm
occurs in the nucleus
is the same as eukaryotic transcription
occurs on ribosomes
occurs in the cytoplasm
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 #3 : Understanding Transcription Regulation
mRNA gets translated by the ribosome in sets of __________ nucleotides.
one
two
four
six
three
three
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 #14 : Transcription
Which of these processes does not play a role in transcription regulation?
Chromatin remodeling complexes
Repressors
DNA binding motifs and the associated proteins
Ubiquitin
Alternative splicing
Ubiquitin
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 #4 : Understanding Transcription Regulation
Which of the following types of RNA forms ribosomes?
miRNA
mRNA
rRNA
tRNA
snRNA
rRNA
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.