Chapter 8
Humans need to have _____ amino acids to build proteins.
20
A protein is made up of two folded chains of amino acids. One is 328 amino acids in length and the other is 252 amino acids in length. Which of these could disrupt the function of this protein?
A change occurs in one or both of the chains.
If a section of messenger RNA has the sequence UCAGUC, what is the corresponding sequence on the complementary DNA?
AGTCAG
Which statement is true of amino acids?
All amino acids have unique chemical side chains.
Which statement is NOT true of the shape of proteins?
All humans are genetically identical and, therefore, produce identical proteins.
Which statement is true of proteins?
All proteins are made of amino acids
If a mutation in a long chain of codons changes a codon sequence of one codon from CUU to CUC, what effect would that have on the protein produced?
Both of the codons code for the same amino acid and no change would be observed in the protein.
How do you think replacing one amino acid in a protein with another amino acid would affect the shape of that protein?
Changing one amino acid may or may not change the shape of the protein.
The information that ultimately encodes the shape and sequence of a protein comes from
DNA
Transcription is the process of copying _____ into
DNA; mRNA
Yeast are the only organisms that can be genetically engineered to produce spider silk.
False
A woman lacks one of the amino acids used to build insulin, a protein that helps control blood sugar levels. What is the expected outcome of this deficiency?
Her insulin will no longer function normally.
Why is it important to inject a recombinant gene into an embryo instead of an adult when working with a multicellular organism?
Injecting the gene into an embryo ensures that all body cells receive a copy of the gene.
Which statement is true of RNA polymerase?
It is an enzyme used in transcription.
Which statement is true about the three-dimensional shape of a protein?
It is determined by the order of the amino acids and is critical for the function of the protein.
Chargaff discovered that the A-T bond has the same width as the G-C bond. What implication does this have for the structure of the DNA molecule?
It means that the molecule will vary in width as you move down its length, depending on the number of A-T and G-C nucleotides.
How many different basic core structures are found in the amino acids in a yeast cell?
One
What allows different cell types the ability to produce different proteins and, therefore, have different identities?
Only certain cells are able to turn on the regulatory sequence and express certain genes.
Which statement does NOT describe proteins?
Proteins are translated into an mRNA sequence.
Why are many drugs either proteins or drugs that interact with proteins?
Proteins play vital roles within cells, which allow cells to function.
How does RNA differ from DNA?
RNA contains uracil (U) instead of thymine (T).
In a recombinant gene, the "on-off switch" is the _____ sequence.
Regulatory
Rosalind Franklin used x-ray diffraction to record how x-rays scatter when bounced off the surface of DNA molecules. Which of the following conclusions about the structure of DNA did her images support?
The DNA helix was likely made of two strands., hydrophilic and extends upon exposure to water, likely helical and uniform in width.
Which of these could be possible if a single nucleotide in the coding sequence of DNA controlling transcription was changed?
The function of the protein could change.
Which of these is NOT required to produce transgenic animals?
The genes used to form recombinant DNA must be from closely related species.
Phospholipids, molecules found within a cell membrane, have hydrophobic tails and hydrophilic heads. These regions act in the same manner that hydrophobic and hydrophilic amino acids act. When phospholipids are found as a sphere in a glass of water, which of the following would you expect?
The hydrophilic heads will point toward the water, and the hydrophobic tails will point away from the water.
Alleles are alternative forms of the same gene. Different alleles have small differences in their nucleotide sequences, which lead to slightly different shapes in the proteins they encode. Which of the following is NOT a true statement regarding alleles?
The proteins that they encode always have identical functions.
A mutation that substitutes one nucleotide for another occurs in the regulatory sequence of the spider silk gene in a transgenic yeast. What would you expect as an outcome?
The timing of spider silk protein production may change.
Which anticodon would bind to a codon with the sequence AUG?
UAC
Which of the following scientists is incorrectly paired with their contribution to the discovery of the structure of DNA?
Watson and Crick; x-ray diffraction images of DNA helix
Denaturation affects the bonds between amino acids in a protein. Would you expect denaturation to affect the function of a protein?
Yes, altering the bonds between amino acids changes the shape of a protein and alters its function.
What is a gene?
a DNA sequence that has the instructions to make one or more proteins
Which of these is NOT an example of a protein?
a chromosome.
The sequence of the _____ in a protein chain will determine the overall shape of the protein and, therefore, the protein's function.
amino acids.
Human cells contain 20 _____ that are used to build macromolecules called
amino acids; proteins.
One end of a tRNA molecule has an anticodon that binds to mRNA. The other end of the tRNA molecule binds to
an amino acid.
The segment of three nucleotides in a transfer RNA (tRNA) molecule that binds with messenger RNA (mRNA) is called a(n)
anticodon.
Of the 64 codons that code for 20 amino acids, three codons are unique because they
are "stop" codons.
Rosalind Franklin did not receive the credit she deserves for her contribution to the discovery of the structure of DNA because
at the time, prevailing attitudes were negative toward women in science, her paper was perceived merely as supporting evidence for Watson and Crick's model, and she died before the Nobel Prize was awarded to Watson, Crick, and Wilkins.
In a recombinant gene, the _____ sequence controls the amino acid sequence of the protein produced.
coding
The triplet code on messenger RNA (mRNA) is referred to as a(n
codon
The triplet code on messenger RNA (mRNA) is referred to as a(n)
codon.
The genetic code table shows the relationship between _____ and
codons; amino acids
Alleles are alternative forms of the same gene(s) that have small differences in their nucleotide sequences. Two alleles produce
different amino acid sequences
Two different proteins have different amino acid sequences. These proteins will have
different shapes and different functions.
The _____ of a protein is determined by its overall three-dimensional shape.
function.
Chromosomes have many _____, which contain the instructions for a cell to produce at least one _____.
genes; proteins
Two amino acids differ in their interactions with water. These two amino acids
have different side chains.
Amino acid side chains
help determine the structure of the protein and its function.
Human proteins can be produced by cells in the milk-producing mammary glands of transgenic mammals if the regulatory sequence of a milk gene is used to produce the recombinant gene. Why is it important to use the regulatory sequence of a milk gene when constructing a recombinant gene used to produce a human protein secreted in milk? The regulatory sequence controls the
location of gene expression.
Translation is the process of using _____ to make
mRNA; proteins
Translation is the process of using _____ to make____
mRNA; proteins
Scientists have used genetic engineering technology to create transgenic plants that contain genes for
natural pesticides.
Exchanging a hydrophilic amino acid with a hydrophobic amino acid in the sequence of a protein can alter the shape of that
protein
A single amino acid change in the sequence of a protein can alter the function of that
protein.
Damage to a cell's ribosomes would affect its ability to make
proteins
Which organelle is the site of protein synthesis?
ribosome
A purified protein is working well in a laboratory test. The researcher adds a new chemical to the mixture in the test tube and notices that the protein stops working. Upon further investigation, the researcher is able to determine that the protein still has its normal sequence of amino acids. The protein must have had a change in its
shape.
Amino acids are unique in their _____, but have the same _____. _ level: 1
side chains; core.
The molecules that bind and transport amino acids through the cytoplasm for translation are
tRNA
Which part of a gene is actually copied into mRNA?
the coding sequence
You create a hybrid transgene containing DNA from a human and a mouse. Which factor would most strongly affect when, where, and how much protein is expressed from that gene?
the gene's regulatory region
You create a hybrid transgene containing DNA from a human and a mouse. Which factor would most strongly affect when, where, and how much protein is expressed from that gene?
the gene's regulatory region.
The conformation of a protein refers to
the protein's unique three-dimensional shape.
Which factor is NOT important in determining the shape of a protein?
the speed of translation.
Altering the regulatory sequence used in producing a transgenic yeast could alter the
timing of gene expression.
DNA is _____into messenger RNA (mRNA) in the nucleus. Messenger RNA (mRNA) then leaves the nucleus to be _____ into proteins in the cytoplasm.
transcribed; translated
Which of the following pieces of critical information did Watson and Crick use to build and propose their model of the structure of DNA?
x-ray diffraction images that show DNA as a double helix, an incorrect model that depicts DNA as a triple helix with the phosphate groups on the inside, A always equals T and G always equals C, and x-ray diffraction images that suggest DNA is hydrophilic and elongates upon exposure to water.
To produce spider silk in yeast requires a regulatory sequence from a _____ gene and a coding sequence from a _____ gene.
yeast; spider