Exam 2 Flashcards
1
Q
DNA contains information for making _____.
A
proteins
2
Q
Proteins play a role in (select any that apply):
- acting as enzymes
- acting as pores to allow substances in or out of a cell
- causing cells to move
- maintaining cell structure
A
All are correct
3
Q
What is the function of mRNA?
A
mRNA delivers information from DNA to the ribosome
4
Q
During transcription, _____ is used to make _____.
During translation, _____ is used to make _____.
During replication, _____ is used to make _____.
A
DNA to RNA, RNA to protein, DNA to DNA
5
Q
Why is it useful for a cell to make a copy of its own DNA?
A
Cells divide to produce new cells, and each daughter cell must contain the same information as the original cell so that it can function in the same way.
6
Q
The primary enzyme that performs transcription is _____. This enzyme produces _____.
A
RNA polymerase, RNA.
7
Q
Promoter sequences are only found on _____, and they signal where a cell should start _____ a gene.
A
DNA, transcribing`
8
Q
Which nucleotide is found in RNA but not DNA?
A
Uracil
9
Q
Terminator sequences are found only on _____. They signal where a cell should stop _____ a gene.
A
DNA, transcribing
10
Q
the -10 and ___ regions within a promoter sequence tend to be identical in all _____ promoter sequences.
A
-35, bacterial
11
Q
The singma factor is a _____ that binds to an enzyme called _____. After the sigma factor binds to this enzyme, the enzyme can then bind to _____.
A
protein, RNA polymerase, promoter sequence.
12
Q
True or false:
All sigma factors within a single bacterial cell are identical. Explain your answer.
A
false; having different sigma factors within a single bacterial cell allow genes to be better equipped to survive in a range of environments
13
Q
Terminator regions/sequences encode for (hint: 2 things):
A
RNA that can form a loop structure, and RNA that is made of a string of U’s.
14
Q
What causes transcription to end?
A
The combination of the hairpin loop, which prevents RNA polymerase from moving forward, and the weak bonds between the A and U nucleotides causes RNA polymerase to fall off and transcription to end
15
Q
Polycistronic mRNA contains information for producing _____ proteins, and it is more commonly produces in _____ cells.
A
Multiple, prokaryotic
16
Q
What is an operon? What is the advantage of having genes arranged in an operon?
A
A string of DNA that contains only 1 promoter sequence and 1 terminator sequence around a grouping of genes. This allows multiple proteins to be produced, and these proteins can all work together to do something.
17
Q
Poly-G caps are added to the mRNA of _____ cells.
Poly-A tails are added to the mRNA of _____ cells.
Introns are found in the mRNA of _____ cells.
A
Eukaryotic (for all 3)
18
Q
Where does translation occur?
A
In the ribosome
19
Q
What are the building blocks of proteins?
A
Amino acids
20
Q
What is the role of tRNA?
A
to bring amino acids to the ribosomes
21
Q
Eukaryotic cells have ___S ribosomes, while prokaryotic cells have ___S ribosomes.
A
80, 70
22
Q
Start codons are found of _____, and their function is to mark where _____ should begin.
A
mRNA, translation
23
Q
Ribosome binding sites are found on _____, and these binding sites are where _____ first bind to begin the process of _____.
A
mRNA, ribosomes, translation
24
Q
Stop codons are found on _____. They signal where _____ should fall off to end the process of _____.
A
mRNA, ribosomes, translation.
25
RNA primers bind to _____ so that _____ can begin the process of _____.
DNA, DNA polymerase, DNA replication
26
Nucleotides that are used by DNA polymerase to build a new DNA strand initially have ___ phosphate groups on them. Why is this number important?
3; the energy represented by the 3 phosphate groups is the energy needed to hold the sugar phosphate backbone together.
27
What is the role of DNA polymerase I?
To remove RNA primers at the end of DNA replication
28
What is the role of DNA polymerase III?
It is the main DNA polymerase; it reads the template strand and uses that information to build a complimentary DNA strand.
29
When is DNA polymerase V used?
Only in situations where the template DNA strand is badly damaged
30
Lactose is a (choose from one of the answers below), and it is made from:
Monosaccharide
Disaccharide
Polysaccharide
Disaccharide, galactose and glucose
31
What is the function of beta galactosidase?
It breaks down lactose into galactose and glucose
32
What is the function of beta galactoside transacetylase?
The exact function in relation to lactose metabolism is currently unknown, although it's known to play a role in exporting sugars
33
What is the role of galactoside permease?
It transports lactose into bacterial cells
34
E. Coli produces galactosidase, galactoside transacetylase, and galactoside permease when there (are/ are not) lactose molecules present in the environment.
ARE
35
Galactosidase permease is encoded for by the _____ gene.
Lac Y
36
Beta galactosidase is encoded for by the _____ gene.
Lac Z
37
Beta galactoside transacetylase is encoded for by the _____ gene.
Lac A
38
CAP-cAMP binds _____ of the promotor region, and it's function is that it strengthens the interaction between _____ and the _____.
upstream, RNA polymerase, promotor
39
The operator region is located _____ of the lac genes and _____ of the promotor region. The operator region is where _____ binds to _____ RNA polymerase __________.
Upstream, downstream, the repressor protein, prevent, from starting transcription
40
The lac I gene is located _____ of the promotor region and it encodes for the _____.
upstream, repressor protein
41
The presence of lactose causes E. Coli to turn ___ its lactose operon.
On
42
If E. coli has access to both glucose and lactose, it would metabolize the _____ first. This means that when glucose is around, E. coli _____ need to use the lactose operon. In other words, the presence of glucose causes the lactose operon to become turned ___.
Glucose, doesn't, off.
43
Why is it beneficial for cells to experience a change in their DNA sequence? Why might it be harmful?
It can cause a change in at least one protein within a cell, which can lead to the protein functioning a little bit better in it's environment, or it can hinder the protein's function.
44
What are two things that can cause genetic change in bacteria?
Mutation or horizontal gene transfer
45
What is a mutagen?
an agent that causes a genetic mutation
46
Other than mutagens, what causes genetic mutations to occur?
DNA polymerase; it regularly makes mistakes
47
When a cell's DNA becomes altered, the altered DNA may be passed on to other bacteria. When the altered DNA is passed on to other cells within the same environment, it's called _____ gene transfer. When the altered DNA is passed on to a bacterial cell's offspring it is called _____ gene transfer.
Horizontal; vertical
48
What are the three stop codons? What is the start codon?
UAA, UAG, UGA; AUG (Met)
49
List the basic structures of a virus from the outside in:
Envelope, Matrix, Capsid, Nucleic acid
50
Stop the Nonsense. You know that nonsense mutations produce a _____ _____ codon.
premature stop
51
Missense mutations produce a protein that is (the same/different) as/from the protein that would have been produced without a mutation.
different
52
When a bacterium loses the ability to produce at least one amino acid it is considered to be:
an auxotroph
53
How can DNA polymerase III repair a mistake? What about DNA polymerase I?
It can proofread and substitute the wrong nucleotide for the correct one. DNA polymerase I can proofread mistakes made by DNA polymerase III.
54
How do mismatch repair enzymes repair mistakes that weren't caught by DNA polymerase III and DNA polymerase I?
They remove the section of nucleotides containing the mistakes and replace it with the correct nucleotide sequence.
55
How do mismatch repair enzymes detect which strand is the original?
The original strand contains methyl groups
56
UV light can cause _____ to form between two Thymine nucleotides. List three ways that this can be fixed:
Dimers; nucleotide excision repair, light repair systems that can activate enzymes and break the dimer, and SOS DNA repair which uses a special type of DNA polymerase to produce a random nucleotide to replicate the DNA (or try to anyway)
57
There are three ways to repair damage from UV light. Which way is present only in prokaryotic cells?
light repair systems
58
What type of DNA polymerase is used during SOS DNA repair?
DNA polymerase V
59
When DNA polymerase III is reading a template strand containing a thymine dimer, it _____ the nucleotides. When DNA polymerase V is reading a template strand containing a thymine dimer, it _____ the nucleotides. Which of the two enzymes can proofread?
skips, randomly replaces, DNA polymerase III
60
What is the name of the gene that encodes for DNA polymerase V?
UmuD gene
61
What is the relationship between the LexA protein and the UmuD gene?
The LexA protein is a repressor protein that prevents the UmuD gene from being turned on to produce DNA polymerase V
62
If the RecA protein is active, it causes DNA polymerase V to _____.
be produced
63
What does the RecA protein do?
It removed the LexA protein from the DNA, causing the UmuD gene to be expressed, which produced DNA polymerase V.
64
When is the RecA protein produced?
ONLY if a bacterial cell's DNA becomes too badly damaged
65
Describe the general difference between conjuction, transduction, and transformation.
Conjuction requires cell to cell contact, transduction requires a virus to infect a bacterial cell, and transformation is when DNA from the environment is picked up by a bacterial cell
66
Can bacteria that has been heated and killed cause disease?
No, they are dead
67
Can non-encapsulated bacteria cause disease?
No, they require a capsule
68
What does it mean when a bacterium is competent?
The bacterium is capable of taking in naked DNA (being transformed)
69
What are two natural things that could cause bacteria to become competent?
When the population has become too dense (to ensure that donor bacteria are around), and not enough nutrients in the cells environment (low concentration of Nitrogen or carbon.
70
What are two things that can be done artificially to cause bacteria to become competent?
Placing the bacteria in an environment that contains calcium ions and heat-shocking the bacteria.
71
How are viruses different than bacteria?
Viruses are not a cell; they do not contain ribosomes, membranes, etc. and they must infect a host cell in order to replicate. Bacteria contain ribosomes and a plasma membrane, and they can replicate on their own. Viruses are 100x smaller than bacteria.
72
How are viruses similar to bacteria?
they are both capable of causing disease
73
mitochondria in our cells are about the same size as:
a bacterium
74
What are three different shapes that a virus can have?
Helical, icosahedron, and complex
75
What are capsids made of?
capsomeres, which consist of individual protein subunits
76
What two structures of a virus go hand in hand?
the matrix and the envelope
77
Describe ways that viral nucleic acids can differ from one another:
Some contain RNA while others contain DNA, some are single stranded while others are double stranded, some are segmented while others are non-segmented, and some have + sense nucleic acids while others have - sense nucleic acids
78
Another term for mRNA is _____sense RNA
+
79
All Sense + RNAs have a _____ and a _____.
ribosome binding site and start codon
80
What is the relationship between Sense + RNA and Anti-Sense - RNA?
They are compliments of each other, because sense + can be translated to make a protein but sense - cannot
81
Can DNA be translated?
No; it must be transcribed to RNA first
82
Which of these can be directly translated to make a protein?
Sense + RNA
Sense + DNA
Antisense - RNA
Antisense - DNA
Sense + RNA only
83
what is a bacteriophage?
a virus that infects bacterial cells
84
What are some basic structural differences between bacteriophage and animal viruses?
bacteriophage have a complex structure, while animal viruses only have a "head" not legs or a body. Animal viruses can have an envelope and a matrix, but bacteriophage rarely have this.
85
In bacteriophage, what's the difference between productive infection and latent infection?
productive infections produce new bacteriophage that leave the host cell to infect other cells, whereas latent infections reproduce nucleic acids only by copying the DNA and passing it on every time the host cell divides
86
what is a lysogenic infection?
the same thing as a latent infection
87
Outline and describe the steps of a productive infection in bacteriophage:
One: Attachment of viral receptors to molecules found on the host cell's surface
Two: Penetration of the viral genetic material into the host cell
Three: Biosynthesis of viral components (viral proteins and viral nucleic acids)
Four: Assembly of the viral components to make new, complete viruses
Five: Release of newly produced viruses
88
What is the function of the nuclease gene found on the genome of bacteriophage?
It encodes for the nuclease enzyme, which degrades the chromosomal DNA of the host cell so it can no longer be used. The host cell's resources can now be devoted to producing viral materials.
89
What is the function of the polymerase gene found on the genome of bacteriophage?
It encodes for the polymerase enzyme, which function in producing nucleic acids.
90
What is a viral early gene?
Genes that are expressed first, after a virus gains entry into its host cell (ex. nuclease and polymerase
91
What is the function of the lysozyme gene that is found on the genome of bacteriophage?
it encodes for lysozyme enzyme that degrades the cell wall of the host bacterial cell so that newly formed viruses can be realeased
92
What are the two ways that newly formed viruses can leave their host cell?
Lysing the host cell open; killing the host cell, or by extrusion where the viral parts are assembled within the host cell's membrane and then pushed out
93
Outline the steps of what happens when a bacteriophage causes a latent infection?
One: Bacteriophage binds to a specific molecule on the surface of a host cell
Two: Bacteriophages DNA enters the host cell
Three: Bacteriophages DNA becomes inserted into the DNA of the host cell
Four: Every time the host cell's DNA become replicated, the phage DNA becomes replicated along with it.
94
What is prophage?
Bacteriophage DNA that has become integrated into host cell DNA
95
What is a lysogen?
a bacterial cell that is infected with latent bacteriophage
96
What is the difference between lytic bacteriophage and temperate bacteriophage?
lytic can only cause productive infections. Temperate can cause latent and switch to productive
97
When would a phage want to switch from latent to productive replication cycle?
If the host cell becomes damaged
98
The excisase gene is found on the _____ DNA.
bacteriophage DNA
99
When the excisase gene is turned off, it causes the bacteriophage to undergo _____ infection. When this gene is turned on, it causes the bacteriophage to undergo _____ infection.
latent; productive
100
Is it easy or difficult for another phage to infect the same cell?
Difficult (due to a repressor protein produced by the first phage)
101
What is lysogenic conversion?
it happens when a latent phage infects a bacterial cell, resulting in the bacterial cell having new abilities. (ex. a cell producing a toxin once infected)
102
What happens during generalized transduction?
One: a bacteriophage enters a host bacterial cell to cause productive infection
Two: bacteriophage produces nuclease to destroy the host cell's DNA.
Three: When new viruses are put together, sometimes a phage "accidentally" picks up a fragment of bacterial DNA instead of viral DNA
Four: When this phage infects a new cell, it transfers bacterial DNA
103
What is the function of restriction enzymes?
they are produced by bacterial cells and they cut up viral DNA that enters the bacterium
104
What is the purpose of the modification gene in bacterium?
It encodes for a protein that adds methyl groups to bacterial DNA. It protects bacterial DNA from getting cut up by its own restriction enzymes.
105
Outline how the CRISPR-cas system works to protect bacteria against repeat viral infections.
One: Bacteriophage injects DNA into host bacterial cell
Two: The Cas1 protein in the bacterial cell takes a piece of the phage DNA and inserts it between two palindromic sequences on the bacterial DNA
Three: Once inserted, the phage DNA is referred to as a spacer. This spacer can be transcribed to produce crRNA
Four: When the bacterial cell is attacked by the same type of virus in the future, the crRNA works with Cas9 protein to bind to and cut the viruses DNA
106
What is the difference between acute infection and persistent infection?
Acute is short lived with severe symptoms, while persistent lasts longer with mild to no symptoms
107
Describe two different ways that viruses can gain entry into their host cell:
Inducing endocytosis; the virus binds to the cell and tricks the cell into taking it in.
Fusion, which only occurs with viruses containing an envelope
108
What happens to the capsid of an animal virus once the virus has entered it's host cell?
It sheds the capsid and it breaks down
109
What are two different ways that animal viruses can exit from their host cell?
Lysing or budding out of the host cell
110
Herpes virus can cause acute infection in what type of cell?
Epithelial cells
111
Herpes virus causes persistent infection in what type of cells?
Nerve cells
112
The herpes virus (does/ does not) integrate its genetic material into the host, and it stays in the nerve cell's cytoplasm _____ replication
does not, without
113
Explain how damage to a host cell's DNA can trigger latent bacteriophage to become productive.
When a host cell's DNA is heavily damaged, it tries to repair the damage by producing Rec A. Rec A removes Lex A (a repressor protein) from the DNA of a bacterial cell. When Lex A is removed it allows the UmuD gene to be turned on. This results in the productive DNA polymerase V to repair the damage.
