Ch.10 Molecular Biology Of The Gene Flashcards
1
Q
Scientists manipulate ____ in the lab and use it to change the heritable characteristics of cells.
A
DNA
2
Q
The study of heredity at the molecular level. Ushered in due to the breakthrough which established the role of DNA in heredity through experiments with bacteria and the viruses that infect them.
A
Molecular biology
3
Q
Viruses that exclusively infect bacteria. Called phases for short.
A
Bacteriophage
4
Q
Describe the phage replication cycle.
A
- The phage attaches itself to a bacterial cell.
- The phage injects it’s DNA into the bacterium.
- The phage DNA directs the host cell to make more phage DNA and proteins- new phases assemble.
- The cell loses and releases the new phages.
5
Q
What convinced Hershey and Chase that DNA, rather than protein, is the genetic material of phage T2?
A
Radioactivity labeled phage DNA, but not labeled protein entered the host cell during infection and directed the synthesis of new viruses.
6
Q
Long chains (polymers) of chemical units (monomers).
A
Nucleotides
7
Q
Nucleotide polymer chain constituting a section of nucleic acid molecule.
A
Polynucleotide
8
Q
Each type of DNA has a different nitrogen containing base what 4 are they.
A
Adenine (A)
Cytosine (C)
Thymine (T)
Guanine (G)
9
Q
The number of possible polynucleotides is enormous because of what 2 reasons?
A
- Nucleotides can occur in a polynucleotide in any sequence
2. Polynucleotides can be very long.
10
Q
Each nucleotide consists of what 3 components.
A
- A nitrogenous base
- A sugar
- A phosphate group
11
Q
Nucleotides are joined together by which type of bond between the sugar of one nucleotide and phosphate of the next forming a sugar-phosphate backbone.
A
Covalent bond
12
Q
This is a repeating pattern of sugar-phosphate-sugar-phosphate, in which nitrogenous bases are like ribs that project from this backbone.
A
Sugar-phosphate backbone
13
Q
What is the full name of DNA?
A
Deoxyribonucleic Acid
14
Q
What does the nucleic part of DNA stand for?
A
Nucleic refers to the location in the nucleic eukaryotic cells.
15
Q
This is the name given to Thymine and Cytosine in single ring structures.
A
Pyrimidines
16
Q
This is the name given to Adenine and Guanine in larger doubling structures.
A
Purines
17
Q
What is the full name of RNA?
A
Ribonucleic Acid
18
Q
RNAs sugar is ribose with a _____ group attached to a C atom.
A
-OH group
19
Q
Instead of Thymine, RNA has a _____ nucleotide.
A
Uracil (U)
20
Q
RNA is identical to a DNA polynucleotide chain except for what two differences?
A
RNA has Uracil instead of thymine
RNA sugar is ribose.
21
Q
The DNA double strand helix was discovered by whome?
A
James D. Watson and Francis Clark
22
Q
What is a double helix?
A
Two polynucleotide strands
23
Q
A double ringed base (purine) on one strand must always be paired with what?
A
A single ringed base (pyrimidine) on the opposite strand to produce a molecule of uniform thickness.
24
Q
Each nitrogenous DNA base has a protruding functional group that can best form hydrogen bond with just one appropriate/complimentary partner, what are they?
A
Adenine with Thymine
Guanine with Cytosine
25
Chargraffs rule states what?
That adenine in DNA of any one species is equal to the amount of thymine, guanine is equal to the amount of cytosine.
26
The side ropes of the double helix represent what? The rungs?
Side ropes- represent the sugar phosphate group
| Rungs- represent pairs of nitrogenous bases joined by H bonds.
27
DNA replication depends on what?
Specific base pairing
28
One can determine the sequence of bases in the covered strand by applying the ___ ____ ____ to the unmasked strand.
base-pairing rules
29
This predicted that a cell applies the same rules when copying its genes during each turn of the cell cycle.
Base-pairing rules
30
Each strand becomes a template for the assembly of a complementary strand from a supply of ____ ____ available with in the nucleus.
Free Nucleotides
31
____ link the nucleotides to form new DNA strands.
Enzymes
32
Type of DNA replication in which the replicated double helix consists of an old strand derived from the old molecule and one newly made strand.
Semiconservative model
33
Replication of a DNA molecule begins at particular sites called what?
Origins of replication
34
What are origins of replication?
Short stretches of DNA having a specific sequence of nucleotides.
35
Proteins that initiate DNA replication attach to DNA at _____ separating the two strands of the double helix.
Origin of replication
36
DNA replication proceeds in ____ direction at many sites simultaneously.
two
37
These are the enzymes that link DNA nucleotides to a growing daughter strand. They add nucleotides only to the 3' end of the strand and never the 5' end.
DNA polymerases
38
DNA strand can only grow in the ____ direction.
5'-3'
39
To make another daughter strand polymerase molecules must work outward from the ____ point.
forking
40
These are short newly synthesized DNA fragments that are formed during DNA replication.
Okazaki fragments
41
This links pieces of okazaki fragments together into a single DNA strand.
DNA ligase
42
These "proofread" and remove nucleotides that have base paired incorrectly.
DNA polymerase
43
These repair DNA damaged by radiation.
DNA ligase
44
DNA replication ensure that all of the somatic cells in a mulitcellular organism are what?
Carry the same genetic information
45
Genes control phenotype traits through the expression of___.
Proteins
46
This is genetic makeup that is heritable information contained in the sequence of nucleotide bases in DNA.
Genotype
47
Physical traits are called?
Phenotype
48
These are the links between genotypes and phenotypes. DNA inherited by an organism specifies traits by dictating the synthesis of these.
Proteins
49
The synthesis of RNA under the direction of DNA is called?
Transcription
50
The synthesis of protein under the direction of RNA is called?
Translation
51
What is the flow of genetic information in eukaryotic cells?
DNA---transcription---RNA---Translation---proteins
Transcription occurs within the nucleus
Translation occurs within the cytoplasm.
52
What is the function of a gene?
To dictate the production of a polypeptide.
53
This is the process of eukaryotic genes coding for a set of polypeptides.
Alternative splicing.
54
What are the functions of transcription and translation?
Transcription is the transfer of information from DNA ro RNA. Translation is the use of the information in RNA to make a polypeptide.
55
Genetic information written in ____ is translated into amino acids.
Codons
56
____ provide the instructions for making specific proteins
Genes
57
___ is the bridge between DNA and protein synthesis.
RNA
58
The genetic code instructions for the amino acid sequence of a polypeptide chain, written in DNA and RNA as a series of non-overlapping three-base words.
Triplet code
59
The series of non overlapping three base words are called?
Codon
60
What is the minimum number of nucleotides necessary to code for 100 amino acids?
300
61
The ___ code dictates how condons are translated into amino acids.
Genetic
62
The amino acid translation of each of the nucleotide triplets
genetic code
63
RNA codons are translated to ___ ___.
Amino acids
64
What are the start codons for RNA?
AUG
65
What are the stop codons for RNA?
UAA
UAG
UGA
66
Translate the RNA sequence CCAUUUACG into the corresponding amino acid sequence.
Pro-Phe-Thr
67
_____ produces genetic messages in the form of RNA.
Transcription
68
Where does transcription occur?
The nucleus
69
This is a specific nucleotide sequence acting as a binding site for RNA polymerase and determines where transcription starts and on which strand.
Promotor
70
This signals the end of a gene.
terminator
71
How does RNA polymerase recognize the start and end of a gene?
Special DNA sequences mark the start and the end of a gene.
72
The start of a gene is called a?
Promotor
73
Eukaryotic RNA is processed ____ leaving the nucleus as mRNA.
before
74
This is a type of RNA that encodes amino acid sequences. It conveys messages from DNA to the translation machinery of the cell.
mRNA, messenger RNA
75
mRNA is transcribed from ____ and then translated into ___.
DNA, polypeptides
76
mRNA occurs in the cytoplasm for which cells?
Prokaryotes
77
mRNA molecules must exit the ____ via nuclear pores and then enter the cytoplasm in eukaryotic cells.
nucleus
78
Polypeptide synthesis occurs where?
Cytoplasm
79
These are internal non-coding regions of nucleotides that interrupt nucleotides that actually code for amino acids. they are removed before leaving the nucleus.
Introns
80
These are coding regions and parts of a gene that are expressed. They are joined with a continuous coding sequences to produce on mRNA.
Exons
81
This is a cutting and pasting process that catalyses complex proteins and small RNA molecules. It provides a means to produce multiple polypeptides from a single gene.
RNA splicing
82
Explain why most eukaryotic genes are longer than the mRNA that leaves the nucleus.
These genes have introns which are spliced out of the initial RNA transcript to produce mRNA
83
This is the molecular interpreter between nucleic acids (codons) and the amino acids of proteins.
tRNA, transfer RNA
84
This has a supply of amino acids in its cytoplasm and are obtained from food or manufactured by the cell.
Cell producing proteins.
85
How does tRNA match amnio acids to the appropriate codon to form a new polypeptide?
1. picks up appropriate amino acids
| 2. recognizes the appropriate codons in the mRNA.
86
This is a special triplet of bases that are complimentary to the codon tripled mRNA.
Anticodon
87
What is the key step in translating mRNA to polypeptide?
A tRNA molecule that couples to a complimentary mRNA.
88
Ribosomes build ______.
polypeptides
89
These are structures in the cytoplasm that coordinate the functioning of mRNA and tRNA and catalyze the synthesis of polypeptides.
ribosomes
90
Ribosomes consist of what 2 subunits?
1. large
2. small
These are made up of proteins and a kind of rRNA (ribosomal)
91
Ribosomes have a binding site for tRNA on the ____ subunit.
large (A site)
92
Ribosomes have a binding site for mRNA on the ____ subunit.
small (P site)
93
What do these subunits do?
They act like a vise holding the tRNA and the mRNA molecules close together and allow the amino acids to be connected into polypeptide chains.
94
How does a ribosome facilitate protein synthesis?
It holds mRNA and tRNA together and connects amino acids fro the tRNA to the growing polypeptide chain.
95
What marks the start of an mRNA message?
an initiation codon
96
What three phases can translation be divided into?
1. Initiation
2. Elongation
3. Termination
97
This brings together mRNA and tRNA bearing the first amino acid and the 2 subunits of ribosomes. It also establishes exactly where translation will begin, ensuring that mRNA codons are translated into the connecting sequence of amino acids.
Initiation
98
What are the first steps in which initiation occurs?
1. mRNA molecule binds to small ribosome subunit. tRNA base pairs with the start codon, tRNA carries the amino acid its start codon base pairs with the start codon.
99
What is the second step of initiation?
2. Large ribosome subunits bind to the small subunit creating a functional ribosome. Initiator fits into one fo the 2 tRNA binding sites on the ribosome called the P-site.
100
What does P site do?
Holds the growing polypeptide.
101
What does A site do?
The acceptor for the growing protein during peptide bond formation.
102
What would happen if a genetic code mutation in a gene changed a start codon to some other codon?
The mRNA transcribed from the mutated gene would be nonfunctional because ribosomes could not initiate translation correctly.
103
This adds amino acids to the polypeptide chain until a stop codon terminates translation.
Elongation
104
Briefly describe the 3 step elongation process.
1. Anticodon of the incoming tRNA, carrying its amino acid, pairs with the mRNA codon on the A site of the ribosome
2. Polypeptide separates from the tRNA in the p site and attached by a new peptide bond to the amino acid carried by the tRNA in the a site.
3. P site tRNA lacking an amino acid leaves the ribosome and the ribosome trans locates the remaining tRNA from the a site to the p site.
105
After elongation codon and anticodon remain _____ bonded and the mRNA and tRNA move as a unit.
Hydrogen
106
The movement of mRNA and tRNA as a unit brings into the a site the next _____ codon to be translated and the process starts again from step one.
mRNA
107
Elongation continues until what?
A stop codon reaches the ribosomes A site.
108
What would happen if a codon in the middle of an mRNA mutated from UUA to UAA?
Translation would stop prematurely because a stop codon was introduced.
109
Which of the following molecules or structures does not participate directly in translation: ribosomes, transfer RNA, messenger RNA or DNA.
DNA
110
Any change in the nucleotide sequence of a cells DNA is called this.
Mutation
111
Mutation can involve large regions of a ____ or just a single nucleotide pair.
Chromosome
112
Mutations can be divided into what 2 general categories?
1. Nucleotide sunstitutions
| 2. Nucleotide insertions or deletions
113
The replacement of one nucleotide and it’s base pairing partner with another pair of nucleotides.
Substitution
114
Effects of substitution?
1. None because of redundancy in genetic code.
| 2. Protein product does not change.
115
Substitution is also called what?
Silent mutation
116
What are two types of substitution?
Missense mutation
| Nonsense mutation
117
This mutation changes one amino acid to another. The protein product is changed due to a change in the mRNA codon.
Missense mutation.
118
This type of mutation changes an amino acid codon into a stop codon. This results in a prematurely terminated protein which will not function properly.
Nonsense mutation
119
This is a type of insertion or deletion mutation of one or more nucleotides in a gene. It adds or subtracts from a triplet codon.
Frameshift mutation
120
What are the effects of frameshift mutation?
May alter the reading frame of the genetic message and produce a Nonfunctional polypeptide.
121
The production of mutation is called?
Mutagenesis
122
This type of mutagenesis results in errors during DNA replication or recombination.
Spontaneous
123
This is a physical or chemical mutating agent including X-rays and anti aids drugs.
Mutagen
124
This is an infectious particle consisting of little more than “genes in a box”.
Virus
125
A virus is a bit of nucleic acid wrapped in a protein coat called a _____.
Capsid or membrane envelope
126
What provides the needs for a virus to replicate, transcribe and translate the viral nucleic acid?
Host cell
127
This results in the lysis/breaking open of the host cell and the release of the viruses that were produced within the cell.
Lytic cycle
128
Describe what occurs in the lytic cycle.
1. The phage injects it’s DNA.
2. The phage DNA circularizes.
3. The new page DNA and proteins are synthesized and phages assemble
4. The cell loses releasing phages where they may infect another cell.
129
Viral DNA replication occurs without destroying the host cell in which cycle?
Lysogenic cycle
130
Describe animal viruses.
Have a membranous outer envelope and projecting spikes of glycoprotein that helps the virus enter and leave host cell
131
What are some examples of RNA viruses?
Common cold, measles, mumps, polio and aids. These replicate in cytoplasm
132
What are some examples of DNA viruses?
Hepatitis, chicken pox, herpes. They replicate in the host cells nucleus. And acquire envelopes from cells nuclear membrane.
133
These are viruses that burst in to the scene quite suddenly.
Emerging viruses.
134
What are the processes contributing to the emergence of viral diseases?
1. Mutation
2. Contact among species
3. Speed from isolated populations
135
The aids virus makes DNA on a _____ template.
RNA
136
HIV contains two identical copies of its RNA instead of _____.
One
137
This RNA virus that reproduces by means of a DNA molecule. It is reverse of the usual DNA to RNA flow of genetic information.
Retrovirus
138
HIV carries molecules of an enzyme called_____ _____.
Reverse transcriptase
139
These are small circular RNA molecules that infect plants. They replicate in host plant cells using cellular enzymes. They interfere with regulatory system that control plant growth.
Viroids
140
These are infectious proteins misfolded form of protein in brain cells. They cause degenerative brain diseases in various animal species.
Prions
141
Bacteria can transfer DNA in what 3 ways?
1. Transformation
2. Transduction
3. Conjugation
142
Bacterial cells reproduce by replication of the bacterial chromosome followed by ____ _____.
Binary fission
143
Bacterial ________ involves the uptake of foreign DNA from the surrounding environment.
Transformation
144
Bacterial_____ is the transfer of bacterial genes by a phage.
Transduction
145
Bacterial ____ is the union of two bacterial cells and DNA transfer between them.
Conjugation
146
The ability of a donor e. Coli to carry out conjugation is usually due to this specific piece of DNA.
F-factor
147
The F-factor has 25 genes for making ___ ____ and other requirements for conjugation.
Sex pili
148
This is a small circular DNA molecule sewerage from the bacterial chromosome.
Plasmid
149
These carry genes that can affect the survival of the cell and pose serious problems for human medicine because it is resistant.
R plasmids
