NUCLEIC ACID Flashcards
(182 cards)
1
Q
Each cell of our bodies contains thousands of ____________
A
different proteins
2
Q
the transmission of hereditary information took place in the nucleus,
more specifically in structures called _________
A
chromosomes
3
Q
The hereditary information was thought to reside in _________ within the
chromosomes.
A
genes
4
Q
Chemical analysis of nuclei showed chromosomes are made up
largely of proteins called ____________ and ___________
A
histones and nucleic acids
5
Q
Backbones of chromosomes
A
NUCLEIC ACIDS:
- Ribonucleic acids (RNA)
- Deoxyribonucleic acids (DNA)
6
Q
_________ stores the genetic information of an organism and transmits that information from one generation to another.
A
DNA
7
Q
__________ translates the genetic information contained in DNA into proteins needed for all cellular function.
A
RNA
8
Q
RNA and DNA are unbranched polymers (monomers: __________).
A
nucleotides
9
Q
Cytosine (C)
A
DNA and some RNA
9
Q
A nucleotide is composed of:
A
- Nitrogen-containing bases (amines)
- Sugars (monosaccharides)
- Phosphate
10
Q
Thymine (T)
A
DNA only
11
Q
Uracil (U)
A
RNA only
12
Q
Adenine (A)
A
(DNA and RNA)
13
Q
Guanine (G)
A
(DNA and RNA)
14
Q
RNA contains:
A
D-Ribose sugar
14
Q
DNA contains:
A
2-Deoxy-D-Ribose sugar (without O on carbon 2)
14
Q
Base + Sugar –>
A
Nucleoside
15
Q
To name a nucleoside derived from a pyrimidine base, use the suffix ‘‘__________’’
A
-idine
16
Q
To name a nucleoside derived from a purine base, use the suffix “____________”
A
-osine
17
Q
For deoxyribonucleosides, add the prefix “__________-”.
A
deoxy-
18
Q
When a N atom of the base forms a glycosidic bond to _______________
A
C1’ (anomeric C) of a sugar
19
Q
A nucleotide forms with the −OH on C5’ of a sugar bonds to ________________
A
phosphoric acid
20
Q
The name cytidine 5′-monophosphate is abbreviated as _____________
A
CMP
21
Q
The name deoxyadenosine 5’-monophosphate is abbreviated as ______________
A
dAMP
22
Each phosphate is linked to ______________of two sugars.
C3’ (free hydroxyl) and C5’ (free phosphate)
23
Primary structure of DNA and RNA
A nucleoside
A nucleotide
A nucleic acid
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Base + Sugar
nucleoside
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Base + Sugar + Phosphate
nucleotide
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A chain of nucleotides
nucleic acid
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Like amino acids (C-terminal and N-terminal):
Base sequence is read from the C5’ (free phosphate) end to the C3’ (free hydroxyl) end.
-ACGU-
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The DNA model is proposed by _________________
Watson and Crick in 1953
29
Two strands of polynucleotide form a ___________________
double helix structure like a spiral
30
Hydrogen bonds link paired bases:
Adenine-Thymine (A–T)
Guanine-Cytosine (G-C)
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_____________ is hydrophilic and stays on the outside (bases are hydrophobic)
Sugar-Phosphate backbone
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_________ base always hydrogen bonds with a pyrimidine.
Purine
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G-C base pair
3 H bonds
33
DNA is coiled around proteins called ______________
histones
33
A-T base pair
2 H bonds
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_______________ are rich in the basic amino acids
Histones
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Acidic DNA basic histones attract each other and form a chain of ___________
nucleosomes
36
DNA double helix
2 nm
37
Nucleosome
11 nm
38
Chromatin:
11 nm
Condensed nucleosomes
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Solenoid (six nucleosomes per turn)
30 nm
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______________ are organized into loops, and the loops into the bands that provide the superstructure of chromosomes.
Chromatin fibers
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Loops (50 turns per loop)
250 nm
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Chromosome (stacked minibands)
840 nm
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DNA molecules contain __________________, while RNA molecules have ______________
several million nucleotides AND
only a few thousand.
43
Miniband (18 loops)
840 nm
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DNA is contained in the ________________of the nucleus, each chromosome having a different type of DNA.
chromosomes
44
Humans have ________________ each made up of many genes.
46 chromosomes (23 pairs)
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A ______________ is the portion of the DNA molecule responsible for the synthesis of a single protein (_______________).
gene
1000 to 2000 nucleotides
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DNA has four bases:
A, G, C, and T
46
RNA has four bases:
A, G, C, and U
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Sugar is 2-deoxy-D-ribose
In DNA
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Sugar is D-ribose
In RNA
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___________ is almost always double-stranded (helical structure)
DNA
50
__________ is single strand.
RNA
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_______is much smaller than DNA.
RNA
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Transmits the genetic information needed to operate the cell
RNA molecules
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Most abundant RNA – is found in ribosomes: sites for protein synthesis.
Ribosomal RNA (rRNA)
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Carries genetic information from DNA (in nucleus) to ribosomes (in cytoplasm)
for protein synthesis.
They are produced in “Transcription” from DNA.
Messenger RNA (mRNA)
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1. It reproduces itself when a cell divides (Replication).
2. It supplied the information to make up RNA, proteins, and enzymes
Functions of DNA
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The smallest RNA.
Translates the genetic information in mRNA and brings specific
Amino acids to the ribosome for protein synthesis.
Transfer RNA (tRNA)
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It reproduces itself when a cell divides
Replication
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Separation of the two original strands and synthesis of two new daughter strands using the original strands as templates.
Replication
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takes place at the same speed in both directions.
Replication is bidirectional
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each daughter molecule has one parental strand and one newly synthesized one.
Replication is semiconservative
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specific point of DNA where replication begins
Origin of replication
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specific point of DNA where replication is proceeding
Replication fork
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__________ is synthesized continuously in the 5’ → 3’ direction toward the replication fork.
Leading strand
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_____________ is synthesized discontinuously in the 5’ → 3’ direction
away from the replication fork.
Lagging strand
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assemblies of “enzyme factories”
Replisomes
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Unwinds the DNA double helix
Helicase
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Synthesizes primers
Primase
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Threads leading strand
Clamp protein
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Joins assembled nucleotides
DNA polymerase
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Joins Okazaki fragments in
lagging strand
Ligase
69
Unwinds the DNA double helix.
Helicases
69
Replication of DNA starts with unwinding of the double helix.
Helicases
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Unwinding can occur at either end or in the middle.
Helicases
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Attach themselves to one DNA strand and cause separation of the
double helix.
Helicases
Helicases
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Catalyze the synthesis of primers.
Primases
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are short nucleotides (4 to 15).
Primers
74
They are required to start the synthesis of both daughter strands.
Primases
74
It joins the nucleoside triphosphates found in the nucleus.
DNA Polymerase
74
______________ are placed at about every 50 nucleotides in the lagging strand synthesis
Primases
75
It catalyzes the formation of the new strands.
DNA Polymerase
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A new phosphodiester bond is formed between the 5’-phosphate of the
nucleoside triphosphate and the 3’-OH group of the new DNA strand.
DNA Polymerase
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In formation of lagging strand, small fragments (Okazaki) are join together by ligase enzyme.
Ligase
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activation of a gene to produce a specific protein.
Gene expression
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Change of sequence -->
New protein
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Only a small fraction (1-2%) of the DNA in a chromosome contains genes.
Protein Synthesis
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Base sequence of the gene carries the information to produce one protein molecule.
Protein Synthesis
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Gene expression
Transcription
Translation
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synthesis of mRNA (messenger RNA)
Transcription
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Genetic information is copied from a gene in DNA to make a mRNA.
Transcription
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Begins when the section of a DNA that contains the gene to be copied unwinds.
Transcription
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Polymerase enzyme identifies a starting point to begin mRNA synthesis.
Transcription
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The DNA splits into two strands:
1. Template strand
2. Coding Strand (Informational strand)
85
Transcription proceeds from the _______________of the template
3’ end to the 5’ end
86
it is used to synthesize RNA
Template strand
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it is not used to synthesize RNA.
Coding Strand (Informational strand)
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When mRNA is released, the double helix of the DNA re-forms.
Transcription
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C is paired with ___
G
90
T pairs with ___
A
91
But A pairs with _________
U (not T).
91
Overall function of RAN’s in the cell:
facilitate the task of synthesizing protein
92
language that relates the series of nucletides in mRNA to the amino acids specified.
Genetic code
93
The sequence of nucleotides in the mRNA determines the ___________order for the protein
amino acid
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Every three bases (triplet) along the mRNA makes up a ___________
codon
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Each codon specifies a particular ___________
amino acid
96
_________ are present for all 20 amino acids.
Codons
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_____________ are possible from the triplet combination of A, G, C, and U.
64 condons
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Codons are written from the _____________ of the mRNA molecule
5’ end to the 3’ end
99
code for termination of protein synthesis
UGA, UAA, and UAG, are stop signals.
99
_________________ are stop signals
UGA, UAA, and UAG
100
AUG has two roles:
1. Signals the start of the proteins synthesis (at the beginning of an mRNA).
2. Specifies the amino acid methionine (Met) (in the middle of an mRNA)
101
translates the codons into specific amino acids
tRNA
102
It contains 70-90 nucleotides
tRNA (transfer RNA)
103
The 3’ end, called the _________ and
always has the nucleotide ACC and a free
OH group that binds a specific amino acid.
acceptor stem
104
a sequence of three nucleotides at the bottom of tRNA, which is complementary to three bases in an mRNA and it can identify the needed amino acid.
Anticodon
105
site of transcription
Nucleus
106
mRNA is made on
DNA
107
mRNA attaches to smaller subunit of a ribosome
Protein synthesis
108
mRNA attaches to smaller subunit of a ribosome.
Protein synthesis
109
tRNA molecules bring specific amino acids to the mRNA.
Protein synthesis
110
Peptide bonds form between an amino acid and the end of the growing peptide chain.
Protein synthesis
111
The ribosome moves along mRNA until the end of the codon (__________).
translocation
112
Ribosome encounters a stop condon.
Termination
112
Amino acids form the three-dimensional structure (____________).
active protein
112
There are 3 stages in translation:
1. Initiation
2. Elongation
3. Termination
113
_____________begins with mRNA binding to the ribosome.
Translation
113
____________ proceeds as the next
tRNA molecule delivers the next
amino acid, and a peptide bond
forms between the two amino acids.
Elongation
113
Translation continues until a stop codon
(UAA, UAG, or UGA) is reached and the completed protein is released.
Termination
113
Often the first amino acid (___________) is not needed and it is removed after protein synthesis is complete.
methionine
114
A heritable change in DNA nucleotide sequence.
Mutation
114
X rays, Overexpose to sun (UV light), Chemicals (mutagens), or Viruses
Mutation
114
Effect of Mutation
Somatic cell (nonreproductive cell)
Germ cell (reproductive cell like an egg or sperm)
115
Altered DNA will be limited to that cell and its daughter cells --> Cancer
Somatic cell (nonreproductive cell)
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All new DNA will contain the same default
and it is passed on to the next generation --> Genetic diseases
Germ cell (reproductive cell like an egg or sperm)
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nonreproductive cell
Somatic cell
118
2 Type of Mutations:
Point (substitution) Mutation
Frameshift Mutation
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reproductive cell like an egg or sperm
Germ cell
120
Replacement of one base in the coding strand of DNA with another --> Different amino acid
Point (substitution) Mutation
120
One or more bases is/are added to or deleted from the normal order of bases in DNA --> All the triplets shift over by one base. Different sequence of amino acids
Frameshift Mutation
121
2 types of Frameshift Mutation
1. deletion mutation
2. insertion mutation
122
A _______________ occurs when one or more nucleotides is/are lost from a DNA molecule.
deletion mutation
123
An _______________ occurs when one or more nucleotides is/are added to a DNA molecule.
insertion mutation
124
The mutation has no effect.
silent mutation
125
A ________________ has a negligible effect to the organism, because the resulting amino acid is identical.
silent mutation
126
___________________is synthetic DNA that contains segments from more
than one source.
Recombinant DNA
127
Three key elements are needed to form recombinant DNA:
1. DNA molecule
2. enzyme
3. gene from a second organism
128
A _____________ into which a new DNA segment will be inserted
DNA molecule
129
An _____________ that cleaves DNA at specific locations
enzyme
130
A _____________that will be inserted into the original DNA molecule.
gene from a second organism
131
First, bacterial plasmid DNA
is cut by the ____________________, which
cuts in a specific place.
restriction endonuclease EcoRI
132
Then, a second sample
of _____________ is cut
with the same EcoRI.
human DNA
132
This gives a double strand
of linear plasmid DNA with
two ends ready to bond,
called ______________
sticky ends
133
Four elements are needed to amplify DNA by PCR:
1. Segment of DNA
2. Two primers
3. DNA polymerase enzyme
4. Nucleoside triphosphate
133
_________________ amplifies a specific portion of a DNA molecule, producing millions of exact copies
Polymerase chain reaction (PCR)
133
Combining the two pieces of DNA (with ____________________) forms DNA
containing the new segment
DNA ligase enzyme
133
This forms human DNA
segments with sticky
ends that are _______________________
complimentary to the
plasmid DNA.
133
This DNA chain is slightly larger because of its ______________________
additional segment
134
The _______________ that must be copied
segment of DNA
135
______________ short polynucleotides that are complementary to the two ends of the segment to be amplified.
Two primers
136
A _______________to catalyze the synthesis of a complementary strand
DNA polymerase enzyme
137
________________the source of the A, T, C, and G needed to make the new DNA.
Nucleoside triphosphates
138
Step [1] Heat the DNA segment to unwind the
double helix to form single strands.
Step [2] Add primers that are complementary to the DNA sequence at either end of the
DNA segment.
Step [3] Use a DNA polymerase and added
nucleotides to lengthen the DNA segment.
HOW TO Use the Polymerase Chain Reaction to Amplify a Sample of DNA
139
The DNA of each individual person is unique, so DNA can be used as a method of _____________
identification
140
Any type of cell (________________________) can be used to obtain a DNA fingerprint.
skin, saliva, semen, blood, etc
141
The DNA is first ________ by PCR, and then cut into fragments by restriction enzymes
amplified
142
The _____________ are then separated by size by gel electrophoresis.
DNA fragments
143
DNA fragments can be visualized on _____________after they have been separated
X-ray film
144
A ________ is an infectious agent consisting of a DNA or RNA molecule that is contained within a protein coating
virus
144
It is incapable of replicating alone (no enzyme, no free nucleotide), so ___________________and makes the host replicate the virus.
it invades a host organism
145
A ___________ is an inactive form of a virus that causes a person’s immune system to produce antibodies to the virus to ward off infection.
vaccine
145
Many ________________ like the common cold, influenza, and herpes are viral in origin
prevalent diseases
146
Retroviruses invade a host and then synthesize viral DNA by ______________
reverse transcription
146
A virus with an RNA core is called a _______________
retrovirus
147
____________________is caused by the retrovirus HIV (Human Immunodeficiency Virus)
AIDS (Acquired Immune Deficiency Syndrome)
147
The viral DNA can then transcribe RNA, which then directs _____________ (new retroviral particles to infect other cells).
protein synthesis
