Ch. 21 - Nucleic Acids and Protein Synthesis Flashcards
(97 cards)
1
Q
structure of a nucleotide includes a
A
- nitrogen-containing base.
- sugar.
- phosphate group.
2
Q
There are two types of nucleic acids:
A
deoxyribonucleic acid (DNA), the genetic material in the
nucleus of a cell, and ribonucleic acid (RNA), which
interprets the genetic information in DNA for the synthesis
of protein.
3
Q
both are unbranched polymers of repeating monomer units
known as nucleotides.
A
DNA and RNA
4
Q
- a base that contains nitrogen.
- a five-carbon sugar.
- a phosphate group.
A
nucleotide
5
Q
- are large molecules
- are found in the nuclei of cells
- store information and direct activities for cellular growth and reproduction.
A
Nucleic acids
6
Q
The bases in DNA and RNA are:
• derivatives of the heterocyclic amines ___ or ___.
• ___ with a single ring containing two nitrogen
atoms.
- ___ with two rings, each containing two nitrogen atoms.
- H+ acceptors at the ___ atoms in each base.
A
• derivatives of the heterocyclic amines pyrimidine or purine.
• pyrimidines with a single ring containing two nitrogen
atoms.
- purines with two rings, each containing two nitrogen atoms.
- H+ acceptors at the nitrogen atoms in each base.
7
Q
KNOW DIFFERENCE BETWEEN NUCLEOSIDE AND NUCLEOTIDE
A
(NUCLEOSIDE DOES NOT HAVE PHOSPHATE GROUP)
8
Q
_____ DOES NOT HAVE PHOSPHATE GROUP
A
NUCLEOSIDE
9
Q
Does pyrimidine or Purine have more cyclic rings?
A
Purine has two rings and Pyrimidine has one
10
Q
In DNA,
• the ___ bases with double rings are adenine (A) and guanine (G).
• the ___ bases with single rings are cytosine (C) and thymine (T).
A
In DNA,
• the purine bases with double rings are adenine (A) and guanine (G).
• the pyrimidine bases with single rings are cytosine (C) and thymine (T).
11
Q
In RNA,
- the ____ bases with double rings are adenine (A) and guanine (G).
- the ___ bases with single rings are cytosine (C) and uracil (U).
A
In RNA,
- the purine bases with double rings are adenine (A) and guanine (G).
- the pyrimidine bases with single rings are cytosine (C) and uracil (U).
12
Q
In DNA,
• the purine bases with double rings are….
• the pyrimidine bases with single rings are….
A
In DNA,
• the purine bases with double rings are adenine (A) and guanine (G).
• the pyrimidine bases with single rings are cytosine (C) and thymine (T).
13
Q
In RNA,
- the purine bases with double rings are …
- the pyrimidine bases with single rings are ….
A
In RNA,
- the purine bases with double rings are adenine (A) and guanine (G).
- the pyrimidine bases with single rings are cytosine (C) and uracil (U).
14
Q
The five-carbon sugar
- in RNA is ___
- in DNA is deoxyribose, with no O atom on ___.
• has carbon atoms numbered with primes to distinguish
them from the atoms in the bases.
A
The five-carbon sugar
- in RNA is ribose.
- in DNA is deoxyribose, with no O atom on C2′.
• has carbon atoms numbered with primes to distinguish
them from the atoms in the bases.
15
Q
• is composed of a nitrogen-containing base and a sugar, either ribose or deoxyribose.
A
A nucleoside
16
Q
• has a base linked by a β-N-glycosidic bond to C1′ of a sugar (ribose or deoxyribose).
A
A nucleoside
17
Q
A nucleotide has a phosphate group attached to the
A
C5′ — OH group of a nucleoside.
18
Q
The addition of a phosphate to a nucleoside forms a
A
nucleotide.
19
Q
The name of a nucleoside that contains a purine ends with
A
osine.
20
Q
The name of a nucleoside that contains a pyrimidine ends
with
A
idine.
21
Q
The names of DNA nucleosides add ___-to the beginning of their names.
A
deoxy
22
Q
The corresponding nucleotides in RNA and DNA are
named by adding _____ to the end of the nucleoside name.
A
monophosphate
23
Q
Look at table 21.2 on page 14 of pdf
A
Nerd Alert!
24
Q
Adding a phosphate group to AMP forms the diphosphate, ADP.
• Adding a phosphate group to ADP forms the triphosphate, ATP.
A
DUH
25
In the primary structure of nucleic acids, each sugar in a sugar–phosphate backbone is attached to a
base .
26
In the primary structure of nucleic acids,
• the nucleotides are joined by...
phosphodiester bonds.
27
In the primary structure of nucleic acids,
• the 3ʹ —OH group of the sugar in one nucleotide bonds
to the
phosphate group on the 5ʹ carbon atom in the
| sugar of the next nucleotide.
28
Each nucleic acid has its own unique sequence of bases, which
• is known as its primary structure.
• carries the genetic information.
• is read from the sugar with the free ___ to ___
• is read from the sugar with the free 5ʹ phosphate to the
| sugar with the free 3ʹ —OH group.
29
In the primary structure of RNA, A, C, G, and U are connected by
3ʹ,5ʹ phosphodiester linkages.
30
Sc ientists determined that • adenine is paired (1:1) with thymine. • guanine is paired (1:1) with cytosine.
This relationship can be summarized: Number of purine molecules = Number of pyrimidine molecules
YEAH WE KNOW
31
DNA contains complementary base pairs in which adenine is always linked by
two hydrogen bonds to thymine (AT).
32
DNA contains complementary base pairs in which guanine is always linked by
three hydrogen bonds to cytosine (GC).
33
consists of two strands of nucleotides that form a
double helix structure like a spiral staircase.
* has two strands held together by the hydrogen bonds between the bases AT and GC.
* has bases along one strand that complement the bases along the other.
DNA DOUBLE HELIX
34
• the strands in the original or parent DNA molecule
separate to allow the synthesis of complementary DNA
strands.
• the process begins with the unwinding of the double
helix by breaking the hydrogen bonds between the
complementary bases.
• the resulting single strands act as templates for the
synthesis of new complementary strands of DNA.
DNA replication
35
Wi thin the nucleus,
• nucleoside triphosphates (dATP, dTTP, dGTP, and
dCTP) on the template strand form hydrogen bonds with
their complementary bases.
• phosphodiester linkages are formed between the
nucleotides as the hydrogen bonds form between the
base pairs:
T forms hydrogen bonds with A. G forms hydrogen bonds with C.
Hydrogen Bonding, Base Pairs
36
* one strand of the double helix is from the parent DNA.
* one is a newly synthesized DNA strand.
• two new daughter DNA strands that are exact copies of
the parent DNA are formed.
• complementary base pairing ensures the correct placement of bases in the daughter DNA strands.
Daughter DNA Strands
37
During DNA replication,
* _____ unwinds the parent DNA at several sections.
* _____ catalyzes the replication process at each of the open DNA sections called replication forks.
* the polymerase moves in the _____, catalyzing the formation of new ____ linkages.
• the lagging strand (growing in the ___ direction) is
synthesized in short sections called ____ fragments.
• ____ joins the Okazaki fragments.
During DNA replication,
• helicase unwinds the parent DNA at several sections.
• DNA polymerase catalyzes the replication process at
each of the open DNA sections called replication forks.
• the polymerase moves in the 3′–5′direction, catalyzing
the formation of new phosphodiester linkages.
• the lagging strand (growing in the 5′–3′ direction) is
synthesized in short sections called Okazaki
fragments.
• DNA ligase joins the Okazaki fragments.
38
READ TABLE 21.4 ON PAGE 38 OF PDF ENSURE YOU'RE GOOD WITH IT
K DAD WE KNOW
39
A typical ribosome consists of a small subunit and a large subunit. The subunit shapes shown contain both
protein and rRNA.
40
* makes up most of the nucleic acid found in the cell.
* transmits genetic information from DNA to operate the cell.
* has several types as shown IN THE PPT
RNA
41
How does RNA differ from DNA? (4 in particular)
* The sugar in RNA is ribose; the sugar in DNA is deoxyribose.
* The base uracil replaces thymine.
* RNA molecules are single stranded; DNA molecules are double stranded.
* RNA molecules are much smaller than DNA molecules.
42
Types of RNA
There are three major types of RNA:
• 5% of RNA is messenger RNA (mRNA), which carries
genetic information from DNA to the ribosomes.
• 15% of RNA is transfer RNA (tRNA), which translates
the genetic information in mRNA into the amino acid
sequence for the protein.
• 80% of RNA is ribosomal RNA (rRNA), which is the
most abundant type of RNA; it is combined with proteins
to form ribosomes.
43
What are the three types of RNA from most to least
rRNA
tRNA
mRNA
44
A typical tRNA molecule
• can be drawn as a two-dimensional cloverleaf.
• shows more twists that illustrate the L-shape of tRNA in
the three-dimensional model.
A typical tRNA molecule
• can be drawn as a two-dimensional cloverleaf.
• shows more twists that illustrate the L-shape of tRNA in
the three-dimensional model.
45
A typical tRNA molecule
• has an acceptor stem at the 3′ end with the nucleotide
sequence ACC where an enzyme attaches an amino by....
• contains an ____, which is a series of three bases
that complements three bases on mRNA.
A typical tRNA molecule
• has an acceptor stem at the 3′ end with the nucleotide
sequence ACC where an enzyme attaches an amino by
forming an ester bond with the free —OH group.
• contains an anticodon, which is a series of three bases
that complements three bases on mRNA.
46
(a) A two-dimensional model of tRNA is represented as a cloverleaf.
(b) The three-dimensional model of RNA has more twists that shows its L-shape.
tRNA Structure
47
In the nucleus, genetic information for protein synthesis
* is copied from a gene in DNA.
* makes mRNA in a process called transcription.
The mRNA molecules move out of the nucleus into the cytosol, where they bind with the ribosomes.
The tRNA molecules convert the information in the mRNA into amino acids in a process called translation.
TRUE
48
The genetic information in DNA is replicated in cell division and used to produce messenger RNA that codes for....
...amino acids used in protein synthesis at the ribosomes.
49
In transcription, a section of DNA containing the gene unwinds.
• RNA polymerase uses the DNA template strand to form
the new mRNA using bases that are complementary to
the DNA template.
• An mRNA is synthesized using complementary base
pairing, with uracil (U) replacing thymine (T).
• The newly formed mRNA moves out of the nucleus to
ribosomes in the cytoplasm.
ALL TRUE
50
DNA undergoes transcription when RNA polymerase makes a complementary copy of a gene using the ____ DNA template strand.
3′ to 5′
51
In eukaryotes,
• DNA contains exons that code for proteins and introns
that do not code for proteins.
Remember exons = expressed
52
exons =
expressed I.e. code for proteins
53
In eukaryotes,
• DNA contains exons that code for proteins and introns
that do not code for proteins.
• a pre-RNA is formed that includes the noncoding
introns.
• the noncoding introns are removed.
• the exons are joined to form mRNA, which goes to the
ribosomes with the information for the synthesis of
protein.
ALL TRUE
54
In eukaryotes,
• DNA contains ___ that code for proteins and ___
that do not code for proteins.
• a ____ is formed that includes the noncoding
introns.
• the noncoding introns are ____.
• the exons are joined to form mRNA, which goes to the
ribosomes with the information for the ____.
In eukaryotes,
• DNA contains exons that code for proteins and introns
that do not code for proteins.
• a pre-RNA is formed that includes the noncoding
introns.
• the noncoding introns are removed.
• the exons are joined to form mRNA, which goes to the
ribosomes with the information for the synthesis of
protein.
55
A pre-mRNA, containing copies of the exons and introns from the gene, is processed to
remove the introns to form a mature mRNA that codes for a protein.
56
Regulation of mRNA syntheses is controlled at the transcription level by a specific mRNA that is synthesized when the cell
requires a particular protein.
57
* The transcription of a gene requires the _____ to bind to DNA in plants and animals.
* A group of protein complexes called a ____ ____ must recognize and bind to promoter segments.
• Other proteins, called ___, bind with the
transcription factor complex to increase the rate of RNA
transcription.
• The transcription of a gene requires the RNA
polymerase to bind to DNA in plants and animals.
• A group of protein complexes called a transcription
factor must recognize and bind to promoter segments.
• Other proteins, called activators, bind with the
transcription factor complex to increase the rate of RNA
transcription.
58
Transcription factors at the promoter region bind RNA polymerase to DNA, which...
which activates the transcription of a gene.
59
The function of the different types of RNA in the cell is to
facilitate the task of synthesizing proteins.
60
An activated tRNA with anticodon AGU bonds to serine at the
acceptor stem.
61
The RNA in a cell facilitates the synthesis of proteins in the following steps:
1. Genetic information encoded in DNA is transcribed and processed into ______. These molecules move out of the nucleus to the ribosomes in the cytosol.
2. mRNA leaves the nucleus and attaches to a ribosome, where the genetic information in the mRNA is....
3. Molecules of tRNA pick up specific amino acids according to their anticodons. tRNA activation occurs when
4. A start codon binds the first tRNA carrying the amino acid
___ to the mRNA. As the ribosome moves along the mRNA, a new amino acid forms a peptide bond to the growing protein chain.
5. Eventually, a ribosome encounters a stop codon with no corresponding tRNAs, which signals the termination of polypeptide synthesis and its release from the ribosome.
(tRNA re-enters the pool of free tRNA and ready to be recharged with a new amino acid.)
mature mRNA molecules
....translated into a sequence of amino acids in a protein.
the correct amino acid is attached to each tRNA.
methionine
62
• There is a different codon for all _____ needed
| to build a protein.
20 amino acids
63
The genetic code consists of sets of ______ in mRNA called codons that specify the amino acids and their sequence in the protein.
three nucleotides (triplets)
64
The genetic code
• has stop signals, __, ___, AND ____, that signal the termination of protein synthesis.
• has a start codon, ___, that signals the start of protein
synthesis.
The genetic code
• has stop signals, UGA, UAA, and UAG, that signal thetermination of protein synthesis.
• has a start codon, AUG, that signals the start of protein
synthesis.
65
The genetic code
• has stop signals, UGA, UAA, and UAG, that signal the ____ of protein synthesis.
• has a start codon, AUG, that signals the ___ of protein
synthesis.
The genetic code
• has stop signals, UGA, UAA, and UAG, that signal thetermination of protein synthesis.
• has a start codon, AUG, that signals the start of protein
synthesis.
66
* is a change in the nucleotide sequence of DNA.
* may result in changes to the sequence amino acids that affect the structure and function of cells.
* results from mutagens, such as radiation and chemicals (possibly some viruses).
A mutation
67
When a mutation severely alters proteins or enzymes, the new cells may not survive or the person may exhibit a
disease or condition that is a result of a genetic defect.
68
is the replacement of one base in the template strand of DNA with another; this may cause a different amino acid to be inserted into the polypeptide.
point mutation
69
point mutation
point mutation is the replacement of one base in the template strand of DNA with another; this may cause a different amino acid to be inserted into the polypeptide.
70
A ______ occurs when a point mutation does not change the amino acid.
silent mutation
71
silent mutation
A silent mutation occurs when a point mutation does not change the amino acid.
72
In a ______, a base is deleted from the
normal order of bases in the template strand of DNA. All
the codons that follow are changed, producing a
different sequence of amino acids from that point.
deletion mutation
73
deletion mutation
In a deletion mutation, a base is deleted from the
normal order of bases in the template strand of DNA. All
the codons that follow are changed, producing a
different sequence of amino acids from that point.
74
In an _______, a base is inserted into the
normal order of bases in the template strand of DNA. All
the codons that follow are changed, producing a
different sequence of amino acids from that point.
insertion mutation
75
For drastic changes in the amino acid sequence,
• the structure of the resulting protein may lose its biological activity.
• proteins (enzymes) may no longer catalyze reactions and
substances may accumulate in the cells until they are
poisonous.
76
result from a defective enzyme caused by mutation in its genetic code.
Genetic diseases
77
If the enzyme that converts ___ to _____ is defective, no melanin is produced, resulting in the genetic disease known as albinism.
tyrosine to melanin
78
is needed for the formation of melanin (skin and hair
| pigment).
Tyrosine
79
DNA can be used in
• _____ that permits scientists to cut and
recombine DNA fragments to form recombinant DNA.
• genetic engineering that permits scientists to cut and
| recombine DNA fragments to form recombinant DNA.
80
In preparing recombinant DNA,
• a DNA fragment from one organism is combined with
DNA from another.
• restriction enzymes are used to cleave a gene from a
foreign DNA and open DNA plasmids in Escherichia
coli.
• DNA fragments are mixed with the plasmids in E. coli,
and the ends are joined by ligase.
• the new gene in the altered DNA produces protein.
How neat is that!
81
Recombinant DNA is formed by placing a gene from another organism in a plasmid DNA of a bacterium. This causes the bacterium to...
...produce a nonbacterial protein.
82
• made it possible to produce multiple
copies of a DNA in a short time.
• separates the sample DNA strands by
heating.
• mixes the separated strands with
enzymes and nucleotides to form
complementary strands.
• is repeated many times to produce a
large sample of the DNA
A polymerase chain reaction (PCR)
83
• allows screening for defective genes.
• can be used to screen for genes associated with breast
cancer.
Multiple defects in two known breast cancer genes, called BRCA1 and BRCA2, correlate to a higher risk of breast cancer.
Polymerase chain reaction (PCR)
84
Viruses are small particles of RNA and DNA containing 3 – 200 genes that cannot replicate without ____
The Epstein–Barr virus (EBV), herpesvirus 4, causes
a host cell.
cancer in humans.
85
Viruses
• are small particles of DNA or RNA that
require a host cell to replicate and cause infection.
• can replicate only in cells, by taking over the
machinery and materials necessary for protein synthesis and growth.
YES
86
A virus causes infection when
• an enzyme in the protein coat of the virus makes a hole
in the outside of the host cell;
• the virus enters the cell and the ______ mixes with the materials in the host cell;
• a _____ processes proteins to produce a protein coat
encasing the new viral RNA or DNA; and
• the new virus particles are released from the cell, ready
to infect more cells.
A virus causes infection when
• an enzyme in the protein coat of the virus makes a hole
in the outside of the host cell;
• the virus enters the cell and the viral nucleic acid mixes
with the materials in the host cell;
• a protease processes proteins to produce a protein coat
encasing the new viral RNA or DNA; and
• the new virus particles are released from the cell, ready
to infect more cells.
87
In reverse transcription,
• a ____, which contains viral RNA but no viral DNA,
enters a cell.
• the viral RNA uses ______ to produce a
viral DNA strand.
• the viral DNA strand forms a complementary DNA
strand.
• the new DNA uses the ___ and ____ in the
host cell to synthesize new virus particles.
• a retrovirus, which contains viral RNA but no viral DNA,
enters a cell.
• the viral RNA uses reverse transcriptase to produce a
viral DNA strand.
• the viral DNA strand forms a complementary DNA
strand.
• the new DNA uses the nucleotides and enzymes in the
host cell to synthesize new virus particles.
88
The HIV virus
* is a retrovirus that infects and destroys ____
* leaves the immune system unable to destroy harmful organisms.
* is associated with an increased chance of developing pneumonia and skin cancer associated with AIDS.
* is a retrovirus that infects and destroys T4 lymphocyte cells.
* leaves the immune system unable to destroy harmful organisms.
* is associated with an increased chance of developing pneumonia and skin cancer associated with AIDS.
89
Treatment for AIDS is based on
* attacking the HIV at different points in its life cycle.
| * developing nucleoside analogs that mimic the structures of the nucleosides used for DNA synthesis.
90
Drugs based on nucleoside analogs used to treat HIV/AIDS include
* AZT (3ʹ-azido-2ʹ-deoxythymidine), which is similar to thymidine.
* ddI (2ʹ, 3ʹ–dideoxyinosine), which is similar to guanosine.
* ddC (2ʹ,3ʹ-dideoxycytidine).
* d4T (2ʹ,3ʹ-didehydro-2ʹ,3ʹ-dideoxythymidine).
91
When a nucleoside analog such as AZT, ddI, ddC, or d4T is incorporated into viral DNA,
```
• the lack of a hydroxyl
group on the 3ʹ-carbon in
the sugar prevents the
formation of the sugar–
phosphate bonds.
```
• the production of viral
DNA is stopped.
92
Current treatment for HIV and AIDS involves a combination of drugs that include
* entry inhibitors.
* reverse transcriptase inhibitors.
* protease inhibitors.
93
Ma tch the following terms to their definitions:
1) virus
2) retrovirus
3) protease inhibitor
4) reverse transcription
A. a virus containing RNA
B. small particles requiring host cells to replicate
C. a substance that prevents the synthesis of viral
proteins
D. using viral RNA to synthesize viral DNA
A. a virus containing RNA
2) retrovirus
B. small particles requiring host cells to replicate
1) virus
C. a substance that prevents the synthesis of viral proteins
3) protease inhibitor
D. using viral RNA to synthesize viral DNA
4) reverse transcription
94
a virus containing RNA
retrovirus
95
small particles requiring host cells to replicate
virus
96
a substance that prevents the synthesis of viral proteins
protease inhibitor
97
using viral RNA to synthesize viral DNA
reverse transcription
