(P) Lesson 1: Molecular Basis of Genetics Flashcards
workbook-based (128 cards)
1
Q
then study of how traits are inherited from one generation to another, how genes are organized and expressed, and how genes behave in populations and evolve over time
A
genetics
2
Q
T or F. Genetics plays a central role in all modern EARTH SCIENCES and is essential for an understanding of the living world.
A
F (biology)
3
Q
scientific discipline focused on investigating the fundamental principles of inheritance and diversity.
A
Genetics
4
Q
T or F. RNA is a macromolecule that contains the genes which encode the amino acid sequences of proteins.
A
F (DNA)
5
Q
units of heredity
A
Genes
6
Q
T or F. DNA does direct protein synthesis
A
F (not - they only code for the sequence of amino acids in proteins)
7
Q
genetic information in the DNA is decoded in the form of
A
MRNA
8
Q
which is translated to amino acid sequence of a protein?
A
MRNA
9
Q
Try to explain the central dogma of molecular biology
A
Main point: DNA to mRNA to protein or DNA replication, transcription and Translation
10
Q
T or F. the flow of information may start from RNA to DNA, the RNA can also be replicated.
A
T
11
Q
This stage shows the genetic information in the DNA is copied into mRNA. The sequence of the mRNA bases is the same as that of the DNA.
A
Transcription
12
Q
What do you call when the genetic code in the mRNA directs the sequence of amino acids in the protein?
It’s a phase
A
Translation
13
Q
Composition of DNA
A
1.) 5-Carbon sugar (2’-deoxyribose or ribose)
2.) Nitrogenous base (Purines and Pyrimidines)
3.) Phosphate group
14
Q
T or F. 2’-deoxyribose is a a 5-carbon sugar that forms a ring.
A
T
15
Q
What bond does the phosphate group form with C5?
A
phosphoester bond
16
Q
What bond does the nitrogenous base form with C1?
A
N-glycosidic bond
17
Q
T or F. This N-glycosidic linkage with the sugar involves either the N-1 of the purine or the N-9 of the pyrimidine.
A
F (opposite)
18
Q
contain nitrogen within the rings
A
heterocyclic bases or nitrogenous bases
19
Q
two types of nitrogenous bases
A
purines and pyrimidines
20
Q
this nitrogenous base consist two fused rings
A
Purine
21
Q
this nitrogenous base consist 6-sided single ring.
A
Pyrimidines
22
Q
enumerate pyrimidine bases
A
T, U and C
23
Q
enumerate purine bases
A
A and G
24
Q
T or F. nucleoside is composed of three components: a phosphate, a sugar and a base.
A
F (nucleotides)
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T or F. It is possible for nucleotides to combine with additional phosphate units to make diphosphates and triphosphates.
T
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relatively short single-stranded nucleic acid chain
oligonucleotide
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single-stranded polymer of several nucleotide units.
polynucleotide
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catalyze the unwinding of the two strands
helicases
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bind to the DNA stabilize the single-
stranded form. A single-stranded DNA is very susceptible to destruction by
nucleases.
SSBP
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relaxes the supercoil that forms ahead of the replication fork and aids
with the unwinding process.
DNA gyrase
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catalyzes the synthesis of RNA primers, which are required for initiation of DNA synthesis. These provide the required free 3' hydroxyl group where a nucleotide is added.
Primase
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the principal polymerase in the DNA replication in bacteria. It catalyzes the incorporation of new nucleotides to the elongating DNA.
DNA polymerase III
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removes the RNA primer. It fills the gaps formed in the growing molecule that result from the removal of the RNA primer. It also proof-reads and corrects any error in base pairing.
DNA Pol 1
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forms a phosphodiester bond between 3'-OH and 5'-PO4 groups between the DNA fragments. This forms a continuous DNA molecule.
DNA ligase
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The 5’–3’ strand that proceeds to the direction of the replication fork is called?
leading strand
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More RNA primers are added by the primase as the DNA helix is unwound, and is elongated by Pol III. The short DNA fragments added to the primase are called the?
Okazaki fragments
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made up of unbranched chain of nucleotides as in DNA
RNA
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T or F. RNA differs from DNA in that the sugar unit is B-D-ribose, uracil pairs with adenine instead of thymine and is in general, double-stranded.
F (single stranded)
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process of copying of a DNA template in the form of RNA
Transcription
40
T or F. All RNAs are synthesized using a DNA template.
T
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This enzyme acts like DNA polymerase, requiring a template, nucleotide triphosphates (ATP, CTP, GTP, and UTP), and magnesium ion.
RNA Polymerase (transcription)
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T or F. The RNA polymerase is able to initiate RNA synthesis without a primer, unlike DNA polymerase.
T
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a core enzyme and a sigma (σ) subunit are referred to as?
holoenzyme
44
What subunit is involved in initiating transcription at the beginning of a gene?
σ subunit
| p'wede rin naman -10 and -35 kasi σ subunit lang rin nakakarecognize nto
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Where specific DNA do subunits bind? Transcription
promoter
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defines the beginning of a gene for transcription
promoter site
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The transcription start site (+1) has two groups before the first base of the DNA that will be transcribed into the first base of RNA.
| Transcription
-35 and -10
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T or F. The bases to the left (negative numbers) of the transcription start site are said to be DOWNSTREAM, and the bases to the right (positive numbers) are said to be UPSTREAM
F (opposite)
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template used for RNA synthesis is the
anti-sense strand
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strand that codes for the sequence of the gene is called the
sense or coding strand
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What phase is this?
The start of RNA synthesis occurs at the +1 position, utilizing nucleotide triphosphates (NTPs). The sigma subunit is no longer required at once the helix is opened and is released from the core polymerase shortly after this phase of synthesis.
| under Transcription
Initiation
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How do the RNA polymerase elongates the RNA?
| Transcription
by adding NTPs to the 3’OH end guided by the DNA template
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What is formed when the termination sequence is reached that stalls the RNA polymerase, which causes the release of the mRNA and RNA polymerase and the reformation of the DNA double helix?
| Transcription
hairpin loop
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Type of RNA: It is a copy of a portion of the gene except that uracil replaces thymine. It is linear and does not form secondary structure.
mRNA
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composed of rRNAs and proteins
ribosomes
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ribosomes subunits of eukaryotes
80S, consisting of 40S and 60S subunits
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ribosomes subunit of prokaryotes
30S and 50S subunits that associate to form a 70S ribosome
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The big subunit has an enzyme component, peptidyl transferase, which is not a protein but RNA called a?
ribozyme
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T or F. Peptidyl transferase catalyzes the formation of peptide bonds between amino acids to form polypeptide chains.
T
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A big ribosome subunit contains two or three binding sites for the tRNAs
called the A-site, P- site, and E-site
| rRNA
## Footnote
A & P in eukaryotes, E is only present in pro
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site where the incoming amino- acyl-tRNA binds
Acceptor site
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site where the elongating peptidyl-tRNA binds
P-site
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the site where the uncharged tRNA binds, and is found in prokaryotes only.
E-site
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carries amino acids to the ribosomes during translation
tRNA
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T or F. The rRNA folds up into precisely defined 3-dimensional structures, a cloverleaf appearance.
F (tRNA)
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T or F. The tRNA carries a specific amino acid and its anticodon (a triplet of nucleotides) binds with the complementary ANTICODON in an mRNA molecule that specified the amino acid to be added to the polypeptide
F (codon)
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set of rules that transmits the message from a gene by specifying the amino acids in proteins
genetic code
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possible combinations that form the genetic code
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each triplet is called a
codon
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4 bases in the mRNA
A, U, C, G
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each codon specifies for an amino acid, an amino acid can be coded by more than one codon
degenerate or redundant
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non-sense or termination codons
UAG, UGA, UAA
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first codon
AUG
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it is universal, meaning it is the same for all types organisms except for some differences in code found mainly in the DNA of the mitochondrial DNA
genetic code
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T or F. The reading of the codons is punctuationless, and the codons are overlapping
F (non-overlapping)
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Translation AKA
protein synthesis
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T or F. Transcription is the process by which the nucleotide base sequence in an mRNA molecule directs what amino acids will be incorporated in the protein
F (Translation)
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Translation of the code from the mRNA involves matching what?
tRNA anticodons and the mRNA codons
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In the initiation phase of Translation, protein synthesis is initiated by the assembly of an?
initiator tRNA
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what comprises the initiation complex?
| Translation
initiator tRNA attached to an N-formylated-methionine, initiation factors (IF) 1, 2, and 3, and the 30S (small) ribosomal subunit
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After forming the initiation complex, this is followed by the binding of the?
| Translation
50S (large) ribosomal subunit to the small subunit
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The initiator tRNA binds to?
P-site
| Translation
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Familiarize yourself with the 3 repeated steps in Elongation
Translation
(a) binding of new aminoacyl-tRNA to the A site, the P-site is already occupied by the initiator tRNA;
(b) peptide bond formation between the previous amino acid and the new amino acid, the tRNA in the P site is uncharged; and
(c) the release of uncharged tRNA.
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The peptidyl t- RNA is translocated to the
P site.
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The next aminoacyl-tRNA occupies the
| Translation
empty A-site
| Elongation
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Termination occurs when an mRNA termination codon is in what site?
| Translation
A site
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In the termination, the entire complex dissociates into
free polypeptide, release factors (RFs), tRNA, mRNA, and small and big subunits of the ribosomes
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What do you call when newly synthesized polypeptides undergo modification before they attain their final form which exhibit biologic activity
Post-Translational Modification
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The N-formyl- methionine in prokaryotes or initiation methionine in eukaryotes are removed.
Proteolytic cleavage
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In the proteolytic cleavage, leader sequences are cleaved by specific proteases, and the finished protein is brought by the?
Golgi apparatus
91
What bonds may form due to proteolytic cleavage?
Disulfide bonds
92
Many polypeptides acquire modifications at their N-terminal ends such as the addition of an?
acetyl group
93
Which among does not belong
Sugar residues
Phosphate groups
Proteolytic cleavage
co-factors
Preproinsulin
Preproinsulin
94
T or F. DNA polymerases sometimes adds one or wrong nucleotides but some of them have proof reading abilities that correct the mistakes.
T
95
any change in the base sequence of DNA that make up the genes
mutation
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occurs during normal genetic and metabolic functions in the cell resulting from internal factors such as error in replication; mistakes in recombination; misrepair of damaged DNA; base modifications, such as depurination or deamination, caused by spontaneous hydrolytic reactions.
spontaneous mutation
97
This results when organisms are exposed, accidentally or purposely, to any chemical or physical agents called mutagens. Mutagens increase the frequency of mutation.
Induced mutation
98
T or F. Mutations are transmitted from a offspring to its parent cell.
F
99
T or F. Higher organisms tend to have two copies of each gene and if one copy is mutated, the other can't function.
F (can)
100
any agent that can alter the structure or sequence of the DNA
Mutagen
101
first reported mutagenic agen
radiation
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two types of radiations that cause mutations
ionizing and non-ionizing radiation
103
- non-ionizing radiation.
- causes formation of pyrimidine dimers (thymine-thymine) in the DNA by forming a covalent cyclobutane ring between two adjacent pyrimidines.
- results in error in replication
UVL
104
- x-rays and gamma rays
- alter the DNA by producing hydroxyl free radicals, which are very reactive to hydrogens present on the DNA
Ionizing radiation
105
This is transferred to the DNA, making it highly reactive, and ultimately, the DNA strand breaks
Radical
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These are compounds that are able to enter the cell, and react with the DNA. These increase the frequency of mutations.
chemical agents
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some chemicals look like normal bases
base analogues
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chemical agents: 5- bromouracyl (5-BU)
base analogues
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chemical agents: Nitrous acid
Chemicals which modify the structure and pairing properties of bases.
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flat, multiple ring molecules which insert between stacked bases that causes helix distortion
Intercalating agents.
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chemical agents: acridine dyes
Intercalating agents
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The DNA polymerase may insert an additional nucleotide opposite an intercalated molecule. These insertions cause?
frameshift
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two types of base pair substitutions
transition and transversion
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substitution of purine to purine or pyrimidine to pyrimidine
transition
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substitution of purine to pyrimidine or pyrimidine to purine
transversion
116
causes replacement of 1 amino acid residue
Missense mutation
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produced if base substitution creates a stop codon, thereby terminating protein synthesis prematurely
nonsense mutation
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when a base substitution produces a different triplet but which codes for the same amino acid as the original triplet (redundancy of the genetic code). The change usually occurs at the 3rd base.
silent mutation
119
the acquisition of one or more nucleotides
insertion
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loss of one or more nucleotides
deletion
121
All the amino acids are changed after the insertion or deletion point
frameshift mutation
122
T or F. All the amino acids are changed after the insertion or deletion point. This mutation can still cause the resulting protein to function.
F (non-functional)
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This is a simple repair system. It uses the enzyme photolyase, which is active only in the presence of visible light. It removes the covalent bond between the pyrimidine dimer restoring the normal DNA structure. This repair mechanism is found in many bacteria and lower eukaryotes.
Photoreactivation or light repair
124
this involves enzymes that remove the altered DNA, usually including the nucleotides on either side of the mutation. DNA polymerase can then fill the gap, repairing the DNA. It does not require light, but it may also occur in the presence of light.
Excision or Dark Repair
125
Use the table
Identify which here is an example of Missense mutation
Original:
AGU-CGU-GGA-AAU-UGU-CCU-CGA
A.) AGU-CGU-UGA-AAU-UGU-CCU-CGA
B.) AGU-CGU-GGU-AAU-UGU-CCU-CGA
C.) AGU-CGU-GCA-AAU-UGU-CCU-CGA
D. AGU-CGU-GAG-AAA-UUG-UCC-UCG-A-
C
126
Use the table
Identify which here is an example of Nonsense mutation
Original:
AGU-CGU-GGA-AAU-UGU-CCU-CGA
A.) AGU-CGU-UGA-AAU-UGU-CCU-CGA
B.) AGU-CGU-GGU-AAU-UGU-CCU-CGA
C.) AGU-CGU-GCA-AAU-UGU-CCU-CGA
D. AGU-CGU-GAG-AAA-UUG-UCC-UCG-A-
A
127
Use the table
Identify which here is an example of Silent mutation
Original:
AGU-CGU-GGA-AAU-UGU-CCU-CGA
A.) AGU-CGU-UGA-AAU-UGU-CCU-CGA
B.) AGU-CGU-GGU-AAU-UGU-CCU-CGA
C.) AGU-CGU-GCA-AAU-UGU-CCU-CGA
D. AGU-CGU-GAG-AAA-UUG-UCC-UCG-A-
B
128
Use the table
Identify which here is an example of Insertion
Original:
AGU-CGU-GGA-AAU-UGU-CCU-CGA
A.) AGU-CGU-UGA-AAU-UGU-CCU-CGA
B.) AGU-CGU-GGU-AAU-UGU-CCU-CGA
C.) AGU-CGU-GCA-AAU-UGU-CCU-CGA
D. AGU-CGU-GAG-AAA-UUG-UCC-UCG-A-
D
