BIOCHEMISTRY- Molecular/ videos Flashcards
(163 cards)
1
Q
What is attached to the last 3’ Carbon of DNA?
A
OH (Hydroxyl)
2
Q
What is attached to the 5’ Carbon of DNA?
A
Phosphate
3
Q
What makes the difference between each human DNA?
A
Sequence of Nitrogen bases
4
Q
Which bond allows Nucleotides to be atteched to each other in the same strand?
A
Phosphodiester bond
5
Q
What holds together the double stranded DNA?
A
Hidrogen bonds
6
Q
Which is the DNA tha predominates?
A
B-DNA right handed helix
7
Q
How many bases are found in each turn of helix?
A
10 bases approximately
8
Q
What forms chromatin?
A
DNA + Protein
9
Q
What forms nucleosome?
A
DNA + Histone Octamer
10
Q
How are DNA and histones stick together?
A
Because histones have positive charges and DNA negative
11
Q
Which aminoacids are included in Histones?
A
Arginine and Lisine
12
Q
Where are Barr bodies found?
A
Heterochromatin
13
Q
Which drugs work at S phase?
A
5’ FU
Methotrexate
14
Q
Which drugs work at G2 phase?
A
Bleomycin
15
Q
Which drugs work at Mitosis phase?
A
Paclitaxel, Vincristin, Vinblastine
16
Q
Drugs non cell cycle specific
A
Cyclophosphamide
Cisplatin
17
Q
Which Purine has amino group?
A
Adenine
18
Q
Which enzyme deaminates Adenine to become Guanine?
A
Adenosine deaminase
19
Q
What is the result of Adenosine deaminase?
A
Form Guanine from Adenosine by deaminating it
20
Q
Which pyrimidin has amino group?
A
Cytosine
21
Q
What is the result of cytosine deamination?
A
Uracyl
22
Q
Which pyrimidine is in both DNA and RNA?
A
Cytosine
23
Q
What is the difference between Uracil and Thymine?
A
Metil Group
24
Q
Which drug inhibits thymidilate synthase?
A
5- FU
25
When does Nucleoside is called Deoxi?
When it lacks OH in 2' Carbon
26
Which Pentose Carbon is attached to base?
1' Carbon
27
What is the function of Telomerase?
To make telomers in order to degrade DNA
| Associated to oncogen cells
28
Which is the small arm of chromosomes?
p (petit), q (long arm)
29
Main characteristics of synthesis
Is always complementary and antiparallel
30
How is DNA template read by DNA polymerase?
3' ---> 5'
31
Order of DNA and RNA production
5' ---> 3'
32
Does RNA polymerase requires RNA primer?
No, just DNA requires RNA primer
33
Which is the direction of exonuclease repair in proofreading?
3' ---> 5'
34
Does RNA polymerase has proofreading repair of wrong bases?
No, just DNA
35
Which pathology has antibodies against topoisomerase?
Scleroderma
36
Heterochromatin or Euchromoatin.... has dark staining
Heterochromatin
37
Heterochromatin or Euchromoatin... has active genes
Euchromatin
38
Which DNA type is more sensitive to nuclease?
the 10 nm
39
Types of DNA
10 nm
| 30 nm
40
Proteins included in histone
2A, 2B, 3, 4 each double forming the octamers
41
Which structures form euchromatin?
DNA double helix ---> 10 nm chromatin ---> 30 nm chromatin ---> 30 Fibre forms loops attached to proteins
42
What structure forms heterochromatin?
Higher order Packaging (includes all Euchromatin structures)
43
What is the function of Nucleolus?
Formation of Ribosomes
44
What happens in DNA methylation?
Inactive transcription
45
What happens in Histone acethylation/ Histone phosphorylation?
More active transcription, more gene expression
46
What causes thymine dimers damage?
By UV radiation
47
Which the recognition enzyme for thymine repair?
Excision endonuclease
48
When is excision endonuclease deficient in thymine repair?
Xeroderma pigmentosum
49
Which enzymes repair DNA damage?
DNA polymerase and DNA ligase
50
When does Thymine dimer repair occur?
During G1
51
When does Mismatched base repair happens?
During G2
52
Which are the two genes that may be affected in Mismatched repair?
hMSH2 or hMLH1
53
Alternative name for Hereditary Nonpolyposis Colorectal Cancer (HNPCC)?
Lynch syndrome, predisposes to cancer
54
What explains HNPCC?
Accumulation of mutations due to defective mismatched repair
55
When does Cytosine deamination occurs?
During G2
56
What causes Cytosine deamination?
Spontaneous Heat
57
Which enzyme corrects if Uracil is present in DNA?
Uracil Glycosylase
| AP endonuclase
58
Clinical manifestations of Xeroderma pigmentosum
Extreme UV sensitivity (vampire existanse)
Excessive Freckling
Multiple skin cancers
Corneal Ulcerations
59
Which is the function of DNA ligase?
Reconect Fosfodiester bonds
60
What is accumulated in cytosine deamination?
Uracil in DNA
61
What is the effect of p 53 in case DNA repair is not done correctly after slowing down DNA repliaction?
Induces Apoptosis
62
Which virus block p53 action?
Hepatitis B and HPV
63
di and tri nucleotide repeats that occur throughout the genome but typically occur in noncoding sequences of DNA
Microsatellites
64
What happens to microsatellites in cells that lack mismatch base repair?
Number of microsatellites will differ in the mutated cells (called microsatellite instability)
65
What does RNA polymerase initially looks for in Transcription?
Initially finds and binds to the promoter, not the coding region
66
Type of RNA that complementes DNA template transcription
mRNA
67
Does TATA box is in the DNA template or coding RNA?
Coding RNA
68
Does the promoter sequense is transcribed?
NO, NEVER
69
Which RNA polymerase is required in prokaryotic for transcription?
Single RNA polymerase (α2ββ')
70
Types of RNA polymerase in Eukaryotic
RNAP 1
RNAP 2
RNAP 3
71
Who are RNAP 1?
rRNA. Except 5s rRNA
72
Who are RNAP 2?
hnRNA/mRNA and some snRNA
73
Who are RNAP 3?
tRNA, 5s rRNA
74
Where is RNA?
Nucleolus
75
Which is the only rRNA that does not belong to RNAP 1?
5s rRNA, it is RNAP 3
76
What do prokaryotic need to initiate a promoter?
Sigma δ (delta)
77
What do prokaryotic require to terminate transcritpion?
rho (p)
78
Drugs that inhibit prokaryotic transcription
Rifampin
| Actinomycin D
79
In Eukaryotic what inhibits transcription?
RNAP 2 inhibited by α amanitin (mushrooms)
| Actinomycin D
80
What does rifampin blocks in prokaryotic?
RNA polymerase (α2ββ')
81
When is Rifampin used?
For TB and Bacterial meningitis prophylaxis
82
What is formed after trancription?
mRNA
83
Once mRNA leaves the nucleous, where does it go to translate?
Ribosomes, after that the protein is formed
84
Who looks similar to coding DNA sequence?
mRNA, but instead of R is U
85
Who is antiparallel to mRNA?
Template sequence of DNA
86
Where are untranslated regions found?
After promoter and before transcription terminates
87
Which parts of DNA does not contain protein info during the transcription?
5' (UTR) and 3' (UTR)
88
What is the coding region?
Is the part of mRNA that is translated to protein between 5' UTR and 3' UTR
89
Characteristics of Prokaryotic mRNA
Policystronic
No introns
Tc and TL are coupled
90
Which is the only structure where RNA is read from 5' --> 3'?
Just in Ribosomes
91
Structure of protein formed after translation
H2N (Amino)- Protein - COOH (Carboxyl) terminus
92
In prokaryotic where does Ribosomes binds to mRNA to initiate translation?
Shine Dalgarno sequence, ubicated before coding region
93
What are Polycistronic mRNA of Prokaryotic?
Various genes that independetly can translate
94
Where does transcription of DNA takes place?
After promoter +1
95
Where are promoter found?
In coding strand CAAT, TATA
96
In eukaryotic what contains the important encoding region?
Exon
97
How do we know is pre-mRNA?
Because is contains introns
98
What is needed in Eukaryotes pre mRNA to become RNA?
Remove introns
99
Characteristics of Eukaryotic mRNA
Monocystronic
Maturation
Tc and TL are not coupled
100
Maturation characteristics of Eukaryotic mRNA
Capping
Splicing
Poli- Adenylation
101
What is the splicing of mRNA in Eukaryotes?
Removal of introns
102
What is the capping of mRNA of Eukaryotes?
Adds a 7 Me- G cap to 5' of mRNA
103
What is poly A of mRNA of Eukaryotes?
Poly A addition to the 3' end of mRNA
104
When is the cap added to mRNA of Eukaryotes?
During Trancription (Co-transcription_
105
When is Poly A addition made in trancritption of Eukaryotes?
At the end of transcription (Post-trancription)
106
Who removes the introns of Pre mRNA?
Spliceosome (snRNA)
107
Where does pre mRNA becomes mRNA?
In the nucleus, after poly A addition to mRNA, it leaves the nucleus
108
In eukaryotes where does ribosome bind to mRNA?
To the capping (5' 7 Me-G), look for the start codon
109
In whom is Alternative splicing specific?
For Eukaryotes
110
Example of Alternative splicing
Membrane Ig versus secreted Ig
Tropomyosin variants in muscle
Dopamine receptors in brain
111
What does S of Ribosomes mean?
Sedimentation Coeficient
112
Which S subunits are found in Prokaryotic Ribosome?
30S+ 50 S = 70 S
113
Which S subunits are found in Eukaryotic Ribosome?
40S + 60S= 80 S
114
Which Ribosome structure binds to Shine Dalgarno Sequence of mRNA?
16 S rNA that belongs to 30 S subunit and starts translation
115
Which Ribosome subunit recognizes 7 Methyl Cap of mRNA in Eukaryotes?
18 S RNA part of 40 S subunit
116
What initiates translation in prokaryotes?
Binding of 16 S RNA subunit to Shine Dalgarno sequence
117
What initiates translation in eukaryotes?
Binding of 18 S RNA subunit to 7 Methyl Cap of mRNA
118
Functions of tRNA
Pick up amino acid
| Recognize codon on mRNA
119
Who pairs with anticodon of tRNA?
mRNA (antiparallel)
120
Who is covalently attached to 3' end OH of tRNA?
Activated aminoacid
121
Who allows the covalent attachement of 3' end OH of tRNA to Aminoacid?
Aminoacyl tRNA synthase
122
Where can Promoter be found in Eukaryotic cells?
(-25) TATA and 970) CAAT
123
Where can promoter be found in Prokaryotic?
(-10) TATAAT
124
How many codons encode AA?
61
125
How many codons exist?
64
126
How many codons are stop codons?
3
127
Which are the Start codons?
AUG in RNA
| ATG in DNA
128
Which are stop codons?
```
UAG= You are gone
UGA= You go away
UAA= You are away
```
129
Which aminoacid is formed by the first triplete of DNA and RNA?
Always Methionine
130
In the missense mutation of Sickle cell anemia which aminoacids are changed?
Glutamine---> Valine
131
What explains Nonsense mutation?
A codon is changed to a stop codon signal like (UGA, UAG, UAA)
132
What is the result of nonsense mutation?
A truncated (shorter) protein. Usually nonfunctional
133
What is the result of missense mutation?
Possible decrease in function: variable effects
134
What is the Missense mutation?
New codon specifies different aminoacid
135
Example of large segmental deletion
α Thalassemia
136
Example of 5' splice site or 3' splice site mutation
β Thalassemia
137
Triplet repeat expansion diseases
Huntignton disease
Myotonic dystrophy
Fragile X
Friedreich's Ataxia
138
What is the result of Triplet repeat Expansion?
Expansions in coding regions cause protein product to be larger than normal and unusable
139
What does Anticipation means?
In every generation the disease appear at younger age and severe
140
Which pathologies have tha anticipation phenomenom?
Triplet repeat expansion disease
141
What aminoacid is encode by CAG?
Gluthamine
142
Which triplet expansion is seen in Huntington disease?
CAG (Gluthamine)
143
What determines which aminoacid is attached to tRNA?
Anticodon
144
What is the structure of aminoacids?
Amino group + Carboxyl + Functional group
145
What kind of bond is formed between aminoacids to form proteins?
Peptide bond, Amino group of one with carboxyl group of the other
146
What is a recombinant DNA?
Splicing together DNA from 2 sources (eg. Human DNA and bacterial vector)
147
Types of DNA
```
Genomic DNA (fragments of entire genome)
cDNA (complementary DNA)
```
148
After we have the Genomic DNA how is recombinant DNA formed?
They are introduce into plasmid, the result recombinant plasmids, then added to bacteria in a process called transfection then the recombinant DNA is formed
149
Which are uses for cloned DNA?
Gene therapy
| Transgenic animals
150
What is a palindrome?
DNA sequence cleaved by a restriction endonuclease
151
What is a exonuclease?
Begins at 1 end and cuts PDE bodn to release single nucleotides (Random)
152
Types of exonuclease
5'---> 3' exonuclease (removes RNA primase)--> replace with DNA
3' ---> 5' exonuclease Exonuclease
153
What is endonuclease?
Cleaves internal PDE bond and release restricion fragments (Particular)
154
Sequence reads same backwards and forwards (usually 4, 6, 8 bp)
Palindrome
155
What is a Palindrome of DNA?
When a DNA is read backward and forward on the opposite strand of DNA
Eg: 5' GAATTC 3'
3' CTTAAG 5'
156
What is required for a Replication vector?
1. Ori (origin)--> DNA sequence recognized by bacteria repliaction enzymes
2. Single side for a given restriction endonuclease
3. Antibiotic resistance to select for Bacteria that take up vector
157
What is required for expression vector?
All replication Vector characterisitcs + Shine Dalgarno sequence + Promoter
158
What is the principle of Retroviral Gene therapy?
Take a piece of Virus, replace a therapeutic drug into virus (Replication defective retrovirus), then virus enters human cell, then express its genes into protein (with therapeutic gene)
159
What is ex vivo replacement therapy?
Cells modified outside the body then transplanted back in the body
160
In which pathologies is ex vivo replacement therapy used?
SCID
Cystic fibrosis
Hyperammonemia
161
Problems in gene ex vivo replacement therapy
Targeting the righ tissue
Integrating the gene in cells
Activating the gene
Avoiding harmful side effects (may be toxic or activates autoimmune response)
162
In which form is DNA analized?
After restriction endonuclease forming DNA fragments (restriction fragments)
163
Are RNA and protein cut up in order to be analized?
False, not cut up and analized directly
