Molecular biochemistry W4 Flashcards
(73 cards)
1
Q
What are genes composed of
A
Short exons and long introns
2
Q
Is gene distribution across the genome uneven or even
A
Uneven
3
Q
Is mRNA coding or nondocing RNA
A
- Coding RNA
4
Q
Give brief description of transcription
A
- Copying DNA into RNA
5
Q
What is the brief description of Translation
A
Converting mRNA into a protein using ribosomes
6
Q
How many nucloetides is a codon
A
- 3 nucleotides
7
Q
What does the codon sequence detemine
A
The amino acid sequence , which defines the protein structure and function
8
Q
What are silent mutations
A
Muttions in the 3rd base of a codon that does not chnage the amino acid
9
Q
Name the 3 regions of the nucleus
A
- Nucleolus
-Heterochromatin
-Euchromatin
10
Q
Explain the characteristics of heterochromatin+
A
- Apperas dark and is dense due to condensed DNA
-Transcriptionally inactive
11
Q
Explain the characteristcs of euchromatin
A
- Appears lighter and contains decondensed DNA
-Transcriptionally active
12
Q
How does the Nucleous appear
A
- Dark and
-dense due to high levels of proteins and rRNA not condensed DNA
-Transcriptioanlly active
13
Q
Name the 2 type of roles RNAs can have
A
Structural or catalytic roles
14
Q
Which RNA is the most abundant
A
- rRNA
15
Q
what is rRNA made by and where
A
- RNA polymerase 1 in the nucleolus
16
Q
What is mRNA made by and where
A
- RNA polymerase 2 , in euchromatine
17
Q
What does euchromatin produce
A
mRNA and tRNA
18
Q
What does RNA polymerase 1 make
A
rRNA
19
Q
What does RNA polymerase 2 make
A
mRNA and other RNAs
20
Q
What does RNA polymerase 3 make
A
tRNA and other RNAs
21
Q
What direction does RNA polymerase read DNA + synthesize RNA
A
-3 to 5 direction
synthesoce RNA in a 5 to 3 direction
22
Q
What is an upstream
A
Towards the 5 end of the DNA
23
Q
What is downstream
A
Towards the 3 end of DNA
24
Q
What do eukaryotic genes have
A
- promotor
-Exon-inton regions
25
Where do exons end up
In mRNA
26
When are constitutive genes active
- Always active`
27
When is facultative genes transcribed
Transcribed only when needed
28
What are strong promotors for
Abundant proteins
29
What are weak promtors for
Rare proteins
30
What is the consensus sequence
- Average sequence from similar functional regions
31
what is TATA box
A common consensus rich in T and A bases found in promoters
32
What do prokaryotes use for transcrition initiation/ to postion RNA polymerase
- Use a sigma factor
33
What do eukaryotes use general transcritpion for
- Position RNA Polymerase 2
-Seperate DNA strands
-Start transcription
34
Where do general transcription factors assemble + what do they form
At the TATA box to form the transcritpion initiation comples
35
Once RNA polymerase 2 starts elongating what happens to the transcrition factors
They are released to be reused
36
Name the 3 phases in which transcription occurs
- Initiation
-Elongation
-Termination
37
Explain what happens in the initiation step in transcription
- RNA polymerase binds to the promotor, and begins RNA synthesis
38
Explain what happens in the second step of transcription- Elongation
- RNA polymerase moves along the template strand in a 3 - 5 direction building it in a 5-3 direction
39
Explain what happens in the last step of transcrition - Termination
- At the termination sequence, transcription ends, RNA gets a poly-Atail on its 3 end and is released
40
What is the template strand read by
RNA Polymerase
41
What does the direction of transcription depend on
- Promotor orientation
42
Explain characteristics of RNA polymerase which differs from DNA polymerase
- RNA polymerase uses ribonucleotides
-Does not reuire a primer
-Froms a transcription bubble as it mo0ves
43
What happens in Combinatorial control
- It is when multiple transcription regulators coordiante to control one gene expression
44
What are enhancers
DNA sequences that bind transcriptional activators
45
What is the function of mediator complexes
- It bridges activators and RNA polymerase 2
46
What do chromatin loops ensure
They ensure enhancers act only on the intended gens
47
What is the functin of loop boundaries
Prevent enhancers from affecting neigbouring genes
48
What does improper loop formation cause
- misexpression, which can lead to cancer or genetic disorders
49
What does DNA winding during transcription cause
Supercoils
50
What relieves supercoiling+ its alternativ name
Topoisomerase 2( DNA gyrase)
51
What targets DNA gyrase( Topoisomerase 2)
- Fluoroquinolone antibiotics
52
What does a-Amanitin inhibit + block
- RNA polmerase 2
- Blocks mRNA synthesis, which leads to liver and kidney failure
53
What needs processing before translation
- Pre-mRNA
54
Name the 3 main post-transcriptional modifications
-Capping
-Tailing
-Splicing
55
Explain the function of capping + what it aids in
Adds a 5’ methyl cap; aids in mRNA recognition, stability, and initiation of translation.
56
Explain the function of Tailing
Adds a poly-A tail to the 3’ end; important for stability, export, and translation.
57
Explain the function of Splicing + what it is guided by
+ what else it involves
Removes introns and joins exons; guided by specific splice sites and involves spliceosomes.
58
Which post-transcription modification protects mRNA
- Capping and tailing
59
What does alternative splicing allow
- Allows one gene to create multipe proteins, increasing genetic diversity
60
What does RNA editing modify
It modifes mRNA nucleotides post-transcriptioanlly
61
What is the function of Rifamycins , antibiotics
They inhibit prokaryotic RNA polymerase
62
What can the antibioitc rifampin be used to treat
Tuberculosis
63
What does resistance to the antibiotic rifampin arise from
- Mutations in the beta subunit of RNA polymerase , that prevents the drug from binding
64
What is FISH- Fluorescence in situ hybridization
A technique used to detect specific DNA sequences using fluorescent probes
65
Explain the FISH procedure
DNA is denatured into single strands.
Complementary probes bind to target DNA (hybridization).
Probes may be directly labeled or indirectly labeled (using fluorescent antibodies).
Fluorescent signals are viewed under a microscope.
66
Wht can FISH be used for
Karyotyping, tumor diagnosis and gene mapping
67
What is Thalassemia
Genetic blood disorder, characterised by reduced or absent synthesis of globin chains in hemoglobin
68
Name the types of thalaseemia
- a thalassemia
-b thalassemia
69
What is a thalassemia
- Reduced or abesnt production of a globin chains
70
What is b thalassemia
Reduced or absent poduction of b globin chains
71
What is the inheritance pattern of thalassemia
- Autosomal recessivr
72
What is a thalassemia caused by
point mutations in the HBB GENE
73
What is b thalassemia caused by
Gene deltions in the HBA1 and HBA2
