Molecular biochemistry W4

Question 1

What are genes composed of

Answer 1

Short exons and long introns

Question 2

Is gene distribution across the genome uneven or even

Answer 2

Uneven

Question 3

Is mRNA coding or nondocing RNA

Answer 3

• Coding RNA

Question 4

Give brief description of transcription

Answer 4

• Copying DNA into RNA

Question 5

What is the brief description of Translation

Answer 5

Converting mRNA into a protein using ribosomes

Question 6

How many nucloetides is a codon

Answer 6

• 3 nucleotides

Question 7

What does the codon sequence detemine

Answer 7

The amino acid sequence , which defines the protein structure and function

Question 8

What are silent mutations

Answer 8

Muttions in the 3rd base of a codon that does not chnage the amino acid

Question 9

Name the 3 regions of the nucleus

Answer 9

• Nucleolus
  -Heterochromatin
  -Euchromatin

Question 10

Explain the characteristics of heterochromatin+

Answer 10

• Apperas dark and is dense due to condensed DNA
  -Transcriptionally inactive

Question 11

Explain the characteristcs of euchromatin

Answer 11

• Appears lighter and contains decondensed DNA
  -Transcriptionally active

Question 12

How does the Nucleous appear

Answer 12

• Dark and
  -dense due to high levels of proteins and rRNA not condensed DNA
  -Transcriptioanlly active

Question 13

Name the 2 type of roles RNAs can have

Answer 13

Structural or catalytic roles

Question 14

Which RNA is the most abundant

Answer 14

• rRNA

Question 15

what is rRNA made by and where

Answer 15

• RNA polymerase 1 in the nucleolus

Question 16

What is mRNA made by and where

Answer 16

• RNA polymerase 2 , in euchromatine

Question 17

What does euchromatin produce

Answer 17

mRNA and tRNA

Question 18

What does RNA polymerase 1 make

Answer 18

rRNA

Question 19

What does RNA polymerase 2 make

Answer 19

mRNA and other RNAs

Question 20

What does RNA polymerase 3 make

Answer 20

tRNA and other RNAs

Question 21

What direction does RNA polymerase read DNA + synthesize RNA

Answer 21

-3 to 5 direction
synthesoce RNA in a 5 to 3 direction

Question 22

What is an upstream

Answer 22

Towards the 5 end of the DNA

Question 23

What is downstream

Answer 23

Towards the 3 end of DNA

Question 24

What do eukaryotic genes have

Answer 24

• promotor
  -Exon-inton regions

Question 25

Where do exons end up

Answer 25

In mRNA

Question 26

When are constitutive genes active

Answer 26

- Always active`

Question 27

When is facultative genes transcribed

Answer 27

Transcribed only when needed

Question 28

What are strong promotors for

Answer 28

Abundant proteins

Question 29

What are weak promtors for

Answer 29

Rare proteins

Question 30

What is the consensus sequence

Answer 30

- Average sequence from similar functional regions

Question 31

what is TATA box

Answer 31

A common consensus rich in T and A bases found in promoters

Question 32

What do prokaryotes use for transcrition initiation/ to postion RNA polymerase

Answer 32

- Use a sigma factor

Question 33

What do eukaryotes use general transcritpion for

Answer 33

- Position RNA Polymerase 2 -Seperate DNA strands -Start transcription

Question 34

Where do general transcription factors assemble + what do they form

Answer 34

At the TATA box to form the transcritpion initiation comples

Question 35

Once RNA polymerase 2 starts elongating what happens to the transcrition factors

Answer 35

They are released to be reused

Question 36

Name the 3 phases in which transcription occurs

Answer 36

- Initiation -Elongation -Termination

Question 37

Explain what happens in the initiation step in transcription

Answer 37

- RNA polymerase binds to the promotor, and begins RNA synthesis

Question 38

Explain what happens in the second step of transcription- Elongation

Answer 38

- RNA polymerase moves along the template strand in a 3 - 5 direction building it in a 5-3 direction

Question 39

Explain what happens in the last step of transcrition - Termination

Answer 39

- At the termination sequence, transcription ends, RNA gets a poly-Atail on its 3 end and is released

Question 40

What is the template strand read by

Answer 40

RNA Polymerase

Question 41

What does the direction of transcription depend on

Answer 41

- Promotor orientation

Question 42

Explain characteristics of RNA polymerase which differs from DNA polymerase

Answer 42

- RNA polymerase uses ribonucleotides -Does not reuire a primer -Froms a transcription bubble as it mo0ves

Question 43

What happens in Combinatorial control

Answer 43

- It is when multiple transcription regulators coordiante to control one gene expression

Question 44

What are enhancers

Answer 44

DNA sequences that bind transcriptional activators

Question 45

What is the function of mediator complexes

Answer 45

- It bridges activators and RNA polymerase 2

Question 46

What do chromatin loops ensure

Answer 46

They ensure enhancers act only on the intended gens

Question 47

What is the functin of loop boundaries

Answer 47

Prevent enhancers from affecting neigbouring genes

Question 48

What does improper loop formation cause

Answer 48

- misexpression, which can lead to cancer or genetic disorders

Question 49

What does DNA winding during transcription cause

Answer 49

Supercoils

Question 50

What relieves supercoiling+ its alternativ name

Answer 50

Topoisomerase 2( DNA gyrase)

Question 51

What targets DNA gyrase( Topoisomerase 2)

Answer 51

- Fluoroquinolone antibiotics

Question 52

What does a-Amanitin inhibit + block

Answer 52

- RNA polmerase 2 - Blocks mRNA synthesis, which leads to liver and kidney failure

Question 53

What needs processing before translation

Answer 53

- Pre-mRNA

Question 54

Name the 3 main post-transcriptional modifications

Answer 54

-Capping -Tailing -Splicing

Question 55

Explain the function of capping + what it aids in

Answer 55

Adds a 5’ methyl cap; aids in mRNA recognition, stability, and initiation of translation.

Question 56

Explain the function of Tailing

Answer 56

Adds a poly-A tail to the 3’ end; important for stability, export, and translation.

Question 57

Explain the function of Splicing + what it is guided by + what else it involves

Answer 57

Removes introns and joins exons; guided by specific splice sites and involves spliceosomes.

Question 58

Which post-transcription modification protects mRNA

Answer 58

- Capping and tailing

Question 59

What does alternative splicing allow

Answer 59

- Allows one gene to create multipe proteins, increasing genetic diversity

Question 60

What does RNA editing modify

Answer 60

It modifes mRNA nucleotides post-transcriptioanlly

Question 61

What is the function of Rifamycins , antibiotics

Answer 61

They inhibit prokaryotic RNA polymerase

Question 62

What can the antibioitc rifampin be used to treat

Answer 62

Tuberculosis

Question 63

What does resistance to the antibiotic rifampin arise from

Answer 63

- Mutations in the beta subunit of RNA polymerase , that prevents the drug from binding

Question 64

What is FISH- Fluorescence in situ hybridization

Answer 64

A technique used to detect specific DNA sequences using fluorescent probes

Question 65

Explain the FISH procedure

Answer 65

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.

Question 66

Wht can FISH be used for

Answer 66

Karyotyping, tumor diagnosis and gene mapping

Question 67

What is Thalassemia

Answer 67

Genetic blood disorder, characterised by reduced or absent synthesis of globin chains in hemoglobin

Question 68

Name the types of thalaseemia

Answer 68

- a thalassemia -b thalassemia

Question 69

What is a thalassemia

Answer 69

- Reduced or abesnt production of a globin chains

Question 70

What is b thalassemia

Answer 70

Reduced or absent poduction of b globin chains

Question 71

What is the inheritance pattern of thalassemia

Answer 71

- Autosomal recessivr

Question 72

What is b thalassemia caused by

Answer 72

Point mutations in the HBB GENE

Question 73

What is a thalassemia caused by

Answer 73

Gene deltions in the HBA1 and HBA2