Transcription

Question 1

Where does transcription occurs ?

Answer 1

In the nucleus

Question 2

What are 3 stop codons also known as non-sense codons?

Answer 2

1) UAA
2) UAG
3) UGA

Question 3

Can there be more than 1 codon for the same protein ?

Answer 3

YES

Question 4

What is transcription ?

Answer 4

1) Process in which cell uses DNA to form mRNA
2) Occurs in nucleus since DNA is present in nucleus.
3) Occurs in 3 steps: initiation, elongation, termination

Question 5

Why dont we use DNA directly for protein synthesis ?

Answer 5

To make sure we dont damage or mutate DNA molecules

Question 6

Transcription in detail

Answer 6

1) Initiation:
RNA polymerase binds to promoter region of the DNA
Promoter region : short specific sequence of DNA
Unwinds the two DNA strands
2) Elongation
RNA polymerase begin to add nucleotide in 5 prime to 3 prime direction on the growing RNA strand however oit reads the DNA in 3 prime to 5 prime direction
Template strand or anti sense is used to synthesize the mRNA
Coding/ sense / non -template strand
3) Termination:
RNA polymerase reaches the end of the gene
RNA polymerase and mRNA molecule detaches from the template strand
Poly A polymerase caps the 3 prime end of the mRNA known as poly A tail— Protects mRNA strand from enzyme degradation

Question 7

What is RNA splicing ?

Answer 7

1) During transcription DNA has been used to create pre m RNA stand
2) Pre mRNA has introns and exons
3) Introns are longer sequences of nucleotide that dont code for anything
4) Introns are removed during RNA splicing

Question 8

Whats translation ?

Answer 8

Using the information stored on mRNA strand to synthesize proteins.

Question 9

Where does translation occurs?

Answer 9

In cytoplasm

Question 10

What is a codon?

Answer 10

Each set of 3 nucleotides on the mRNA strand is called a codon.
Each Codon matches up with specific amino acid.

Question 11

What is anti-codon ?

Answer 11

The anticodon region of a transfer RNA is a sequence of three bases that are complementary to a codon in the messenger RNA.

Question 12

Translation steps in detail

Answer 12

1) Initiation
Start codon ‘AUG’ is read
which corresponds to the UAC anti codon of tRNA
This tRNA molecule enters the ribosome at P site
2) Another tRNA molecule enters the A site and during this process a peptide bond is formed between the amino acids of two tRNA molecules.
As this process goes on, the tRNA molecule in the P site moves to the E site, leaving behind its amino acid.
This polypeptide chain is going to grow as new tRNA molecules enter the A site.
3) Termination
This process stops when a stop codon is read at A site
They cause a release factor to enter a A site which causes the small and large sub unit to disassemble.

Question 13

How many possible codons ?

Answer 13

64

Question 14

Whats the function of active site E, P and A

Answer 14

E= site from where the tRNA that has losts its amino acids is discharged
P= Holds the tRNA carrying the growing polypeptide chain. 
A= Holds the tRNA carrying the next amino acid to the added to the polypeptide chains.

Question 15

Protein produced from the Free Ribosome

Answer 15

Is use within the cell

Question 16

Protein produced by bound ribosomes

Answer 16

is secreted outside the cell.

Question 17

What are polysomes

Answer 17

Group of ribosomes moving along and translating the same mRNA strand.

Question 18

Amylase

Answer 18

catalyses the hydrolysis of starch

Question 19

Actin and myosin

Answer 19

Bring about muscle movement

Question 20

What is the function of non-coding DNA sequences ?

Non coding DNA examples

Answer 20

REGULATOR OF GENE EXPRESSION

1) Introns
2) Telemeres
3) Tandem repeats

Question 21

What is gene expression?

Answer 21

Instructions in our DNA are converted into a functional product.

Question 22

Factors that can affect Gene expression

Answer 22

1) Environmental Factors (can be internal or external) like diet and radiation

Question 23

What is telemere and what is its function ?

Answer 23

Telomere is the repetitive nucleotide sequence at each end of a chromosome
it protects the ends of chromosomes from fusion with neighboring chromosomes

Question 24

What is telomere and what is its function ?

Answer 24

Telomere is the repetitive nucleotide sequence at each end of a chromosome
it protects the ends of chromosomes from fusion with neighboring chromosomes

Question 25

What are introns ?

Answer 25

Long stretch of non-coding DNA found between coding regions in a gene

1) Helps in gene expression
2) they increase gene length
3) increase the likelihood of crossing over

Question 26

Motives of human genome project

Answer 26

1) Identification of all human genes
2) Discover protein structure and functions
3) Evidence for evolutionary relationships
4) Find mutations
5) Find genes causing diseases
6) Develop new gene threpies

Question 27

Nucleosomes

Answer 27

1) Found in eukaryotes

Question 28

what was Rosalind and Franklin experiment ?

Answer 28

1) X Ray diffraction

2) Identify the double helix structure of DNA

Question 29

What was Alfred Hershey and Martha Chase experiment ?

Answer 29

1) Helped confirm DNA as genetic material for life
2) Made use of radioisotopes
3) P-32 and S-35
4) Bacteriophage virus-grew in 2 diff cultures
5) One in P-32 and the other one in S-35
6) Bacteriophage grew in P-32 culture had dectatble Phosphorus in their DNA
7) Bacteriophage grew in S-35 had Sulfur present in outer protein coat.
8) These 2 types of bacteriophage were allowed to infect E.coli (bacterium)
9) E.coli infected with P-32 had radioactivity inside its cell wall
10) E.coli infected with S-35 had no radioactivity inside its cell wall.
11) Because DNA contains phosphorus not sulfur-this concluded that DNA is genetic material

Question 30

What is phosphodiester bond ?

Answer 30

2 molecules of DNA nucleotide are held by covalent bond.

1) Forms between hydroxyl group of carbon-3 and phosphate group attached to carbon-5