Protein synthesis

Question 1

What does the genome code for?

Answer 1

• synthesis of proteins
• synthesis of RNA molecules
  this leads to specific traits/ phenotypes

Question 2

what is the genome made up of?

Answer 2

23 chromosome pairs (haploid)
–> 46 chromosomes in total

Question 3

What is the importance & role of proteins?

Answer 3

Proteins are the link between genotype and phenotype
- transcription factors
- inhibiting proteins
- enzymes
- ribosomes, etc

and can influence gene expression & implement regulatory measures at different stages in protein synthesis (amplify or inhibit gene expression)

Question 4

How do proteins cause albinism? TO STILL CORRECT AND COMPLETE!!!

Answer 4

• albino donkeys lack the enzyme tyrosinase, responsible for melanin production
• there is therefore an incomplete metabolic pathway
• which means there is no production of melanin
• since melanin is absent, donkeys have white fur

Question 5

Overview of TRANSCRIPTION

Answer 5

= the synthesis of RNA strand that is complementary to its DNA template strand
- occurs in nucleus
- read up, write down
- mRNA enables genetic info to leave the cell

Question 6

Overview of RNA PROCESSING

Question 7

Overview of TRANSLATION

Answer 7

= the synthesis of a polypeptide chain using the info in mRNA
- mRNA is translated into an aa sequence (polypeptide)
- occurs via ribosomes

Question 8

central dogma

Answer 8

dna –> rna –> protein

Question 9

Differences in protein synthesis between prokaryotes & eukaryotes?

Answer 9

Prokaryotes:
- transcription & translation can occur simultaneously, due to no compartmentalisation
- dont have organelles
- no mRNA processing
- only 1 type of RNA polymerase

Eukaryotes:
- lots of compartmentalisation & organelles
- broken up into lots of steps: transcription & processing in nucleus, translation in cytoplasm
–> easier to manage and control
–> more regulation of gene expression
- RNA processing occurs
- multiple types of RNA polymerase: RNA polymerase 2

Question 10

Molecular components of transcription

Answer 10

• DNA (template strand)
• RNA polymerase
• RNA nucleotides
• transcription factors (proteins) –> activators, repressors
• promoter: where rna polymerase attaches to tata box and initiates transcription
• TATA box
• terminator: signals the end of transcription

Question 11

What is the role of the promoter?

Answer 11

• certain region of dna where rna polymerase attaches, with guidance of transcription factors
  –> binding determines direction, start location and template DNA strand of transcription
• place of transcription initiation
• located upstream of transcription unit (downstream: 5’–> 3’, upstream: 3’–>5’)

Question 12

TRANSCRIPTION
in prokaryotes

Answer 12

Initiation:
RNA polymerase recognises & binds to the promoter on the DNA template strand. RNA polymerase unwinds the DNA DS and initiates transcription.

Elongation:
RNA polymerase moves along & unwinds the DNA double helix, exposing NT for pairing with RNA NTs
- NTs are added at 3’ end
- newly synthesised RNA stand gradually peels away from the template strand

Termination:
a terminator sequence in DNA signals to the RNA polymeraseto detach from DNA and release the mRNA strand

mRNA has no further processing

Question 13

TRANSCRIPTION
Eukaryotes

Answer 13

Initiation:
- transcription factors help guide the RNA polymerase II to bind to the promoter
- forms the transcription

Question 14

Pros and cons of eukaryotic transcription

Answer 14

+ve: Eukaryotic transcription is highly regulated & controlled
-ve: slightly less efficient