Chapter 2 (Transcription and Translation)

Nucleus

Transcription happens here

Cytoplasm

Translation happens here

Transcription

DNA → mRNA

Translation

mRNA → protein

Ribosomes

What is mRNA translated into proteins by?

Triplet

Nucleotide sequence that codes for a specific amino acid, 3

A, G, T, C

DNA has these nucleotides

A, U, G, C

RNA has these nucleotides

U

A translates to

C

G translates to

A

T translates to

20

How many amino acids are there?

AUG (methionine)

The initiation codon

Initiation, Elongation, Termination

The steps of transcription

RNA polymerase binds to the promotor region

What happens during initiation in transcription?

RNA polymerase “unzips” DNA and reads it to translate it into pre-mRNA

What happens during elongation in transcription?

The RNA polyermase stops at the terminator region

What happens during termination of transcription?

pre-mRNA

What do you have at the end of transcription?

Add the 5’ cap, add the poly A tail 3’, splice, export to cytoplasm

The steps of post-transcription

5’ cap

Part of mRNA that initiates translation

The poly A tail 3’

Part of mRNA that protects against degradation

The introns and spliced out and the exons are kept

What happens during splicing in post-transcription?

Nuclear pores

Where is the mRNA exported out of the nucleus?

Alternative slicing

The splicing of exons can lead to different sequences

Initiation, Elognation, and Termination

The steps of translation

By the 5’ cap of mRNA or the start codon AUG

What happens during initiation in translation?

rRNA reads and creates and empty codon, mRNA is translated, and tRNA brings amino acids

What happens during elongation of translation?

The codes UAA, UAG, and UGA code for stop the process

What happens during termination of translation?

AUG (are u good…to start?), UAA (u are away), UAG (u are gone), UGA (u go away)

What are the fun ways to remember AUG, UAA, UAG, and UGA?

Folding, cleavage, modification, and transport

The steps of post-translation

The amino acid is folded into a functional 3D structure

What happens during folding of post-translation?

Inactive parts of the amino acid are clipped

What happens during cleavage of post-translation?

Carbohydrates or lipids are added

What happens during modification of post-translation?

The leader sequence brings the protein/amino acid to its destination

What happens during transport of post-translation?

The protein/amino acid stays in the cytoplasm

What happens if there is no leader sequence to take the protein/amino acid?

By RNA polymerase binding, it can be induced or repressed

How can transcription be regulated?

During initiation, it can activate or inactivate initiating factors

How can translation be regulated?

Proteases

Degrade proteins

Ubiquitin

Tags proteins for degredation