RNA, Transcription and Translation 3.4 U3

Question 1

What is a gene?

Answer 1

sequence of DNA that codes for a particular protein

Question 2

DNA vs RNA

Answer 2

Sugar used
T vs U
Double vs single stranded

Question 3

Types of RNA

Answer 3

tRNA
mRNA
rRNA

Question 4

tRNA

Answer 4

T-shaped structure made of RNA nucleotides. Amino acids are attached on the top, and the anticodon is on the bottom loop.
Transfer RNA (tRNA) is responsible for carrying amino acids to the ribosome during translation and transferring them on to the growing polypeptide (amino acid) chain.

Question 5

mRNA

Answer 5

Single stranded sequence of RNA nucleotides.
Messenger RNA (mRNA) is an RNA copy of a gene that carries the instructions for producing a specific protein from the nucleus to the ribosome.

Question 6

rRNA

Answer 6

Sequence of RNA nucleotides that bind to ribosomal proteins in order to form the whole ribosome.
Ribosomal RNA (rRNA) is a structural component of ribosomes that assists with translation of messenger RNA .

Question 7

Transcription in Prokaryotes vs. Eukaryotes

Answer 7

PROKARYOTES
Occurs in the cytoplasm
No processing required
EUKARYOTES
Occurs in the nucleus
Processing required before leaving nucleus

Question 8

What is a promoter?

Answer 8

Certain DNA sequences right before genes, where proteins bind to initiate transcription
TFs = regulate
Transcription factors

Question 9

What is RNA polyamerase?

Answer 9

puts RNA nucleotides together in a growing chain using DNA strand as a template

also unzips DNA like Helicase!

makes RNA strand in 5’ to 3’ direction!

Question 10

What is a 5’ Cap?

Answer 10

Specially modified guanine nucleotide that is added to the 5’ end of the transcript. It protects the mRNA from degradation in the cytoplasm and also helps the ribosome to bind at the the mRNA start codon to initiate translation.

Question 11

What is a exons?

Answer 11

Sequences of mRNA that actually code for part of the protein.

Question 12

What is a introns?

Answer 12

Sequences of mRNA that exist between exons and allow for alternative splicing.

Question 13

What is a Poly A Tail?

Answer 13

A series of A nucleotides added to the 3’ end of the transcript. It aids in nuclear export ,protects the mRNA from degradation in the cytoplasm, and also helps the ribosome to bind at the the mRNA start codon to initiate translation.

Question 14

Purpose of 5’ cap?

Answer 14

modified guanine nucleotide

Question 15

Purpose of Poly A Tail?

Answer 15

aids in nuclear export

Question 16

Purpose of of 5’ Cap and Poly A Tail?

Answer 16

protects from degradation, help ribosome to bind

Question 17

What is alternative splicing?

Answer 17

Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be included within or excluded from the final, processed messenger RNA (mRNA) produced from that gene.[1] This means the exons are joined in different combinations, leading to different (alternative) mRNA strands. Consequently, the proteins translated from alternatively spliced mRNAs will contain differences in their amino acid sequence and, often, in their biological functions

Question 18

Where does Eukaryotic Translation occur?

Answer 18

Eukaryotic translation occurs on ribosomes attached to the rough endoplasmic reticulum or those found free-floating in the cytoplasm.

Question 19

What is a codon?

Answer 19

three bases in mRNA that code for a particular amino acid

Question 20

What are the processes of Translation?

Answer 20

Initiation, Elongation, Termination

Question 21

What is Initiation in Translation?

Answer 21

Large and small subunit of the ribosome bind to the start codon.
The small ribosomal subunit binds to the mRNA (aided by interaction with rRNA) The tRNA that matches the start codon (AUG) base pairs, followed by the large ribosomal subunit binding.

Question 22

What is Elongation in Translation?

Answer 22

The ribosome reads the mRNA in sequences of 3 nucleotides called codons.
Ribosome translocates from codon. At each codon the matching tRNA binds to the mRNA, transfers its specific amino acid to the growing polypeptide chain

Question 23

What is Termination in Translation?

Answer 23

Ribosome continues translating until it reaches the stop codon.
Translation of the stop codon results in a release factor protein binding to the ribosome, causing it to release both the mRNA and the newly synthesized polypeptide