BABS1201 Lecture Notes - Lecture 15: Peptide, Release Factor, Tata Box

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carmineporpoise43

8 Jun 2018

School

UNSW, UNSW Sydney

Department

Biotechnology & Biomolecular Sciences

Course

BABS1201

Professor

All

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BABS1201 Notes – LEC 15, 16

LEC 15: Gene Expression I

• Central dogma: DNA → RNA → protein

• DNA vs RNA (OH group difference)

• Thymine vs Uracil

• DNA strand (template) → Transcription of mRNA → Translation of mRNA to a

protein

• Transcription:

o Only 1 strand of DNA is used as the template

o RNA polymerase attaches to the start of the gene (promoter (i.e. TATA box))

being transcribed

o Makes a strand of mRNA using free bases (U replaces T) in the nucleus and

ends at the terminator (termination point) which makes the polymerase

detach

o Moves in the 5’ to 3’ diretion

• Before pre-mRNA leaves the nucleus it is processed where some sections are

removed (introns) before translation to form the mRNA used to make the protein

• Before entering the nucleus the mRNA strand is proteted y adding a 5’ ap and a

poly(A) tail

• The modified mRNA is transported to the cytoplasm for protein synthesis

• Exons (coding sections of the gene) can be spliced in different ways to produce

different proteins from the same gene sequence.

• Transcription factors control the rate of transcription and mediate transcription

initiation

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Related Questions

1. A region of a chromosome contains two strands of DNA, yet only one is used to transcribe a gene because

A. all genes are found on the same strand of DNA in a chromosome.

B.both strands are transcribed, but only one strand of DNA contains a reading frame.

C.RNA polymerase binds to the terminator, stopping transcription on one strand of DNA.

D.RNA polymerase binds to the promoter, which precedes the gene only on the template strand of DNA.

E.the start of transcription is random along the chromosome and doesn't always occur on a gene.

2. In eukaryotes an mRNA molecule can only be translated by one ribosome at a time.

True or False

3.The process by which cells use the information of RNA molecules to make proteins is transcription.

True or False

Place the following steps of protein synthesis in order from first(1) to last.

TATA binding protein attaches to the promoter region of agene.
Dehydration synthesis links adjacent amino acids to create adipeptide.
mRNA strand exits the nucleus of eukaryotic cells.
Large ribosomal subunit attaches to the mRNA transcript.

Determine whether each of the following statements is true offalse.

The promoter region of eukaryotic genes is identified by a seriesof guanine preceeding the TATA box followed by a series ofcytosine.

Transcription factors are the molecules which grab RNA nucleotidesand add them to the growing mRNA strand during transcription.

A eukaryotic cell needs to produce more hemoglobin. To increasetranscription of the gene for this molecule, the cell would likelyincrease the production of the transcription factors which targetthe promoter region of the gene.

The function of transcription is to allow cells to replicate theirDNA (i.e. make extra copies of DNA).

Which type of RNA is unique to eukaryotes?

		mRNA
		rRNA
		tRNA
		snRNA
		Its a trick, all cells have all four types of RNA.

1 points

QUESTION 2

The region of DNA to which RNA polymerase binds to initiate transcription is the:

		origin
		promoter
		enhancer
		none of the above are correct

1 points

QUESTION 3

Holoenzyme:

		is RNA polymerase core enzyme.
		is sigma factor.
		is core plus sigma factor.
		none of the above are correct.

1 points

QUESTION 4

Which of these is formed FIRST when RNA polymerase binds to a promoter?

		The closed promoter complex
		The open promoter complex
		A rho-independent terminator
		none of the above are correct.

1 points

QUESTION 5

A hairpin loop followed by a run of Us:

		is the sequence formed in the sense strand of a gene using a rho-independent terminator.
		is the sequence recognized by the rho protein.
		is the structure formed in RNA that causes rho-independent termination.
		is formed immediately after the open promoter complex is formed.

1 points

QUESTION 6

RNA polymerase:

		reads the template strand of the DNA in the 3' to 5' direction.
		synthesizes the RNA in the 5' to 3' direction.
		can begin transcription without a primer.
		all of the above are correct.

1 points

QUESTION 7

Which of the following statements is FALSE?

		Bacteria like E. coli have only one type of sigma factor.
		RNA polymerase has no proofreading activity.
		The promoter of a gene is upstream of the RNA-coding region.
		Bacterial transcriptional terminators are copied into RNA to cause termination.

1 points

QUESTION 8

If the template strand of a gene has the sequence 5' ATGCGAT 3', then:

		the RNA produced will have the sequence 5' AUGCGAU 3'.
		the RNA produced will have the sequence 5' UAGCGUA 3'.
		the RNA produced will have the sequence 5' AUCGCAU 3'.
		None of the above are correct.

1 points

QUESTION 9

The sense strand:

		is the lagging strand
		is also the template strand.
		always goes left to right.
		none of the above are correct.

1 points

QUESTION 10

Which of these is transcribed but not translated?

		mRNA
		tRNA
		rRNA
		all of the above
		tRNA and rRNA are transcribed but not translated.

please help i am a bit confused

BABS1201 Lecture Notes - Lecture 15: Peptide, Release Factor, Tata Box

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