L5: From genes to traits.

Question 1

What is the central dogma?

Answer 1

Transcription to translation - information flows from DNA to RNA (transcription) and RNA to protein (translation).

Question 2

What is structural RNA?

Answer 2

RNA that plays a structural role in DNA ie rRNA and tRNA - ribosonal and transport RNA.

Question 3

What is the difference between structural RNA ie ribosomal and transport RNA, and small RNA?

Answer 3

Structural RNA plays a role in the structure, while small RNA regulates genes.

Question 4

What are the nucleotides in RNA?

Answer 4

guanine: cytosine, adenosine: uracil

Question 5

What is coupled transcription-translation, and why does it occur?

Answer 5

in bacterial replication, coupled transcription-translation means the two processes happen at the same time. This is because bacteria do no have a nucleus separating the two processes. In bacteria, it all goes down in the cytoplasm.

Question 6

What is an open reading frame?

Answer 6

Part of the gene that is transcribed as is marked by start and stop codons.

Question 7

How are genes named?

Answer 7

Four letter names based on phenotype. ie. lacZ.
Modified genes = an allele number is given ic lacZ600.
Italics = Yes
‘+’ = phenotype
‘-‘ = loss of function

Question 8

How are proteins named?

Answer 8

They are written without italics and with a capital first letter ie LacZ. A ‘+’ means a particular phenotype, and a ‘-‘ means loss of function.

Question 9

What is the size of bacterial ORF, and how many amino acids does it code for?

Answer 9

1000bp, 333 amino acids.

Question 10

In transcription, what are the 5 regions of transcription? (Where does it start and end?)

Answer 10

1. Promoter - RNA polymerase recognition and binding sites
2. Noncoding region (aka antileader)
3. Coding region
4. non coding region (antitrailer)
5. Terminator

Question 11

In open reading frames, what do -35 and -10 represent, and in what region?

Answer 11

in the promoter region of the ORF, -35 is the RNA polymerase recognition site, and -10 in the RNA polymerase binding site. They are 6 nucleotides long.

Question 12

what is the difference between a weak promoter and a strong promoter?

Answer 12

While they will still bind, a strong promoter will efficiently recruit RNA polymerase and produce a high level of transcription initiation.

a weak promoter is less efficient, results in lower level transcription initiation, and often have deviations in consensus sequence.

Question 13

What is a classical example of transcriptional regulation?

Answer 13

The lac operon.