Genetics 4

Suppose a researcher decides to sequence a short fragment of DNA. She uses polymerase chain reaction and a series of four dideoxy reactions. She then separates the products of the reactions using gel electrophoresis and obtains the banding pattern below. ddTTP, ddCTP, ddGTP, ddATP, ddCTP, ddGTP, ddTTP, ddATP, ddGTP. Enter the sequence of the original template strand.

5' AGCTGCATC3'

Order the steps required to sequence a region of DNA using dideoxy sequencing

1. Amplify the region of DNA to be sequenced 2. Add a primer, deoxynucleotides, labeled dideoxynucleotides, and a DNA polymerase 3. Generate a single stranded DNA template 4. A primer binds to the single stranded DNA template 5. DNA polymerase extends the primer, incorporating deoxynucleotides 6. A labeled, dideoxynucleotide terminates the growing DNA chain 7. Capillary electrophoresis separates the mixture of DNA fragments by size 6. The DNA sequence is determined

Match each term with its definition: 1. Promoter 2. Repressor 3. Insulator 4. Regulatory gene 5. Inducer 6. Operator

1. a sequence of DNA located upstream of a gene that signals the start of transcription 2. a transcription factor that prevents mRNA synthesis by binding to the operator of a gene 3. A transcriptional element that blocks the signal between enhancers and promoters 4. a gene that controls the expression of one or more genes by promoting of inhibiting transcription 5. a small molecule that activates transcription by inhibiting the action of a repressor protein 6. a short sequence of DNA located near the promoter region that is recognized by a repressor protien

How does comparative genomics aid in the search for factors that contribute to complex human conditions?

Conserved genetic sequences likely influence similar phenotypic traits across species

Classify the differences between dideoxy sequencing or next generation sequencing

Dideocy sequencing: suitable for determining the sequence of one DNA molecule, typically results in sequence reads of about 500 to 1000 base pairs, low error rate per sequence read Next-Generation sequencing: suitable for sequencing an entire genome, typically results in sequence reads of about 100 base pairs, high error rate per sequence read

Classify the descriptions as pertaining to dideoxy sequencing, next generation sequencing or both

Dideoxy sequencing: reaction produces sets of DNA strands of different lengths, suitable for sequencing a PCR product Next-Generation sequencing: many simultaneous reactions, suitable for personal genomics applications BOTH: requires a primer, computers can be used to read the DNA sequence

All of the cells in the human body contain the same genes. How do cells have different morphological and functions when they contain the same genetic information?

Different cell types express particular genes at different levels

Select the gene regulatory mechanisms that are different between prokaryotes and eukaryotes

Eukaryotic DNA contains enhancers Chromatin packaging occurs in eukaryotes Multiple general transcription factors are found in eukaryotes

Computer programmers, working with molecule geneticists, have developed computer programs that can identify genes within long strands of DNA sequences. Imagine that you are working with a computer programmer on such a project. On the basis of what you know about the process of transcription, what sequences should be used to identify the beginning and end of a prokaryotic gene with the use of this computer program?

Short, inverted repeats followed by at least seven T nucleotides indicating potential intrinsic termination sites. Sequences with close similarity to the -35 and -10 sequences upstream of start site

Many molecules, including transcription factors, work together to transcribe genes and translate the information taken from the genes into proteins. What is a transcription factor?

a protein that binds to a specific DNA sequence to regulate transcription