Section 9.1 Manipulating DNA – Flashcards

artificial nucleotides

artificial copies of genes

chemical mutagens

often from bacteria, are used to cut and copy DNA

A gene is a sequence of DNA nucleotides, and a chromosome is one long DNA molecule. A whole chromosome is too large for scientists to study a specific gene easily, so they had to find a way to get much smaller pieces of DNA.

Bacteria produce enzymes that cut up DNA of the viruses

The sequence of nucleotides that is identified and cut by a restriction enzyme

Because they restrict, or decrease, the effect of the virus on the bacterial cell

fragements of DNA left over from the process of cutting DNA through restriction enzymes

4 and 8 base pairs long

Some enzymes make cuts straight across while others are staggered.

When restriction enzymes make staggered cuts that leave tails of free DNA bases on each side of the cut. The nucleotide tails of cut DNA strands are called ____ ____. They are like tiny pieces of velcro that are ready to hook on to their opposite sides.

The two segments of DNA will join by hydrogen bonding.

A sample of DNA is loaded into a gel, which is like a thin slab of hard gelatin. A positive electrode is at one end of the gel. At the other end is a negative electrode. Because DNA has a negative charge, the fragments move towards the positive electrode , or the positively charged pole. The tiny pores running through the gel allow small molecules to move quickly. Larger molecules cannot easily move through the gel and travel more slowly. Therefore, the length of a DNA fragment can be estimated from the distance it travels through a gel in a certain period of time.

the lengths of DNA fragments

First, a mutation may add or delete bases between restriction sites, which would change the lengths of DNA fragments on a gel. Second, a mutation may change a restriction site, and the DNA would not be cut in the same places.

It can help diagnose genetic diseases. A restriction map from a person's DNA can be compared with a restriction map from DNA that is known to be normal. If the maps differ , it is an indication that the person has inherited a disease-causing allele of the gene.