3 billion base pairs of DNA and about 30,000 genes

97% of human DNA is junk, as it does not code for protein products

Of this junk, some are regulatory sequences controlling gene expressions, some are introns that interrupt genes and most are repetitive sequences that never get transcribed

Some genetic disorders (Huntington’s disease) are caused by abnormally long stretches of tandem repeats (back-to-back repetitive sequences) within affected genes

These tandem repeats can also make up telomeres

Polymorphic regions of DNA are noncoding and vary from one region to the next

Taking DNA from two sources and combining them

Happens naturally during viral transduction, bacterial transformation and conjugation

Transposons jumping around the genome

Also known as biotechnology

Scientists manipulate and engineer genes in the laboratory

Genetic engineering brings about many medical uses as well as ethical issues

Uses:◦ Produce a protein product, like insulin

◦ Replace a nonfunctioning gene in a person’s cells with a functioning gene by gene therapy, which does not look very promising

◦ Prepare multiple copies of a gene for analysis (more genes copied, the more they can be researched)

◦ Engineer bacteria to clean up the environment (some can eat toxic waste)

Isolate a gene (insulin) Insert gene into a plasmid Insert eh plasmid into a vector, a cell that

will carry the plasmid Clone the gene

◦ as bacteria reproduce through fission, plasmid and selected gene are also cloned

Identify the bacteria that contain the selected gene and harvest it from the culture

Restriction enzymes extracted from bacteria ◦ Help bacteria protect themselves against phages

These enzymes cut DNA at specific recognition sequences, such as GAATTC

Often, these cuts are staggered, leaving single stranded sticky ends to form a temporary unit with other sticky ends

The fragments that result from the cuts made by restriction enzymes are called restriction fragments

Common examples are EcoRI, BamHI and HindIII

Used in gene cloning

Separates large molecules of DNA based on their movement through agarose gel in an electrical field

Smaller molecules of DNA run faster and further through the gel

DNA is negative (phosphate groups) and flows from cathode (-) to anode (+)

Also separates proteins and amino acids

In order to run through a gel, the DNA must be cut by restriction enzymes into small enough pieces to move through the gel

DNA can be sequenced to determine the sequence of bases

Can also be used to compare other DNA samples

http://learn.genetics.utah.edu/content/labs/gel/

Radioactively labeled single strand of nucleic acid molecule used to tag a specific sequence in a DNA sample

The probe bonds to the complementary sequence and enables scientist to detect its location

Used to identify a person who carries an inherited genetic disorder

Cell-free, automated technique by which a piece of DNA can be rapidly copied

Billions of copied DNA fragments can be produced within hours

The DNA piece that is to be copied is placed into a test tube with Taq polymerase (heat-stable form of DNA polymerase extracted from extremophile bacteria)

Along with Taq polymerase, a supply of DNA nucleotides and primers are added to the test tube to promote DNA synthesis

Once DNA is amplified, these copies can be studied or used in comparison with other DNA samples

Information regarding target DNA nucleotide sequence must be known

Size of the piece to be amplified must be very short

CONTAMINATION

Restriction fragment is a segment of DNA that results when DNA is treated with restriction enzymes

When scientists compared junk DNA of a population, they discovered that the restriction fragment pattern is different in every individual

Differences are called RFLPs

Pronounced “riflips”

A RFLP analysis of someone’s DNA gives a human DNA fingerprint that looks like a bar code

Everyone’s RFLP is unique, except for identical twins

Can determine fathers in paternity suits

Can identify perps in rape and murder cases

Introns prevent bacterium from cloning human genes ◦ Introns are long, intervening, noncoding

sequences)

Bacteria cannot delete introns after transcription

In order to clone, scientists must insert a gene without introns

In order to do this, scientists extract fully processed mRNA from cells and then use reverse transcriptase to make DNA transcripts of the RNA

The resulting DNA molecule carries the complete coding sequence of interest without introns

Safety◦ Much of the milk available to consumers has

come from cows that were given bovine growth hormone (BGH)

◦ Vegetables have been genetically engineered to produce special characteristics in the vegetables people eat (size, taste, color)

Privacy◦ DNA probes are being used to create DNA

chips, which are about ½ inch square and can hold personal information about someone’s genetic identity

◦ These chips can scan a person for mutations

◦ The main concern is that the information may not remain private, and insurance companies or possible employers can find out personal information