Biology Unit 8

Identify the steps in gene cloning.

1. Isolate DNA from organism containing desired gene. 2. Attach target gene to small, circular piece of DNA called a plasmid. 3. Put plasmid into the bacteria. 4. Grow the bacteria. 5. Once bacteria population reaches the desired amount, break bacteria apart. 6. Filter mixture of broken bacteria cells and collect only the plasmids with bonds. 7. put plasmids into human cells. 8. Over time plasmid will be incorporated into host cell DNA and new genes will change the proteins produced. 9. Observe physical changes between cells with plasmid and those without plasmid.

Describe the structure of a nucleotide

A nucleotide consists of a sugar (deoxyribose), one of four bases (Cytosine, Thymine, Adenine, Guanine), and a phosphate.

Describe a bacterial plasmid, and explain how it can serve as a carrier for gene transfer.

A small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independetly. An F factor "fertility" carries info for sex pili and other proteins.

DNA Ligase

An enzyme essential for DNA replication, catalyzes the covalent bonding of adjacent DNA polynucleotide strands. DNA ligase is used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector.

Explain how genetic info is written as codons and translated into amino acid sequences.

Codons are three base "word" triplets. These triplets specify specific amino acids.

Name the four nucleotides found in DNA and explain how they differ

Cytosine, thymine, adenine, and guanine. They differ in their nitrogen containing bases.

Give the two differences between DNA and RNA.

DNA: Sugar is deoxyribose. Bases are A,T,C,G. RNA: Sugar is ribose. Bases are A,U,C,G.

Define emerging viruses and give several examples.

Emerging Virus: A virus that has appeared suddenly or has recently come to the attention of medical scientists. Examples: HIV, H1N1, ebola, west nile virus, and SARS.

Define mutagen and explain how mutation can change the meaning of genes.

Mutagen: A chemical or physical agent that interacts with DNA and causes a mutation. Mutations can change the meaning of genes. Because they typically change the amino acids.

Explain how enzymes are used to "cut and paste" DNA.

Restriction enzymes cut DNA, a piece of DNA from another source (gene of interest) is cut by same R. Enzyme, and added to the original DNA. Both molecules of DNA are cut unevenly, yielding "sticky ends". Complementary ends on two different fragments stick together throug hbase pairing. Temporary union between two DNA molecules becomes permament through DNA ligase, thus creating new covalent bonds.

Describe the structure and the role of ribosomes in the synthesis of polypetides.

Ribosomes consist of 2 subunits, one large and one small, each consisting of proteins and ribosomal RNA. Ribosomes are structures in the cyoplasm that coordinate the functioning of mRNA and tRNA and catalyze synthesis of polypeptides.

Explain how transcription produces genetic messages in the form of RNA.

Specialized proteins attach to the DNA strand and make a copy of the DNA sequence in the form of a molecule called messenger RNA (mRNA). mRNA encodes amino acid sequences.

Explain how the replication of DNA depends on specific base pairing.

The bases that go together will attach when the original DNA molecule is split apart, creating a new one. A pairs with T, and C with G. New DNA known as Daughter DNA.

Describe recombinant DNA technology

The process of combining DNA to form two different species in a test tube.

Describe transcription

The synthesis of RNA on a DNA template.

Describe translation

The synthesis of a polypeptide using genetic information encoded in an mRNA molecule.

Explain how nucleotides are arranged to make up a polynucleotide (a polymer of nucleotides)

Through a covalent bond between the phosphate group of one, and the third carbon atom of the pentose sugar in the next.

What are the two main stages of protein synthesis?

Transcription and translation.

Describe the double stranded helix of a DNA molecule.

Two strands that wind around each other like a twisted ladder.

Describe the role of mRNA in getting the genetic message translated to the cytoplasm.

mRNA is genetic messages from DNA. mRNA info gets translated into polypeptides. In Eukaryotic cells this process occurs in the cytoplasm.

Explain the role of transfer RNA in the translation into polypeptides.

tRNA is the translator for nucleic acid "words" known as codons, to amino acid "words" of proteins.