When referring to DNA transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

, the coding strand is the DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 strand which has the same base

Nucleobase

Nucleobases are a group of nitrogen-based molecules that are required to form nucleotides, the basic building blocks of DNA and RNA. Nucleobases provide the molecular structure necessary for the hydrogen bonding of complementary DNA and RNA strands, and are key components in the formation of stable...

 sequence as the RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 transcript produced (although with thymine

Thymine

Thymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. As the name suggests, thymine may be derived by methylation of uracil at...

 replaced by uracil

Uracil

Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...

). It is this strand which contains codons, while the non-coding strand contains anti codons.

Alternative terms for strands

Wherever a gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 exists on a DNA molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

, one strand is the coding strand (or sense strand or non-template strand), and the other is the noncoding strand (also called the antisense strand [antisense is a general term for a sequence of DNA or RNA that is complementary to mRNA]
http://books.google.com/books?id=BrNpbPkzoxAC&pg=PA129&lpg=PA129&dq=coding+strand+antisense&source=web&ots=t6yUAob0Km&sig=O3UVL8ZYlFi0ljVYax8hp695sRo#PPA75,M1, anticoding strand, template strand, or transcribed strand).

Strands in transcription bubble

During transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

, RNA polymerase

RNA polymerase

RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...

 unwinds a short section of the DNA double helix near the start of the gene. This unwound section is known as the transcription bubble

Transcription bubble

A transcription bubble is a molecular structure that occurs during the transcription or replication of DNA when DNA helicase and DNA topoisomerase "unzip" the DNA double strand. DNA polymerase or RNA polymerase may then bind to the exposed DNA and begin synthesizing a new strand of DNA or RNA...

. The RNA polymerase, and therefore the transcription bubble, travels along the noncoding strand in the opposite, 3' to 5', direction, as well as polymerizing a newly synthesized strand in 5' to 3' or downstream

Upstream and downstream (DNA)

In molecular biology and genetics, upstream and downstream both refer to a relative position in DNA or RNA. Each strand of DNA or RNA has a 5' end and a 3' end, so named for the carbons on the deoxyribose ring. Relative to the position on the strand, downstream is the region towards the 3' end of...

 direction. The DNA double helix is rewound by RNA polymerase at the rear of the transcription bubble (Lewin, pp 235 http://books.google.com/books?id=BrNpbPkzoxAC&pg=PA129&lpg=PA129&dq=coding+strand+antisense&source=web&ots=t6yUAob0Km&sig=O3UVL8ZYlFi0ljVYax8hp695sRo#PPA75,M1). Like how a zipper works, only it unzips it and rezips it without going back and forth.

RNA-DNA hybrid

Where the helix is unwound, the coding strand consists of unpaired bases, whilst the template strand consists of an RNA:DNA composite, followed by a number of unpaired bases at the rear. This hybrid consists of the most-recently-added nucleotides of the RNA transcript, complementary base-paired to the template strand. The number of base-pairs in the hybrid is under investigation, but it has been suggested that the hybrid is formed from the last 10 nucleotides added (Griffiths, pp 259-265).