RNA

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nucleotides in DNA and RNA

other key elements of the structure of DNA and its implications for DNA replication and RNA transcription

alternative structures of DNA

the structure of RNA

the enzymes involved with DNA replication, RNA transcription, and protein translation

RNA viruses and how they contradict the central dogma

Prokaryotic Gene Regulation

subject to regulation - an mRNA copy is made from the DNA and

mRNAs which have AUG (start) and stop codons and are translated into

proteins. (Note: some structural genes produce RNAs that are themselves

functional without being translated: tRNAs, for example.)

lac operon promoter DNA site. This is where RNA polymerase

sequence. RNA polymerase can be blocked from further transcription of the

sequence which prevents RNA polymerase from ever binding and initiating

Large Molecules

Diagram Structure of DNA and RNA

E. coli

percent RNA, 3 percent carbohydrate, 2 percent lipid, and 1 percent

Control of the Cell Cycle

As an alternative, the daughter cells may decide to cease active

through the cell cycle on the basis of their own, autonomous, internally

Introduction to the 7.01 Hypertextbook

(1) ESG. The Experimental Study Group, an alternative Freshmen program at MIT--

Use of DNA in Identification

trace maternal lineage.

An Interview with DNA Forensics Authority Dr. Bruce Weir

data in peer-reviewed journals, sharing raw data with other researchers

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maternal inheritance and gene imprinting

MIT Biology Hypertextbook: Enzyme Mechanisms

proteins (the exception is catalytic RNA). A catalyst is a molecule

Alternatively, for a reaction such as the one shown below, the

Membrane Proteins Introduction

It must keep its molecules of life ( DNA , RNA , and its assortment of

continuously monitor the external conditions and adapt to them. For example,

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RNA processing in eukaryotes

Receptors

Note that the GF ligand itself does not need to become internalized

Membrane Transport Mechanisms

called an ion channel. Alternatively, the transmembrane protein may

3 Enzyme Kinetics

Two alternative substrates for b-galactosidase are:

Chemical Energetics

molecules, atomic vibrations, and external energy sources (such as

another reaction may remove D as soon as it is made. Alternatively,

Culturing cells in vitro

internal program, not by the requirements of the outside world. This

Membrane Proteins

acids) alternate with hydrophobic domains. The protein chain as a whole

regions that are looped out alternatively into either the cytoplasm or the

G Protein Receptors

internalized into the cell. Instead, while bound for a short period of

Basic Virus Structure

DNA or RNA . A number of viruses contain their genetic information in RNA

Biological Macromolecules

nucleotides found in DNA and RNA

Structure and Function of Organelles

This is where the DNA is kept and RNA is transcribed. RNA is

Ribosomes are the sites of protein synthesis , where RNA is

RNAs intricately bound together. Ribosomes have no membrane.

Southerns, Northerns, Westerns, & Cloning: Molecular Searching Techniques

RNA, and protein. These sections will describe how they work and how

Purves, Oriens, and Heller pp. 315-8. DNA-RNA hybridization is

2) DNA-RNA. A single-stranded DNA (ssDNA) probe molecule can

form a double-stranded, base-paired hybrid with an RNA (RNA is usually a

search for one DNA molecule, or one RNA molecule, or one protein

thousands of genes, thousands of different mRNA species, and thousands

of different proteins. When the cell is broken open to extract DNA, RNA,

or protein, the result is a complex mixture of all the cell's DNA, RNA,

or protein. It is impossible to study a specific gene, RNA, or protein

RNA - probed with radioactive DNA or RNA.

necessarily molecular weight. For example, two 1000 nucleotide RNA

preparing DNA, RNA and protein samples for electrophoresis.

Preparing RNA for Northern Blots

Although RNA is single-stranded, RNA molecules often have small

the RNA is pre-treated with formaldehyde.

different units for DNA, RNA, and protein:

RNA: Molecular weight is measured in nucleotides, or

On most gels, one well is loaded with a mixture of DNA, RNA, or

plasmid, a pure mRNA transcript, or a purified protein. In this case,

total cellular RNA, or total cellular protein would look like in a gel

Staining RNA

RNA is stained with ethidium bromide (EtBr), which binds to nucleic

aids. The RNA-EtBr complex fluoresces under UV light.

After the DNA, RNA, or protein has been separated by molecular

used. DNA, RNA, and protein stick well to nitrocellulose in a

The DNA, RNA, or protein can be transferred to nitrocellulose in

single-stranded molecules. RNA an protein are run in the gels in a state

in a blocking solution which contains a high concentration of DNA, RNA,

7.012 Cloning Project: Agricultural Biotechnology

RNA polymerase.

7.01 Genetics Meets "The Real World"

Anne's Maternal Grandparents

Anne's Paternal Grandparents

Solving Problems

You extract RNA from male and

you tell this?), explain the difference between the mRNA for this gene

i) First, what do the blots show? Since the target molecule is mRNA,

detect the presence of a different exon or exons in the final mRNA.

From this, we can determine which exons are present in the mature mRNA's.

Blot A shows that exon 1 is present in both male and female mRNA

Blot B shows that exon 1 and/or exon 2 are present in both mRNA

Blot C shows that exon 2 is present in the female mRNA but not

in the male mRNA - note that this does not conflict with Blot B's

Blot D shows that exon 3 is present in both male and female mRNA

Summarizing: female mRNA for this gene contains exon 1, 2, and 3 - this

is expected pattern of splicing; male mRNA for this gene contains only

sizes of the mRNA's in both sexes. We would predict that in females,

mature mRNA = 0.5 + 0.2 + 0.6 = 1.3knt; and in males, mature mRNA = 0.5

Note that the size of the mRNA observed in each sex does not change even

You would predict that the mature mRNA for this gene would be 0.5 + 0.2

apparently normal splicing of the pre- mRNA. Therefore, in females, the

In males, the mature mRNA is 0.2knt shorter. There are three

exons would be present in the mature mRNA. This is not observed - blot C

that exon 2 is missing in the mature mRNA from this gene in males.

exon 2, and only exon 2 is somehow missing from the mature mRNA in

another 90nt along the mRNA. (the average amino acid is 0.1kDa)

- Lane 2: No gene W mRNA will be produced, so no protein W will be

mRNA made by the F' of 40KDa; and mutant, from mRNA made from the