The illustrated ribosome is translucent and looks like an upside-down glass jug. The mRNA is composed of many nucleotides that resemble pegs aligned side-by-side along the molecule, in parallel. Each type of nucleotide is represented by a different color yellow, blue, orange, or green.
The first three nucleotides, bound to the ribosome, are highlighted in red to represent the stop codon. In step 2, a tRNA molecule is bound to the stop codon. At the end of the tRNA molecule opposite this point of attachment is an amino acid, represented as a sphere.
In step 3, a tRNA bound to a single amino acid is attached to the 7 th , 8 th , and 9 th nucleotide from the left. In eukaryotic cells, however, the two processes are separated in both space and time: mRNAs are synthesized in the nucleus, and proteins are later made in the cytoplasm. This page appears in the following eBook. Aa Aa Aa.
Ribosomes, Transcription, and Translation. Figure 1: DNA replication of the leading and lagging strand. The helicase unzips the double-stranded DNA for replication, making a forked structure. Figure 3: RNA polymerase at work. What Is the Function of Ribosomes? This Escherichia coli cell has been treated with chemicals and sectioned so its DNA and ribosomes are clearly visible.
Figure 7: The ribosome and translation. A ribosome is composed of two subunits: large and small. Figure 8: The major steps of translation. Cellular DNA contains instructions for building the various proteins the cell needs to survive. In order for a cell to manufacture these proteins, specific genes within its DNA must first be transcribed into molecules of mRNA; then, these transcripts must be translated into chains of amino acids, which later fold into fully functional proteins.
Although all of the cells in a multicellular organism contain the same set of genetic information, the transcriptomes of different cells vary depending on the cells' structure and function in the organism.
Cell Biology for Seminars, Unit 2. Topic rooms within Cell Biology Close. No topic rooms are there. Or Browse Visually. Student Voices.
Creature Cast. Simply Science. Green Screen. Green Science. Bio 2. The Success Code. Why Science Matters.
The Beyond. Plant ChemCast. Postcards from the Universe. Brain Metrics. Mind Read. Eyes on Environment. Accumulating Glitches. Saltwater Science. Microbe Matters. A letter or sequence of letters can be inserted or deleted. A sequence of letters can be inverted cut out, flipped and re-inserted.
A sequence of letters can be duplicated one or more times. Here's what that sentence might look like after each kind of mutation:. Substitution : The quick brown fo g jumped over the lazy dog. The x became a g. The sentence remains intelligible but meaning has shifted slightly. This is also sometimes called a " point mutation " because it affects only a single point on the DNA sequence. Insertion : The quick brown fox gjumpe dove rth elaz ydog. A single letter g inserted after the x shifts letters to the right, changing the breaks between our word codons and making everything after the insertion nonsensical.
However, we accidentally created the word "dove" which is was unintentional but does have meaning. Maybe this is a beneficial mutation? Deletion : The quick brown foj umpedo vert hel azyd og. After the single letter x is deleted, every letter is shifted one position to the left. The sentence makes sense up to the point of the mutation, but then becomes scrambled. Multi-letter deletion : The quick fox jumped over the lazy dog. If an entire codon gets deleted, there is no shift to the left or right.
The sentence remains intelligible but the meaning might change. If the deletion doesn't happen exactly at the word codon breaks however, this would end up more like the previous two examples. Inversion : The quick muj xof nworb ped over the lazy dog. Nucleic Acids Research 15 , — Shine, J. Determinant of cistron specificity in bacterial ribosomes.
Nature , 34—38 doi Restriction Enzymes. Genetic Mutation. Functions and Utility of Alu Jumping Genes. Transposons: The Jumping Genes. DNA Transcription. What is a Gene? Colinearity and Transcription Units. Copy Number Variation. Copy Number Variation and Genetic Disease. Copy Number Variation and Human Disease. Tandem Repeats and Morphological Variation.
Chemical Structure of RNA. Eukaryotic Genome Complexity. RNA Functions. Citation: Clancy, S. Nature Education 1 1 How does the cell convert DNA into working proteins? The process of translation can be seen as the decoding of instructions for making proteins, involving mRNA in transcription as well as tRNA. Aa Aa Aa. Figure Detail. Where Translation Occurs. Figure 3: A DNA transcription unit. A DNA transcription unit is composed, from its 3' to 5' end, of an RNA-coding region pink rectangle flanked by a promoter region green rectangle and a terminator region black rectangle.
Genetics: A Conceptual Approach , 2nd ed. All rights reserved. The Elongation Phase. Figure 6. Termination of Translation. Comparing Eukaryotic and Prokaryotic Translation. References and Recommended Reading Chapeville, F. European Journal of Biochemistry , — Grunberger, D. Nucleic Acids Research 15 , — Pierce, B.
Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Applications in Biotechnology.
DNA Replication. Jumping Genes. Discovery of Genetic Material. Gene Copies. No topic rooms are there. Or Browse Visually. Other Topic Rooms Genetics.
0コメント