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This file is about DNA anatomy animation using swf format or flash media. DNA is doble helix. To learn more about it you can download this animation.
Showing posts with label genetics. Show all posts
Showing posts with label genetics. Show all posts
This file is about DNA anatomy animation using swf format or flash media. DNA is doble helix. To learn more about it you can download this animation.
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Now you can learn about DNA Sequencing using flash media or swf format.
Knowledge of DNA sequences has become indispensable for basic biological research, other research branches utilizing DNA sequencing, and in numerous applied fields such as diagnostic, biotechnology, forensic biology and biological systematics. The advent of DNA sequencing has significantly accelerated biological research and discovery. The rapid speed of sequencing attained with modern DNA sequencing technology has been instrumental in the sequencing of the human genome, in the Human Genome Project. Related projects, often by scientific collaboration across continents, have generated the complete DNA sequences of many animal, plant, and microbial genomes.
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This animation is about Enhancher animation. What is enhancher? enhancer is a short region of DNA that can be bound with proteins (namely, the trans-acting factors, much like a set of transcription factors) to enhance transcription levels of genes (hence the name) in a gene cluster. While enhancers are usually cis-acting, an enhancer does not need to be particularly close to the genes it acts on, and sometimes need not be located on the same chromosome.
This file is about DNA replication and replication fork animation. You will understand more about the process after watch this animation that use flash media and swf format.
DNA replication needed to make copying of information in cell. There are many process that happened. DNA replication begins when helicase unwinds a segment of the DNA and breaks the hydrogen bonds between the two complementary strands of DNA.
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DNA animation will you get after download this file. This DNA animation will take you to make journey on cell that contain of DNA so you can clearly know how DNA is. First you will show about Cell and then it will be zoom, so we can see that cell contain of DNA, then you also will see about the structure of it. Its so completly.
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This file will show you about inversion of DNA animation using flash media or swf format. It happen when DNA wrong to translate.
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This file Will show you about animation of PCR (Polymerase Chain Reaction).swf or flash media
The polymerase chain reaction (PCR) is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.
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This file will show you about spllicing process in DNA.
Splicing: In genetic engineering, a set of foreign genes is spliced - inserted - into the middle of the DNA 'code words' (see DNA to find DNA moleculeout about the 'instructions': the genetic code). This splicing can mess up the normal coded instructions in the DNA. And that can go on to mess up how the cell works. No-one can know in advance what might happen and whether it might be hazardous. It is unpredictable. The insertion or splice could make the chromosome behave in a quite unexpected way. This does not happen in normal mating because the arrangement of the coded instructions does not change when the chromosomes of the father and mother combine. So when people claim that GE is more or less the same as natural mating (sexual reproduction), they are wrong. For a brief comparison of mating and genetic engineering, check out this PSRAST page.
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The structure of DNA is illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn. Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C).
Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three.
This structure was first described by James Watson and Francis Crick in 1953.
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Materi Tentang Pewarisan sifat di buat oleh Dosen Biologi Universitas Negeri Semarang / UNNES
- Dominan Resesif
- Intermediate
- Alel Ganda
- Kodominan
- Alel Letal
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Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring, although some organelles (e.g. mitochondria) are self-replicating and are not coded for by the organism's DNA.
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DNA replication is a biological process that occurs in all living organisms and copies their DNA; it is the basis for biological inheritance. The process starts with one double-stranded DNA molecule and produces two identical copies of the molecule. Each strand of the original double-stranded DNA molecule serves as template for the production of the complementary strand, a process referred to as semiconservative replication. Cellular proofreading and error toe-checking mechanisms ensure near perfect fidelity for DNA replication.
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For gene expression, prokaryotes require one kind of RNA polymerase, in addition to three regulatory elements: promoter sequences, termination sequences, and operator sequences.
Eukaryotes require three RNA polymerases:
* RNA polymerase I synthesizes ribosomal RNA (rRNA is 90% of RNA in cell) and needs accessory factors to initiate transcription (positive control factors). RNA polymerase I appears to be species specific because rDNA from one species often can not be transcribed by the RNA polymerase I from another species.
* RNA polymerase II synthesizes pre-messenger RNAs (pre-mRNAs). It is the most delicately regulated eukaryotic RNA polymerase, it needs accessory proteins (transcription factors) and is not species specific.
* RNA polymerase III is responsible for the synthesis of tRNA, 5S RNA and snRNA (small nuclear RNA).
Transcription Termination
For RNA polymerase I and usually for III, there exists a specific termination signal (sequence of nucleotides) on the DNA. This sequence tells the RNA polymerase when to stop the transcription process and release the RNA.
For RNA polymerase II, however, there is no specific termination sequence. The RNA polymerase continues until it "falls off," then the precursor RNA is trimmed at a specific site to produce the final pre-mRNA product.
Since the RNA is produced in the nucleus and is necessary for protein synthesis in the cytoplasm, the RNA must be transported out of the nucleus. This process is controlled by a regulating system.
Characteristics of pre-mRNAs
When the pre-mRNA is synthesized a cap is added to the 5' end of the pre-mRNA. This specific unique structure interacts with eukaryotic ribosomes to help initiate translation. The cap serves as a binding site for ribosomes in the translation process.
Since the cap is needed for initiation of translation, a polycistronic eukaryotic mRNA will not function because the cap can only reside at the 5' end of the RNA - the middle cistrons cannot be translated because they do not have a nearby cap. Thus, there are no polycistronic RNAs in eukaryotes, only in prokaryotes.
The 3' end is formed when the pre-mRNA recognizes a sequence downstream of the 3' end of the coding region (called the 3' untranslated region, or the trailer sequence): AAUAAA. This sequence specifies that the pre-mRNA is to get cut at about 20 nucleotides past the AAUAAA sequence. A string of adenosines called the poly(A) tail is then added to the 3' end of pre-mRNA. The poly(A) tail seems to protect the RNA from degradation in the cell. Without it, the mRNA would be degraded in a matter of minutes. So the poly(A) tail serves to help stabilize the mRNA. The length of the poly(A) tail may be related to the age of that mRNA strand.
Eukaryotic pre-mRNAs also contain introns (for intervening sequences), which are sequences between coding sequences (called exons for expressed sequences) that don't code for anything. The process of RNA splicing removes introns and joins the exons together to create mature mRNAs that consist only of a usable sequence, and are ready for export from nucleus to cytoplasm.
Methylation of DNA
Methyl groups (-CH3) attach themselves to the cytosines that reside in CG (cytosine-guanine) doublets on DNA. Extensive methylation near a gene promoter on DNA will generally prevent transcription of that gene. If the methyl groups are removed, transcription can, but not necessarily will, occur again. In other words, the absence of methylation is a necessary but not sufficient condition for transcription to occur.
Enzymes that add methyl groups are called methylases - they recognize certain locations on DNA and add methylation to them.
No demethylase enzymes have been found; that is, no enzyme has been discovered that can remove the methyl groups once they become attached to the DNA. The only way methyl groups can be removed is through the creation of new DNA strands, which are not methylated at first - this only occurs during DNA replication.
If a demethylase could be found and inserted into cells, it might allow rejuvenation of cells, but there could be consequences to demethylization: preventing methylation could turn genes on and off, could create tumors and other problems. Methylation cannot be a universal method of regulation gene expression because at least some organisms (like fruit flies) don't methylate their DNA.
Transcription of Eukaryotic Genes/Transcription Factors
Before a gene can be turned on for transcription, it must be physically exposed to interact with control factors. Since DNA is packed into chromatin which is organized into nucleosomes, the chromatin must first unravel so as to make the binding sites on the DNA available.
Proteins called transcription factors regulate the level of transcription from a given gene. These transcription factors are similar to gene activators in prokaryotic cells. Each transcription factor recognizes a specific sequence on DNA. Since the transcription factors can also bind to DNA sequences which are close to (but not identical to) the ideal sequence, the binding sequence is often called a consensus sequence. This means that certain DNA sequences could be recognized by more than one transcription factor if the sequences are similar to those recognized by two different transcription factors.
Each element of the promoter might be capable of recognizing a few different transcription factors and each transcription factor is capable of recognizing a number of promoter elements. If more than one transcription factor can bind to a particular promoter element, the different transcription factors will compete for binding to that element. The level of transcription from the regulated gene will depend on the number of different preceding transcription factors.
Enhancers
Some sequences don't seem to be connected with the promoter of a gene but still can influence the level of transcription from that gene. These elements, called enhancers, exist elsewhere on the DNA but must reside on the same DNA molecule to work. Enhancers, which can point in either direction, can be up to 20,000 basepairs away from the gene and can be present upstream, downstream, or even internally with respect to the gene it is regulating. Enhancers can increase the level of transcription by stimulating transcription from all nearby genes. Some transcription factors can also recognize and bind to enhancer elements. This allows for additional control on broader level, providing control of a set of connected genes.
Problems can arise if enhancers are where they shouldn't be, for example: viruses can have enhancers in their genome that when inserted near a gene, turn on a promoter and express a gene that wasn't being expressed previously.
In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is missing. Deletion is the loss of genetic material. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome.[1] Deletions can be caused by errors in chromosomal crossover during meiosis. This causes several serious genetic diseases. Deletion is also causing frameshift.
A promotor is the part of genes that is not actively transcribed but contains response elements that regulate the expression of that gene.
Prokaryotic promoters
In prokaryotes, the promoter consists of two short sequences at -10 and -35 positions upstream from the transcription start site. Sigma factors not only help in enhancing RNAP binding to the promoter but also help RNAP target specific genes to transcribe.
The sequence at -10 is called the Pribnow box, or the -10 element, and usually consists of the six nucleotides TATAAT. The Pribnow box is essential to start transcription in prokaryotes.
The other sequence at -35 (the -35 element) usually consists of the seven nucleotides TTGACAT. Its presence allows a very high transcription rate.
Both of the above consensus sequences, while conserved on average, are not found intact in most promoters. On average only 3 of the 6 base pairs in each consensus sequence is found in any given promoter. No promoter has been identified to date that has intact consensus sequences at both the -10 and -35; artificial promoters with complete conservation of the -10/-35 hexamers has been found to promote RNA chain initiation at very high efficiencies.
Some promoters contain a UP element (consensus sequence 5'-AAAWWTWTTTTNNNAAANNN-3'; W = A or T; N = any base) centered at -50; the presence of the -35 element appears to be unimportant for transcription from the UP element-containing promoters.
It should be noted that the above promoter sequences are only recognized by the sigma-70 protein that interacts with the prokaryotic RNA polymerase. Complexes of prokaryotic RNA polymerase with other sigma factors recognize totally different core promoter sequences.
Heredity is the passing of traits to offspring (from its parent or ancestors). This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve. The study of heredity in biology is called genetics, which includes the field of epigenetics.
DNA carries the genetic information of a cell and consists of thousands of genes. Each gene serves as a recipe on how to build a protein molecule. Proteins perform important tasks for the cell functions or serve as building blocks. The flow of information from the genes determines the protein composition and thereby the functions of the cell.
The DNA is situated in the nucleus, organized into chromosomes. Every cell must contain the genetic information and the DNA is therefore duplicated before a cell divides (replication). When proteins are needed, the corresponding genes are transcribed into RNA (transcription). The RNA is first processed so that non-coding parts are removed (processing) and is then transported out of the nucleus (transport). Outside the nucleus, the proteins are built based upon the code in the RNA (translation).
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Early estimates of the number of human genes that used expressed sequence tag data put it at 50 000–100 000. Following the sequencing of the human genome and other genomes, it has been found that rather few genes (~20 000 in human, mouse and fly, ~13 000 in roundworm, >46 000 in rice) encode all the proteins in an organism. These protein-coding sequences make up 1–2% of the human genome. A large part of the genome is transcribed however, to introns, retrotransposons and seemingly a large array of noncoding RNAs. Total number of proteins (the Earth's proteome) is estimated to be 5 million sequences
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