what's a gene?

Answer 1

Genes (say: jeenz), that's what they're talking about. Genes are the things that determine physical traits — how we look — and lots of other stuff about us. They carry information that helps make you who you are: curly or straight hair, long or short legs, even how you might smile or laugh, are all passed through generations of your family in genes. Keep reading to learn more about genes and how they work.

What Is a Gene?
Each cell in the human body contains about 25,000 to 35,000 genes, which carry information that determines your traits (say: trates). Traits are characteristics you inherit from your parents; this means your parents pass some of their characteristics on to you through genes. For example, if both of your parents have green eyes, you might inherit the trait of green eyes from them. Or if your mom has freckles, you might inherit that trait and wind up with a freckled face. And genes aren't just in humans — all animals and plants have genes, too.

Genes hang out all lined up on thread-like things called chromosomes (say: kro-moh-somes). Chromosomes come in pairs, and there are hundreds, sometimes thousands, of genes in one chromosome. The chromosomes and genes are made of DNA, which is short for deoxyribonucleic (say: dee-ox-see-ri-bo-nyoo-clay-ik) acid.

Chromosomes are found inside cells, the very small units that make up all living things. A cell is so tiny that you can only see it through the lens of a strong microscope, and there are billions of cells in your body. Most cells have one nucleus (say: noo-clee-us). The nucleus, which is sort of egg-shaped, is like the brain of the cell. It tells every part of the cell what to do. How does the nucleus know so much? It contains our chromosomes and genes. As tiny as it is, the nucleus has more information in it than the biggest dictionary you've ever seen.

In humans, a cell nucleus contains 46 individual chromosomes or 23 pairs of chromosomes (chromosomes come in pairs, remember? 23 X 2 = 46). Half of these chromosomes come from one parent and half come from the other parent. But not every living thing has 46 chromosomes inside of its cells. For instance, a fruit fly cell only has four chromosomes!

How Do Genes Work?
Each gene has a special job to do. It carries blueprints — the instructions — for making proteins (say: pro-teens) in the cell. Proteins are the building blocks for everything in your body. Bones and teeth, hair and earlobes, muscles and blood, all are made up of proteins (as well as other stuff). Those proteins help our bodies grow, work properly, and stay healthy. Scientists today estimate that each gene in the body may make as many as 10 different proteins. That's over 300,000 proteins!

Like chromosomes, genes come in pairs. Each of your biological parents has two copies of each of their genes, and each parent passes along just one copy to make up the genes you have. Genes that are passed on to you determine many of your traits, such as your hair color and skin color.

Maybe Nancy's mother has one gene for brown hair and one for red hair, and she passed the red hair gene on to Nancy. If her father has two genes for red hair, that could explain her red hair. Nancy ended up with two genes for red hair, one from each of her parents.

You can see genes at work if you think about all the breeds of dogs there are. They all have the genes that make them dogs instead of cats, fish, or people. But those same genes that make a dog a dog also make different dog traits. So some breeds are small and others are big. Some have long fur and others have short fur. Dalmatians have genes for white fur and black spots, and toy poodles have genes that make them small with curly fur. You get the idea!

When There Are Problems With Genes
Scientists are very busy studying genes. What do the proteins that each gene makes actually do in the body? What illnesses are caused by genes that don't work right? Researchers think genes that have changed in some way, also known as altered (or mutated) genes, may be partly to blame for lung problems, cancer, and many other illnesses.

Take the gene that helps the body make hemoglobin (say: hee-muh-glow-bin), for example. Hemoglobin is an important protein that is needed for red blood cells to carry oxygen throughout the body. If parents pass on altered hemoglobin genes to their child, the child may only be able to make a type of hemoglobin that doesn't work properly. This can cause a condition known as anemia (say: uh-nee-mee-uh), a condition in which a person has fewer healthy red blood cells.

Anemias that are inherited can sometimes be serious enough to require long-term medical care. Sickle cell anemia is one kind of anemia that is passed on through genes from parents to children.

Cystic fibrosis (say: sis-tick fi-bro-sus), or CF, is another illness that some kids inherit. Parents with the CF gene can pass it on to their kids. People who have CF often have trouble breathing because their bodies make a lot of mucus (say: myoo-kus) — the slimy stuff that comes out of your nose when you blow — that gets stuck in the lungs. They will need treatment throughout their lives to keep their lungs as healthy as possible

Answer 2

1

Answer 3

A man's name: Gene = English Abbreviation of Eugene

or

What Is a Gene?
Each cell in the human body contains about 25,000 to 35,000 genes, which carry information that determines your traits (say: trates). Traits are characteristics you inherit from your parents; this means your parents pass some of their characteristics on to you through genes. For example, if both of your parents have green eyes, you might inherit the trait of green eyes from them. Or if your mom has freckles, you might inherit that trait and wind up with a freckled face. And genes aren't just in humans — all animals and plants have genes, too.
http://216.83.169.90/kid/talk/qa/what_is_gene.html

Answer 4

A trait from your parents!..When a baby is produced They get one gene from each parent..That chooses wheather its a gurl or boy and what it looks like such as color of eyes and hair!...Well Each parents donates one set of instructions to the offspring Which are genes. The fertilized egg would then have 2 forms of the same gene for every characteristic--one from each parent.The 2 forms of a gene are known as alleles.

Answer 5

A gene is the unit of heredity and carries inherited information. Genes interact with each other to influence physical development and behavior.

Answer 6

ok. dominant. it efficient hides the recessive trait. keep in mind a punnit sq.? its the tremendous letter. recessive is the small letter. keep in mind, this stuff is the genotype. the variety of genes someone has. in case you opt for to apply an party to tutor your instructor you recognize this stuff: brown eye vs. blue blue are 2 recessive genes. say (aa). brown is a dominant function. (A-) you dont recognize no matter if it truly is paired with a recessive or yet another dominant gene, yet you do recognize that it truly is expressed. so it truly is dominant. the above party is a phenotype. keep in mind that!!! guarenteed which will be a query on that in case you obtain some punnit squares and gene question i wish this become functional! save on interpreting and chugging.

Answer 7

A SECTION OF DNA THAT CONTAINS A START CODON AND STOP CODON THAT TELL RNA POLYMERASE WHEN TO START AND HOW TO START PRODUCING A PROTEIN.

TO MAKE IT SHORT IT IS A PEICE OF DNA THAT CONTAINS THE INFORMATION TO CREATE PROTEINS

Answer 8

One of my uncles, short for Eugene...

Answer 9

1.A segment of DNA, occupying a specific place on a chromosome, that is the basic unit of heredity. Genes act by directing the production of RNA, which determines the synthesis of proteins that make up living matter and are the catalysts of all cellular processes. The proteins that are determined by genetic DNA result in specific physical traits, such as the shape of a plant leaf, the coloration of an animal's coat, or the texture of a person's hair. Different forms of genes, called alleles, determine how these traits are expressed in a given individual. Humans are thought to have about 35,000 genes, while bacteria have between 500 and 6,000 and A hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism. Genes undergo mutation when their DNA sequence changes. 2. any small, Old World carnivore of the genus Genetta, esp. G. genetta, having spotted sides and a ringed tail.
3.The fur of such an animal.A gene is the unit of heredity and carries inherited information. Genes interact with each other to influence physical development and behavior. Genes consist of a long strand of DNA (RNA in some viruses) that contains a promoter, which controls the activity of a gene, and a coding sequence, which determines what the gene produces. When a gene is active, the coding sequence is copied in a process called transcription, producing a RNA copy of the gene's information. This RNA can then direct the synthesis of proteins via the genetic code. However, RNAs can also be used directly, for example as part of the ribosome. These molecules resulting from gene expression, whether RNA or protein, are known as gene products.

Most genes contain non-coding regions that do not code for the gene products, but regulate gene expression. The genes of eukaryotic organisms can contain non-coding regions called introns that are removed from the messenger RNA in a process known as splicing. The regions that actually encode the gene product , which can be much smaller than the introns, are known as exons. One single gene can lead to the synthesis of multiple proteins through the different arrangements of exons produced by alternative splicings.

The total complement of genes in an organism or cell is known as its genome. The genome size of an organism is loosely dependent on its complexity; prokaryotes such as bacteria and archaea have generally smaller genomes, both in number of base pairs and number of genes, than even single-celled eukaryotes. However, the largest known genome belongs to the single-celled amoeba Amoeba duria, with over 6 billion base pairs.[1] The estimated number of genes in the human genome has been repeatedly revised downward since the completion of the Human Genome Project; current estimates place the human genome at just under 3 billion base pairs and about 20,000-25,000 genes.[2] The gene density of a genome is a measure of the number of genes per million base pairs (called a megabase, Mb); prokaryotic genomes have much higher gene densities than eukaryotes. The gene density of the human genome is roughly 12-15 genenerations.

The modern conception of the gene originated with work by Gregor Mendel, a 19th century Austrian monk who systematically studied heredity in pea plants. Mendel's work was the first to illustrate particulate inheritance, or the theory that inherited traits are passed from one generation to the next in discrete units that interact in well-defined ways. Danish botanist Wilhelm Johannsen coined the word "gene" in 1909 to describe these fundamental physical and functional units of heredity.[4] The word was derived from Hugo De Vries' term pangen, itself a derivative of the word pangenesis coined by Darwin (1868).[5] The word pangenesis is made from the Greek words pan (a prefix meaning "whole", "encompassing") and genesis ("birth") or genos ("origin").

According to the theory of Mendelian inheritance, variations in phenotype - the observable physical and behavioral characteristics of an organism - are due to variations in genotype, or the organism's particular set of genes, each of which specifies a particular trait. Different genes for the same trait, which give rise to different phenotypes, are known as alleles. Organisms such as the pea plants Mendel worked on, along with many plants and animals, have two alleles for each trait, one inherited from each parent.

Alleles may be dominant or recessive; dominant alleles give rise to their corresponding phenotypes when paired with any other allele for the same trait, while recessive alleles give rise to their corresponding phenotype only when paired with another copy of the same allele. For example, if the allele specifying tall stems in pea plants is dominant over the allele specifying short stems, then pea plants that inherit one tall allele from one parent and one short allele from the other parent will also have tall stems. Mendel's work found that alleles assort independently in the production of gametes, or germ cells, ensuring variation in the next generation.

Prior to Mendel's work, the dominant theory of heredity was one of blending inheritance, which proposes that the traits of the parents blend or mix in a smooth, continuous gradient in the offspring. Although Mendel's work was largely unrecognized after its first publication in 1866, it was rediscovered in 1900 by three European scientists, Hugo de Vries, Carl Correns, and Erich von Tschermak, who had reached similar conclusions from their own research. However, these scientists were not yet aware of the identity of the 'discrete units' on which genetic material resides.

A series of subsequent discoveries led to the realization decades later that chromosomes within cells are the carriers of genetic material, and that they are made of DNA (deoxyribonucleic acid), a polymeric molecule found in all cells on which the 'discrete units' of Mendelian inheritance are encoded. The modern study of genetics at the level of DNA is known as molecular genetics and the synthesis of molecular genetics with traditional Darwinian evolution is known as the modern evolutionary synthesis.The vast majority of living organisms encode their genes in long strands of DNA. DNA consists of a chain made from four types of nucleotide subunits: adenosine, cytosine, guanosine, and thymidine.

Each nucleotide subunit consists of three components: a phosphate group, a deoxyribose sugar ring, and a nucleobase. Thus, nucleotides in DNA or RNA are typically called 'bases'; consequently they are commonly referred to simply by their purine or pyrimidine original base components adenine, cytidine, guanine, thymine. Adenine and guanine are purines and cytosine and thymine are pyrimidines. The most common form of DNA in a cell is in a double helix structure, in which two individual DNA strands twist around each other in a right-handed spiral. In this structure, the base pairing rules specify that guanine pairs with cytosine and adenine pairs with thymine (each pair contains one purine and one pyrimidine). The two strands in a double helix must therefore be complementary, that is, their bases must align such that the adenines of one strand are paired with the thymines of the other strand, and so on.

Due to the chemical composition of the pentose residues of the bases, DNA strands have directionality. One end of a DNA polymer contains an exposed hydroxyl group on the deoxyribose, this is known as the 3' end of the molecule. The other end contains an exposed phosphate group, this is the 5' end. The directionality of DNA is vitally important to many cellular processes, since double helices are necessarily directional (a strand running 5'-3' pairs with a complementary strand running 3'-5') and processes such as DNA replication occur in only one direction. All nucleic acid synthesis in a cell occurs in the 5'-3' direction, because new monomers are added via a dehydration reaction that uses the exposed 3' hydroxyl as a nucleophile.

The expression of genes encoded in DNA begins by transcribing the gene into RNA, a second type of nucleic acid that is very similar to DNA, but whose monomers contain the sugar ribose rather than deoxyribose. RNA also contains the base uracil in place of thymine. RNA molecules are less stable than DNA and are typically single-stranded. Genes that encode proteins are composed of a series of three-nucleotide sequences called codons, which serve as the "words" in the genetic "language". The genetic code specifies the correspondence during protein translation between codons and amino acids. The genetic code is nearly the same for all known organisms.In most cases, RNA is an intermediate product in the process of manufacturing proteins from genes. However, for some gene sequences, the RNA molecules are the actual functional products. For example, RNAs known as ribozymes are capable of enzymatic function, and miRNAs have a regulatory role. The DNA sequences from which such RNAs are transcribed are known as non-coding DNA, or RNA genes.

Some viruses store their entire genomes in the form of RNA, and contain no DNA at all. Because they use RNA to store genes, their cellular hosts may synthesize their proteins as soon as they are infected and without the delay in waiting for transcription. On the other hand, RNA retroviruses, such as HIV, require the reverse transcription of their genome from RNA into DNA before their proteins can be synthesized. In 2006, French researcher came across a puzzling example of RNA-mediated inheritance in mouse. Mice with a loss-of-function mutation in the gene Kit have white tails. Offspring of these mutants can have white tails despite having only normal Kit genes. The research team traced this effect back to mutated Kit RNA [6]. While RNA is common as genetic storage material in viruses, in mammals in particular RNA inheritance has been observed very rarely.All genes have regulatory regions in addition to regions that explicitly code for a protein or RNA product. A universal regulatory region shared by all genes is known as the promoter, which provides a position that is recognized by the transcription machinery when a gene is about to be transcribed and expressed. Although promoter regions have a consensus sequence that is the most common sequence at this position, some genes have "strong" promoters that bind the transcription machinery well, and others have "weak" promoters that bind poorly. These weak promoters usually permit a lower rate of transcription than the strong promoters, because the transcription machinery binds to them and initiates transcription less frequently. Other possible regulatory regions include enhancers, which can compensate for a weak promoter. Most regulatory regions are "upstream" - that is, toward the 5' end of - the transcription initiation site. Eukaryotic promoter regions are much more complex and difficult to identify than prokaryotic promoters.

Many prokaryotic genes are organized into operons, or groups of genes whose products have related functions and which are transcribed as a unit. By contrast, eukaryotic genes are transcribed only one at a time, but may include long stretches of DNA called introns which are transcribed but never translated into protein.In most cases, RNA is an intermediate product in the process of manufacturing proteins from genes. However, for some gene sequences, the RNA molecules are the actual functional products. For example, RNAs known as ribozymes are capable of enzymatic function, and miRNAs have a regulatory role. The DNA sequences from which such RNAs are transcribed are known as non-coding DNA, or RNA genes.

Some viruses store their entire genomes in the form of RNA, and contain no DNA at all. Because they use RNA to store genes, their cellular hosts may synthesize their proteins as soon as they are infected and without the delay in waiting for transcription. On the other hand, RNA retroviruses, such as HIV, require the reverse transcription of their genome from RNA into DNA before their proteins can be synthesized. In 2006, French researcher came across a puzzling example of RNA-mediated inheritance in mouse. Mice with a loss-of-function mutation in the gene Kit have white tails. Offspring of these mutants can have white tails despite having only normal Kit genes. The research team traced this effect back to mutated Kit RNA [6]. While RNA is common as genetic storage material in viruses, in mammals in particular RNA inheritance has been observed very rarely.


[edit] Functional structure of a gene
All genes have regulatory regions in addition to regions that explicitly code for a protein or RNA product. A universal regulatory region shared by all genes is known as the promoter, which provides a position that is recognized by the transcription machinery when a gene is about to be transcribed and expressed. Although promoter regions have a consensus sequence that is the most common sequence at this position, some genes have "strong" promoters that bind the transcription machinery well, and others have "weak" promoters that bind poorly. These weak promoters usually permit a lower rate of transcription than the strong promoters, because the transcription machinery binds to them and initiates transcription less frequently. Other possible regulatory regions include enhancers, which can compensate for a weak promoter. Most regulatory regions are "upstream" - that is, toward the 5' end of - the transcription initiation site. Eukaryotic promoter regions are much more complex and difficult to identify than prokaryotic promoters.

Many prokaryotic genes are organized into operons, or groups of genes whose products have related functions and which are transcribed as a unit. By contrast, eukaryotic genes are transcribed only one at a time, but may include long stretches of DNA called introns which are transcribed but never translated into protein.


[edit] Chromosomes
The total complement of genes in an organism or cell is known as its genome, which may be stored on one or more chromosomes; the region of the chromosome at which a particular gene is located is called its locus. A chromosome consists of a single, very long DNA helix on which thousands of genes are encoded. Prokaryotes - bacteria and archaea - typically store their genomes on a single large, circular chromosome, sometimes supplemented by additional small circles of DNA called plasmids, which usually encode only a few genes and are easily transferable between individuals. For example, the genes for antibiotic resistance are usually encoded on bacterial plasmids and can be passed between individual cells, even those of different species, via horizontal gene transfer. Although some simple eukaryotes also possess plasmids with small numbers of genes, the majority of eukaryotic genes are stored on multiple linear chromosomes, which are packed within the nucleus in complex with storage proteins called histones. The manner in which DNA is stored on the histone, as well as chemical modifications of the histone itself, are regulatory mechanisms governing whether a particular region of DNA is accessible for gene expression. The ends of eukaryotic chromosomes are capped by long stretches of repetitive sequences called telomeres, which do not code for any gene product but are present to prevent degradation of coding and regulatory regions during DNA replication. The length of the telomeres tends to decrease each time the genome is replicated in preparation for cell division; the loss of telomeres has been proposed as an explanation for cellular senescence, or the loss of the ability to divide, and by extension for the aging process in organisms.[7]

While the chromosomes of prokaryotes are relatively gene-dense, those of eukaryotes often contain so-called "junk DNA", or regions of DNA that serve no obvious function. Simple single-celled eukaryotes have relatively small amounts of such DNA, while the genomes of complex multicellular organisms, including humans, contain an absolute majority of DNA without an identified function.In all organisms, there are two major steps separating a protein-coding gene from its protein: first, the DNA on which the gene resides must be transcribed from DNA to messenger RNA (mRNA), and second, it must be translated from mRNA to protein. RNA-coding genes must still go through the first step, but are not translated into protein. The process of producing a biologically functional molecule of either RNA or protein is called gene expression, and the resulting molecule itself is called a gene product.