Describe the part played by genes in the process of evolution.?

Question

thanks
it's a GCE O-Level biology question.

Answer 1

http://en.wikipedia.org/wiki/Genes
Gene
This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). Introns are regions often found in eukaryote genes which are removed in the splicing process: only the exons encode the protein. This diagram labels a region of only 40 or so bases as a gene. In reality many genes are much larger, as are introns and exons.A gene is the unit of heredity in living organisms. Genes are encoded in an organism's genome, composed of DNA or RNA, and direct the physical development and behavior of the organism. Most genes encode proteins, which are biological macromolecules comprising linear chains of amino acids that effect most of the chemical reactions carried out by the cell. Some genes do not encode proteins, but produce non-coding RNA molecules that play key roles in protein biosynthesis and gene regulation. Molecules that result from gene expression, whether RNA or protein, are collectively known as gene products.

Most genes contain regions, called non-coding regions, that do not code for the gene products, but often dictate gene regulation. A critical non-coding region is the promoter, a short DNA sequence that is required for initiation of gene expression. The genes of eukaryotic organisms often contain non-coding regions called introns which 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.



Definitions
The word "gene" was coined in 1909 by Danish botanist Wilhelm Johannsen for the fundamental physical and functional unit of heredity.[1] The word was derived from Hugo De Vries' term pangen, itself a derivative of the word pangenesis coined by Darwin (1868).[citation needed] The word pangenesis is made from the Greek words pan (a prefix meaning "whole", "encompassing") and genesis ("birth") or genos ("origin").

Although classical genetics and evolutionary biology use the term "gene" to refer to a conceptual entity or "unit of inheritance", modern molecular genetics typically uses the term to refer to a physical molecule. The Sequence Ontology Project, an effort directed by the larger Gene Ontology system, defines a gene as "a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions and/or other functional sequence regions".[2]

The word "gene" is also used in common speech to refer to the inheritance of a trait, as in "a cancer gene" or "the gene for obesity"; however, biologists rarely use the term in this sense because it is highly unlikely that such complex and large-scale phenomena would be attributable to the influence of a single molecular gene.

Molecular properties
In molecular biology, a gene is a region of DNA (or RNA, in the case of some viruses) that determines the amino acid sequence of a protein (the coding sequence) and the surrounding sequence that controls when and where the protein will be produced (the regulatory sequence). The genetic code determines how the coding sequence is converted into a protein sequence. The protein-coding regions of genes are composed of a series of three-nucleotide sequences called codons. Each codon specifies a particular amino acid to be added to the protein chain; thus genes determine the protein's primary structure. Most genes are expressed in a two-stage process: first, the DNA is transcribed by enzymes known as RNA polymerases to produce an RNA molecule known as messenger RNA (mRNA), and second, the mRNA is translated by specialized cellular machinery known as the ribosome into a polypeptide chain that then folds into a functional protein. The genetic code is essentially the same for all known life, from bacteria to humans.

Through the proteins they encode, genes govern the cells in which they reside. In multicellular organisms, they control the development of the individual from the fertilized egg and the day-to-day functions of the cells that make up tissues and organs. The roles of their protein products range from mechanical support of the cell structure to the transportation and manufacture of other molecules and to the regulation of other proteins' activities.


Types
Due to rare, spontaneous errors (e.g. in DNA replication), mutations in the sequence of a gene may arise. Once propagated to the next generation, this mutation may lead to variations within a species' population. Variants of a single gene are known as alleles, and differences in alleles may give rise to differences in traits, for example eye colour. A gene's most common allele is called the wild type allele, and rare alleles are called mutants. (However, this does not imply that the wild-type allele is the ancestor from which the mutants are descended.)

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 small interfering RNAs have a regulatory role. The DNA sequences from which such RNAs are transcribed are known as non-coding RNA, or RNA genes.

Most living organisms carry their genes and transmit them to offspring as DNA, but some viruses carry only RNA. Because they use RNA, 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.

Human gene nomenclature
For each known human gene the HUGO Gene Nomenclature Committee (HGNC) approve a gene name and symbol (short-form abbreviation). All approved symbols are stored in the HGNC Database. Each symbol is unique and each gene is only given one approved gene symbol. It is necessary to provide a unique symbol for each gene so that people can talk about them. This also facilitates electronic data retrieval from publications. In preference each symbol maintains parallel construction in different members of a gene family and can be used in other species, especially the mouse.


Typical numbers of genes in an organism
Gene content and genome size of various organisms organism genes base pairs
Plant <50,000 <1011
Human, mouse or rat 25,000 3×109
Fugu fish 40,000 4x108
Fruit Fly 13,767 1.3×108
Worm 19,000 9.7×107
Fungus 6,000 1.3×107
Bacterium 500–6,000 5×105–107
Mycoplasma genitalium 500 580,000
DNA virus 10–900 5,000–800,000
RNA virus 1–25 1,000–23,000
Viroid 0–1 ~500
The attached table gives typical numbers of genes and genome size for some organisms. Estimates of the number of genes in an organism are somewhat controversial because they depend on the discovery of genes, and no techniques currently exist to prove that a DNA sequence contains no gene. (In early genetics, genes could be identified only if there were mutations, or alleles.) Nonetheless, estimates are made based on current knowledge.

Answer 2

The answe to this question is very simple, the genes have a major role in evolution. The genes in our DNA get modified due to several environmental factors like heat, cold radiations etc.(The classic example is our skin color,which varies from place to place). These genetic changes are, however, not noticeable until the next generation. The changes also become more significant after a long oeriod of times.

Answer 3

Keyword: Inheritance.

If you want to evolve, you've gotta pass something down to be acted upon. Genes allow you to connect through the generations

Answer 4

hey the genes basically help in maintaining uniformity in all forms of life...mostly in the animal kingdom...the genes are what make you and your parents similar. it is what differentiates between two people....it contains DNA which gives individuality to a person.

i hope this helps.....I'm not quite sure that my answer's right...but whatever... verify it.

Answer 5

Hormones

Answer 6

genes decides the creation.