Uncovering the Relationship Between Genes and Proteins - ATA Scientific
BIO - From Genes To Traits: How Genotype Affects Phenotype factoids, relationship with the rest of their lives rather than relationship with. The arrangement of nitrogenous bases in DNA determines an organism's traits. Every three Each gene, a distinct segment of DNA codes for a different protein. Take-Home Assignment #6 - Gene Expression and Mutation Due at Lecture Thursday April 8. The Relationship Between Genes, Proteins, and Traits. A gene.
Genes may also influence some behavioural characteristics, such as intelligence and natural talents. Genes are the blueprint for our bodies. Almost every cell in the human body contains a copy of this blueprint, mostly stored inside a special sac within the cell called the nucleus.
Genes are part of chromosomes, which are long strands of a chemical substance called deoxyribonucleic acid DNA. Therefore, genes are made up of DNA. A DNA strand looks like a twisted ladder.
The genes are like a series of letters strung along each rung. These letters are used like an instruction book. The letter sequence of each gene contains information on building specific molecules such as proteins or hormones, both essential to the growth and maintenance of the human body.
The working parts of the cell read the RNA to create the protein or hormone according to the instructions. Each gene codes the instruction for a single protein only, but one protein may have many different roles in the human body.
Also, one characteristic, such as eye colour, may be influenced by many genes. A variation can occur spontaneously no known cause or it can be inherited. Variations in the coding that make a gene not work properly faulty are called mutations and can directly or indirectly lead to a wide range of conditions. Chromosomes and sperm and egg cells Humans have 46 paired chromosomes, with about 23, genes.
The 46 chromosomes in the human cell are made up of 22 paired chromosomes. These are numbered from 1 to 22 according to size, with chromosome number 1 being the biggest. These numbered chromosomes are called autosomes. Cells in the body of a woman also contain two sex chromosomes called X chromosomes, in addition to the 44 autosomes.
Body cells in men contain an X and a Y chromosome and 44 autosomes. The 23, genes come in pairs. A sperm and an egg each contain one copy of every gene needed to make up a person one set of 23 chromosomes each. When the sperm fertilises the egg, two copies of each gene are present 46 chromosomesand so a new life can begin. The chromosomes that decide the sex of the baby are called sex chromosomes. An XX pairing means a girl, while an XY pairing means a boy.
As well as determining sex, these chromosomes carry genes that control other body functions. There are many genes located on the X chromosome, but only a few on the Y chromosome.
How we inherit characteristics We can inherit characteristics in many different ways. Variations in the gene for that characteristic cause these different forms. We can inherit different alleles of the gene pair one from each parent in different ways. Dominant and recessive genes The two copies of the genes contained in each set of chromosomes both send coded messages to influence the way the cell works.
Generally, for example, the coded message from the genes that tells the eye cells to make brown colour is dominant over blue eye colour.
Genes and genetics explained - Better Health Channel
However, a number of different genes together determine eye colour and so blue-eyed parents can have a child with brown eyes. Dominant and recessive blood-group inheritance Dominant inheritance is when one allele of a gene is dominant within the pair.Biology Lecture - 61 - Genes, Traits, and Alleles
For blood groups, the A allele is dominant over the O allele, so a person with one A allele and one O allele has the blood group AO. Another way of saying this is that the O group is recessive — a person needs two O alleles to have the blood group O.
So a child may have blood group A because the blood group A gene inherited from their mother is dominant over the blood group O gene inherited from their father. The father has two O alleles OOso he has the blood group O. Each one of their children has a 50 per cent chance of having blood group A AO and a 50 per cent chance of having blood group O OOdepending on which alleles they inherit.
Co-dominant genes Not all genes are either dominant or recessive.
Sometimes, each allele in the gene pair carries equal weight and will show up as a combined physical characteristic. So someone with one copy of A and one copy of B has the blood group AB. Continuing the example of blood groups, a person with the alleles AO will have the blood group A.
The observable trait — blood group — is known as the phenotype. The genotype is the genes that produce the observable trait. Chemical communication Although every cell has two copies of the 23, genes, each cell needs only some specific genes to be switched on in order to perform its particular functions.
The unnecessary genes are switched off. Genes communicate with the cell in chemical code, known as the genetic code. The cell carries out its instructions to the letter. A cell reproduces by copying its genetic information then splitting in half, forming two individual cells.
Occasionally, a mistake is made, causing a variation genetic mutation and the wrong chemical message is sent to the cell. Genetic mutations are permanent. Some of the causes of a spontaneous genetic mutation include exposure to radiation, chemicals and cigarette smoke.
Genetic mutations also build up in our cells as we age. In more complex cases, relatively complicated interactions occur amongst the genes at various loci. In the presence of allele a1 at locus A, allele b1 at locus B can determine the formation of trait Z1 and allele b2 the formation of trait Z2; however, in the presence of allele a2, the situation can be quite the opposite, allele b1 can determine the formation of trait Z2 and allele b2 that of trait Z1.
Of course, the genes of more than two loci participate in a great many interactions. Table a depicts the result of crossing two homozygotes. Each of the homozygotes produces only a single type of gamete, so that all offspring in the F1-generation have the same heterozygote genotype from the standpoint of the given gene.
Table b depicts the result of crossing two F1-heterozygotes. Each heterozygote produces two types of gametes and their random combination leads to the formation of four types of zygote, i. Table c depicts the result of crossing two heterozygote individuals at two loci. Each heterozygote produces four types of gamete and their random combination leads to the formation of individuals in a ratio of 1: The existence of interactions greatly complicates both the search for the locus at which the gene determining a certain trait is located and also the delimitation of the particular gene.
Basically, it even complicates the very concept of a gene and especially the molecular biological definition of a gene as a cistron. If the interaction amongst several genes, and not a particular gene, is responsible for the formation of a particular trait, then there is no point in searching for the locus at which the particular gene is located.