Cell Biology
In the world of genetics, understanding the lingo is crucial. Gregor Mendel developed the concepts of genetics through his work with pea plants. Genetic information is stored in chromosomes, which can be found in the nucleus of a cell. A locus is the location of a specific gene on a chromosome, and genes are sections of DNA that code for traits. Alternative forms of a gene are called alleles, and variations in these alleles can change the function of the gene product.
The complete set of genetic material in an organism is termed its genome, while the genotype is the collection of genes in an organism that codes for traits. Chromosomes in human cells exist as pairs called homologs, with one passed down from each biological parent. The number of complete chromosome sets per cell is called the ploidy. Haploid cells have only one set of chromosomes, whereas diploid cells have two sets. Homologous chromosomes can carry the same or different alleles of a gene, resulting in homozygous and heterozygous genotypes, respectively. Hemizygosity occurs when one allele is present in a diploid organism, such as in the case of human sex chromosomes.
Lesson Outline
<ul> <li>Introduction to genetics</li> <ul> <li>Gregor Mendel's principles</li> </ul> <li>Chromosomes</li> <ul> <li>Eukaryotic chromosomes and their structure (linear)</li> </ul> <li>Locus and loci</li> <ul> <li>Definition and explanation</li> </ul> <li>Genes and alleles</li> <ul> <li>Definition and concept</li> <li>Gene variations and function</li> </ul> <li>Genome and genotype</li> <ul> <li>Genome: a full compilation of genetic material</li> <li>Genotype: a collection of genes, usually in the context of those that drive a single trait</li> </ul> <li>Ploidy and types of cells</li> <ul> <li>Haploid cells with one set of chromosomes</li> <li>Diploid cells with homologs and two sets of chromosomes</li> </ul> <li>Genotypic combinations</li> <ul> <li>Homozygosity with same alleles</li> <li>Heterozygosity with different alleles</li> <li>Hemizygosity with only one allele present</li> </ul> </ul>
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FAQs
Gregor Mendel is considered the father of modern genetics. He was an Austrian monk who conducted a series of experiments on pea plant cross-breeding between 1856 and 1863. These experiments helped him discover the fundamental principles of inheritance, such as the concept of dominant and recessive traits, by observing the patterns in which traits were passed down through generations. Mendel's work laid the foundation for our understanding of how genes are inherited from parents to offspring.
Haploid and diploid refer to the number of sets of chromosomes present in an organism's cells. A haploid organism has a single set of chromosomes, while a diploid organism has two sets of chromosomes, one from each parent. For example, in humans, somatic (body) cells are diploid as they carry two sets of 23 chromosomes (46 total), while reproductive cells, or gametes (sperm and egg cells), are haploid with only one set of 23 chromosomes. Haploid cells are produced by a process called meiosis, which results in the formation of gametes for sexual reproduction.
Alleles are alternative forms of a gene that can be found at a specific location on a chromosome. An individual's genotype refers to the specific combination of alleles present in an organism's genome. These alleles determine traits or characteristics that are expressed by an organism, which is known as their phenotype. For example, an individual may have a genotype consisting of two alleles for eye color, one from each parent, and their phenotype could be a specific eye color resulting from the interaction of these two alleles.
Homozygous and hemizygous gene states describe the relationship between the alleles present at a specific genetic locus. Homozygous refers to the situation where both alleles at a given locus are identical (either both dominant or both recessive). Hemizygous, on the other hand, occurs when a gene is present only on one chromosome but not the other. This is commonly seen in the X and Y chromosomes of males, as they possess only one X chromosome, so any gene located on the X chromosome is considered hemizygous.
Chromosomes are structures composed of DNA and proteins that carry the genetic information of an organism. They serve as the repository for an organism's genes and ensure that the genes are accurately passed on from cell to cell during cell division and from parent to offspring during reproduction. A genome refers to the complete set of genetic material present in an organism, which is organized into chromosomes. In humans, there are 46 chromosomes divided into 23 pairs, with one of each pair inherited from each parent. These chromosomes together make up the human genome.
