Explain what is haploid mean? how many set of chromosomes in haploid cell? what does it mean that prokaryotic has no genetic masking? give examples?
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Ploidy refers to the number of complete sets of chromosomes (genes) present in a cell. The number of chromosomes in a complete set is a fixed characteristic of a species. Humans are diploid with two sets of 23 chromosomes. Fruit flies are diploid with two sets of 4 chromosomes. Sexually reproducing organisms are diploid, each somatic cell of an organism has two complete sets ("di" is a prefix indicating 2.). To complete a life cycle and reproduce new members of a species, mating is required. Mating brings a donation from a male and a donation from a female together. However, if the male and female cells remain diploid, the fertilization will result in a tetraploid zygote. In general, these are not viable. A mechanism is needed to form special haploid cells, gametes. The diploid set is split precisely into two complete haploid sets. That mechanism is meiosis. The complete set of chromosomes of a species is also the complete set of genes of a species, the genome. (Yes, there is a minor contribution from mitochondria and chloroplasts. Inheritance of this information is "cytoplasmic".) Please answer the following questions: 1. How many chromosomes in a brain cell of a fruit fly? How many chromosomes are in a liver cell of a human? Explain both answers. 2. How many chromosomes are in a fruit fly unfertilized egg? How many chromosomes are in a human egg? Explain both answers. 3. Why is meiosis necessary for sexually reproducing organisms? How many chromosomes are in a human zygote? Relate the two answers. 4. What is a gene allele? Suppose there is a gene called "bingo" and it is present once in a complete haploid set. How many alleles of "bingo" does a diploid individual have? How many copies or versions of the gene "bingo" are present in a diploid individual? 5. Modern DNA sequencing clearly identifies alleles by showing the different DNA sequence of each allele. These alleles may be termed structural alleles (I coined the term for this problem.). Classical genetics only dealt with phenotypes or visible traits. As a result, alleles of genes were identified by functionality, usually normal or non-functional. Using your knowledge of gene structure and gene expression, postulate a relationship between structural alleles and functional alleles. (include relative amounts; more, less, or equal).
Adi S.
Background: The vast majority of cells contain chromosomes. Each chromosome contains a long molecule of DNA. Each DNA molecule contains many genes. A gene is a segment of a DNA molecule that is a unit of information that is transcribed. Different versions of the same gene are called alleles. In genetics, we use a variable to refer to a full set of all types of chromosomes in an organism: n. A cell that contains one of each type of chromosome has a ploidy number of 1n. In humans, a 1n cell has 23 chromosomes. A cell that has two versions of each type of chromosome has a ploidy number of 2n (diploid). In humans, a 2n cell has 46 chromosomes. Most organisms are diploid, however, other ploidies exist, especially in plants. For example, seedless watermelon is triploid (3n), white potato is tetraploid (4n), and some types of wheat are hexaploid (6n). Complete the table below: In this activity, you will be working with an organism with a diploid chromosome (2n) number of four. * What is the haploid chromosome number (n)?
Nicole C.
Humans and many other complex organ isms are diploid, possessing two sets of genes, one inherited from the mother and one from the father. However, a number of eukaryotic organ isms spend most of their life cycles in a haploid state. Many of these eukaryotes, such as Neurospora and yeast, still undergo meiosis and sexual reproduction, but most of the cells that make up the organism are haploid. Considering that haploid organ isms are fully capable of sexual reproduction and generating genetic variation, why are most complex cukaryotes diploid? In other words, what might be the evolutionary advantage of existing in a diploid state instead of a haploid state? And why might a few organisms, such as Neurospona and yeast, exist as haploids?
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