Which type of chromosomes is found in larvae of Drosophila?
THE basic karyotype of Drosophila melanogaster, which can be seen in mitotically active neuroblasts of the larval brain, is comprised by four chromosomes, the X and Y sex chromosomes, two larger autosomal elements, chromosomes 2 and 3, and the small dot fourth chromosome (Figure 1) (Metz 1914; Deng et al. 2007) .
How many instars are in Drosophila larval stage?
In Drosophila, these stages correspond to four morphologically distinct developmental states: embryo, larva (three instar stages), pupa, and adult. Embryogenesis, along with the first and second larval instars (L1 and L2), each last one day, followed by two days of third instar larval development (L3).
How many chromosome pairs are in Drosophila?
It has only four pairs of chromosomes – three autosomes, and one pair of sex chromosomes.
What is the size of Drosophila 3rd instar larva?
The length of the egg is about 0.5 mm, and after two moltings the 3rd instar larva is 5mm in length (Fig. 1A).
Why are polytene chromosomes in fly larvae?
Polytene chromosomes are usually found at the interphase nuclei of some tissue of the larvae of flies. Polytene chromosomes are considered to be very useful for the analysis of many facets of eukaryotic interphase chromosome organization and the genome as a whole.
Are polytene chromosomes haploid or diploid?
The end product of the replication cycles is a nucleus with a haploid number of chromosomes, each containing up to 2,000 or more parallel strands. In the Collembola, however, the polytene chromosomes typically remain unpaired and the nuclei contain the diploid number (Fig. 92).
What are the 4 stages of the Drosophila life cycle?
Drosophila is a holometabolous insect, and its life cycle can be divided into four stages: embryo, larva, pupa, and adult (Fig. 1). The Drosophila life cycle is divided into four stages: embryo, larva, pupa, and adult.
How many instar stages are there in the life cycle of Drosophila?
There are 3 instars of larval stages spanning over 4 days approximately. At this time of growth, most of the types of cells are differentiated already and are operating, and a moulting shift takes place between the various larval stages.
How many chromosomes are there in each stage of mitosis in Drosophila?
The fruit fly, Drosophila melanogaster, has a total of eight chromosomes (four pairs) in each of its somatic cells. Somatic cells are all cells of the body except those that will divide to form the gametes (ova or sperm). Review the events that occur in the various stages of mitosis. 7.
What is the third stage of a fly life cycle?
Stage 3 of the Fly Life Cycle:
they develop into pupae which the term “pupate” is the resting period between the larvae/maggot stage into the adult fly. Pupae appears dark and cylinder shaped, and hardens before becoming an adult fly.
How many chromosomes are in a polytene chromosome?
Polytene homologues are held together by somatic pairing. The centromeres of all four chromosomes aggregate to form a chromocentre that is seen amorphous and consists largely of heterochromatin.
What is 2n chromosome?
Humans have 46 chromosomes in each diploid cell. Among those, there are two sex-determining chromosomes, and 22 pairs of autosomal, or non-sex, chromosomes. The total number of chromosomes in diploid cells is described as 2n, which is twice the number of chromosomes in a haploid cell (n).
What is an individual with the correct number 2n of chromosomes called?
Diploid. A cell with two sets of chromosomes is diploid, referred to as 2n, where n is the number of sets of chromosomes. Most of the cells in a human body are diploid. A cell with one set of chromosomes, such as a gamete, is haploid, referred to as n. Sex cells are haploid.
What is the correct order of Drosophila development?
What does 2n 6 mean in mitosis?
Hence, an organism with cells 2n=6 would be an organism that is diploid and has 6 chromosomes total. In other words, this organism has 3 pairs of chromosomes. Meiosis is a reduction division in that it produces daughter cells with half the genetic material of the starting cell.
What does 2n 4 mean?
In this example, a diploid body cell contains 2n = 4 chromosomes, 2 from mom and two from dad.
What is the second stage of a fly’s life cycle?
The second stage of the fly life cycle is the larva, also known and referred to as the maggot. Fly larvae are worm-like in shape and pale in colour. They stay close to their source of food and feed best when on animal corpses, manure and garbage. Maggots eat in order to grow and begin their moulting process.
How many polytene chromosomes are found in Drosophila melanogaster?
Bridges , we take this as the final number of bands in Drosophila melanogaster polytene chromosomes. Taking into account that doublets are formed by black bands, the approximate number of black bands is 1200, the number of grey bands is about 3500-1200=2400.
What does 2n 23 mean?
Somatic human cells contain 23 paired chromosomes or 46 total chromosomes. Forty-six is considered the “diploid” number (2n), while 23 is considered the “haploid” number (1n) or half the diploid number. “ Aneuploidy” refers to the presence of an abnormal number of chromosomes.
What the meaning of 2n 46?
For example, humans are diploid (2n) and have 46 chromosomes in their normal body cells. These 46 chromosomes are organized into 23 pairs: 22 pairs of autosomes and 1 pair of sex chromosomes. The sex cells of a human are haploid (n), containing only one homologous chromosome from each pair.
What does 2n 46 mean?
chromosomal diploid number
The chromosomal diploid number in humans is 46 (i.e. 2n=46 chromosomes or 23 pairs of chromosomes). All the body cells like, blood cells, skin cells, muscle cells are diploid. Only sex cells or gametes are not diploid; sex cells are haploid.
What does 2n stand for?
2n refers to having two sets of chromosomes or diploid organisms. E.g. humans are diploid with 2n = 46. Gametes are haploid and contain n = 23 chromosomes each.
What is the correct order of gene expression in the early Drosophila embryo?
The correct option is (a) maternal-effect genes, gap genes, pair-rule genes, segment-polarity genes. Maternal-effect genes: The polarity of the egg and the embryo is determined by maternal impact genes. Differentially distributed mRNA molecules polarise the developing egg (oocyte).
What does 2n 4c mean?
2n 2c means two homolog (diploid) unreplicated chromosomes (two chromatids). 1n 1c one single chromosome (haploid) that is unreplicated. 2n 4c Two homolog chromosomes (diploid) consisting each of two sister chromatids (two yellow and two blue), thus 4c in total.
What is 2n and 4N?
The DNA content of a cell in the G1 phase is 2N (N is the number of chromosomes), also known as diploid, whereas the DNA content of a cell in the G2 phase is 4N (tetraploid). The DNA content of a cell in the S phase varies between 2N and 4N, depending on the stage of replication of the cell.