homologous pairs and sister chromatids?
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So in short, sister chromatid are duplicates of the homologous pairs. I hope this helped If so 333 (I) would like the 10 points. :)\n\nThe normal chromosome number in human cells is 46. This number is called a diploid or a 2n number of chromosomes. The chromosomes consist of 23 pairs. Each pair of chromosomes is called a homologous pair. One chromosome of each homologous pair is from the male parent, and the other is from the female parent. The chromosomes of each homologous pair look alike, and they contain genes for the same traits. \n\nSister chromatids are two identical copies of a single chromosome that are connected by a centromere. \n\nFirst, consider mitosis (typical cell division) in a normal diploid cell, with two copies of each chromosome. The chromosomes are duplicated during DNA replication, and the duplicates, called sister chromatids, remain attached to one another until chromosome segregation. Each daughter cell then receives one of the sisters from each homologue pair. Importantly, this means that the daughter cells are exact copies of the mother cell, with two copies of each chromosome, so they can go through the same process again. Thus, we call this process the cell cycle.
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none\n\n\nyou start with one pair of homologous chromosomes in prophase I of meiosis I.  at metaphase I, these homologues line up across the metaphase plate, and at anaphase, they seperate so that one homologue goes to one pole, and the other homologue goes to the other pole.  after cytokinesis at the end of telophase I, you have one homologue in each cell...that homologue then goes through meiosis II, and at metaphase II, that homologue lines up at the metaphase plate with each sister chromatid facing each pole, and the chromosome is "pulled apart".  Anaphase II pulls the sister chromatids to each pole, and cytokinesis splits the one cell into two....two cells, each containing one sister chromatid of a homologous pair. (although in some text books this is refered to as a single homologue)
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A homozygote's cells are diploid or polyploid and have the same alleles at a locus (position) on homologous chromosomes. When an organism is referred to as being homozygous for a specific gene, it means that it carries two identical copies of that gene for a given trait on the two corresponding chromosomes (e.g., the genotype is AA or aa). Such a cell or such an organism is called a homozygote.\n\nA homozygous dominant genotype occurs when a particular locus has two copies of the dominant allele (e.g., AA). A homozygous recessive genotype occurs when a particular locus has two copies of the recessive allele (e.g., aa). This can occur when both parents carry at least one copy of the allele.\n\nPut simply: Homozygous is just having two of the same alleles.
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This is an example of a chimera. We all carry two copies for each gene, one from each parent. Rarely, one copy of one gene can get inactivated in a cell, or in a group of cells.\n\nPeople with two different coloured eyes carry two different eye colour genes, let's say brown and blue. Normally, the dominant gene would be the one you'd see, i.e. brown. If, however, during development the brown gene gets turned off or mutated in a cell that ends up giving rise to the area of the body that makes one eye, then that eye will be blue, and the other brown.\n\nNote that the same thing can happen within one eye - it means that the mutation happened later, so it was in a cell making only part of the iris, rather than the whole iris. There's a summary and theory discussion at the link below.
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2 recessive alleles - Homozygotes
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Base-pairing with the complementary strand of DNA.
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They are genetically related. But not the same.They are in different spaces.
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I worked with a lesbian who has an identical twin. The twin has NO interest in women. The lesbian has NEVER been with a man. She swears that its a choice, not genetics. Makes sense to me.
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Chromosome Terms before and after DNA Duplication (Replication)\nNote: Duplication and replication mean exactly the same thing.\n• An unduplicated chromosome is one chromosome. A chromosome more or\nless consists of two arms that extend from a narrow "centralized" region called\nthe centromere. The centromere region is often visible when chromosomes\nduplicate.\n• When a chromosome duplicates, it becomes one duplicated chromosome,\nand the two copies remain attached to each other. Note it is still one\nchromosome.\n• The two exact copies of the duplicated chromosome, which remain attached by\nthe protein cohesin, are called "sister" chromatids. They are identical to\neach other. It is essential that you remember this!\n• At the centromere region of the duplicated chromosome, structures (made of\nprotein and DNA) called kinetochores form during division. The three-layered\nkinetochores attach to microtubules of the spindle during mitosis. The\nkinetochores of the two sister chromatids face in opposite directions.\nKinetochore – TEM\n• After the identical sister chromatids are separated during mitosis, each (called\na "daughter" chromosome now) becomes a single unduplicated chromosome\nagain.\nRemember: A chromatid must be attached to its identical chromatid and the two sister\nchromatids comprise one duplicated chromosome. "Sister" chromatids are not two\nchromosomes. They are one duplicated chromosome that consists of two identical\nchromatids. Once sister chromatids are separated they are no longer chromatids!
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the ploidy no is 2n\nbut the dna amount is double. it changes in the metaphase or late prophase
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If you are talking about Somatic division (mitosis) , just before division the mother cell will  have 23x2 chromosome pairs that is 23x2x4 chromatids in all. The daughter cells get 23x2x2 chromatids=23 pairs of chromosomes each. In case of meiosis, one more division leads to 23 singlet chromosomes (=23x2 chromatids) each in a daughter cell.
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They're found in pairs in normal cells and singles in gametes.
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dna and genetic coding of chromosomes.
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no each ovul has different combinations of genes.  When meiosis occurs each chromosome seperates independantly of the other chromosome so there can be a mix there, also there is occassional crossover where a chromosome will switch some of it's homologous (same) info with it's sister chromosome, since the genes on each sister chromosome may be different variations of each other, recombination can occur here as well
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During metaphase in mitosis the chromosomes are aligned at the metaphase plate so that sister chromatids can separate during anaphase. missing this important step will lead to unequal distribution of chromatids between daughter cells which could be fetal to these cells or make them abnormal in terms of chromosome number.
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normal cell has 23 pairs of chromosomes (46 chromatids)\nbefore mitotic division the number doubles to 46 pairs (92 chromatids) the chromosomes are arranged as sister chromatids joined by the centromere and aligned with their copies (this is where recombination events can take place). the pairs are then pulled apart and separated in to the two new cells (each with 23 pairs). \n\nNote: for meiotic division (production of gametes (sperm and egg)) 23 pairs of chromosomes are divided in to 2 lots of 23 single chromosomes.
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no, because it is a defect on human chromosome 21, where 3 copies are made instead of 2. this has never been seen to occur in the genomes of other organisms.