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Homologous chromosomes

Biology  Homologous chromosome  Homologous recombination

homologous chromosomes
a pair of chromosomes, one from each parent, that have relatively similar structures and gene values
Source: Noland, George B. 1983. General Biology, 11th Edition. St. Louis, MO. C. V. Mosby ...


Homologous Chromosomes
Homologous chromosomes are two chromosomes that are the same. This happens because diploid organisms have two of each chromosome. Each of the pairs is a homologous pair.

Homologous chromosomes move toward opposite poles during Anaphase I. In Anaphase II sister chromosomes separate.
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homologous chromosomes
(home-ol-uh-gus) [Gk. homologia, agreement]
Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.

Homologous chromosomes. Chromosomes that have the same linear arrangement of genes--a pair of matching chromosomes in a diploid organism. See Chromosomes.

homologous chromosomes: A pair of chromosomes containing the same linear gene sequences, each derived from one parent. DOE ...

Homologous Chromosomes the two matching chromosomes of a pair (one from the father and one from the mother)
(homo = same‚ like‚ alike; logos = a word) ...

Homologous chromosomes: Chromosomes that occur in pairs one having come from the male parent and the other from the female parent. They pair participate in crossing-over during meiosis.

Homologous chromosomes condense ( synapsis ) to form bivalents. The chromatids become coiled around each other.

Homologous chromosomes are all different where as sister chromatids are identical.

Homologous chromosomes: chromosomes with the same genes as each other, in the same sequence but do not necessarily have the same allele of those genes.

Homologous chromosomes will swap genetic material in a process known as crossing over (abbreviated as XO)
Crossing over serves to increase genetic diversity by creating four unique chromatids ...

homologous chromosomes Chromosomes that exist in pairs; each homologue possesses the same genes or loci, but the homologues may have different alleles at the same locus; one member of each pair comes from each parent.

Homologous chromosomes a pair of chromosomes having the same gene loci and which are capable of pairing during meiosis.
Homozygote a condition in which the allele of a particular gene are identical.

The homologous chromosomes must pair up gene for gene. Each homolog has already duplicated and is composed of two chromatids. The chromatids crossover, break and rejoin.

Prophase - Homologous chromosomes in the nucleus begin to pair up with one another and then split into chromatids (one half of a chromosome) where crossing over can occur. Crossing offer can increase genetic variation.

Any pair of homologous chromosomes may be expected to cross over three or four times during meiosis. This aids evolution by increasing independent assortment, and reducing the genetic linkage between genes on the same chromosome.

In meiosis, homologous chromosomes line up. The DNA of the chromosome is broken on both chromosomes in several places and rejoined with the other strand.

chromatid homologous chromosomes joined to each other at the centromere; present during the prophase of mitosis.
chromatin compacted DNA and protein.
chromosomes linear units of DNA.

Homologous chromosomes -- chromosomes that pair during meiosis; each homologue is a duplicate of one chromosome from each parent. Homozygote -- having identical alleles at one or more loci in homologous chromosome segments.

homologous chromosomes The pair of chromosomes in a diploid individual that have the same overall genetic content. One member of each homologous pair of chromosomes in inherited from each parent.

During meiosis, homologous chromosomes line up and exchange segments, a process called crossing over. Following this, homologs are separated from each other in the first meiotic division.

homologs /HŌM-É™-lawgs/ (also homologous chromosomes /hÉ™-MALL-É™-gÉ™s/) (1) chromosomes having the same loci, in the same order (a diploid cell has two copies of each homolog, one derived from each parent), ...

The behavior of homologous chromosomes during meiosis can account for the segregation of the alleles at each genetic locus to different gametes.

During meiosis, homologous chromosomes align with one another in a process known as synapsis. Each maternal chromosome aligns with its homologous paternal chromosome; this alignment is generally exact to the base pair.

A process in which homologous chromosomes exchange parts normally reciprocally but sometimes unequally.

During Metaphase I, homologous chromosomes will line up. A karyotype can be made by cutting and arranging photomicrographs of the homologous chromosomes thus revealed at Metaphase I. Two types of chromosome pairs occur.

Alternate forms of a gene or DNA sequence, which occur on either of two homologous chromosomes in a diploid organism. (See DNA polymorphism.) Alternative mRNA splicing. The inclusion or exclusion of different exons to form different mRNA transcripts.

AlleleAn alternative form of a gene that occurs at the same locus on homologous chromosomes, e.g., A, B, and O genes are alleles. AmorphA silent gene that does not produce a detectable product (antigen), e.g., O genes in the ABO BGS.

Synapses[in nervous system] [immunological] SynapsisUnion, side-by-side, of homologous chromosomes early in meiosis I. Synaptonemal complex (SC) SyncytiumMass of cytoplasm containing many nuclei. It is formed by the fusion of cells.

The presence of different alleles at one or more loci on homologous chromosomes. (ORNL)
Heterozygote
See: heterozygosity (ORNL)
Highly conserved sequence
DNA sequence that is very similar across several different types of organisms.

Now what's their crossing over stuff well let's put them back you recall meiosis during prophase I, the homologous chromosomes come together and then randomly they get broken by enzymes and then other enzymes specifically the enzyme used in your ...

Heterozygosity The presence of different alleles at one or more loci on homologous chromosomes.
Homeobox A short stretch of nucleotides whose base sequence is virtually identical in all the genes that contain it.

During the prophase of meiosis I, homologous chromosomes pair and form synapses. The paired chromosomes are called bivalents. The bivalent has two chromosomes and four chromatids, with one chromosome coming from each parent.
Related Terms:
Prophase ...

The term proposed by Muller (1916) for the interaction between cross-overs such that the occurrence of one exchange between homologous chromosomes reduces the likelihood of another in its vicinity.

Chromosomes that carry the same genes are termed homologous chromosomes. The alleles on homologous chromosomes may differ, as in the case of heterozygous individuals. Organisms (normally) receive one set of homologous chromosomes from each parent.

And it turns out that there are these things called chiasmata, which are actually where strands of the duplicated homologous chromosomes break and recombine with the same strand of the other homolog.

Crossing-over (recombination): The exchange of genetic material between non-sister chromatids of homologous chromosomes (i.e., between maternal and paternal chromosomes) during meiosis.

According to the modern synthesis, genetic variation in populations arises by chance through mutation (mistakes in DNA replication) and recombination (crossing over of homologous chromosomes during meiosis).

Referring to an organism or cell having two full sets of homologous chromosomes and hence two copies (alleles) of each gene or genetic locus. Somatic cells contain the diploid number of chromosomes (2n) characteristic of a species. See also haploid.

bivalent A pair of homologous chromosomes closely adjacent to each other formed during the first meiotic division within a primary spermatocyte or oocyte.

Synapsis
The pairing of homologous chromosomes or of homologous chromosomal regions.
Synteny
Genes which occur in the same order on the chromosome of different species.

Label two chromatids with each letter. This way they can line up the pairs of homologous chromosomes during metaphase I and demonstrate all of the phases of meiosis. This leads right into a lesson on dihybrid crosses and probability.

Translocation — A structural chromosomal abnormality whereby chromosome segments are swapped between non-homologous chromosomes.

See also: See also: Chromosomes, Homologous, Chromosome, Homologous chromosome, DNA

Biology  Homologous chromosome  Homologous recombination

 
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