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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
(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
chromosome pairs of the same length centromere position, and staining pattern that possess genes for the same traits at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother.
Covered in BIOL1020 Lab 7 Genetics ...

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)
Homozygote an individual with a pair of two of the same allele
(homo = same‚ like‚ alike; zygo = yoke) ...

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 contain the same array of genes but may contain different alleles at those loci.

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

~ are all different where as sister chromatids are identical.

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

~ - pairs of chromosomes which exist in any diploid cell that have the same genes (but possibly different versions or alleles)
interphase - the portion of the cell cycle when the cell is not going through mitosis or meiosis ...

~ 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
Compare Prophase I to Prophase II and to the Prophase stage of mitosis.

~ 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.

~ 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.
Humus a black gum-like substance, derived from decayed plant and animal remains.

The ~ must pair up gene for gene. Each homolog has already duplicated and is composed of two chromatids. The chromatids crossover, break and rejoin. At least one crossing over event per chromosome arm is obligatory for successful meiosis.

Prophase - ~ 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 ~ 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, ~ line up. The DNA of the chromosome is broken on both chromosomes in several places and rejoined with the other strand. Later, the two ~ are split into two separate cells that divide and become gametes.

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

11. What are ~? Which are the human cells that do not have ~?

~ -- 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.

~ 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. homozygous Both alleles for a trait are the same in an individual.

During meiosis, ~ 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 ~ /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), also called ~; ...

The behavior of ~ during meiosis can account for the segregation of the alleles at each genetic locus to different gametes.
The behavior of non~ can account for the independent assortment of alleles for two or more genes located on different chromosomes.

During meiosis, ~ 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 ~ exchange parts normally reciprocally but sometimes unequally. The exchange of corresponding chromosome parts between homologues by breakage and reunion of DNA molecules normally during prophase I of meiosis but also occasionally during mitosis.

During Metaphase I, ~ will line up. A karyotype can be made by cutting and arranging photomicrographs of the ~ 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 ~ in a diploid organism. (See DNA polymorphism.) Alternative mRNA splicing. The inclusion or exclusion of different exons to form different mRNA transcripts. (See RNA.) Amino acid.

AlleleAn alternative form of a gene that occurs at the same locus on ~, 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. AneuploidyHaving an abnormal number of chromosomes, i.

Synapses[in nervous system] [immunological] SynapsisUnion, side-by-side, of ~ 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 ~. (ORNL)
See: heterozygosity (ORNL)
Highly conserved sequence
DNA sequence that is very similar across several different types of organisms.
See also: gene, mutation (ORNL) ...

Now what's their crossing over stuff well let's put them back you recall meiosis during prophase I, the ~ come together and then randomly they get broken by enzymes and then other enzymes specifically the enzyme used in your cells is an enzyme called ligase in this case I call ...

Heterozygosity The presence of different alleles at one or more loci on ~.
Homeobox A short stretch of nucleotides whose base sequence is virtually identical in all the genes that contain it. It has been found in many organisms from fruit flies to human beings.

Translocation refers to the type of rearrangement of parts moved to non-~. For inversion errors, the error probability (Pinv) was defined as number of markers involved in inversion divided by total number of markers for each chromosome. (Pinv) of 0.

During the prophase of meiosis I, ~ 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 ~ reduces the likelihood of another in its vicinity.

In this picture the two "hot dog" shapes represent a pair of ~. ~ are the same size & have the same genetic info (genes). Each letter in the diagram stands for an allele (form of a gene).

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

Synapsis - The process of physical association of ~ during prophase I of meiosis.
Telophase - The last stage of mitosis, and of meiosis I and II, when, having reached the poles, chromosomes become decondensed, and a nuclear envelope forms around each group.

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

Diploid. A cell or organism with two complete sets of ~.
Dominant. Nature of inheritance of a phenotype, not a gene. A dominant phenotype is detectable when only one variant allele can be detected. If both alleles are detected, then co-dominant.

Label two chromatids with each letter. This way they can line up the pairs of ~ during metaphase I and demonstrate all of the phases of meiosis. This leads right into a lesson on dihybrid crosses and probability.
Contributed by Shannon Tice
Questions? Comments??
Shannon Tice ...

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

Referring to an organism or cell having two full sets of ~ 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.

The site where two homologous DNA strands originating from ~ are resealed to form the recombinant chromosome. The reciprocal exchange of genetic material to produce genetic recombinants. Sometimes abbreviated as X-over.
Cross reacting material
See CRM.

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

Having the same allele (gene form) present at a given locus on both ~.
View Dr Chromo's school on 'The basic vocabulary of genetics'.
Related Links ...

NHGRI Narrower terms: autosome, centromere, chromatin, euchromatin, heterochromatin, ~, telomere Related terms chromosome maps, cytogenetics, diploid, euchromatic, haploid, karyotype, ploidies, ploidy, somatic cell hybridization ...

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

See also: See also: What is the meaning of Homologous, Chromosomes, Chromosome, Homologous chromosome, DNA?

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