Main distinction – Homologous Chromosomes vs sister Chromatids

Most organisms have actually DNA together their genetic material. Diploid organisms such as people bear two duplicates of comparable chromosomes. This are recognized as homologous chromosomes. Throughout metaphase i of meiosis I, homologous chromosomes appear in pairs. Sister chromatids space the two exact duplicates which are formed by the replication of one DNA molecule in ~ the S step of the interphase. The key distinction between homologous chromosomes and also sister chromatids is that homologous chromosomes may not carry identical information all the time whereas sister chromatids lug identical details all the time.

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Key locations Covered

1. What are Homologous Chromosomes – Definition, Characteristics 2. What room Sister Chromatids – Definition, Characteristics 3. What is the Difference between Homologous Chromosomes and Sister Chromatids – comparison of crucial Differences


What are Homologous Chromosomes

Homologous chromosomes room the chromosomes pairing in metaphase i of meiosis. One chromosome in the pair bears maternal origin while the other chromosome bear the paternal origin. One chromosome that the homologous pair is referred to as a homologue. Chromosome length and also their location of the centromeres room the very same within the pair. Every copy includes an appropriate number of same genes, i ordered it in the exact same order (same loci). Hence, banding sample of each chromosome in the pair appears the same. However, the very same locus may contain either the very same allele or a various allele top top both chromosomes. Thus, one individual may be homozygous or heterozygous for a details character. Humans have 22 homologous pairs of autosomes and 2 sex chromosomes . Mrs sex chromosomes, X and X room homologous while masculine sex chromosomes, X and Y space not truly homologous. X and also Y different from their size and genetic composition. The pairing the homologous chromosomes enables random distinction of hereditary material. Homologous chromosomes exchange their DNA through recombination. Recombination at sex-related reproduction leader to hereditary variations in the offspring which consequently facilitates the evolution. Homologous chromosomes separate throughout anaphase i of meiosis I. 4 haploid daughter cells are produced at the end of the meiosis. Chromosomal abnormalities such as trisomy and monosomy have the right to occur because of the nondisjunction the homologous chromosomes.


Figure 1: Homologous Chromosomes

What are Sister Chromatids

Sister chromatids room two identical chromatids bring about DNA replication throughout the S phase of interphase. They space joined together by the centromere. A sisters chromatid is a one-half of a replicated chromosome. Hence, every replicated chromosome is composed of two sister chromatids. Sisters chromatids are similar to each other; one of them is the specific replica that the other. The exception is crossing over at prophase i of meiosis I. Chromosomal crossover exchanges hereditary material end homologous chromosomes. Sister chromatids separate from every other during anaphase of mitosis and also the anaphase II the meiosis II.


Figure 2: sister Chromatids

Difference in between Homologous Chromosomes and Sister Chromatids


Homologous Chromosomes: Homologous chromosomes are made up of both maternal and also paternal chromosomes.

Sister Chromatids: sisters chromatids are comprised of either a maternal or paternal chromosome.

Genetic Composition

Homologous Chromosomes: Homologous chromosomes might contain very same or different alleles that the exact same gene. Thus, the gene sequence is not identical at every the times.

Sister Chromatids: sister chromatids contain the same gene succession throughout the chromatids other than in the chromosomal crossover.


Homologous Chromosomes: Homologous chromosomes show up in the metaphase i of meiosis I.

Sister Chromatids: sister chromatids are formed during the DNA replication in the S step of interphase.


Homologous Chromosomes: Homologous chromosomes execute not rod together. They exist in pairs.

Sister Chromatids: sister chromatids room joined together by your centromere.

Number that DNA Strands

Homologous Chromosomes: Homologous chromosomes space composed of 4 DNA strands.

Sister Chromatids: solitary sister chromatid is composed of a single DNA strand.


Homologous Chromosomes: Homologous chromosomes room segregated throughout the anaphase i of meiosis I.

Sister Chromatids: sister chromatids room separated from your centromere throughout anaphase II the meiosis II and the anaphase that mitosis.


Homologous Chromosomes: Homologous chromosomes allow random distinction of chromosomes and genetic recombination throughout metaphase I.

Sister Chromatids: sisters chromatids permit random segregation of chromatids and chromosomal crossover during metaphase II the meiosis and also metaphase that mitosis.

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Homologous chromosomes room composed the both maternal and also paternal chromosomes. Therefore, various alleles that the very same gene have the right to be uncovered most of the times. Top top the various other hand, sisters chromatids are composed of exact same allele the a gene in both strands due to the fact that they space synthesized by the DNA replication of a strand. Thus, the an essential difference between homologous chromosomes and sister chromatids is in their genetic composition.

Reference: 1. “Homologous Chromosomes”. Pearson – The biologic Place. Accessed 12 Feb. 2017 2. “Homologous chromosome”. Wikipedia, the totally free encyclopedia. 2017, Accessed 12 Feb. 2017 3. Mccarthy E. M. “Sister chromatids”. Virtual Biology Dictionary. Accessed 17 Feb. 2017

Image Courtesy: 1. “PloSBiol3.5.Fig7ChromosomesAluFish.”. Through Bolzer et al., (2005) Three-Dimentional Maps that all human being Male Fibroblast Nuclei and Prometaphase Rossttes. PloS Biol 3(5): e157 DOI: 10.1371/journal.pbio.0030157, figure 7a (CC-BY-2.5) via Commons Wikimedia 2. “HR in meiosis”. By Emw – Own work-related (CC-BY-SA-3.0) via Commons Wikimedia