Root Words for Poly- in Biology

May 23, 2023, 16:45 IST

Our NEET syllabus contains many definitions and processes. One of the most important terms is that which starts with poly, which could be a polypeptide, polyploidy, polydactyly etc.

These terms are very important to exclude wrong options in multiple choices (MCQs) or to understand the concept, be it translation, transcription, disorders etc.

The present article aims to bring all the terms and processes that start with the word poly. Studying these terms will refresh your syllabus in just a few minutes. For ease of your understanding, the terms have been classified- genetics, disorders, immunity, sexual reproduction, fish farming and abnormal fertilisation.

Use in Genetics

• Polypeptide: A polypeptide is a long chain of amino acids. This sequence is specific for a particular protein and is governed by the codon sequence of the gene or cistron that controls its formation. For example- corticoliberin is a polypeptide hormone and neurotransmitter involved in response to stress.
• Polyploidy: Polyploidy is the condition in which more than one pair of homologous chromosomes are present in a cell. It can be induced artificially by colchicine (alkaloid). Polyploidy is of three types:

1. Autopolyploidy is the increase in the number of the same genome, e.g. AAA.
2. Allopolyploidy: The increase in the number of chromosome sets due to the coming together of the genome of two or more species, e.g. AABB.
3. Autoallopolyploidy: The increase in the chromosome set due to the coming together of different genomes and the occurrence of one genome in more than the diploid state, e.g. AAAABB.

• Polymorphism: Poly means many and morph means types. This refers to two or more distinct forms of individuals in the same popula­tionor species. For example- the presence of four different types of blood groups (A, B, AB and O) in the human population.
• Polytypic species: Species that contain two or more subspecies are called polytypic species. For example, the African elephant species has two subspecies- the African forest elephant and the African savanna elephant. Both subspecies vary in size and habitat.
• Polygenic inheritance: Quantitative or polygenic inheritance is a type of inheritance in which more than one pair of genes controls a single phenotypic trait. Such genes are called polygenic genes. For example-skin colour in men is controlled by three separate pairs of genes-Aa, Bb, and Cc.
• Polyhybrid cross: It is a type of cross in which there is the involvement of more than two allelic pairs. For example- the cross of leaf shape and stem colour inheritance pattern.
• Polymerase: An enzyme that helps form long chains of nucleic acids. For example-DNA polymerase helps in the formation of DNA molecules whereas RNA in RNA molecules.
• Polycentric chromosomes: Chromosomes with more than two centromeres are called polycentric chromosomes. For example- in Ascaris, the centromere lies in the diffused condition along the length of the chromosome.
• Polytene chromosome: A polytene chromosome is a giant chromosome in which many chromatids are arranged in parallel. They were first observed byBalbiani (1881) in the salivary gland of Chironomus tantans. They are common in insects' salivary glands and are called salivary chromosomes.
• Polynucleotide: A biopolymer comprising multiple nucleotide monomers in a chain. For example-DNA helix is made up of two long polynucleotides.
• Polyribosomes: Polyribosomes or polysomes are groups of ribosomes on an mRNA strand. It helps synthesise multiple copies of a protein from the same message. They occur free in the cytoplasm and are attached to the rough endoplasmic reticulum membranes.

Also, read - Genes

Use in Disorders and Symptoms

• Polydactyly: Polydactyly is a disorder in which a child is born with more than five digits in their fingers. It is a disease caused due to dominant defective autosomal genes.
• Polyuria: It is a disorder in which excess urine is passed due to an increase in the water content of urine as in diabetes insipidus.
• Polycythemia is a condition in which bone marrow makes excessive red blood cells. Their excessive production makes the blood thick, reduces its flow and can make clots. It results in blood cancer.
• Polyphagia: Polyphagia is when an individual suffers from extreme hunger due to an underlying illness or medical condition such as hypoglycemia. However, hunger does not go away even after eating.
• Polydipsia is a symptom of diabetes in which a person feels extremely thirsty.

Also, read - Animal Kingdom

Use in Fish Farming

Polyculture: It is a type of culture fishery in which two or more types of fish are grown in the same water body. For example- growing a mixture of Chinese carp, grass carp and bighead carp. It is also sometimes called composite culture.

Use in Sexual Reproduction in Plants (Microsporogenesis)

• Polyspory: “Poly” means “many” and “spory” means “spores”. It is the condition of occurrence of more than 4 spores in a pollen tetrad, e.g. Cuscuta reflexa.
• Polyembryony: “Poly” means “many” and “embryony” means “embryo”. Polyembryony refers to the formation of more than one embryo inside a single seed. For example- the Pinus ovule has 2­8 archegonia. It was first discovered by Leeuwenhoek (1719) and later confirmed by Schnarf (1929).

Use in Abnormal Fertilisation

• Polyspermy: “Poly” means “many” and “spermy” means “sperms”. Polyspermy is abnormal fertilisation in which more than two male gametes fuse with the ovum during fertilisation.
• Polygyny is abnormal fertilisation in which two female pronuclei unite with a male pronucleus. For example-bats. In this one, males mate with several females.
• Polyandry is abnormal fertilisation in which two or more male pronuclei unite with a female pronucleus. In this one, females mate with several males. It is opposite to that of polygyny in which one male mate with several females.

Use in Immunity

• Polyclonal antibodies are mixtures of antibodies that recognise and bind to many different epitopes of a single antigen.
• Polymorphonuclear cells (PMC) consist of a multilobed nucleus. They include neutrophils,basophils and eosinophils. They destroy the microbes by phagocytosis.

Frequently Asked Questions FAQ’s

Q1. What is the function of DNA polymerase enzymes?

Ans. The DNA polymerase enzyme adds the nucleotide complementary to the DNA template in a 5’ – 3’ direction in the presence of ATP.

Q2. What is transcription?

Ans. Transcription refers to the copying of DNA to mRNA.

Q3. What is the function of RNA polymerase?

Ans. There are three types of RNA polymerase (I, II and III). RNA polymerase I form rRNA, RNA polymerase II synthesises hnRNA and RNA polymerase III synthesises tRNA.

Q4. What is translation?

Ans. Translation refers to the formation of protein from RNA.

Q5. What is microsporogenesis?

Ans. Microsporogenesis refers to the formation of microspores or pollen.