Anas Zoology

Fossil of  Alethopteris serlii Alethopteris serlii: Alethopteris   serlii  is a extinct seed producing plant. It is an extinct plant of gymnosperms. It belongs to the Carboniferous period (around 360 to 300 million years ago). They went extinct during the Cretaceous period. Alethopteris had compound pinnate fronds, consisting of thick, strongly veined leaflets. References: Image source ( Fossil of  Alethopteris serlii) :  https://www.kgg.org.uk/alethopterish.html

  (Image Source:  https://pmgbiology.files.wordpress.com/2015/10/chromosomes.jpg?w=300 ) Chromosomes are found inside the nucleus of the cell. The number of chromosomes differ from organism to organism. Humans have 23 pairs i.e. 46 chromosomes. Out of these 23 pairs, 22 pairs are autosomes and 1 pair is of sex chromosomes. Human female have XX as the sex chromosome and human male have XY as the sex chromosome. One set (23 chromosome) is inherited from the maternal (female parent) and another set from the paternal (male parent). Since two sets are present inside the cell, the cell is called as diploid (di=two, ploid=set). All somatic cells of the body are diploid. Gametes (sperm and ovum) contains only one set of chromosomes and hence are called haploid. The number of chromosomes in each somatic cell is the same for all members of a given species.  Chromosome Morphology: (Image Source:  https://microbiologynotes.org/wp-content/uploads/2020/07/types-of-Telomere.jpg ) C...

  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER) is a system of sac like structures and tubes found in all eukaryotic cells. They are known as sarcoplasmic reticulum in skeletal muscles, Nissl granules in neurons and myeloid bodies in retinal pigment cells. They are absent in RBCs, eggs and embryonic cells. Endoplasmic Reticulum arise by evagination of nuclear membrane. Endoplasmic Reticulum have three parts: Cisternae: It is a sac like, parallel tubules having ribosomes on their surface. It is unbranched. Tubules: It is tube like, irregular, branched and without ribosome. Vesicles: They are round or spherical, without ribosomes Parts of Endoplasmic Reticulum . There are two types of endoplasmic reticulum  Rough Endoplasmic Reticulum (RER): They have ribosomes on their surface. The 60S unit of ribosomes are attached to the ER by means of a protein ribophorin I and ribophorin II. Number of cisternae and tubules are more. They are abundant near the nuclear membrane. ...

An amino acid contains an amino group (-NH2) as well as a carboxyl group (-COOH). The carboxyl group is acidic (proton donor) and amino group is basic (proton acceptor). Therefore amino acids are amphoteric in nature. (Amphoteric compounds are those compounds which can act both as an acid or a base).  At low pH the carboxyl group accepts a proton and becomes uncharged so the overall charge on the molecule is positive.  At high pH the amino group loses its proton and becomes uncharged so the overall charge on molecule is negative. The pH at which the molecule carries no electrical charge is called the isoelectric point. At this point the amino acids exist as a dipolar ion or Zwitterion. A Zwitterion is a molecule with no electrical charge because it contains equal number of both positively and negatively charged ions.                         Low pH                  ...

Amino acids are compounds containing carbon, hydrogen, oxygen and nitrogen. They serve as monomers of proteins. Amino acids contains an amino group, a carboxyl group, a hydrogen atom and a distinctive side chain, all these are bonded to the same carbon atom, this carbon atom is called as ∝-carbon. The amino acids differ with respect to the side chain attached to their ∝-carbon. General structure of Amino Acid This general structure is common to all amino acids except for one i.e. proline. The side chain attached to the ∝-carbon atom is different for each amino acid. In ∝-amino acids the amino group and the carboxyl group are attached to the same carbon atom. Amino acids can be classified as β Ɣ δ or ε based on the location of carbon atom to which the amino group is attached.

 It is the most accepted model of Plasma Membrane/Cell Membrane. It was proposed by Singer and Nicolson in the year 1972. Phospholipids form bilayer in the centre. their unsaturated fatty acids forms the tail and glycerol forms the head, which prevents the close packing of the molecules. Phospholipids show two types of movements: Transition and Flip-Flop movement. Transition: Molecules change their position in the same layer. Flip-Flop: Molecules interchange between two layers. There are two types of proteins in cell membrane/plasma membrane Extrinsic/Peripheral proteins - Form 30% of the total membrane protein, superficial, easily removed, some are covered by glycolipids/glycoproteins. They provide structural and functional specificity to the membrane. eg. ATPase, spectrin, acetycholinesterase etc. Intrinsic/Integral Proteins - Form 70% of the total membrane proteins, embedded in lipid bilayer, can be extracted by rupturing membrane, held in position by polar and nonpolar side of ...

A) Danielli - Davson Model / Sandwich Model / P-L-P Model: This model of plasma membrane was proposed by Danielli and Davson in the year 1935. According to this the plasma membrane is trilaminar, where lipids bilayer is sandwitched between the two protein layers. Hence it is also called as P-L-P model (P=protein, L=lipid). This model fails to explain functional specificity and active transport through membranes. B) Unit Membrane Model / Robertson Model: This model of plasma membrane was proposed by Robertson in the year 1959. According to Robertson, all membranes have the same basic structure but they have their own distinctive composition. Example: Internal organelles have more proteins than lipids in eukaryotic cells whereas plants and bacteria have more lipids than proteins. This model fails to explain the membranes stability and permeability. Related Articles: 1) Biomembranes https://anaszoology.blogspot.com/2022/08/biomembranes.html

Biomembrane/Biological Membrane is a semipermeable covering around the cell and organelles, which separated them from the external environment. Biomembrane which covers the cell is called a cell membrane/Plasmalemma, biomembrane which covers the organelle is called subcellular membrane. Composition of Biomembrane Biomembranes are tripartite or trilaminar i.e. made up of three layers Proteins : 59-75% fibrous or globular proteins Lipids : 20-40 % Phospholipid, sterol, glycolipid, sphingolipid Carbohydrates : 1-5% Hexose, hexamine, sialic acid Functions of Biomembranes: Helps to transport the solutes across the membrane. Biomembrane only allow certain types of molecules to enter the cell and organelle, they keep the toxins from entering into the cell. The receptors present on biomembranes helps the cells to communicate.

  An important tool of molecular biology is DNA fingerprinting. It is a way to distinguish individuals as it is unique for every living being (except clones) and cannot be altered by any process. Applications of DNA Fingerprinting: Paternity Test - The DNA fingerprint of child is matched with the prints of parents to determine family relationships. In parental disputes this technique is used to determine the true parents of the child. Criminal identification - DNA fingerprint from blood/hair/semen of suspect is picked up from the scene of crime, prepared and compared with the sample collected from scene. Many cases have been solved by this technique. Study Evolution - It is helpful in finding out genetic relationship between different races of man. Related Articles: DNA Fingerprinting:  https://anaszoology.blogspot.com/2022/08/dna-fingerprinting.html

An important tool of molecular biology is DNA fingerprinting. It is a way to distinguish individuals as it is unique for every living being (except clones) and cannot be altered by any process. All segments of DNA do not code for protein. Some segments have regulatory function, others are Introns (Interviewing sequence/IVS) still others are repetitive DNA sequences/Mini satellite sequences . The most important segment for DNA fingerprinting are short repetitive nucleotide sequences which vary from person to person. These are also called Variable number tendem repeats (VNTR). To prepare a DNA fingerprint a small amount of saliva/blood/hair/semen or any other cell of the body is required. Steps of DNA fingerprinting are as follows: Extract the DNA from the sample. If DNA is not sufficient, amplify it using PCR i.e. make more copies of DNA using PCR. Cut DNA with restriction endonucleases. The cut segments possess DNA of different length in different individuals called restriction length ...

 The organisms whose cells contain a membrane bound nucleus and membrane bound organelles are called a eukaryotes. Structure of Eukaryotic Cell Characteristics of Eukaryotic Cell: Cell size and volume depend on the activities performed by it (5 - 100 μm). Cellulosic cell wall is present only in plant cells. Capsule is absent. Mesosome is absent. Well organized nucleus is present. Mononucleate condition is more common. DNA is linear and is covered by histonic protein (except in mitochondria and plastid). Monocistronic DNA is more common. Three kinds of RNA polymerase are present. One for each - rRNA, mRNA, tRNA. Transcription occurs in the nucleus and translation in the cytoplasm. Extranuclear chromosome are absent. Ribosome is 80S (60S + 40S). Protein synthesis is inhibited by cyclohexamide. All organelles are present. Cilia and flagella show characteristic 9+2 arrangement of microtubule and are made up of protein tubulin. Microfilaments are present. True sap vacuoles are common in...

A prokaryote is a single celled organism that lacks a true nucleus and other membrane bound organelles. Structure of Prokaryotic Cell Characteristics of Prokaryotic Cells:  Cell is small in size (0.1 - 5 micrometers). Cell wall is made up of muramic acid (amino acid derivative of peptidoglycan). In many cells mucopolysaccharide capsule is present. Mesosomes controls cellular respiration and cell division. An organised nucleus is absent. DNA is circular and naked. Usually polycistronic DNA is present. Only one kind of RNA polymerase is present. Transcription and translation both occurs in the cytoplasm. Extracellular chromosomes are present in the form of plasmid or episome. Ribosome id 70S (50S + 30S) Cytoplasm lack cell organelles. If flagella is present, it is made up of single stranded protein called flagellin. Microfilaments - Actin and myosin are absent. Sap vacuoles are absent instead they have gas vacuoles. Endocytosis and exocytosis are absent. They divide by amitosis or si...

  What is Allelopathy ? Allelopathy is a biological phenomenon in which an organism releases chemicals which have positive or negative effects on other organism. The biochemicals produced by these organisms are known as allelochemicals. Examples: The River Tamarind contains toxic amino acid that inhibits other plants growth but not its own species growth. The leaf litter of some Eucalyptus species is allelopathic to certain microbes and plant species. The algae Chlorella vulgaris produces a toxin called chlorellin which is toxic to other algal species and bacteria.

  What is Amensalism ? Amensalism is association between two species, in which one species is harmed and other species is unaffected.  Examples: The mould penicillium creates a substance known a penicillin, this is extremely toxic to bacteria. The mould is unaffected but the bacteria dies. The black walnut secretes a chemical from its roots known as juglone, this harms the neighbouring plants, the black walnut is unaffected.

Mineral : Mineral is any substance which is required by plants for physiological functioning and it is mostly taken from the soil. What are Essential Elements ? Any element that is important for a physiological role in plant and the absence of this element prevents the plant from completing its life cycle is an essential element. According to Arnon and Stout three criteria must be met for an element to be considered essential, these are: A plant must be unable to complete its life cycle in the absence of the essential element. The function of the essential element cannot be replaced by another element i.e. deficiency of any one element cannot be met by supplying other element. The essential element must be directly involved in plant metabolism. Essential elements are divided into two categories : Macroelements and Microelements Macroelements: The mineral/element is required in large quantity, conc > 1ppm. Also known as major elements. Macroelements consists of Phosphorous (P), Potas...