Plant Physiogy:- Transporte In Plants.

TRANSPORT IN PLANTS

POINTS TO REMEMBER :

• Translocation : Transport of substances in plants over longer distances through the vascular tissue (Xylem and Phloem) is called translocation.


• Means of transport : The transport of material into and out of the cells is carried out by a number of methods. These are diffusion, facilitated diffusion and active transport.


• Diffusion : Diffusion occurs from region of higher concentration to region of lower concentration across the permeable membrane. It is passive and slow process. No energy expenditure takes place.


• Facilitated diffusion : The diffusion of hydrophilic substances along the concentration gradient through fixed membrane transport
  
  protein without involving energy expenditure is called facilitated diffusion. For this the membrane possesses aquarporins and ion channels. No energy is utilized in this process.

Methods of Facilitated Diffusion :

• Some carrier or transport proteins allow diffusion only if two types of molecules moves together.
  
• Symport: both molecules cross the membrane in the same direction.
• Antiport: both molecule moves in opposite direction.
• Uniport: one type of molecule moves across the cell membrane.

Active transport :

• Active transport is carried by the movable carrier proteins (pumps) of membrane.
• Active transport uses energy to pump molecules against a concentration gradient from a low concentration to high concentration (uphill-transport).
• It is faster than passive transport.

Water potential :

• Water molecule possesses kinetic energy.
• The greater the concentration of water in a system, the greater is its kinetic energy or water potential.
• Pure water has the highest water potential.
• Water always moves from higher water potential to lower water potential.
• Water potential is denoted by Ψw (Psi) and measured in Pascals (Pa). The water potential of a cell is affected by solute potential (Ψs) and pressure potential (Ψp).
• Ψ w  = Ψ s + Ψ p
• Water potential of pure water at standard temperature which is not under any pressure is taken to be zero (by convention).

Osmosis :

• Osmosis is movement of solvent or water molecules from the region of their higher diffusion pressure or free energy to the region of their lower diffusion pressure or free energy across a semi-permeable membrane.
• Water molecules move from higher water potential to lower water potential until equilibrium is reached. 

• Study this figure in which the two chambers, A and B, containingsolutions are separated by a semi-permeable membrane. 

• (a)Solution of  which chamber has a lower water potential 
  

• (b)Solution of  which chamber has a lower solute potential? 

• (c)In which direction will osmosis occur? 

• (d)Which solution has a higher solutepotential? 

• (e)At equilibrium which chamber willhave lower water potential? 

• (f)If one chamber has a Ψ Ψ Ψ Ψ Ψ of – 2000kPa, and the other – 1000 kPa, whichis the chamber that has the higherΨΨΨΨΨ? 

• (g)What will be the direction of themovement of water when twosolutions with  Ψw = 0.2 MPa andΨw = 0.1 MPa are separated by aselectively permeable membrane? 

Plasmolysis :

• Process of shrinkage of protoplasm in a cell due to exosmosis in hypertonic solution.
• Turgor pressure: a plant cell placed in hypotonic solution, water enters into it due endosmosis and the cytoplasm exert pressure against the cell wall called turgor pressure.
• Imbibition: Imbibition is the phenomenon of adsorption of water or
  
  any other liquid by the solid particles of a substance without forming a solution.

Some examples of Imbibition :

• If a dry piece of wood is placed in water, it swells and increases in its volume.
• If dry gum or pieces of agar-agar are placed in water, they swell and their volume increases.
• When seeds are placed in water they swell up.

 Long distance transport of water :

• Mass flow: Mass flow is the movement of substances (water, minerals and food) in bulk from one point to another as a result of pressure differences between two points.
• Translocation: the bulk movement of substance through the conducting or vascular tissue is called translocation.

How do plants absorb water?

• Transport of water in plants: Water is absorbed by root hairs, then water moves upto xylem by two pathways − apoplast and symplast pathway.
  


• Apoplast pathway :
  • Movement of water takes place exclusively through the intercellular spaces and the walls of the cells.
  • Movement through the apoplast does not involve crossing the cell membrane.
  • Movement depends on the gradient.
  • The apoplast does not provide any barrier to water movement.
  • Water movement is trough mass flow.
• Symplast pathway :
  • System of interconnected protoplasts.
  • Neighboring cells are connected through cytoplasmic strands that extend through plasmodesmata.
  • Water enters into the cytoplasm by crossing the plasma membrane.
  • Intercellular movement is through the plasmodesmata.
• Casparian strip : endodermis is impervious to water because of a band of suberised matrix called casparian strip.
  

Water movement up a plant :

• Root pressure : A hydrostatic pressure existing in roots which push the water up in xylem vessels.


• Guttation : The water loss in its liquid phase at night and early morning through special openings of vein near the tip of leaves.


• Transpiration pull : The transport of water to the tops of trees occurs through xylem vessels. The forces of adhesion and cohesion maintain thin and unbroken columns of water in the capillaries of xylem vessels through which it travels upward. Water is mainly pulled by transpiration from leaves. (Cohesion-tension-transpiration pull Model)


• Transpiration : The loss of water through stomata of leaves and other aerial parts of plants in form of water vapour.
  


• Transpiration driven ascent of xylem sap depends on the following physical properties of water:
  • Cohesion : mutual attraction between water molecules.
  • Adhesion : attraction of water molecules to polar surface(such as the surface of tracheary elements)
  • Surface tension : water molecules are attracted to each other in the liquid phase more than to water in the gas phase.
    

Role of transpiration :

• Creates transpiration pull for absorption and transport of plants.
• Supplies water for photosynthesis.
• Transports minerals from the soil to all parts of the plants.
• Cools leaf surfaces, sometimes 10 to 15 degrees, by evaporative cooling.
• Maintains the shape and structure of the plants be keeping cells turgid.

Factors affecting transpiration : Temperature, light, humidity, wind speed, number and distribution of stomata, water status of plant.

Uptake and transport of mineral nutrients :

• Ions are absorbed by the roots by passive and active transport.
• The active uptake of ions requires ATP energy.
• Specific proteins in membranes of root hair cells actively pump ions from the soil into the cytoplasm of epidermal cells and then xylem.
• The further transport  of  ions  to  all  parts  of  the  plant  is  carried  through  the  transpiration stream.

The Pressure or Mass Flow Hypothesis :

• The glucose is prepared at the source by the process of photosynthesis and is converted to sucrose (sugar).
• This sugar is then moved into sieve tube cells by active transport. It produces hypertonic condition in phloem.
• Water in the adjacent xylem moves into phloem by osmosis.
• Due to osmotic (turgor) pressure, the phloem sap moves to the areas of lower pressure.
• At the sink, osmotic pressure is decreased.
• The incoming sugar is actively transported out of the phloem and removed as complex carbohydrates (sucrose).
• As the sugar is removed, the osmotic pressure decreases, the water moves out of the phloem and returns to the xylem.

Author- Azeem Farooqui (Biochemist)
Expert NEET/AIIMS Medical Biology Faculty Kota.

Plant Physiology :- Respiration In Plants

RESPIRATION IN PLANTS

POINTS TO REMEMBER :

• The breaking of C-C bonds of complex compounds through oxidation within the cells, leading to release of considerable amount of energy is called respiration.
• The compound that oxidized during this process is known as respiratory substrates.
• In the process of respiration the energy is released in a series of slow step-wise reactions controlled by enzymes and is trapped in the form of ATP.
• ATP acts as the energy currency of the cell.

Glycolysis : 

• The term has originated from the Greek word, glycos =glucose, lysis = splitting or breakdown means breakdown of glucose molecule.
• It is also called Embeden-Meyerhof-Paranus pathway. (EMP pathway)
• It is common in both aerobic and anaerobic respiration.
• It takes place outside the mitochondria, in the cytoplasm.
• One molecule of glucose (Hexose sugar) ultimately produces two molecules of pyruvic acid through glycolysis.
• Glucose and fructose are phosphorylated to give rise to glucose-6-phosphate, catalyzed by hexokinase.
• This phosphorylated form of glucose is then isomerizes to produce fructose-6-phosphate.
• ATP utilized at two steps:
  • First in the conversion of glucose into glucose-6-phosphate
  • Second in fructose-6-phosphate→fructose 1, 6-diphosphate.
• The fructose-1, 6-diphosphate is split into dihydroxyacetone phosphate and 3-phosphoglyceraldehyde (DPGA).
• In one step where NADH + H⁺ is formed form NAD⁺; this is when 3-phosphogleceraldehyde (PGAL) is converted into 1, 3-bisphophoglyceric acid (DPGA).
• The conversion of 1, 3-bisphophoglyceric acid into 3-phosphoglyceric acid is also an energy yielding process; this energy is trapped by the formation of ATP.
• Another ATP synthesized when phosphoenolpyruvate is converted into pyruvic acid.
• During this process 4 molecules of ATP are produced while 2 molecules of ATP are utilized. Thus net gain of ATP is of 2 molecules.

FERMENTATION :

• There are three major ways in which different cells handle pyruvic acid produced by glycolysis:
  • Lactic acid fermentation.
  • Alcoholic fermentation.
  • Aerobic respiration.
• Alcoholic fermentation :
  • The incomplete oxidation of glucose to achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted into CO₂ and ethanol.
  • The enzyme pyruvic acid decarboxylase and alcohol dehydrogenase catalyze these reactions.
  • NADH + H⁺ is reoxidised into NAD⁺.
• Lactic acid fermentation:
  • Pyruvic acid converted into lactic acid.
    
  • It takes place in the muscle in anaerobic conditions.
  • The reaction catalysed by lactate dehydrogenase.
  • NADH + H⁺ is reoxidised into NAD⁺.
• Aerobic respiration:
  • Pyruvic acid enters into the mitochondria.
  • Complete oxidation of pyruvate by the stepwise removal of all the hydrogen atoms, leaving three molecules of CO₂.
  • The passing on the electrons removed as part of the hydrogen atoms to molecular oxygen (O₂) with simultaneous synthesis of ATP.

AEROBIC RESPIRATION:

• The overall mechanism of aerobic respiration can be studied under the following steps :
• Glycolysis (EMP pathway)
• Oxidative Decarboxylation
• Krebs’s cycle (TCA-cycle)
• Oxidative phosphorylation

Oxidative decarboxylation:

• Pyruvic acid formed in the cytoplasm enters into mitochondria.
• Pyruvic acid is converted into Acetyl CoA in presence of pyruvate dehydrogenase complex.
• The pyruvate dehydrogenase catalyses the reaction require several coenzymes, including NAD⁺ and Coenzyme A.
  
• During this process two molecules of NADH are produced from metabolism of two molecules of pyruvic acids (produced from one glucose molecule during glycolysis).
• The Acetyl CoA (2c) enters into a cyclic pathway, tricarboxylic acid cycle.

Tri Carboxylic Acid Cycle (Krebs cycle) or Citric acid Cycle :

• This cycle starts with condensation of acetyl group with oxaloacetic acid and water to yield citric acid.  This reaction is catalysed by citrate synthase.
• Citrate is isomerised to form isocitrate.
• It is followed by two successive steps of decarboxylation, leading to formation of α-ketoglutaric acid and then succinyl-CoA.
• In the remaining steps the succinyl CoA oxidized into oxaloacetic acid.
• During conversion of succinyl CoA to succinic acid there is synthesis of one GTP molecule.
  
• In a coupled reaction GTP converted to GDP with simultaneous synthesis of ATP from ADP.
• During Krebs cycle there production of :
  • 2 molecule of CO₂
  • 3 NADH₂
  • 1 FADH₂
  • 1 GTP.
• During the whole process of oxidation of glucose produce:
  • CO₂
  • 10 NADH₂
  • 2 FADH₂
  • 2 GTP.( 2 ATP)

Electron transport system and oxidative phosphorylation :

• The metabolic pathway, through which the electron passes from one carrier to another, is called Electron transport system.
• it is present in the inner mitochondrial membrane.
• ETS comprises of the following:
  • Complex I – NADH Dehydrogenase.
  • Complex II – succinate dehydrogenase.
  • Complex III – cytochromes bc1
  • Complex IV – Cytochromes a-a₃ (cytochromes c oxidase).
  • Complex V – ATP synthase.
• NADH₂ produced in the citric acid cycle oxidized by NADH
  
  Dehydrogenase, and electrons are then transferred to ubiquinone located in the inner membrane.
• FADH₂ is oxidized by succinate dehydrogenase and transferred electrons to ubiquinone.
• The reduced ubiquinone is then oxidized with transfer of electrons to cytochrome c via cytochromes bc1complex.
• Cytochrome c is small protein attached to the outer surface of the inner membrane and acts as a mobile carrier for transfer electrons from complex III and complex IV.
• When electrons transferred from one carrier to another via complex I to IV in the electron transport chain, they are coupled to ATP synthase for the synthesis of ATP from ADP and Pi.
• One molecule of NADH₂ gives rise to 3 ATP.
• One molecule of FADH₂ gives rise to 2ATP.
• Oxygen plays a vital role in removing electrons and hydrogen ion finally production of H₂O.
  
• Phosphorylation in presence of oxygen is called oxidative phosphorylation.

Total ATP Production -

Process Total ATP produced :

• Glycolysis 2ATP + 2NADH₂ (6ATP) = 8ATP
• Oxidative decarboxylation 2NADH₂  (6ATP) = 6ATP
• Krebs’s Cycle 2GTP (2ATP) + 6NADH₂ (18ATP) + 2FADH₂ (4ATP) = 24 ATP
• Energy production in prokaryotes during aerobic respiration = 38 ATP
• Energy production in eukaryotes during aerobic respiration = 38 − 2 = 36 ATP
• (2ATP are used up in transporting 2 molecule of pyruvic acid in mitochondria.)

Abbreviations :

ATP −          Adenosine tri phosphate
ADP −         Adenosine di phosphate
NAD −         Nicotinamide Adenine dinucleotide
NADP −       Nicotinamide Adenine dinucleotide Phosphate
NADH −       Reduced Nicotinamide Adenine dinucleotide
PGA −          Phosphoglyceric acid
PGAL −        Phospho glyceraldehyde
FAD −          Flavin adenine dinucleotide
ETS −          Electron transport system
ETC −          Electron transport chain
TCA −          Tricarboxylic acid
OAA −          Oxalo acetic acid
FMN −          Flavin mono nucleotide
PPP −          Pentose phosphate pathway

 Amphibolic Pathway : A biochemical pathway that serves both anabolic and catabolic processes.
• An important example of an amphibolic pathway is the Krebs cycle, which involves both the catabolism of carbohydrates and fatty acids and the synthesis of anabolic precursors for amino-acid synthesis (e.g. α-ketogluturate and oxaloacetate).

Author- Azeem Farooqui (Biochemist)
Expert NEET/AIIMS Medical Biology Faculty Kota.

Hormone Imbalance & Hormone Harmony(Menstural Cycle)

Hormone Imbalance & Hormone Harmony

Hormone imbalance is best understood by knowing how a normal menstrual cycle works. A menstrual cycle is the result of a hormonal dance between the pituitary gland in the brain and the ovaries. Every month the female sex hormones prepare the body to support a pregnancy, and without fertilization there is menstruation (a period).

Menstrual Cycle
A menstrual cycle is determined by the number of days from the first day of one period to the first day of the next. So day one of the menstrual cycle is the first of full bleeding day of the period. A typical cycle is approximately 24 to 35 days (average 28 days for most women). It is not abnormal for a woman¹s cycle to occasionally be shorter or longer.

On Day 1 of the menstrual cycle, estrogen and progesterone levels are low. Low levels of estrogen and progesterone signal the pituitary gland to produce Follicle Stimulating Hormone (FSH). FSH begins the process of maturing a follicle (fluid-filled sac in the ovary containing an egg).

The follicle produces more estrogen to prepare the uterus for pregnancy. At ovulation, usually around Day 12 – 14, increased estrogen levels trigger a sharp rise in Luteinizing Hormone (LH) from the pituitary gland, causing release of the egg from the follicle.

The ruptured follicle (corpus luteum) now secretes progesterone and estrogen to continue to prepare the uterus for pregnancy. If the egg is not fertilized, estrogen and progesterone levels drop and, on Day 28, the menses begin.

The menstrual cycle occurs in three phases: follicular, ovulatory and luteal. The first half of the cycle is known as the follicular phase and the second half of the cycle is considered the luteal phase. Midway through the cycle between days 12 and 16 ovulation occurs, known as the ovulatory phase.

Hormone Imbalance
Knowing how a normal menstrual cycle works helps to understand the symptoms of premenstrual syndrome (PMS), perimenopause and menopause. Symptoms are often the result of too much or too little hormone(s).

During perimenopause hormone levels fluctuate as a result of fewer ovulations, so less progesterone is produced in the second half of the menstrual cycle. Periods can be erratic, skipped or have heavy bleeding /clots. Symptoms result from the change in ratio of estrogen to progesterone ­ so the imbalance creates the symptoms.

During menopause, estrogen is no longer produced by the ovaries and is made in smaller amounts by the adrenal glands and in fat tissue. Estrogen is still produced in the body, but in lower amounts than younger cycling women. The most significant hormone change of menopause is the lack of progesterone, so a time of estrogen dominance and low progesterone.

Important Menstrual Cycle Hormones

Follicle Stimulating Hormone (FSH) -­ released from the pituitary gland in the brain, and stimulates the ovarian follicles (fluid-filled sacs on the ovary containing an egg or ovum) to mature.

Luteinizing Hormone (LH) -­ also released from the pituitary gland in the brain at ovulation, and causes the rupture of the mature ovarian follicle, releasing the egg.

Estrogen -­ One of the female sex hormones and often referred to as the ³growing hormone² because of its role in the body. Estrogen is responsible for growing and maturing the uterine lining (lining that is shed during menstruation) and also matures the egg prior to ovulation. Estrogen is produced mostly by the ovaries but also in smaller amounts by the adrenal glands and in fat tissue. It is most abundant in the first half of the menstrual cycle (follicular phase).

Progesterone -­ Another of the female sex hormones. It works in the body to balance the effects of estrogen and is often referred to as the relaxing hormone. Progesterone is produced after ovulation by the corpus luteum (sack that the egg comes from) and dominates the second half of the cycle (luteal phase). Progesterone¹s main job is to control the build up of the uterine lining and help mature and maintain the uterine lining if there is a pregnancy. If there is no pregnancy, our progesterone levels fall and the lining of the uterus is shed, beginning the menstrual cycle.

Testosterone -­ An important sex hormone for both women and men, although women have much lower levels. Is produced by the ovaries and adrenal glands (right on top of the kidneys), and has a surge at time of ovulation and slight rise just before the menses. Testosterone helps women maintain muscle mass and bone strength, enhances sex drive and helps with overall sense of well-being and zest for life.

Hormone Testing & Diagnostic Resources

As part of assessing baseline health and ongoing hormone balance many providers use tests to check and monitor hormone levels.

Testing Hormone Levels

The following are tests and biological markers that can be used to test hormone levels:

• Saliva Testing  It has been shown that saliva testing is the most accurate measurement of the body’s availability of the hormones Cortisol, DHEA, Estrogen, Progesterone, and Testosterone. Saliva testing is much more specific and correctly identifies the level of hormones at the cellular level, in contrast to a serum (blood) test, which measures the level of hormones circulating in the bloodstream.

• Serum or Blood Testing  Most serum testing measures the level of “free” hormone (the hormone that can easily enter the cell), the level of the “total” hormone (the hormone attached to substances that carry hormones in the bloodstream), or a calculated combination of both free and total levels of hormone. It is not an accurate reflection of the bioavailable hormone (the amount of hormone that is active in organs and tissues).

• Follicle-Stimulating Hormone (FSH) Testing  FSH is frequently used to determine the hormonal status of premenopausal women who may complain of hot flashes, mood changes, or other symptoms. The FSH test should not be used as an accurate measure of sex steroid hormone production or as an indication of reproductive status for most women, because the level of FSH fluctuates widely during the decade before menopause.

Look in our Symptoms and Solutions section for more information on blood tests and other biological markers, like saliva and urine

Assignment(19) Excretory Product &Their Elimination. Exercise#1 contains- Topic wise Objective Question. Exercise#2 Contains- Olympaids, CBO, ABO type Question. Exercise#3 Contains- AIIMS corner ie Assertion Reasoning type question. Exercises#4 Contains- Level#1- Previous year AIPMT/NEET Questions Level#2- Previous years P.M.T Exam Questions

Author :- Azeem Farooqui (Biochemist)
Excretory product(Assignment)

Chapter 19:Excretory Products and their Elimination.

Chapter 19:Excretory Products and their Elimination

Auther:- Azeem Farooqui

                   (Biochemist)

https://documentcloud.adobe.com/link/track?uri=urn%3Aaaid%3Ascds%3AUS%3A476e46fe-1051-4d45-96e0-39bae65219b9

Anthrax

Anthrax is an Acute Infectious Disease of Farm Animals

Anthrax is a contagious disease of domestic animals such as cattle, caused by the bacterium Bacillus anthracis, whose spores can remain potent in soil for decades. It may be transmitted to humans by inoculation, inhalation and ingestion. It causes malignant pustule (skin lesion) with septicaemia. In man the disease attacks either the lungs, causing pneumonia, or the skin, producing severe ulceration. The cutaneous form of the disease is not as dangerous as the pulmonary form (caused by inhaling spores). Woolsorter's disease is a serious infection of the skin or lungs by B. anthracis, affecting those handling wool or pets. Untreated anthrax can be fatal but administration of large doses of penicillin or tetracycline is usually effective.

Relationship between osmotic potential & pressure potential with water potential

Explain the relationship between osmotic potential & pressure potential with water potential.

·        Water potential mainly depends on concentration, pressure, and gravity. If the symbols of water potential, the effects of solutes, pressure, & gravity are denoted by Ψw, Ψs, Ψp & Ψg  , then water potential can be expressed as;

Water Potential (Ψw) = Ψs + Ψp+ Ψg 

·        In plants of small height (less than 5 meters), Ψg is negligible. So the equation becomes as;

                        Ψw = Ψs + Ψp

·        Pure water is usually defined as having osmotic potential (Ψs) of zero. As the solute is added solute potential or osmotic potential (Ψs) decreases. So, in this case solute potential can never be positive.

·        The pressure potential (turgor potential) on the other hand in living plant cell is usually positive. In plasmolysed cells & open system , Ψp = 0. Negative pressure potential occurs when water is pulled through an open system such as a plant xylem vessels.

Ø So, in the living cells,

·        If , Ψs = -ve  & Ψp = +ve (or, when pressure potential is less negative than the osmotic potential) then,  Ψw =  -ve.

·        If Ψs =  Ψp i.e., for e.g. Ψs = -1 &  Ψp = +1 ( or, when pressure potential equals to osmotic potential) then, Ψw =   0 (zero).

·        If the value of pressure potential exceeds the value of osmotic potential then, Ψw =  +ve. ( But this is not practically feasible because  it is considered that the value of water potential for pure water is zero).

Give the different parameters involved in the determination of water potential.

OR,

What are the factors involved in affecting the water potential?

·        Basically, there are three parameters involved in the determination of water potential (Ψw). They are:

1.     Solute concentration

2.     Pressure

3.     Gravity

·        Sometimes matrix potential of the system also affects the water potential.

a.     Solute concentration:

 In pure water the value of water potential is maximum i.e., it is zero. Addition of solutes reduces the free energy of water. The term Ψs is used for denoting the concentration of the solute and its effect on the water potential. It is termed solute potential or the osmotic potential.

b.    Pressure:

During osmosis the entry of water results in the development of hydrostatic or turgor pressure which is here called as pressure potential (Ψp). If the pressure potential is positive it will add to the water potential but if it is negative it reduces the value of water potential.

c.      Gravity:

The term Ψg termed gravity potential denotes the effect of gravity on the water potential of a water column in a vertically growing plant. It’s magnitude depends on the height of the plant from the ground level as well as on the density of water and the acceleration due to gravity. In plants of small height (less than 5 meters) the Ψg is negligible.

Ø Water potential is decreased by factors which reduce the relative water vapor viz., by addition of solutes, negative pressure or tensions, reduction in temperature and by matrix forces.

Ø Water potential is increased by factors which increase the negative vapor pressure, mechanical pressure and increase temperature.

RNA World Hypothesis Flow chart

The RNA world is a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existence of this stage.

Alexander Rich first proposed the concept of the RNA world in 1962, and Walter Gilbert coined the term in 1986. Alternative chemical paths to life have been proposed, and RNA-based life may not have been the first life to exist.  Even so, the evidence for an RNA world is strong enough that the hypothesis has gained wide acceptance.

Parental Care

Parental Care Increases Survival of the Young

Parental care refers to the level of investment provided by the mother and the father to insure development and survival of their offspring. In most birds, parents invest profoundly in their offspring as a mutual effort. Parental care is a behaviour pattern in which a parent invests time or energy in feeding and protecting its offspring. Parental care is a form of altruism since this type of behaviour involves increasing the fitness of the offspring at the expense of the parents. The degree of parental care differs widely. For example, most species of fish show little or no parental care while humans and many other mammals care for their offspring until they reach adolescence.

From the Author, Azeem Farooqui

Stuctures of Eukariyotic Cells

Eukaryotic Cells Have a  Variety of Membranous Organelles, Which Can Be Isolated for Study
Typical eukaryotic cells, are much larger than prokaryotic cells—commonly 5 to 100  m in diameter, with cell volumes a thousand to a million times larger than those of bacteria. The distinguishing characteristics of eukaryotes are the nucleus and a variety of membranebounded organelles with specific functions: mitochondria, endoplasmic reticulum, Golgi complexes, and lysosomes. Plant cells also contain vacuoles and chloroplasts. Also present in the cytoplasm of many cells are granules or droplets containing stored nutrients such as starch and fat. In a major advance in biochemistry, Albert Claude, Christian de Duve, and George Palade developed methods for separating organelles from the cytosol and from each other—an essential step in isolating biomolecules and larger cell components and investigating their structures and functions.
From Auther- Azeem Farooqui

Three Domians of Life

There are Three Distinct Domains of Life

All living organisms fall into one of three large groups (kingdoms, or domains) that define three branches of evolution from a common progenitor. Two large groups of prokaryotes can be distinguished on biochemical grounds:  archaebacteria (Greek  arche-, “origin”) and  eubacteria (again, from Greek  eu, “true”). Eubacteria inhabit soils, surface waters, and the tissues of other living or decaying organisms. Most of the well studied bacteria, including  Escherichia coli, are eubacteria. The archaebacteria, more recently discovered, are less well characterized biochemically; most inhabit extreme environments—salt lakes, hot springs, highly acidic bogs, and the ocean depths. The available evidence suggests that the archaebacteria and eubacteria diverged early in evolution and constitute two separate domains, sometimes called Archaea and Bacteria. All eukaryotic organisms, which make up the third domain, Eukarya, evolved from the same branch that gave rise to the Archaea; archaebacteria are therefore more closely related to eukaryotes than to eubacteria. Within the domains of Archaea and Bacteria are subgroups distinguished by the habitats in which they live. In  aerobic habitats with a plentiful supply of oxygen, some resident organisms derive energy from the transfer of electrons from fuel molecules to oxygen. Other environments are  anaerobic, virtually devoid of oxygen, and microorganisms adapted to these environments obtain energy by transferring electrons to nitrate (form(energy from organic compounds) Examples: •Most prokaryotes •All nonphototrophic eukaryotes atoms exclusively from CO2 (that is, no chemotrophs are autotrophs), but the chemotrophs may be further classified according to a different criterion: whether the fuels they oxidize are inorganic  (lithotrophs) or organic  (organotrophs). Most known organisms fall within one of these four broad categories—autotrophs or heterotrophs among the photosynthesizers, lithotrophs or organotrophs among the chemical oxidizers. The prokaryotes have several gening N2), sulfate (forming H2S), or CO2 (forming CH4). Many organisms that have evolved in anaerobic environments are  obligate anaerobes: they die when exposed to oxygen. We can classify organisms according to how they obtain the energy and carbon they need for synthesizing cellular material. There are two broad categories based on energy sources:  phototrophs (Greek  trophe-, “nourishment”) trap and use sunlight, and  chemotrophs derive their energy from oxidation of a fuel. All chemotrophs require a source of organic nutrients; they cannot fix CO2 into organic compounds. The phototrophs can be further divided into those that can obtain all needed carbon from CO2 (autotrophs) and those that require organic nutrients (heterotrophs). No chemotroph can get its carbon eral modes of obtaining carbon and energy.  Escherichia coli, for example, is a chemoorganoheterotroph; it requires organic compounds from its environment as fuel and as a source of carbon. Cyanobacteria are photolithoautotrophs; they use sunlight as an energy source and convert CO2 into biomolecules. We humans, like  E. coli, are chemoorganoheterotrophs.

From the Auther- Azeem Farooqui

Balbiani ring

Puff (Balbiani ring) is a Swelling of Polytene Chromosome

Puff (Balbiani ring) is swelling that is seen in certain areas of the giant (polytene) chromosomes found in the salivary glands and other tissues of certain dipterous insects at certain times. Puff is consisting of many strands of de-condensed DNA and its associated messenger RNA. Puffs originate in different regions of the chromosome in a certain sequence and their occurrence can be correlated with specific developmental events. Others occur only in certain tissues. The puffs are sites of active transcription of probably just a single gene, though present as numerous copies. This idea is reinforced by the fact that such puffs occur at regular intervals, suggesting that gene switching is in operation.

From the Author, Azeem Farooqui

Brain, Basal Ganglia connected to cerebrum

Basal Ganglia Connect the Cerebrum with other Parts

The basal ganglia form a set of interconnected nuclei in the forebrain. These are several large masses of grey matter embedded deep within the white matter of the cerebrum. They include the caudate and lenticular nuclei (together known as the corpus striatum) and the amygdaloid nucleus. Inside the basal ganglia there are too many connections and pathways. The basal ganglia have complex neural connections with both the cerebral cortex and thalamus. They are involved with the regulation of voluntary movements at a subconscious level. Disruption of the basal nuclei leads to involuntary motions (dyskinesias) characteristic of parkinson’s disease.

From the Author- Azeem Farooqui

What is Death ?

Death is Irreversible Cessation of Vital Functions

Clinical death is declared when the heart beat and breathing have stopped, pupil becomes fixed and do not react to light. This is considered as near or apparent death and it may be reversed. Biological death is permanent brain dearth due to lack of oxygen. This death is final. Death may be expected and occurs when one or more organs or systems fails to maintain homeostasis. Sudden death occurs when the flow of blood to the brain ceases. This might be due to serious haemorrhage, myocardial infarction, cardiac arrest, or suicide. Brain death is defined as permanent functional death of the centres in the brainstem that control breathing, heart rate, and other vital reflexes. Brain death (biological death) occurs four to six minutes after clinical death.

© (From the Author, Azeem Farooqui (S.C.I)