Download Lows of thermodynamics

Medical Biology
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Shorooq Wessam
Spermatogenesis
Spermatogenesis is the process by which male spermatogonia develop
into mature spermatozoa .spermatozoa are the mature male gametes,in
many sexually reproducing organisms .Thus ,spermatogensis is the male
version of gametogensis.The entire process permatogenesis produces
mature male gaemes,commonly called sperm but specifically Known as
spermatozoa ,which are able to fertilize the counterpart female gamete
,the oocyte,during conception to produce a single-celled individual
known as a zygote .Spematogenasis takes place wihin several structures
of the male reproductive system .the initial stages occur within the testis
and progress to the epididymis where the developing gametes are stored
until ejaculation .The seminiferous tubules of the testes are the starting
point for the process ,where stem cells adjacent to the inner tubule wall
divide in a centripetal direction beginning at the walls and proceeding
into the innermost part or lumen to produce immature sperm .maturation
occurs in the epididymis and involves the acquisition of a tail and hence
motility. spermatocytogenesis is the male form of gametocyogenesis and
results in the formation of sparmatocytes possessing half the normal
complememt of genetic material. in spermatoytogenesis diploid….divides
mitotically to produce adiploid intermediate cell called a primary
spermatocyte .each prim spermatocyte duplicates its DNA and
subsequently undergoes meiosis I to produce two haploid secondary
spermatocytes.This division implicates sources of genetic variation, such
as random inclusion of either parerntal chromosomes ,and chromosomal
crossover ,to increase the genetic variability of the gamete.
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Oogenesis in mammals
It is interesting to note that such an important process in animal life
cycles is done completey without he aid of spindle – coordinating
centrsosomes. It consists of several process : oocytogensis ,
ootidogenesis and the final maturity to form an ovum.
Folliculogenesis is a separate process during ootidogenesis . the
creation of oogonia traditionally doesn’t belong to oogenesis , but
to the common path of gametogenesis together with
spermatogensis .
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Lows of thermodynamics
Energy exists in many forms such as heat , light , chemical energy and
electrical energy . energy is the ability to bring about change
or to do work . thermodynamics is the study of energy . in
bioenergetics the cells convert potential energy , usually in
the form of C-C covalent bonds or ATP molecules into
kinetic energy to accomplish cell division , growth ,
biosynthesis and active transport among other things .
First law of thermodynamics : energy can be changed from one form to
another but it cannot be created or destroyed . the total
amount of energy and matter in the universe remains
constant , merely changing from one form to another . the
first low of thermodynamics (conservation) states that
energy is always conserved , it cannot be created or
destroyed
Second low of thermodynamics : states that "in all energy exchanges if
no energy enters or leaves the system , the potential energy
of the state will always be less than that of the initial state" .
this is also commonly referred to as entropy , awatch spring
– driven watch will run until the potential energy in the
spring is converted and not again until energy is reapplied to
the spring to rewind it . A car that has run out of gas will not
run again until you walk 10 miles to a gas station and refuel
the car . one the potential energy locked in carbohydrates is
converted into kinetic energy (energy in use or motion) , the
organism will get no more until energy is input again. In the
process of energy transfer some energy will dissipate as heat
entropy is a measure of disorder : cells are not disordered
and so have low entropy . the flow of energy maintains order
and life , entropy wins when organisms cease to take in
energy and die.
Ctabolism and Anabolism
Anabolism is the total series of chemical reactions involved in synthesis
of organic compounds . autotrophs must be able to
manfacture (synthesize) all the organic compounds they need
heterotrophs can obtain some of their compounds in their
diet (along with their energy) . for example humans can
synthesize 12 of the 20 amino acids , we must obtain the
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other 8 in our diet .catabolism is the series of chemical
reactions that breakdown larger molecules . energy is
released this way , some of it can be utilized for anabolism ,
products of catabolism can be reassembled by anabolic
processes ito new anabolic molecules .
Endrogonic and Exergonic
Energy releasing processes , ones that "generate" energy are termed
exergonic reactions. Reactions that require energy to initiate
the reaction are known as endergonic reaction . all natural
processes tend to proceed in such a direction that the
disorder or randomness of the universe increase (the second
law of thermodynamics).Biochemical reactions in living
organisms are essentially energy transfers .often they occur
together , "linked" , in what are referred to as oxidation
reduction reactions
Reduction is the gain of an electron . sometimes we also havefor the ride ,
H ions along for the ride , so reduction also becomes the
gain of H . oxidation is the loss of an electron (or hydrogen).
In oxidation /reductions , one chemical is oxidized and its
electrons are passed to another (reduced, then) chemical.
Such coupled reactions are referred to as redox reactions ,
the metabolic processes glycolysis , krebs cycle and electron
transport phosphorylation involved the transfer of electrons
(at varying energy states) by redox reaction.
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