CHAPTER 3 Composition of Cells (part 1) By Muhammad Bilal
Javed
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Learning Objectives 1.Be familiar with some basic concepts of
biochemestry 2.Understand inorganic and organic chemicals
(compounds) 3.Types of bonds (hydrogen, covalent and ionic)
4.Understand the roles of water in organisms 5.Observe the
biochemistry that confers water its significant properties
6.Understand the biological significance of pH 1.Be familiar with
some basic concepts of biochemestry 2.Understand inorganic and
organic chemicals (compounds) 3.Types of bonds (hydrogen, covalent
and ionic) 4.Understand the roles of water in organisms 5.Observe
the biochemistry that confers water its significant properties
6.Understand the biological significance of pH
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What Builds &fuels cells ? All cells and hence all living
things are composed of compounds made up of chemicals. What type of
chemicals make compounds ?? two categories: 1. Organic, chemicals
are complex of two or more carbon and hydrogen atoms. 2.Inorganic,
chemicals are with either one or none of carbon and hydrogen atoms.
All cells and hence all living things are composed of compounds
made up of chemicals. What type of chemicals make compounds ?? two
categories: 1. Organic, chemicals are complex of two or more carbon
and hydrogen atoms. 2.Inorganic, chemicals are with either one or
none of carbon and hydrogen atoms.
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Organic OR Inorganic !! Organic Carbohydrates proteins Lipids
Nucleic acids Organic Carbohydrates proteins Lipids Nucleic acids
Inorganic Water: H 2 O Carbon dioxide: CO 2 Oxygen: O 2 And other
mineral, ions such as Cl -, K +, Mg 2+, Na +, Ca 2+ and NO 3 -
Inorganic Water: H 2 O Carbon dioxide: CO 2 Oxygen: O 2 And other
mineral, ions such as Cl -, K +, Mg 2+, Na +, Ca 2+ and NO 3 - What
about; Water, Carbon dioxide and Oxygen ??
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Holding it together How are these atoms held together to make
compound and molecules ?? They are held together by bonds !! Atoms
are joined by chemical bonds to form compounds and molecules. There
are several types of chemical bonds important in biological
molecules. The three basic bonds are; what do you think ?? Hydrogen
bonds Covalent bonds Ionic bonds How are these atoms held together
to make compound and molecules ?? They are held together by bonds
!! Atoms are joined by chemical bonds to form compounds and
molecules. There are several types of chemical bonds important in
biological molecules. The three basic bonds are; what do you think
?? Hydrogen bonds Covalent bonds Ionic bonds
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Hydrogen bond Are the attraction of hydrogen, and its proton
positive nucleus thus (H + ), for electronegative atoms like
oxygen. Hydrogen bonds are the weakest of the three bonds and are
easily broken. Important, in DNA as opposing chains are attracted
and bonded by thousands of these bonds giving an overall strong
bond. For example Water molecules (H 2 O ) show inter- molecular
hydrogen bonding. Are the attraction of hydrogen, and its proton
positive nucleus thus (H + ), for electronegative atoms like
oxygen. Hydrogen bonds are the weakest of the three bonds and are
easily broken. Important, in DNA as opposing chains are attracted
and bonded by thousands of these bonds giving an overall strong
bond. For example Water molecules (H 2 O ) show inter- molecular
hydrogen bonding.
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Covalent bonds Covalent bonds are the strongest bonds. These
bonds are typical of organic compounds (carbon compounds) and some
inorganic compounds. Most biological molecules are held together by
Covalent bonds, which occur when two or more atoms share their
electrons. Example one molecule of (H 2 O ) shares its electron(e -
) with another electron(e - ) of(H 2 O ) molecule. Others include
Carbon dioxide, methane and sugar are covalently bonded. If sharing
of (e - ) is very equal non-polar molecules results. If sharing of
(e - ) is not equal polar molecules results. Can be (-ve) or (+ve)
Covalent bonds are the strongest bonds. These bonds are typical of
organic compounds (carbon compounds) and some inorganic compounds.
Most biological molecules are held together by Covalent bonds,
which occur when two or more atoms share their electrons. Example
one molecule of (H 2 O ) shares its electron(e - ) with another
electron(e - ) of(H 2 O ) molecule. Others include Carbon dioxide,
methane and sugar are covalently bonded. If sharing of (e - ) is
very equal non-polar molecules results. If sharing of (e - ) is not
equal polar molecules results. Can be (-ve) or (+ve)
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Covalent bonds in between oxygen and hydrogen atoms. Hydrogen
bonds in between water molecules give cohesion (tend to stick
together) and Electronegativity gives polarity. Is water polar or
non-polar ?? water is polar molecule. Since the oxygen has a
partial negative charge and the hydrogen a partial positive
charge
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Ionic bonds Ionic bonds are common to almost all inorganic
compounds such as salts, inorganic acids and bases. One element
donates an electron to another element which receives the electron.
The resulting union is an ionic compound. NaCl, HCl, and NaOH are
simple examples. Bond strengths are modest. Ionic bonds are common
to almost all inorganic compounds such as salts, inorganic acids
and bases. One element donates an electron to another element which
receives the electron. The resulting union is an ionic compound.
NaCl, HCl, and NaOH are simple examples. Bond strengths are
modest.
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Roles of water in organisms Major components of cells, i.e. 40
-to-42 liters approximately 70% distributed to different regions of
human body. The rest is 30 % of other chemicals in the body Is the
most abundant compound in our bodies as well as the main solvent
for many organic molecules present. Making it the ideal medium for
chemical reactions taking place in our body. This sum total of the
reaction is called METABOLISM Major components of cells, i.e. 40
-to-42 liters approximately 70% distributed to different regions of
human body. The rest is 30 % of other chemicals in the body Is the
most abundant compound in our bodies as well as the main solvent
for many organic molecules present. Making it the ideal medium for
chemical reactions taking place in our body. This sum total of the
reaction is called METABOLISM
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Roles of water in organisms For example; catabolism is the
breakdown of compounds to release energy and other compounds or
atoms and anabolism the syntheses of new compounds from simpler
ones. Bothe of these reactions readily occur in solution. As water
is the predominate solvent in the body and many organic compounds
dissolve in water. Thus metabolism occurs in watery solution. Is a
versatile solvent due to its cohesive nature as a solvent
Thermoregulation. For example, materials shrink as the temperature
falls because movement of molecules within material decreases. Is
able to freeze Or heated and becomes steam Environmental factor,
eg. Pants, Oceans, rain, etc. for example, water can be protection
for organism living beneath water by forming a lattice as
temperatures falls. These roles have come about due to the unique
biochemical properties of water For example; catabolism is the
breakdown of compounds to release energy and other compounds or
atoms and anabolism the syntheses of new compounds from simpler
ones. Bothe of these reactions readily occur in solution. As water
is the predominate solvent in the body and many organic compounds
dissolve in water. Thus metabolism occurs in watery solution. Is a
versatile solvent due to its cohesive nature as a solvent
Thermoregulation. For example, materials shrink as the temperature
falls because movement of molecules within material decreases. Is
able to freeze Or heated and becomes steam Environmental factor,
eg. Pants, Oceans, rain, etc. for example, water can be protection
for organism living beneath water by forming a lattice as
temperatures falls. These roles have come about due to the unique
biochemical properties of water
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Polarity Water is a polar molecule Regions of slight positive
and slight negative charge Other polar substances can dissolve
easily in water. What is the scientific term for these substances
which dissolve in water?? Hydrophilic. Eg. Salts, sugars Substances
that do not dissolve in water are said to be non-polar or
hydrophobic. Good example is Oil Water is a polar molecule Regions
of slight positive and slight negative charge Other polar
substances can dissolve easily in water. What is the scientific
term for these substances which dissolve in water?? Hydrophilic.
Eg. Salts, sugars Substances that do not dissolve in water are said
to be non-polar or hydrophobic. Good example is Oil
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Solvent ability of water What enables water to be a good
solvent?? Cohesion and polarity enable water to be an excellent
solvent Predominant solvent in organisms Polarity breaks up solutes
Cohesiveness keeps solution together What enables water to be a
good solvent?? Cohesion and polarity enable water to be an
excellent solvent Predominant solvent in organisms Polarity breaks
up solutes Cohesiveness keeps solution together
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ACID or ALKALINE Pure water has a pH of 7.0 (neutral solution).
But wait..!! What is pH?? A scale that provided measures of
hydrogen ions in a solution and hence the state of acidity and
alkalinity of a solution. pH Range is from 0 14. pH below 7 acidic
(higher concentration of H+ ions) pH above 7 alkaline (higher
concentration of OH- ions) Pure water has a pH of 7.0 (neutral
solution). But wait..!! What is pH?? A scale that provided measures
of hydrogen ions in a solution and hence the state of acidity and
alkalinity of a solution. pH Range is from 0 14. pH below 7 acidic
(higher concentration of H+ ions) pH above 7 alkaline (higher
concentration of OH- ions)
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pH scale
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Why we need pH ?? When the pH value of blood fluids, for
example, blood or urine, is outside the normal ranges expected in
healthy persons, it may be an indication of some metabolic problem
or other defect. Cells contain buffer substances, that is, these
compounds combined with or release hydrogen ions in a cell as
required to prevent severe shift in the pH of cell or fluid When
the pH value of blood fluids, for example, blood or urine, is
outside the normal ranges expected in healthy persons, it may be an
indication of some metabolic problem or other defect. Cells contain
buffer substances, that is, these compounds combined with or
release hydrogen ions in a cell as required to prevent severe shift
in the pH of cell or fluid
