CHAPTER 3 Composition of Cells (part 1) By Muhammad Bilal Javed

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

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.

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 ??

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

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.

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)

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

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.

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

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

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”

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

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 » 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 » pH below 7 acidic (higher concentration of H+ ions) » pH above 7 alkaline (higher concentration of OH- ions)

pH scale

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

HOMEWORK!! sighhh... Attempt quick check questions p55, (Question 1,2,3) Bio-challenge question 1

Thank you