Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Molecules of Life Chapter 3.

Similar presentations

Presentation on theme: "The Molecules of Life Chapter 3."— Presentation transcript:

1 The Molecules of Life Chapter 3

2 Polymers Are Built of Monomers
Organic molecules are formed by living organisms. Carbon-based core The core has attached groups of atoms called functional groups. The functional groups confer specific chemical properties on the organic molecules.

3 Five principal functional groups
Found In Group Structural Formula Ball-and- Stick Model O– P O OH C H N Lipids Proteins DNA, ATP Carbohydrates Carboxyl Carbonyl Hydroxyl Amino Phosphate 3

4 Macromolecules The building materials of the body are known as macromolecules because they can be very large. There are four types of macromolecules: Proteins Nucleic acids Carbohydrates Lipids

5 Macromolecules Large macromolecules are actually assembled from many similar small components, called monomers. The assembled chain of monomers is known as a polymer.

6 Dehydration Synthesis
All polymers are assembled the same way. A covalent bond is formed by removing a hydroxyl group (OH) from one subunit and a hydrogen (H) from another subunit.

7 Dehydration Synthesis
Because this amounts to the removal of a molecule of water (H2O), this process of linking together two subunits to form a polymer is called dehydration synthesis. H Energy HO H2O

8 Hydrolysis H2O H Energy HO
The process of disassembling polymers into component monomers is essentially the reverse of dehydration synthesis. A molecule of water is added to break the covalent bond between the monomers. This process is known as hydrolysis. H HO Energy H2O

9 Proteins Proteins are complex macromolecules that are polymers of many subunits called amino acids.

10 Proteins The covalent bond linking two amino acids together is called a peptide bond. The assembled polymer is called a polypeptide. O C N H H2O R Amino acid OH Polypeptide chain

11 Proteins Amino acids are small molecules with a simple basic structure, a carbon atom to which three groups are added: an amino group (—NH2) a carboxyl group (—COOH) a functional group (R) The functional group gives amino acids their chemical identity. There are 20 different types of amino acids.

12 Proteins Protein structure is complex.
The order of the amino acids that form the polypeptide is important. The sequence of the amino acids affects how the protein folds together.

13 Proteins The way that a polypeptide folds to form the protein determines the protein’s function. Some proteins are comprised of more than one polypeptide.

14 Proteins There are four general levels of protein structure: Primary
Secondary structure β-pleated sheet α-helix Tertiary Quaternary Amino acids Primary There are four general levels of protein structure: Primary Secondary Tertiary Quaternary

15 Proteins Primary structure—the sequence of amino acids in the polypeptide chain. Determines all other levels of protein structure. Amino acids Primary structure

16 Proteins Secondary structure forms because regions of the polypeptide that are nonpolar are forced together; hydrogen bonds can form between different parts of the chain. The folded structure may resemble coils, helices, or sheets. N H C O Secondary structure β-pleated sheet α-helix

17 Proteins Tertiary structure—the final 3-D shape of the protein.
The final twists and folds that lead to this shape are the result of polarity differences in regions of the polypeptide. Tertiary structure

18 Proteins Quaternary structure—the spatial arrangement of proteins comprised of more than one polypeptide chain. Quaternary structure

19 Proteins The shape of a protein affects its function.
Denaturation Folded protein Denatured protein The shape of a protein affects its function. Changes to the environment of the protein may cause it to unfold or denature. Increased temperature or lower pH affects hydrogen bonding, which is involved in the folding process. A denatured protein is inactive.

20 Proteins Active-site cleft Enzymes are globular proteins that have a special 3-D shape that fits precisely with another chemical. They cause the chemical that they fit with to undergo a reaction. This process of enhancing a chemical reaction is called catalysis.

21 Nucleic Acids Nucleic acids are very long polymers that store information. Comprised of monomers called nucleotides. Each nucleotide has 3 parts: a five-carbon sugar a phosphate group an organic nitrogen-containing base

22 Nucleic Acids There are five different types of nucleotides.
Information is encoded in the nucleic acid by different sequences of these nucleotides. N O P –O O– R C H H3C 4 5 1 3 2 2 8 7 6 3 9 4 5 1 Structure of nucleotide Nitrogenous base Nitrogenous bases Guanine Uracil (RNA only) Sugar Thymine (DNA only) Cytosine Phosphate group H in DNA OH in RNA Adenine OH CH2 NH2 (a) (b)

23 Nucleic Acids There are two types of nucleic acids:
G C A T Phosphodiester bond Hydrogen bonds between nitrogenous bases Sugar-phosphate “backbone” OH There are two types of nucleic acids: Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) RNA is similar to DNA except that it uses uracil instead of thymine it is comprised of just one strand it has a ribose sugar

24 Nucleic Acids The structure of DNA is a double helix because:
There are only two base pairs possible Adenine (A) pairs with thymine (T) Cytosine (C) pairs with Guanine (G) Properly aligned hydrogen bonds hold each base pair together. A sugar-phosphate backbone comprised of phosphodiester bonds gives support.

25 A G C T G and C can align to form three hydrogen bonds. A and T can align to form two hydrogen bonds. G and T cannot properly align to form hydrogen bonds. A and C cannot properly

26 Nucleic Acids The structure of DNA helps it to function.
The hydrogen bonds of the base pairs can be broken to unzip the DNA so that information can be copied. Each strand of DNA is a mirror image so that the DNA contains two copies of the information. Having two copies means that the information can be accurately copied and passed to the next generation.

27 Carbohydrates Carbohydrates are monomers that make up the structural framework of cells and play a critical role in energy storage. A carbohydrate is any molecule that contains the elements C, H, and O in a 1:2:1 ratio.

28 Carbohydrates The sizes of carbohydrates varies:
Simple carbohydrates—consist of one or two monomers. Complex carbohydrates—are long polymers.

29 Carbohydrates Simple carbohydrates are small.
Monosaccharides consist of only one monomer subunit. An example is the sugar glucose (C6H12O6). Disaccharides consist of two monosaccharides. An example is the sugar sucrose, which is formed by joining together glucose and fructose.

30 Carbohydrates Complex carbohydrates are long polymer chains.
Because they contain many C-H bonds, these carbohydrates are good for storing energy. These bond types are the ones most often broken by organisms to obtain energy. The long chains are called polysaccharides.

31 Carbohydrates Plants and animals store energy in polysaccharide chains formed from glucose. Plants form starch. Animals form glycogen. Some polysaccharides are structural and resistant to digestion by enzymes. Plants form cellulose cell walls. Some animals form chitin for exoskeletons.

32 Lipids Lipids—fats and other molecules that are not soluble in water.
Lipids are nonpolar molecules. There are many different types of lipids. fats oils steroids rubber waxes pigments

33 Lipids Fats are converted from glucose for long-term energy storage.
Fats have two subunits 1. fatty acids 2. glycerol Fatty acids are chains of C and H atoms, known as hydrocarbons. The chain ends in a carboxyl (—COOH) group.

34 Saturated and unsaturated fats
Because there are 3 fatty acids attached to a glycerol, another name for a fat is triglyceride H C O (a) Fat molecule (triacylglycerol) Glycerol backbone Fatty acids

35 Lipids Fatty acids have different chemical properties due to the number of hydrogens that are attached to the non-carboxyl carbons If the maximum number of hydrogens are attached, then the fat is said to be saturated. If there are fewer than the maximum attached, then the fat is said to be unsaturated.

36 Saturated and unsaturated fats
H H H H C C C C H H (b) Hard fat (saturated): Fatty acids with single bonds between all carbon pairs (c) Oil (unsaturated): Fatty acids that contain double bonds between one or more pairs of carbon atoms

37 Phospholipids Biological membranes involve lipids.
Phospholipids make up the two layers of the membrane. Cholesterol is embedded within the membrane. Outside of cell Carbohydrate chains Cell membrane Membrane proteins Phospholipid Cholesterol Inside of cell

Download ppt "The Molecules of Life Chapter 3."

Similar presentations

Ads by Google