1. Course lecturer : Jasmin Šutković 17th May 2017
Lecture 12 and 13: Nucleic Acids and Metabolic pathways and energy production
Chemistry - SPRING 2017
Course lecturer :
Jasmin Šutković
17th May 2017

2. Contents Nucleosides and Nucleotides Nucleic Acids
International University of Sarajevo
Nucleosides and Nucleotides
Nucleic Acids
The DNA Double Helix
Replication
RNA
Transcription
The Genetic Code
Translation and Protein Synthesis
Flow of energy
ATP
Metabolism
How Enzymes work
Cellular respiration

3. Introduction
WHETHER you are tall or short, fair-skinned or dark-complexioned, blue-eyed or brown-eyed, your unique characteristics are determined by the nucleic acid polymers that reside in the chromosomes of your cells.
The nucleic acid DNA stores the genetic information of a particular organism!
Even minor alterations in the nucleic acid sequence can have significant effects on an organism, sometimes resulting in devastating diseases like sickle cell anemia and cystic fibrosis.
Cystic fibrosis (CF) is a genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine.
The term sickle cell disease (SCD) describes a group of inherited red blood cell disorders. People with SCD have abnormal hemoglobin

4. NUCLEOSIDES AND NUCLEOTIDES
Nucleic acids are unbranched polymers composed of repeating monomers called nucleotides.
There are two types of nucleic acids.
DNA, deoxyribonucleic acid, stores the genetic information of an organism and transmits that information from one generation to another.
RNA, ribonucleic acid, translates the genetic information contained in DNA into proteins needed for all cellular functions.
The nucleotide monomers that compose DNA and RNA consist of three components—a monosaccharide, a nitrogen-containing base, and a phosphate group.

5. Humans have 46 – other species have different numbers
About DNA
Found in Chromosomes
Humans have 46 – other species have different numbers
Chromosomes are divided into genes
A gene is a portion of the DNA molecule responsible for the synthesis of a single protein.

6. Bases
Only five common nitrogen-containing bases are present in nucleic acids.
Three bases with one ring (cytosine, uracil, and thymine) are derived from the parent compound pyrimidine.
Two bases with two rings (adenine and guanine) are derived from the parent compound purine.
Each base is designated by a one-letter abbreviation.

8. NUCLEOSIDES—JOINING A MONOSACCHARIDE AND A BASE
The nucleotides of both DNA and RNA contain a five-membered ring monosaccharide, often called simply the sugar component.
In RNA, the monosaccharide is the aldopentose D-ribose.
In DNA the monosaccharide is D-2-deoxyribose, an aldopentose that lacks a hydroxyl group at C2.

9. NUCLEOTIDES—JOINING A NUCLEOSIDE WITH A PHOSPHATE
Nucleotides are formed by adding a phosphate group to the 5'-OH of a nucleoside.
Ribonucleotides are derived from ribose, while deoxyribonucleotides are derived from 2-deoxyribose.

12. THE DNA DOUBLE HELIX
Our current understanding of the structure of DNA is based on the model proposed initially by James Watson and Francis Crick in 1953
DNA consists of two polynucleotide strands that wind into a right-handed double helix.

15. Central Dogma
What comes after ...how we synyhesise the protein then?

16. Each chromosome contains many genes, those portions of the DNA molecules that result in the synthesis of specific proteins.
We say that the genetic message of the DNA molecule is expressed in the protein. Only a small fraction (1–2%) of the DNA in a chromosome contains genetic messages or genes that result in protein synthesis.

17. RNA
While RNA is also composed of nucleotides, there are important differences between DNA and RNA.
In RNA, The sugar is ribose.
U (uracil) replaces T (thymine) as one of the bases.
RNA is single stranded.
RNA molecules are much smaller than DNA molecules
Ribosomal RNA (rRNA)
Messenger RNA (mRNA)
Transfer RNA (tRNA)

18. Mutations

19. Metabolism and energy production
Lecture 13
Metabolism and energy production

20. Energy: the capacity to do work -kinetic energy: the energy of motion
Flow of Energy
Energy: the capacity to do work
-kinetic energy: the energy of motion
-potential energy: stored energy
Energy can take many forms: chemical, mechanical, electric current, heat, light

22. ATP - Energy Currency of Cells
ATP is the molecule that cells use to store, transfer, and provide energy
The energy from ATP is used to fuel anabolic reactions
recall: for growth, repair, and reproduction
ATP = Adenosine TriphosPhate
Adenosine (same molecule from DNA and RNA) +
Three inorganic phosphates (functional group PO4)

23. ATP - Energy Currency of Cells
ATP = adenosine triphosphate
the energy “currency” of cells
ATP structure:
ribose, a 5-carbon sugar
adenine
three phosphates

24. Photo Courtest of Dr. O’Steen

26. ATP - Energy Currency of Cells
ATP - 1 PO4 = ADP (Adenosine Diphosphate)
ADP - 1 PO4 = AMP (Adenosine Monophosphate)
ADP + 1 PO4 = ATP 26

27. ATP is a molecule that is used as an Energy Currency in cells
ATP’s can be broken down to provide energy for endergonic reactions
Cells use energy to build ATP’s
Enzymes of allow cells to efficiently build ATP’s - Cells can make ATP’s for less energy than ATP’s can provide

28. ATP - Energy Currency of Cells
ATP stores energy in the covalent bonds between phosphates:
Phosphates are highly negative, therefore:
the phosphates repel each other
much energy is required to keep the phosphates bound to each other
Energy is released when the bond between two phosphates is broken

29. Energy Currency of Cells
When the bond between phosphates is broken:
ATP ADP + Pi
energy is released
ADP = adenosine diphosphate
Pi = inorganic phosphate
This reaction is reversible...

30. ATP/ADP Cycling

31. ATP regulates enzyme activity
Other Functions of ATP
ATP regulates enzyme activity
Phosphorylation and dephosphorylation - process of adding or removing phosphate groups - can activate or deactivate enzymes
ATP serves as a source of phosphate groups 31

32. Three rules to be considered an enzyme
Enzymes
Enzymes: molecules that catalyze - speed up - biochemical reactions in living cells
Three rules to be considered an enzyme
Most are proteins (some RNA enzymes)
Lower the energy of activation required for a reaction to occur
Are not changed or consumed by the reaction
Cofactors, Coenzymes 32

33. Metabolism Enzymes catalyze cellular chemical reactions
Metabolism - the chemical reactions in a cell:
Two categories of cellular chemical reactions:
Anabolic Reactions
Build larger molecules for growth, repair, reproduction
Dehydration Synthesis Reactions
require energy and nutrients
Catabolic Reactions
Breakdown larger molecules
Hydrolysis Reactions
mobilize nutrients for energy making it available to the cell

34. Metabolism
Metabolism is the sum total of all anabolic and catabolic reactions that occur in the cell
The metabolism of cells is carried out and controlled by the enzymes
There are catabolic enzymes – those that cleave larger molecules into smaller ones
Ex. Hydrolysis Reactions
There are also anabolic enzymes – those that assemble smaller molecules into larger ones
Ex. Dehydration Reactions

35. Enzymes interact with substrates.
substrate: molecule that will undergo a reaction
active site: region of the enzyme that binds to the substrate
Binding of an enzyme to a substrate causes the enzyme to change shape, producing a better induced fit between the molecules.

36. Enzymes lower the activation energy of biochemical reactions.
How Enzymes Work
Enzymes lower the activation energy of biochemical reactions.
Enzymes make it easier for chemical reactions to occur:
by destabilizing the bonds in the substrate
by bringing substrates together so they react
by decreasing entropy - disorder - in the system
Enzymes make the chemical reactions possible in the cell’s environment
Enzymes make cells very efficient 36

38. Enzymes make cells very efficient
How Enzymes Work
Enzymes make cells very efficient
Through enzymes, cells can carry out anabolic and catabolic reactions and end up with a net profit of energy.
Metabolic reactions and
Cellular respiration 38

39. The Energy is in the form of ATP
Cellular Respiration
Cellular Respiration is a metabolic pathway that breaks down glucose and extracts the energy to produce energy
C6H12O6 + 6O H2O + 6CO2 + Energy
Glucose Oxygen Water Carbon Dioxide
The Energy is in the form of ATP

40. Metabolic Pathways
Metabolic Pathways are series of chemical reactions carried out by separate enzymes
It is a sequence of chemical reactions where each reaction is controlled by a separate enzyme
The product of one enzyme serves as the substrate for the enzyme of subsequent reaction in the metabolic pathway

41. The metabolism of cells is carried out and controlled by ENZYMES
There are catabolic enzymes – those that cleave larger molecules into smaller ones
Ex. Hydrolysis Reactions
There are also anabolic enzymes – those that assemble smaller molecules into larger ones
Ex. Dehydration Reactions