Proteins are important macromolecules that have many functions in organisms, including serving as enzymes, hormones, antibodies, and performing structural and transport roles. They are composed of amino acids that are linked together by peptide bonds. There are over 20 different amino acids, with proteins containing thousands in long chains that fold into complex three-dimensional shapes determined by their primary, secondary, tertiary, and sometimes quaternary structures. This folding allows proteins to specifically bind other molecules and perform their diverse functions. Nucleic acids DNA and RNA also have important roles, with DNA containing the genetic code and RNA having roles in protein synthesis.

1. The Chemicals of Life cont’d
Proteins – enzymes, hormones, antibodies
Nucleic acids – DNA and RNA

2. proteins
 These are important molecules containing an –
NH2 (amino) functional group and a –COOH
(carboxylic acid)
 They are made up of one or more amino acids.

3.  Proteins are macromolecules.
 Two amino acids are linked together by peptide bonds.
 There are 20 amino acids, 8 of these are essential because
they cannot be created by the human body.
 Most organisms have thousands of different protein
molecules.
 Each protein has its own structure
 This determines its properties and function
 The number of amino acids in a protein can range in the
10000’s.

4. Proteins can have many different functions in
organisms:
 Structural _________________________
 Catalyse reactions _________________________
 Contraction _________________________
 Transport _________________________
 Defence _________________________
 Coordination _________________________
 Storage _________________________

5. Three dimensional protein structure
is directly linked proteins to its
function
They facilitate recognition and binding of specific
molecules (enzymes to substrates) as well as cell
membrane receptors and hormones.
The function of a protein nearly always involves
binding in a specific complementary manner to
another molecule
Song -
http://www.youtube.com/watch?v=ID6KY1QBR5s

6. Primary Structure
Specific sequence of amino acids directed by codons on
the mRNA transcribed from a DNA template . A change in
one amino acid can lead to a significantly altered protein
(mutation)
i.e. Haemoglobin sickle cell anaemia
Secondary Structure
Coiling or folding of a polypeptide chain

7. Tertiary Structure
Three dimensional shape of a polypeptide, forming as
result of attraction and repulsions between various amino
acids. Includes enzymes, antibodies, haemoglobin and
hormones
Quaternary Structure
Arise from the bonding of two or more poly peptides

8. 4 Levels of structure in
Haemoglobin

9. Sickle cell anemia
 Haemoglobin consists of 4 polypeptide bonds.
 Sickle cell anemia is caused when the 6th
amino acid in one of the chains is changed
from glutamic acid to valine.
 The haemoglobin molecule changes from a
round to long fibrous sticky structure.
 This change means fewer oxygen molecules
that can be carried.

10. Nucleotides
Nucleic acids are macromolecules which are made up of
subunits, called nucleotides. These are the building blocks
of DNA. Nucleotides consist of
 A 5 carbon sugar (ribose or deoxyribose)
 A phosphate group
 A nitrogenous base
 Weak hydrogen bond will depend on base pairing
There are two types of nucleic acid:
 DNA –Deoxyribose Nucleic Acid
 RNA – Ribose Nucleic Acid
DNA nucleotides contain deoxyribose sugar
RNA nucleotides contain ribose sugar

11. Nitrogenous Bases
DNA and RNA differ in their Nucleotides.
Each has 4 nitrogen bases
DNA
 Adenine (A), Cytosine (C), Guanine (G), Thymine (T)
RNA
 Adenine (A), Cytosine (C), Guanine (G), Uracil (U)
In DNA, Because of the shape of these molecules, they will only
pair in certain ways.
 Adenine – Thymine
 Cytosine – Guanine
Weak hydrogen bonds are formed between DNA bases.

12. Nucleotides
Complementary bases
DNA RNA
A-T A-U
C-G C-G
DNA RNA

13. RNA
RNA is single stranded
Made up of 4 types of Nucleotide
 Adenine (A), Cytosine (C), Guanine (G), Uracil (U)
In RNA, because of the shape of these molecules, they
will only pair in certain ways.
 Adenine – Uracil
 Cytosine – Guanine
There are a THREE different types:
 Messenger RNA (m-RNA)
 Transfer RNA (t-RNA)
 Ribosomal RNA (r-RNA)

14. Types of RNA
There are three types of RNA
1. Ribosomal RNA (rRNA)
- forms 80% of cellular RNA forming ribosomes, sites of
protein synthesis.
2. Transfer RNA (tRNA)
- Specific carriers of amino acids (anti-codons) during
protein synthesis
3 Messenger RNA (mRNA)
- Carries messages out to ribosomes (codons/triplets) for
translation during amino acid sequencing.

15. DNA & RNA

16. Brief History of Discovery of DNA
DNA is the chemical found in all cells that
controls virtually everything that happens
in cells
DNA was first isolated in 1869 by a Swiss
chemist, Fredrich Miescher.
He identified a molecule that was acidic
and contained phosphorous.
Since it was found primarily in the nucleus,
it was named Nucleic Acid.

17. Brief History of Discovery of DNA
 It wasn’t until the 1940’s that the structure of
DNA began to be worked out.
 In 1953, two scientists working together, an
American, James Watson and a British scientist
Francis Crick, formulated their model of DNA.
 Rosalind Franklins work on the X-ray diffraction
of DNA was invaluable to their working out the
model.
 In 1962 Watson and Crick were awarded the
Nobel Prize.

18. DNA
Determines our genetic “blueprint”.
Directs the synthesis of proteins which enables cells to
reproduce or replicate themselves
DNA: is a double helix consisting of 2 complementary
strands. Each strand is made up of repeating nucleotides.
DNA has a long sugar phosphate backbone made up of 4
types of nitrogenous base
 Adenine, Thymine, Cytosine, Guanine
 Each pair has a complementary base pairing
 C-G (3 hydrogen bonds) and A-T (2 hydrogen bonds)

19. Repeating nucleotide sequence forming a DNA molecule

20. Base pairing in DNA

21. Bases

22. DNA double
helix

23. Nucleotide

25. Key Points: DNA
The chemical located in all cells which codes for
and controls all cell activities
Chemical basis of the genes which code for all
characteristics of an organism
Codes for and directs protein synthesis ( the
building up of proteins)
Codes for and regulates cell division, clones (
copies) for repair & growth and reproduction
Built up from sugar phosphate backbone ( ladder
uprights) and complementary pairing of nitrogen
bases ( rungs of ladder)

26. Chromosomes
Found in nucleus of all eukaryotic cells.
Chromosomes are composed of chromatin which is DNA
and protein molecules.
Each chromosome consists of two chromatids joined at
the centromere
DNA in turn is composed of hereditary units call genes.
A genes specific location is termed its locus
There are thousands of such genes on each chromosome
(many are referred to as “junk”)

27. Chromosomes

28. Chromosomes
Each gene codes for a specific protein.
The human genome has approx. 25,000 genes and
3 billion DNA bases. In 1990 their “loci” (location)
were mapped out by the Human Genome Project
The Adelaide Women's and Children's Hospital
sequenced the DNA on chromosome 16.
The knowledge of their location and sequencing
has revealed factors and information regarding
many diseases which allow for their treatment
and prevention

30. Key Points: Chromosomes
 Rod shaped strands of genes
 Composed of chromatin a complex mixture of
protein and DNA
 Each chromosome is a very long strand
composed of many nucleotides
 Human cells contain 23 pairs of homologous
chromosomes ( 46 in all)
 Males contain a shorter y chromosome and X
 Females only have X chromosome ( so the Dad
dictates the gender of offspring)

31. Note key points
Do focus questions on p19 and 31 and 32

32. Genes
A gene is:
a segment of chromosomes that contain the code required to
direct the manufacture of a polypeptide or RNA molecule.
The unit of hereditary
The specific location of a gene on a chromosome is termed its
locus
Genes represent sequences of the base A T G and C on
chromosomes
Genes prescribe the features of an organism eg eye colour
In a human with 46 chromosomes there are around 100000
genes with each chromosome containing hundreds or
thousands of genes.

33. Cells, chromosomes, genes
and DNA

34. Karotype
Chromosomes are visible when the cell starts to divide.
Human body cells have 46 chromosomes;
23 pairs of chromosomes
one set from the mother and one set from the father
22 pairs of autosomes (non sex chromosomes)
1 pair of sex chromosomes
XX –female XY – male
A complete set of chromosomes is called a karyotype.
Each chromosome has genes specific for that
chromosome making it identifiable.

35. A human set of chromosomes (46) is called
a Karyotype

36. Human Genome Project
Humans have approximately 100,000 genes in what is called
the Human Genome.
It is estimated that there are about 3 billion nucleotides in
the human genome.
In the late 1980’s The human Genome Project was set up.
It is an international effort of scientists from all over the
world.
Its aim is to sequence (map) the entire human genome of
one man and one woman.
It was originally estimated to take 15 years but was finished
in 2003.

37. Homework
 Read Chapter 1
 Note key points
 Write answers to focus questions 1-5 pg5

38. M2 The structural unit of information
in the cell is the chromosome
Read Key Ideas
- Note key points
- Do Focus Questions 1-4 page 7
Clickview The Human Genome Project
Homework Do Worksheet 2 page 8-9
Essentials

39. M2 practical
Enzymes and preferred conditions