The Basics of Protein Structure and Function

1. THE BASICS OF PROTEIN
STRUCTURE AND
FUNCTION
prepared
By
Cl.Ph: Joseph Talaat William
Clinical pharmacist, on Urology &
Nephrology Hospital
Assiut University

2. DEFINITION:
 Proteins are the macromolecules that carryout all of a cell'
activities ;they are the molecular tools and machines that
make things happens.
 They are polymers made of amino acid monomers.
 20 different amino acid are commonly used in the
construction of proteins whether from a virus or human.

3. GENERAL STRUCTURE OF
PROTEINS
 The backbone of all protein molecules is a continuous chain of
carbon and nitrogen atoms joined together through peptide
bonds between adjacent amino acids. At one end (the amino-
terminus) is a free amino group, and at the other end (the
carboxy-terminus) is a free carboxyl group.

5. PRIMARY STRUCTURE OF
PROTEINS
 refers to the total number of amino acids and their sequence in
that particular protein

6. SECONDARY STRUCTURE
OF PROTEINS:
 It refers to the twisting of the polypeptide chain into a helical
form.
 (a) Alpha helix
 (b) Beta pleated

8. TERTIARY STRUCTURE
OF PROTEINS:
 The helical form of polypeptide folds into spherical, globular,
ellipsoidal or other conformation, which is called the tertiary
structure of proteins. This folding is necessary for the biological
activity of the proteins. e.g., enzymes, immunoglobulin’s.

9. QUATERNARY STRUCTURE
OF PROTEINS:

10. SYMMARY

11. PROTEIN FUNCTION

12. CHROMOSOMES
 DEFINITION:
The term chromosome was coined by W. Waldeyer in 1888.
Chrome is coloured and soma is body, hence they mean “colored
bodies” and can be defined as higher order organized
arrangement of DNA and proteins. It contains many genes or
the hereditary units , regulatory elements and other nucleotide
sequences. Very simply chromosomes can be considered as being
made up of genes

14. AUTOSOMES
 Many animals, including humans, have two types of
chromosomes : autosomes and sex chromosomes. Sex chromosomes
are those that are needed for determining sex (male or female) of
an individual. Autosomes are all the rest of the chromosomes that
are not needed for sex determination

16. CHROMATIN
Definition:
Chromatin is a mass of genetic material composed of DNA and
proteins that condense to form chromosomes during eukaryotic
cell division. Chromatin is located in the nucleus of our cells.

17. FUNCTION&STRUCTURE
1-The primary function of chromatin is to compress the DNA
into a compact unit that will be less voluminous and can fit
within the nucleus.
2-Chromatin makes it possible for a number of cell processes to
occur including DNA replication, transcription, DNA repair,
genetic recombination, and cell division.

19. CHROMATIN TIGHTLY
PACKAGES OUR DNA

20. EUCHROMATIN AND
HETEROCHROMATIN:
 Difference between Euchromatin and Heterochromatin:
 1- Chromatin makes up the nucleus. It is made up of DNA and
protein.
 2- Chromatin has two forms: euchromatin and heterochromatin.
 3- When stained and observed under an optical microscope,
euchromatins are the light-colored bands while heterochromatins are
the dark-colored bands.

21. CONT.…
 4- Heterochromatins are compactly coiled regions while euchromatins are loosely
coiled regions.
 5- Euchromatin contains less DNA while heterochromatin contains more DNA.
 6- Euchromatin is early replicative while heterochromatin is late replicative.
 7- Euchromatin is found in eukaryotes, cells with nuclei, and
prokaryotes, cells without nuclei.
 8- Heterochromatin is only found in eukaryotes.
 9- The functions of euchromatin and heterochromatin are gene expression, gene
repression, and DNA transcription.

22. CENTROMERE
 A centromere is a region on a chromosome that joins sister
chromatids.
 The primary function of the centromere is to serve as a place of
attachment for spindle fibers during cell division.
 The DNA in the centromere region of a chromosome is
composed of tightly packed chromatin known as
heterochromatin.

23. CENTROMERE LOCATION

24. TELOMERE
 • Telomeres are sections of DNA found at the ends of
each of our chromosomes.
 • They consist of the same sequence of bases repeated over
and over.
 • In humans the telomere sequence is TTAGGG.
 • This sequence is usually repeated about 3,000 times and
can reach up to 15,000 base pairs in length

26. WHAT DO TELOMERES DO?
 Telomeres serve three major purposes:
 1. They help to organise each of our 46 chromosomes in the
nucleus (Control centre) of our cells.
 2. They protect the ends of our chromosomes by forming a cap,
much like the plastic tip on shoelaces. If the telomeres were not there, our
chromosomes may end up sticking to other chromosomes.
 3. They allow the chromosome to be replicated properly during
cell division.

27. USE OF TELOMERES IN
MEDICINE
 • Research on telomeres and the role of telomerase could uncover
valuable information to combat ageing and fight cancer.
 • The medical relevance of telomeres is uncertain.
 • Human cells cultured in the lab have been observed to stop
dividing when telomerase is inactivated, because the length of telomeres is
not maintained after cell division.
 • The cells then enter a state of inactivity called senescence.
However, once telomerase is reactivated, the cells are able to continue
dividing.

28. THANK YOU