2. UNLOCKING DIFFICULTIES
DNA or Deoxyribonucleic acid is double stranded
material that carries genetic information for the
development and functioning of an organism.
RNA or ribonucleic acid is a single stranded material
that stores information and helps in the synthesis of
proteins in our body.
Enzymes are proteins that help speed up chemical
reactions in our bodies.
3. UNLOCKING DIFFICULTIES
NUCLEOTIDES Nucleotides are organic
molecules composed of a
nitrogenous base, a
pentose sugar and a
phosphate. They serve as
monomeric units of the
nucleic acid polymers
7. CENTRAL DOGMA OF MOLECULAR BIOLOGY
The central dogma of molecular biology states that
genetic information flows only in one direction, from
DNA, to RNA, to protein, or RNA directly to protein.
STEPS: Replication, Transcription, and Translation
It is suggested that the information present in a DNA
is essential to make up all proteins and RNA acts
as a messenger that carries information through the
ribosomes.
8. CENTRAL DOGMA OF MOLECULAR BIOLOGY
REPLICATION TRANSCRIPTION TRANSLATION
9. In DNA replication, the DNA makes multiple copies of
itself.
STEPS: Initiation, Elongation, Termination
Semi-conservative process - the original strand of DNA
acts as a template for the newly synthesized strand.
Enzymes Used: Helicase, Primase, DNA Polymerase
I,II,III, and Ligase
REPLICATION
10. DNA Polymerase I, II, III – repairs, extends, and
proofreads the DNA during replication.
Helicase – unzips/unwinds the DNA strands by breaking
the hydrogen bonds between the nitrogenous bases,
forms the replication fork.
Ligase - enzyme which joins together the Okazaki
fragments of the discontinuous DNA strands.
ENZYMES IN REPLICATION
11. Primase - This enzyme helps in the synthesis of RNA
primer complementary to the DNA template strand.
ENZYMES IN REPLICATION
13. DNA REPLICATION: INITIATION
The process of replication
starts at the origin of replication
where the enzyme Helicase
unwind/unzip the double
stranded DNA creating the
replication fork.
14. DNA REPLICATION: ELONGATION
As the strands of DNA
separates, the DNA
polymerase synthesizes the
complementary sequence of
the strand, the parental strand
acts as a template for the new
nucleotide sequences.
15. DNA REPLICATION: ELONGATION
In this process, one strand is
continuous (3’ 5’ direction)
and follows continuous
replication by DNA. It is called
the leading strand. The other
strand is discontinuous called
lagging strand (5’ 3’
direction) and form fragments
called Okazaki fragments.
16. DNA REPLICATION: TERMINATION
During termination, primers are
removed and replaced with
new DNA nucleotides and the
backbone is sealed by the
enzyme ligase. After the ligase
has connected all the nicks, the
newly synthesized DNA
molecule is complete.
17. DNA REPLICATION: TERMINATION
During termination, primers are
removed and replaced with
new DNA nucleotides and the
backbone is sealed by the
enzyme ligase. After the ligase
has connected all the nicks, the
newly synthesized DNA
molecule is complete.
18. CENTRAL DOGMA OF MOLECULAR BIOLOGY
REPLICATION TRANSCRIPTION TRANSLATION
PROTEIN
SYNTHESIS
19. TRANSCRIPTION
Transcription is the process by which the information
is transferred from one strand of the DNA to RNA by
the enzyme RNA Polymerase.
The DNA strand that synthesizes the RNA is called
the template strand and the other strand is called
the coding strand.
The RNA polymerase reads and adds nucleotides
from 3’5’ direction.
20. RNA Polymerase -
RNA polymerase is a
multi-unit enzyme that
synthesizes RNA
molecules from a
template of DNA.
ENZYME IN TRANSCRIPTION
21. TRANSCRIPTION: INITIATION
RNA polymerase binds to a
specific sequence within the gene
called promoter.
As the RNA polymerase moves
along from 3’5’ direction, the
DNA unwinds.
Half of the DNA strand will act as
the template strand or the
antisense strand and will be used
to synthesize the RNA.
22. TRANSCRIPTION: ELONGATION
RNA polymerase reads the
antisense strand from 3’5’
direction and catalyzes the
addition of ribose nucleotides
to the antisense strand
synthesizing the pre-mRNA
strand. The RNA strand is built
from 5’ to 3’.
23. TRANSCRIPTION: TERMINATION
At the end of the gene,
RNA polymerase
encounters a sequence of
DNA called the termination
signal. RNA polymerase
detaches from the DNA
and releases the pre-
mRNA molecule.
24. mRNA PROCESSING
ADDITION OF 5’ CAP
POLYADENYLATION
INTRON SPLICING
The 5’cap is a modified
guanine (G)
nucleotide, and it
protects the transcript
from being broken
down.
The enzyme poly(A)
polymerase adds a
chain of 100-250
adenine nucleotides
to the pre-mRNA.
The enzyme
spliceosome cuts the
introns (non-coding
regions), exons
(coding regions are
spliced together by the
same enzyme.
25.
26. CENTRAL DOGMA OF MOLECULAR BIOLOGY
REPLICATION TRANSCRIPTION TRANSLATION
27. TRANSLATION
Translation is the process by which the mRNA codes for
specific proteins.
It is an active process which requires energy. This
energy is provided by the charged tRNA molecules.
The bases (3s’) on the mRNA (codons) will code for a
specific amino acid.
28. mRNA (messenger RNA) - the genetic material that
codes for specific amino acids.
tRNA (transfer RNA) – helps decode the mRNA, carry
amino acids to the ribosome during protein synthesis.
Ribosomal units - composed of two subunits with
densities of 50S and 30S, translate the codons in mRNA
and serve as a factory where a growing polypeptide chain
is assembled.
MATERIALS FOR TRANSLATION
29. Codon - A sequence of three consecutive nucleotides in a DNA
or RNA molecule that codes for a specific amino acid.
Amino acids – building blocks of proteins, 20 amino acids
make up proteins found in the human body.
Polypeptide - is a string of amino acids connected together by
peptide bonds. They make up proteins.
Proteins - serve as structural support, biochemical catalysts,
hormones, enzymes, building blocks, and initiators of cellular
death.
TRANSLATION TERMINOLOGIES
31. TRANSLATION: INITIATION
The tRNA (Transfer RNA)
brings the corresponding
amino acid to each codon as
the ribosomal units moves
along the mRNA strand.
32. TRANSLATION: TERMINATION
Reading of the final mRNA codon
(stop codons) which ends the
synthesis of the polypeptide chain
and release it.
The release factor signals the
ribosomal units to terminate the
translation and release the
polypeptide chain.
34. AMINO ACIDS
An amino acid is an organic
chemical with carbon-
hydrogen bonds.
Amino acids are the monomers
that make up proteins.
Amino acid chains are bonded
by peptide bonds.
36. AMINO ACIDS
Though more than 200 amino
acids are identified in nature,
only 20 amino acids serve as
building blocks of body
proteins.
They are known as common
amino acids.
44. KARYOTYPING
Karyotyping is a diagnostic
tool used in medical
genetics to examine the
chromosomes of an
individual to detect any
abnormalities.
45. KARYOTYPING TECHNIQUES
To make a karyotype,
scientists take a picture of
the chromosomes from a
cell and arrange them in
terms of:
a. Size
b. Banding pattern
c. Centromere positions
46. KARYOTYPING
It involves arranging and analyzing the
chromosomes from a cell sample to create a visual
representation of the chromosome complement, known
as a karyogram.
It is an important tool in identifying genetic disorders,
determining the sex of an individual, and studying
evolutionary relationships between species.
47. LETS TRY!
Which of the following is best pair
of this chromosome?
A B C D
48. LETS TRY!
Which of the following is best pair
of this chromosome?
A B C D
49. LETS TRY!
Which of the following is best pair
of this chromosome?
A B C D
51. HUMAN CHROMOSOMES
Humans typically have 23
pairs of chromosomes, or 46
chromosomes in total.
Any missing or excess
chromosome results to
chromosomal
abnormalities.
52. FACTORS OF CHROMOSOMAL ABSNORMALITIES
Chromosome abnormalities often
happen due to 1 or more of these:
Errors during dividing of sex cells
(meiosis)
Errors during dividing of other cells
(mitosis)
53. TRISOMY 21
Down syndrome is a genetic condition
where a person is born with an extra
copy of chromosome 21.
This can affect how their brain and
body develop.
The majority of Down syndrome
cases happen randomly
(sporadically).
54. TURNER SYNDROME
Turner syndrome happens when a baby assigned
female at birth is born with one missing or partial X
chromosome.
Monosomy X: This type means each cell has only one
X chromosome instead of two.
Mosaic Turner syndrome: An individual’s cell have a
pair of X chromosomes, while other cells only have one
55. TURNER SYNDROME
Turner syndrome presents
in many ways.
It can cause several
different characteristics —
or features — as well as
certain health conditions,
which can vary in severity.
56. EDWARDS SYNDROME
Trisomy 18, also called Edwards
syndrome, is a chromosomal
condition associated with
abnormalities in many parts of the
body.
Individuals with trisomy 18 often
have slow growth before birth
(intrauterine growth retardation)
and a low birth weight.
57. PATAU SYNDROME
Trisomy 13, also called
Patau syndrome, is a severe
chromosomal condition, with
multiple malformations due
to an additional copy of all or
part of chromosome 13.
The cause of this additional
copy of chromosome 13 is
unknown.
58. KLINEFELTER SYNDROME
Klinefelter syndrome is a
common genetic condition in
which people assigned male
at birth (AMAB) have an
additional X chromosome.
Symptoms may include
breast growth, infertility,
osteoporosis and learning
difficulties.
Editor's Notes
The replication fork is a very active area where DNA replication takes place.
The numbers 3′ and 5′ refer to the number of carbon atoms in a deoxyribose sugar molecule that a phosphate group binds to.
E-P-A site ( Aminoacyl site, peptidyl site, exit site)
