DNA RNA

A chemical bond
involving the
sharing of electron
pairs between
atoms

A chemical bond
involving the
sharing of electron
pairs between
atoms

HEREDITY:

INHERITANCE and

VARIATION

DNA

DNA is double strand
Can be found in the nucleus
3 Types of Component Molecule:

1 Phosphate group


1 Sugar Deoxyribose


1 Bases; Adenine, Thymine, Cytosine

and Guanine (A, T, C, G)

A pairs with T
G pairs with C

RNA

 A Single strand

 Can be found in the cytoplasm

 Sugar is Ribose

 4 Nitrogenous Bases

 Uracil (U) paired with Adenine

 G with C
3 Types of RNA

 mRNA

 rRNA

 tRNA

Replication

 James Watson and Frances Crick worked

out that DNA is DOUBLE HELIX like a
twisted staircase.

 REPLICATION is the process of making

copies of DNA.

 As DNA replicates, two identical copies

of DNA molecule are produced, same as
the origin.

Process of Replication

Step 1, An enzyme called helicase
breaks the bond between nitrogenous
bases. The two strands of DNA split.

Process of Replication

Step 2. The bases attached to each
strand then pair up with the free
nucleotides found in the
cytoplasm.

 Step 3. The complementary nucleotides

are added to each strand by DNA
polymerase to form new strands. Two
new DNA molecules, each with a parent
strand and each with a new strand are
formed. The DNA replication is known as
semi-conservative

replication,

because

one

of

the

old

strands

is

conserved in each new molecule.

Replication is the process by which
a double-stranded DNA molecule
is copied to produce two identical
DNA molecules. DNA replication
is one of the most basic processes
that occurs within a cell.

 The following is the base sequence

replicated on one strand of a DNA
molecule.

 Exampe:
G A G C C C T C A A T C - DNA molecule

strand

C T C G G G A G T T A G - Replicated

TRANSCRIPTION

The order of nucleotides in DNA

determines the order of
nucleotides in messenger RNA in
a process called transcription.

RNA

RNA molecules or the workers

for

protein

synthesis

get

the

instructions from the DNA on
how

the

protein

should

be

assembled.

mRNA

messenger RNA (mRNA) brings

information from the DNA in the
nucleus

to

the

protein

manufacturing area, the cytoplasm.

In

the

cytoplasm,

the

mRNA

becomes

the

template

of

information to make proteins.

rRNA

Ribosomes, made

of

ribosomal

RNA

(rRNA),

and

ribosomal

proteins

hold

tightly

into

the

mRNA using its information to
assemble

the

amino

acids

in

correct order.

tRNA

Transfer RNA (tRNA) supplies

amino acids to the ribosome to
be assembled as protein.

The mRNA carries the
information in DNA to the
ribosomes found in the
cytoplasm.

If the replicated strand
transcribed into an mRNA, what
would be the resulting strand?

 Example:
C T C G G G A G T T A G - Replicated

strand

G A G C C C U C A A U C -Transcribed

strand

TRANSLATION

The process of converting the

information in messenger RNA into
a sequence of amino acids that
make a protein is known as
translation.

The role of transfer RNA (tRNA) is

to bring the amino acids in the
cytoplasm to the ribosomes to
make proteins.

The DNA directs the production

of proteins and determines the
formation of mRNA.

The order of bases of mRNA

determines the protein
synthesized.

 Example:
G A G C C C U C A A U C -Transcribed

strand

C UC G G G A G U U A G - translated

strand

 These process makes nucleotides

constitute a unit known as the CODON,
which codes for an amino acid.

 The sequence of codons in the mRNA

determines the sequence of amino acids
in the protein.

Activity:

Activity:

The following is the base sequence on one strand of a
DNA molecule:

A AT G C C A G T G GT

1. If this strand is replicated, which of the following is
the complementary strand that is produced?
a. T C G T C C G T C T A G c. T T A C G G T C A C C A
b. A G C A G G C A G G G T d. U C G U C C U C U A G A

2. If transcribed into an mRNA, what would be the
resulting strand?
a. U U A C G G U C A C C A c. A G C A G G C A G A U C
b. A G C A G G A G A T C d. T C G T C C G T C T A G

What are the amino acids of the

ff

:

 3. CGU

 4. UCA

 5. UCG

 6. AGC

 7. CAA

 8. GAU

 9. AGA

 10. GGG