The document provides an overview of molecular biology, focusing on the structures and functions of DNA and RNA, including key definitions and processes like transcription and translation. It explains the significance of DNA in genetics and its role in protein synthesis while detailing the differences between DNA and RNA. The document also covers the mechanisms of DNA replication, including the contributions of various enzymes and proteins involved.

1. DNA AND RNA
DONE BY DR AYA ALII

2. MOLECULAR BIOLOGY DEFINATION
• Molecular biology is a branch of biology that seeks to understand
the molecular basis of biological activity in and between cells,
including biomolecular synthesis, modification, mechanisms, and
interactions

3. SOME IMPORTANAT DEFINETION
• genome : genatic material of organism
_gene : part of dna that code for synthesis of single poly peptide
_polypeptide : polymer of amino acid that form protein
_codone :three successive nucleotide base that code for single pro
_intron : three successive nucleotide that dose not encode any amino
acid
_exon :sequence of codon which code number of amino acid
_ promoter :sequence of bases in dna near the start of the gene very
important in rna transcription
_cds : portion of the dna composed of exon that code for protein

5. DNA
• DNA IS ABLUEPRINT OF LIFE .
_DNA contain structure of protein synthesis in the cell
_dna is amolecules that carries the genetic instruction used in growth
development ,functioning reproduction of all known living organism
and many viruses
_one strand on dna in one chromosome can be up to 245 million base
pair long
_human have 46 chromosomes

6. Impotance of DNA
• It central importance to all life on earth
_medical benefit such as cure for diseases
_better food crops
_healing and regeneration
_growth and development

7. Chromosome
• It has been estimated that if all dna from just one cell of human body
was untwisted it would stretceh about 6 feet
_it mean that dna in one cell is about 100000 time longer than the
cell it self
_its all present in cell that represent 10% of cell volumes

9. _Chromosomes are found in the nucleus of every cell of our
bodyand are made up of DNA, tightly coiled around proteins. We
have23 pairs of chromosomes altogether, and they can only be
easily observed during cell division.
_ chromosome thread like structure of nucleic acid and protein
_chromatid each of two thread like strand into which chromosome
divide longtodinally during vell devesion connected to each other
by centromere
_chromatin the material of which the chromosome of organism are
composed consisting of dna and rna and protein

11. Dna component
• 1- suger
both dna and rna are composed of 5 carbon suger
the carbon on suger are numbered from one to five
suger molecule made up of C,H,O2 with molecule formuls CH2O
suger is closed to form ring structure
2_ phosphate group
link the 3 end of one nuvleotide to the 5 end of the next by phosphor
di_ ester bond
3_ nitrogen base
attached to carbon no 1
are two classes purines (adeninr and guanine )and pyrimidines (
cytosine and thyamine )

12. Building of nucleotide
• The suger is the central component of the nucleotide
_ the phosphate is attached to carbon number 5 of the suger
_the nitrogen base is attached to carbon number 1
_nucleotide within dna are connected by covalent bond
_ two dna strand are connected by hydrogen bond between
nucleotides
A=T (DOUBLE BOND )
C=G ( TRIPLE BOND )

13. BULIDING OF POLYMER
• _NUCLEOTIDE JOINED TOGETHER TO FORM POLYMER BY PHOSPHATE
GROUP BOND COVALENTELY WITH CARBON NO 3 IN SUGER
_HYDROEN BONDBETWEEN PHOSPHATE GROUP CAUSE DNA TO
TWIST
_BULIDING OF NUCLEOSOME
_dna coil tightly around protein called histone
-histone with phosphate bond together to form
nucleosome

15. DNA REPLICATION
• TRANSCRIPTION : the process by which the information in one
strand of dna is copied into new molecules of messenger rna
_ translation :occur in ribosomes when masenger rna translated
into protein
_DNA REPLICATION STEP
1) INTIATION
2)SYNTHESIS
3) TERMINATION
4) POST REPLICATIVE MODIFICATION OF DNA

16. 1) INTIATION PROCESS OF DNA
• Process begin at site origin of replication
_ first step to separate the two strand of dna by enzymes called
helicase enzymes result in formation of dna fork
_two strand each provide atemplete for new strand
_an enzymes called primase start the process
_this enzymes make asmall piece of rna called primer that marking
starting point for construction of the new strand of dna
_the enzymes called polymerase bind to the primer and will
make the new strand of dna from 5 to 3
_ single strand dna protein attached to dna strand to prevent
rewinding of dna

18. Synthesis phase
• Begin when rna primer with polymerase enzyemes add bases from 5
to 3 called leading phase
_the other strand the lagging strand cannot be made contioniously
because it run in opposite direction
_ the dna polymerase can make this strand in form of small fragement
called okzaki fragement
_ dna polymerase the add ashort row of dna bases in the 5 to 3
direction

19. Comparison between leading and lagging
_
from 3 to 5 prime
_contionous synthesis
_one rna
Lagging strand
•From 5 to 3
_dicontious
synthesis
_many rna prime
Leading strand

21. termination
• Once the dna strand has been made the enzyes called
exonuclease remove all rna primer from both strand
_ onather polymerase enzymes fill in the gap that are left
behind dna
_finally the dna ligase enzymes seal the fragment of the dna in
both strand to form continuous duble strand

24. Type of RNA
• MRNA
_ encode all information nessary for synthesis of polypeptide of
protein
intermediate carrier of genatic information deliver genatic material to
cytoplasm
TRNA
CARRY AMINO ACID TO THEIR POSITION ALONG MRNA TEMPLETE TO BE ADDED
BY GROWING POLYPEPTIDE CHAIN
Rrna
_the central component of ribosome
_it provide mechanism of decoding mrna into amino acid

25. COMPARISON BETWWEN DNA AND RNA
DNA
• DEOXY RIBONUCLEIC ACID
_LONG TERM STORAGE OF
GENATIC INFORMATION
_ TRANSIMITE OF GENATIC
MATERIAL TO MAKE OTHER CELL
AND NEW ORGANISM
RNA
• RIBO NUCLEIC ACID
_ USED TO TRANSFORM THE
GENATIC MATERIAL TO THE
CYTOPLASM
_MAY BE THE MOLECULES USED
TO STORE GENATIC MATERIAL IN
PRIMATIVE FORM

26. COMPARISON BETWWE DNA AND RNA
DNA
• _ DNA B FORM DOUBLE HELIX
_ dna is double stranded
molecules consisit of long chain
of nucleotides
_composition
deoxyribose SUGER
phosphate group
nitrogenous base
adenine guanine
cytosine thyamine
RNA
• A FORM HELIX
_Sdingle strand helix consist of
shorter chain of nucleotides
_composition
phosphate group AND RIBOSE
SUGER
nucleotide base
adenine
guanine
cytosine
uracil

27. Comparison betwwen DNA AND RNA
DNA
• SELF REPLICATING
_ BASES PAIR ( AT) ADENINE –
THYAMINE
(GC) GUANINE – CYTOSINE
_REACTIVITY : C-H BOND MAKE
IT MORE STABLES
_ BODY DESTROY ENZYMES
THAT ATTACK IT
_ SMALL GROOVES IN HELIX ACT
AS PROTECTION FOR DNA
RNA
• SYNTHESIS FROM DNA
_ BASES PAIR (ADENINE -URACIL)
(GUANINE –CYTOSINE )
_REACTIVITY : O-H BOND MAKE
IT MORE REACTIVE
_NOT STABLE UNDER ALKALINE
CONDITION
_LARGE GROOVE MAKE IT MORE
PRON TO ENZYMETIC ATTACK

28. DNA
• SUCCETIPLE TO UV DAMAGE
TRANSCRIPTION
RNA
• RESISTANCE TO UV DAMAGE
TRAANSLATION

29. PROTEINMOLECULES THAT SUPPORT GROWTH OF THE BODY DIVIDED INTO
• ESSENITIAL AMINO ACID :obtain from protein reach food as meat
_ non essential protein :synthesis naturally in your body
TYPE OF PROTEIN
1)PRIMARY : SEQUENCE OF CHAIN Of amino acid
2)secondary :chain of amino acid linked by hydrogen bond
3) teriary :occur when certain attraction occur between alpha helics and pleated
sheet
4) quaternary :protein containing more than chain of amino acid

32. Protein synthesis
• Intiantion :
mrna enter cytoplasm and become assossiated with ribosomes
trna each carry specific amino acid pair up with mrna codon iside
ribosome
paring of a-u and g-c between mrna and trna determine the order of
amino acid in protein

34. Elongation phase
•Addition of aminoacid one by one
_as the ribosomes move along the mrna each
trna transfer its amino acid to the growing chain
producing protein
TERMINATION PHASE
_when the ribosome hit stop codon ribosome
stop protein synthesis