Transcript DNA - benanbiology

Nucleic Acids
• Monomer = Nucleotides
• Functions
Store & Transmit the Information to
Make Proteins = DNA and RNA in the
nucleus and cytoplasm
TYPES OF
NUCLEIC ACIDS
DNA
(Deoxyribonucleic acid )
RNA
( Ribonucleic acid )
3.16 Nucleic acids are information-rich polymers of
nucleotides
• DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid) are composed of monomers
called nucleotides
– Nucleotides have three parts
– A five-carbon sugar called ribose in RNA and deoxyribose
in DNA
– A phosphate group
– A nitrogenous base
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Nitrogenous
base
(A,G,C,T,U)
Phosphate
group
Sugar (can be ribose or deoxyribose)
• Nucleotides are joined together by dehydration
synthesis.
• Firstly base and sugar get together and form
nucleoside.
• Then nucleoside and phosphoric acid join and
form nucleotide.
1.Organic base+Pentose
2. Nucleoside + Phosphate
Nucleoside+Water
Nucleotide+Water
P
S
Base
Nucleoside
Nucleotide
Nucleotide
Sugar-phosphate
backbone
Property
Location
DNA
Nucleus, mitochondria,
chloroplasts,
Bases
A,T,G,C
RNA
Cytoplasm,
mitochondria,
chloroplasts, nucleus,
ribosomes
U,A,G,C
Sugar (5C)
Phosphate
Number of
chains
Replication
Deoxribose
same
2 (double stranded)
Ribose
same
1(single strand)
Kinds
Yes
1
Function
Store genetic codes
No
3 mRNA(messenger),
tRNA(transfer),
rRNA(ribosomal)
Protein synthesis
DNA
RNA
3.16 Nucleic acids are information-rich polymers of
nucleotides
• Two polynucleotide strands wrap around each
other to form a DNA double helix
– The two strands are associated because particular
bases always hydrogen bond to one another
– A pairs with T, and C pairs with G, producing base
pairs
• RNA is usually a single polynucleotide strand
Copyright © 2009 Pearson Education, Inc.
Base
pair
3.16 Nucleic acids are information-rich polymers of
nucleotides
• A particular nucleotide sequence that can instruct
the formation of a polypeptide is called a gene
– Most DNA molecules consist of millions of base pairs
and, consequently, many genes
– These genes, many of which are unique to the species,
determine the structure of proteins and, thus, life’s
structures and functions
Copyright © 2009 Pearson Education, Inc.
DNA
• DNA molecular structure is established by
Watson and Crick in 1953 .
• There are two chains linked together in DNA
molecule.(Double stranded) . Nucleotides are
bound together by hydrogen bonds.
• A= T
G≡C
• If A number is equal to T number, then C
number equals to G number.
A+C =T+G
or
A+G=T+C
• Adenine nucleotide joins with onlyThymine with 2 H
bonds
• Guanine nucleotide joins with only Cytosine with 3 H
bonds
• ***So in a DNA molecule;
The number of Adenine =The number of Thymine
(A=T)
The number of Guanine =The number of Cytosine
(G≡C)
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Classification of bases
Purine
Pyrimidine
A
C
A
A
T
G
G
C
= T
≡ G
= T
= T
=A
≡C
≡ C
≡ G
A +G = 1
T+C
DNA chain
DNA complementary chain
Chargaff’s rule
2 rings
1 ring
PhosphoDiesther
bond
Esther
bonds
Glycoside
bond
Question
1. The order of nucleotides in a chain of DNA is
AGCTTA.
a. What is the order of nucleotides in the
complementary chain of this DNA?
b. What is the total number of hydrogen bonds
between chains?
1. a. DNA
AGCTTA
Complementary DNA TCGAAT
b. between A= T there should be 2 bonds
between G ≡ C there should be 3 bonds.
So A= T 2 x 4 = 8 bonds ,
G ≡C 3x2=6
8 + 6 = 14 total hydrogen bonds.
There are 3600 nucleotides in a DNA molecule. If 400 of
them are adenine, Find
a. The number of the other nucleotides.
b. Give number of purines and pyrimidines.
c. the number of deoxyribose sugars and
phosphate groups.
a. . A= 400 so T= 400 too. 400+400= 800
3600 – 800= 2800 2800 / 2 = 1400 Guanine and
1400 Cytosine
b. A, G are purines 400 + 1400 = 1800 purines
C, T are pyrimidines 400 + 1400 = 1800 pyrimidines
c. Number of nucleotides = number of deoxribose = number of
phosphate
3600 nucleotides = 3600 deoxyribose = 3600 phosphate
3. In a DNA molecule there are 1000 pairs of nucleotide. If
300 of them are guanine, what is the number of T?
• 1000 pairs of nucleotide= 2000 nucleotides
If G= C , then G+C= 600 nucleotides
2000-600= 1400 nucleotides= T+A
If T=A then T is 1400 / 2 = 700 nucleotides of T
In an experimental condition, there are 1500 A, 500 T,
1100 G, 800 C and 3000 deoxyribose and 3000
phosphate.
• How many nucleotides can be formed?
1500+500+1100+800= 3900 bases can be used but there are
only 3000 deoxyribose and phosphate only 3000 nucleotides
can be formed.
 How many nucleotide long DNA can be formed?
A should be equal to T
G should be equal to C because DNA is double chained.
If T number is 500, A=T= 500
G= C= 800 DNA should be 1300 nucleotides long
But we spent 2600 nucleotides because it is double stranded.!!
In a DNA molecule with 220 nucleotide,
there are 50 A, what is the number of
C?
• A= 50=T A+T= 100
• 220 – (A+T)= G+C
• 220- 100= 120= G+C if G= C
then
• G= 120 / 2= 60
In a DNA molecule 30 % of nucleotides are Guanine
,what is the percentage of Thymine?
• G= 30 % = C
C+G= 60 %
• 100 – (30+30)= A+T= 40 % if A=T
• T= 40/2= 20 %
In an experimental procedure 60 A, 80 T, 50 C, 50 G and
250 deoxiribose and phosphate molecules are found.
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How many nucleotide long DNA can be formed?
A should be equal to T
C should be equal to G
60 A 80T only 60 of then combine together to form
DNA double chain.
• 50 C 50 G all of C and G combine together.
60A=60T
+ 50C=50T
110 = 110 nucleotide long ; but 220 nucleotides are
used
If a DNA molecule has 6400 hydrogen bonds and 600 guanine
molecules ,What is the number of Thymine nucleotides?
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Guanine has 3 H bond with Cytosine
So 600 x 3 = 1800 H bond between G and C
The remaining bonds are between A and T
6400 – 1800 = 4600 bonds between A and T
There are 2 bonds between A and T
4600/2 = 2300 is the number of A = number of T
If G + C number is 600 and there are total 2600
deoxyribose molecules, What is the H bond number?
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If G + C = 600 , G should be 300.
The bonds between G and C = 300 x 3= 900
If G+C= 600 then A+T= 2600 – 600=2000
And A should be 1000
The bond between A and T = 1000 x 2= 2000
Total bond number = 2000+900=2900
Importance of nucleotides:
• DNA carries the genetic code of the organism.
Genetic code of each organism is different from
each other(except identical twins). Genetic
code differs in the base sequences.
• Each organism has same chromosome number
and same base sequence in his/her all cells.
• DNA can copy itself. This
process is necessary for cell
division. As a result each cell
will take equal amount of
DNA. The copying process is
called as replication. DNA
replication is a semi
conservative process. 2 chains
of the DNA open and each
strand replicates itself. As a
result each new DNA recieves
one old an done new strand.
• DNA also carries information for protein
synthesis in the cell. It sends message for
protein synthesis to the cytoplasm. These
processes are shown by this figure.
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DNA
Transcription
mRNA
Translation
Protein
• Replication
Replication always
occurs where the
DNA is.
Transcription also
always occurs where
the DNA is.
Translation also
always occurs where
the m RNA and
ribosomes are.
• DNA replication is a semi
conservative process. 2 chains of
the DNA open and each strand
replicates itself. As a result each
new DNA recieves one old and
one new strand.
• Replication occurs where the DNA
is.(In bacteria there is no nucleus
)
If a cell can’t divide, it can not replicate its DNA (sperm cells, nerve
cells, red blood cells)
•Transcription occurs where the DNA is, because it copies DNA
•Translation occurs where the ribosome is, because it needs
ribosomes.
RNA
• RNAs also are synthesized from DNA. RNAs are
important for protein synthesis. There are 3 types of
RNA.
• mRNA –messenger RNA. It carries information from
DNA to ribosome. The formed mRNA is
complementary to one of the strand of
DNA(meaningful strand) .
• r RNA-ribosomal RNA. It forms the ribosome
structure with proteins. It is synthesized from
nucleolus.
• t-RNA transfer RNA It carries aminoacids to
ribosomes for protein synthesis.
• TRANSFERING OF GENETIC CODE
• DNA
A C T - T A G
CODE
• m-RNA
• t-RNA
U G A -
A U C
CODON
A C U - U A G ANTICODON
• 3 nucleotides = 1 Codon = 1 Aminoacid
• Starting codon = AUG
• Stop codons = UAA ,UAG , UGA
VITAMINS
• Vitamins are a group of substances essential for normal
metabolism,
• growth and development, and
• regulation of cell function.
• Animals can’t synthesize vitamins but plants do.
• Most vitamins are taken as provitamins.
• Vitamins work together with enzymes, as co-enzymes
• They can be destroyed by light, high temperatures and
metals.
• Important in bone formation
• Blood cell formation, Blood clotting
• Prevents diseases, increase resistance of the body
Types of Vitamins
fat-soluble vitamins
• the vitamins are stored
in the fat tissues in
your body and in your
liver.
• They can be
poisonous.
• Vitamins A, D, E, and K
are all fat-soluble
vitamins.
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water-soluble vitamins
When you eat foods
that have watersoluble vitamins, the
vitamins don't get
stored in your body .
The excess is thrown
out by urine.
B group and C vitamins
are water soluble
A. FAT-SOLUBLE VITAMINS
A Helps you see at night (nightblindness)
D Helps make strong bones (rickets-rachitis)
E Protect your skin
K Helps stop bleeding (synthesized by the
bacteria in our intestine)
These vitamins are stored in the fatty tissues of
the body and liver for a few days, some of them
for months, until the body needs them.
B.WATER-SOLUBLE VITAMINS :
Vitamin C : Essential for immunity of
the body against cold and flu.(Scurvy)
Vitamin B complexes : Essential for
nerves ,joints, muscles and metabolism
Deficiency of Vitamin B1 : Beriberi
illness.
Deficiency of Vitamin B3 : Pellegra
illness.(Nervous system illness)
• Which one is not a property of vitamins?
a. They are not hydrolyzed(broken down)
b. They pass to blood easily
c. They give energy
d. They have regulatory function
e. They can activate enzymes
• Which statement is a common property for
vitamins A, B and C?
I.
II.
III.
IV.
They are lipid soluble
They are not stored in cells
They are not digested
They work as coenzymes
ENERGY MOLECULE
- ATP
• ATP is formed by cellular respiration. Every cell
needs energy as ATP (Adenosine Tri
Phosphate)
ATP
Phosphorylation
Formation of ATP by:
*Cellular respiration
Dephosphorylation
Using ATP for :
*photosynthesis
•Movement
•Dehydration(anabolism)
•Protein synthesis
ADP
• Which one of the following reactions need
(require) ATP?
a. Hydrolysis of a protein
b. Breakdown of starch to glucose
c. Production of lipid from fatty acid and
glycerol
d. Formation of aminoacids from protein
e. Digestion of glycogen
Structure of ATP
5C sugar- Ribose and Adenine base: they are called Adenosine
3 phosphate groups can be added to the adenosine. If one is added It
is Adenosine mono phosphate,
2- Adenosine di phosphate ; 3- Adenosine tri phosphate
• Which one of the statements is wrong about
ATP?
a) ATP is used and formed within the cell.
b) ATP is not stored
c) When ATP is broken down, adenine base,
deoxyribose sugar and P groups are formed
d) ATP is similar to RNA adenine nucleotide
e) ATP is used in anabolic reactions.
Function and importance of ATP
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Hydrolysis of 3rd bond gives 7300 cal.(7.3 kcal)
It is ONLY produced and used within the cell.
It can not be stored.
Hydrolysis gives out energy, dehydration takes in
energy.
• Used in dehydration reactions, muscle contraction,
nerve impulses not in hydrolysis.
• Phosphorylation: Adding P to ADP(occurs in cytoplasm,
mitochondria and chloroplasts) EXERGONIC
• Dephosphorylation: breaking P bond from ATP(occurs
in cytoplasm and chloroplasts and in
anabolic(dehydration reactions)) ENDERGONIC