Running head: Introduction to Biology 1
INTRODUCTION TO
BIOLOGY
Summary
Name
Institution
Course
Tutor
Date
,Introduction to Biology 2
Task 1 – Excursion to the international Museum for Family History
1) Structure of the DNA:
Most crucial evidence was obtained by x-ray crystallography method
Francis Crick and James Watson first described the structure of a double
helix
The DNA is helical with 2 polynucleotide chains
DNA is a polymer of nucleotides from which each nucleotide consists of a
molecule of the sugar deoxyribose, a phosphate group, and a nitrogen
containing base
Nitrogenous bases: Adenine; Guanine; Cytosine; Thymine;
A pyrimidine (T;C) is always paired with a purine (A;G) on opposite
strands (complementary base pairing)
The amount of (A)=(T) is equal and the amount of (G)≡(C) is equal
The strands run in opposite directions (antiparallel) (right-handed)
The nucleotide bases are on the interior of two strands, with a sugar-
phosphate backbone on the outside
Outer edges of the nitrogenous bases are exposed
The two chains are held together by hydrogen bonding between
(Chargaff’s rule)
A=T (two hydrogen bonds), G≡C (three hydrogen bonds) are equal of
length
(‘) designates the position of a carbon atom in the sugar
,Introduction to Biology 3
the phosphate groups are connected to 3’ carbon of one deoxyribose
molecule and the 5’ carbon of the next
At one end is a 5’phosphate group, at the other end is a 3’ hydroxyl group
The difference between ribonucleotide and deoxyribonucleotide is the
sugar
2) Detailed knowledge of DNA replication
DNA is replicated through the interaction of the template strand with a
huge protein complex called the replication complex, which contains at
least 4 proteins, including DNA polymerase (from 5’ to 3’)
Two steps in DNA Replication which involve a number of different
enzymes / proteins
The first event at the origin of replication is the localized unwinding and
separation of the DNA strands to make them available for new base
pairing
A necessary energy is required from ATP hydrolysis to unwind the
strands
Special proteins (single-strand binding proteins) bind to the unwound
strands to keep them from re-associating into a double helix
The leading strand grows continuously forward, but the lagging strand
grows into short discontinuous stretches of OKAZAKI fragments
As new nucleotides form complementary base pairs with template DNA,
they are covalently linked together by phosphodiester bonds, forming a
polymer whose base sequence is complementary to the bases in the
template strand
DNA polymerases add nucleotides to the growing chain, this elongates a
polynucleotide strand by covalently linking new nucleotides to a
previously existing strand
All chromosomes have a region called the origin of replication to which
the replication complex binds. The attachment occurs when proteins in the
, Introduction to Biology 4
complex recognize a specific DNA sequence within the origin of
replication
The starter strand is called primer (usually short single RNA strand,
sometimes DNA)
The primer is synthesized one nucleotide at a time by an enzyme called
primase
The DNA polymerase adds nucleotides to the 3’ end of the primer and
continues until the replication of that section of DNA has been completed
Then the RNA primer is degraded, DNA is added in its place, and the
resulting DNA fragments are connected by the action of other enzymes
3) Basic understanding of transcription and translation
Transcription is the first step of gene expression, in which a particular
segment of DNA is copied into RNA by the enzyme RNA polymerase
Translation is the decoding of mRNA by a ribosome to produce a specific
amino acid chain or polypeptide
Messenger RNA (mRNA): carries information from DNA to the ribosome
Transfer RNA (tRNA): transfers a specific amino acid to a growing
polypeptide chain
Ribosomal RNA (rRNA): catalytic component of the ribosomes
Anticodon: three nucleotides corresponding to three bases of the codon on
the mRNA
2% of our DNA is coding, 98% or non-coding
Task 2 – The Cell, The Basic Unit of Life
1) Differences between prokaryotic & Eukaryotic cells
INTRODUCTION TO
BIOLOGY
Summary
Name
Institution
Course
Tutor
Date
,Introduction to Biology 2
Task 1 – Excursion to the international Museum for Family History
1) Structure of the DNA:
Most crucial evidence was obtained by x-ray crystallography method
Francis Crick and James Watson first described the structure of a double
helix
The DNA is helical with 2 polynucleotide chains
DNA is a polymer of nucleotides from which each nucleotide consists of a
molecule of the sugar deoxyribose, a phosphate group, and a nitrogen
containing base
Nitrogenous bases: Adenine; Guanine; Cytosine; Thymine;
A pyrimidine (T;C) is always paired with a purine (A;G) on opposite
strands (complementary base pairing)
The amount of (A)=(T) is equal and the amount of (G)≡(C) is equal
The strands run in opposite directions (antiparallel) (right-handed)
The nucleotide bases are on the interior of two strands, with a sugar-
phosphate backbone on the outside
Outer edges of the nitrogenous bases are exposed
The two chains are held together by hydrogen bonding between
(Chargaff’s rule)
A=T (two hydrogen bonds), G≡C (three hydrogen bonds) are equal of
length
(‘) designates the position of a carbon atom in the sugar
,Introduction to Biology 3
the phosphate groups are connected to 3’ carbon of one deoxyribose
molecule and the 5’ carbon of the next
At one end is a 5’phosphate group, at the other end is a 3’ hydroxyl group
The difference between ribonucleotide and deoxyribonucleotide is the
sugar
2) Detailed knowledge of DNA replication
DNA is replicated through the interaction of the template strand with a
huge protein complex called the replication complex, which contains at
least 4 proteins, including DNA polymerase (from 5’ to 3’)
Two steps in DNA Replication which involve a number of different
enzymes / proteins
The first event at the origin of replication is the localized unwinding and
separation of the DNA strands to make them available for new base
pairing
A necessary energy is required from ATP hydrolysis to unwind the
strands
Special proteins (single-strand binding proteins) bind to the unwound
strands to keep them from re-associating into a double helix
The leading strand grows continuously forward, but the lagging strand
grows into short discontinuous stretches of OKAZAKI fragments
As new nucleotides form complementary base pairs with template DNA,
they are covalently linked together by phosphodiester bonds, forming a
polymer whose base sequence is complementary to the bases in the
template strand
DNA polymerases add nucleotides to the growing chain, this elongates a
polynucleotide strand by covalently linking new nucleotides to a
previously existing strand
All chromosomes have a region called the origin of replication to which
the replication complex binds. The attachment occurs when proteins in the
, Introduction to Biology 4
complex recognize a specific DNA sequence within the origin of
replication
The starter strand is called primer (usually short single RNA strand,
sometimes DNA)
The primer is synthesized one nucleotide at a time by an enzyme called
primase
The DNA polymerase adds nucleotides to the 3’ end of the primer and
continues until the replication of that section of DNA has been completed
Then the RNA primer is degraded, DNA is added in its place, and the
resulting DNA fragments are connected by the action of other enzymes
3) Basic understanding of transcription and translation
Transcription is the first step of gene expression, in which a particular
segment of DNA is copied into RNA by the enzyme RNA polymerase
Translation is the decoding of mRNA by a ribosome to produce a specific
amino acid chain or polypeptide
Messenger RNA (mRNA): carries information from DNA to the ribosome
Transfer RNA (tRNA): transfers a specific amino acid to a growing
polypeptide chain
Ribosomal RNA (rRNA): catalytic component of the ribosomes
Anticodon: three nucleotides corresponding to three bases of the codon on
the mRNA
2% of our DNA is coding, 98% or non-coding
Task 2 – The Cell, The Basic Unit of Life
1) Differences between prokaryotic & Eukaryotic cells
