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Review
Introduction
Main contents
Group discussions
Unless otherwise noted, all pictures are taken from wikipedia.org
Review 1
— 
Living cells assume which of the following shaped?
1. spheres
2. rectangles
3. spirals
4. polygons
5. all of the above
Review 1
— 
Living cells assume which of the following shaped?
1. spheres
2. rectangles
3. spirals
4. polygons
5. all of the above
Review 2
— 
The major type of molecule in the cell membrane is
1. phospholipid
2. proteins
3. carbohydrates
4. water
5. DNA
Review 2
— 
The major type of molecule in the cell membrane is
1. phospholipid
2. proteins
3. carbohydrates
4. water
5. DNA
Review 3
— 
Which type of molecule serves as special receptors in the cell
membrane?
1. phospholipids
2. carbohydrates
3. proteins
4. sugars
5. phosphoprotein
Review 3
— 
Which type of molecule serves as special receptors in the cell
membrane?
1. phospholipids
2. carbohydrates
3. proteins
4. sugars
5. phosphoprotein
Review 4
— 
The most prominent and important interior organelle of a cell is
the
1. nucleus
2. mitochondrion
3. ribosome
4. chloroplast
5. Golgi apparatus
Review 4
— 
The most prominent and important interior organelle of a cell is
the
1. nucleus
2. mitochondrion
3. ribosome
4. chloroplast
5. Golgi apparatus
Review 5
— 
The organelle that releases energy for metabolism is the
1. nucleus
2. mitochondrion
3. ribosome
4. chloroplast
5. vacuole
Review 5
— 
The organelle that releases energy for metabolism is the
1. nucleus
2. mitochondrion
3. ribosome
4. chloroplast
5. vacuole
DNA
Why do offsprings resemble their parents
: the genetic code - DNA
Today’s Keywords
genetics, nucleic acids, DNA, RNA,
double helix, gene, mRNA, tRNA, rRNA
Contents — 
Introduction: the birth of molecular genetics
— 
Nucleic acids
- Nucleic acids
- DNA
- DNA and RNA structures
— 
The Replication of DNA
— 
Transcription of DNA
— 
The Synthesis of Proteins
1. Introduction
1. Introduction
— 
Genetics: the study of the mechanism that passes genetic
information from parents to offspring
— 
The Birth of Molecular Genetics: By mid-20th C, biochemists
analyzed chromosomes (Recall cell divisions!) and showed they
that they are primarily DeoxyriboNucleic Acids
— 
Molecular genetics
: the study of the mechanism that passes genetic
information from parents to offspring at the molecule level
— 
Genes: the units in the cells of a living thing that control its
physical characteristics
Cell Division
Recall!
: cells divide and reproduce themselves by two separate
processes
1. 
2. 
Mitosis 体細胞分裂
Meiosis 減数分裂
The information of reproduction is in DNA which is
contained in an organelle chromosome in eukaryote cells
(chromosomes come in pairs, the number of pairs depends
on species: humans-23 pairs, dogs-39pairs, mosquitos-3pairs,
etc.)
2. Nucleic acids
2. Nucleic acids — 
— 
Nucleic acids: biological molecules essential for life, including DNA
and RNA
Nucleotides: the building blocks of nucleic acids, formed by a sugar,
a base, a phosphate group
2. Nucleic acids
Nucleic acids — 
— 
Nucleic acids: biological molecules essential for life, including DNA and RNA
Nucleotides: the building blocks of nucleic acids, formed by a sugar(S), a base,
a phosphate group(P)
nucleotide
— 
Nucleic acids are made by putting
nucleotides together in a long chain
(P’s and S’s are linked, making
a long strand à a half of a ladder shape)
nucleic acid
Nucleic acids — 
— 
2. Nucleic acids
Nucleic acids: biological molecules essential for life, including DNA and RNA
Nucleotides: the building blocks of nucleic acids, formed by a sugar(S), a base,
a phosphate group(P)
— 
— 
Nucleic acids are made by putting
nucleotides together in a long chain
(P’s and S’s are linked, making
a long strand à a half of a ladder shape)
In DNA,
there are four different types of basses,
presented by a singe letter:
A(adenine), T(thymine),
C(cytosine) and G(guanine)
nucleotide
Nucleic acids — 
— 
2. Nucleic acids
Nucleic acids: biological molecules essential for life, including DNA and RNA
Nucleotides: the building blocks of nucleic acids, formed by a sugar(S), a base,
a phosphate group(P)
— 
— 
Nucleic acids are made by putting
nucleotides together in a long chain
(P’s and S’s are linked, making
a long strand à a half of a ladder shape)
nucleotide
In DNA,
there are four different types of basses,
presented by a singe letter:
A(adenine), T(thymine),
C(cytosine) and G(guanine)
nucleic acid
2. Nucleic acids
DNA: consisting of two strands of nucleotides
(nucleic acids)
a nucleic acid
a nucleotide
2. Nucleic acids
DNA structure
— 
— 
— 
Sugar in DNA is deoxyribose (DNA: DeoxyriboNucleic Acid)
Bases sticking out to the sides of two nucleotides strands join together
Each type of base on one strand forms a bond with just a certain type of
base on the other strand: A – T, G – C.
Therefore, there are only four possible rungs that can exist in a DNA
ladder.
AT, TA, GC, CG
2. Nucleic acids
DNA structure: a spiral staircase shaped double helix
Each rung slightly
twisted
è  Spiral staircase
2. Nucleic acids
RNA structure
— 
RNA (RiboNucleic Acid) is very similar to DNA, but differ in
function.
— 
Differences in RNA structure from DNA structure
1. The shape of half the ladder
2. Sugar in RNA nucleotide is ribose
3. The base T is replaced by U (Uracil) in RNA bases
( èPossible pairs of nucleotide bases in RNA: A-U, C-G)
3. Replication of DNA
3. Replication of
DNA
— 
Before a cell divides, its DNA is replicated under support of enzymes
: DNA replication is one of the first steps in passing genetic information
from one generation to the next
— 
The replication of DNA is possible because each base has only one
partner
The procedure of replication
1. 
2. 
3. 
4. 
5. 
6. 
3. Replication of
DNA
The length of the DNA double helix about to be copied must be
unwound.
Then, the two strands must be separated, by breaking the weak
hydrogen bonds that link the paired bases. (Imagine both sides of a
zipper)
The separated strands of the DNA must be held apart to expose the
bases.
Each strand can be used as a pattern or template to produce a
complementary strand. The enzyme DNA polymerase then moves along the exposed DNA
strand, joining newly arrived nucleotides into a new DNA strand that
is complementary to the template.
Each template and its new complement together then form a new
DNA double helix, identical to the original. Replication of DNA
3. Replication of
DNA
Replication of DNA
3. Replication of
DNA
4. Transcription of
DNA
4. Transcription of DNA-the role of RNA
— 
DNA is the template for synthesis of RNA: transcription from DNA
to RAN is done under the aegis of enzymes
4. Transcription of
DNA
— 
The process of transcription of DNA
1. The DNA double helix unwinds (helicase).
2. RNA nucleotides are paired with complementary basses on a
strand of DNA.
3. Transcription starts at a particular location (promoter) where enzyme
RNA polymerase indicates RNA synthesis.
5. Hydrogen bonds of RNA+DNA break, freeing the newly synthesized
DNA.
— 
The new RNA is short so that it moves out through tiny pores of walls of
nucleus into the cell, with the information contained in the original DNA
strand
è messenger RNA (mRNA)
Transcription of DNA-the role of RNA
4. Transcription of
DNA
5. Synthesis of Proteins
— 
5. Synthesis of
proteins
One of DNA’s roles is to supply the information of mechanism of
chemical reactions within each individual cell, and the chemical
reactions are controlled by protein enzymes
è Q: How is cell chemistry regulated? = Q:?
5. Synthesis of Proteins
— 
5. Synthesis of
proteins
One of DNA’s roles is to supply the information of mechanism of
chemical reactions within each individual cell, and the chemical
reactions are controlled by protein enzymes
è Q: How is cell chemistry regulated? = Q: How can the information in
DNA be used
to produce proteins?
Q: How is cell chemistry regulated? = Q: How can the information in DNA be used
to produce proteins
— 
The process of protein synthesis
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
(Q: How many different kinds of tRNA molecules are possible? )
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
Q: How many different kinds of tRNA molecules are possible?
A: Four types are possible for an exposed base of a tRNA.
All 4 x 4 x 4 = 64 different kinds of tRNA molecules are possible.
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
genetic code table
from every possible
codon to one amino
acid
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
3. As tRNA molecules attach along the mRNA, a string of amino
acids in a specific order – a protein – is assembled
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
3. As tRNA molecules attach along the mRNA, a string of amino
acids in a specific order – a protein – is assembled
(Q: A string of amino acids is called what? – Recall the structure)
— 
The process of protein synthesis
5. Synthesis of
proteins
1. mRNA arrives at the place where proteins are synthesized, then
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
3. As tRNA molecules attach along the mRNA, a string of amino
acids in a specific order – a protein – is assembled
(Q: A string of amino acids is called what?)
A: The primary structure of protein
— 
The process of protein synthesis
1. mRNA arrives at the place where proteins are synthesized, then
5. Synthesis
of proteins
meet a second type of RNA, transfer RNA (tRNA)
tRNA: 3 exposed bases of RNA nucleotide + one amino acid
2. tRNA reads coded messages from codons on the sequence of bases
of mRNA codon: a set of 3 bases
è The set of 3 bases of a codon determines the single amino acid
of a tRNA
3. As tRNA molecules attach along the mRNA, a string of amino
acids in a specific order – a protein – is assembled
4. Once its amino acid has been incorporated into the protein, a tRNA
moves away to be used for another amino acid
à The place of protein synthesis is a ribosome, and the ribosome
attracts the appropriate tRNA and shift along the mRNA
Ribosome: An organelle composed of proteins + ribosomal RNA
(rRNA)
The Synthesis of Proteins
The Synthesis of Proteins
Today’s Keywords
genetics, nucleic acids, DNA, RNA,
double helix, gene, mRNA, tRNA, rRNA
(viruses, bacteria, human genome are in HW5)
Next lecture is on,
Recombination of DNA: Chapter 17
www.sci.hokudai.ac.jp/~epark/ekpark_e.html