LIFE122 STUDY NOTES
UNIT 1
NUCLEOTIDE MONOMER OF A NUCLEIC ACID, CONSISTS OF 3 COMPONENTS :
NITROGENOUS BASES (PURINE OR PYRIMIDINE BASES), 5 CARBON-SUGAR
MOLECULE, PHOSPHATE BACKBONE.
NUCLEIC ACID POLYMER THAT IS MADE UP OF NUCLEOTIDES. EXAMPLES OF NUCLEIC
ACIDS ARE: DNA AND RNA
PURINE BASES NITROGENOUS BASES THAT ARE LARGE, HAS 2 RING STRUCTURE
COMPOSED OF 5 AND 6 MEMEBRED NITROGEN CONTAINING RING;
ADENINE AND GUANINE ARE EXAMPLES
PYRIMIDINE BASES NITROGENOUS BASES THAT ARE SMALLER THAN PURINE BASES AND HAVE
A SINGLE STRANDED 6 MEMEBERED NITROGEN CONTAINING RING;
URACIL, THYMINE AND CYTOSINE ARE EXAMPLES
DNA/DEOXYRIBONUCLEIC A NUCLEIC ACID THAT CARRIES GENETIC MATERIAL OF AN ORGANISM
ACID LONG-TERM AND THE INSTRUCTIONS NEEDED FOR PROTEIN
SYNTHESIS.MADE UP OF DEOXYRIBOSE SUGAR, PHOSPHATE BACKBONE,
HAS A DOUBLE HELIX AND NITROGENOUS BASES (ADENINE, THYMINE,
CYTOSINE,GUANINE)
RNA/RIBONUCLEIC ACID IS A NUCLEIC ACID THAT HAS A ROLE IN THE SYNTHESIS OF PROTEINS; IT IS
MADE UP OF RIBOSE SUGAR, PHOSPHATE BACKBONE AND NITROGENOUS
BASES (ADENINE, URACIL,CYTOSINE, GUANINE)
COMPLEMENTARY BASE REFERS TO THE SPECIFIC PAIRING OF NITROGENOUS BASES
PAIRING
GENETIC CODE IS THE SET OF INSTRUCTIONS ENCODED IN A GENE THAT IS NEEDED OF
PROTEIN SYNTHESIS
MRNA; MESSENGER RNA IS A TEMPORARY COPY OF A GENE THAT CARRIES THE GENETIC CODE FOR
PROTEIN SYNTHESIS FROM THE NUCLEUS TO THE RIBOSOMES LOCATED IN
THE CYTOPLASM. mRNA HAS CODONS.
CODONS CODONS ARE THE 3 BASE SEQUENCE THAT CODES FOR A SPECIFIC AMINO
ACID. CODONS ALSO SIGNAL THE START AND STOP OF PROTEIN
SYNTHESIS.
START CODON IS AT THE START OF EVERY GENE ,USUALLY AUG, AND IT SIGNALS THE START
OF PROTEIN SYNTHESIS
STOP CODON IS AT THE END OF EVERY GENE, USUALLY UAA/UAG/UGA, THESE 3 BASES
DO NOT CODE FOR AMINO ACID, THE SIGNAL WHERE POLYPEPTIDE CHAIN
ENDS
tRNA; TRANSFER RNA S SINGLE STRANDED BUT IS FOLDED IN THE SHAPE OF A CLOVERLEAF AND
IS HELD BY HYDROGEN BONDS; ITS ROLE IS TO CARRY AMINO ACIDS TO
THE RIBSOMES IN THE CYTOPLASM. LOCATION OF tRNA IS THE
CYTOPLASM. tRNA HAS THE ANTICODON.
, ANTICODON ANTICODON IS THE 3 BASE SEQUENCE THAT ATTACHES TO SPECIFIC
AMINO ACIDS THAT IS COMPLEMENTARY TO IT.
rRNA; RIBSOMAL RNA IS MADE IN THE NUCLEOLUS; COMBINES WITH RIBSOMAL PROTEINS TO
FORM SUBUNITS; THE LARGE SUBUNIT CARRIES THE RYBOZYME, THAT IS
NEEDED ALONG WITH ATP TO FORM PEPTIDE BONDS BETWEEN ADJACENT
AMINO ACIDS THAT ARE ASSEMBLED BY THE RIBOSOMES IN A CHAIN
RIBOSOME ORGANELLE THAT IS THE BINDING SITE FOR MRNA AND TRNA; READS
MRNA SEQUENCE AND ASSEMBLES THE AMINO ACIDS BOUGHT BY THE
TRNA MOLECULES IN A CHAIN, FORMING A POLYPEPTIDE CHAIN. BINDS TO
MRNA AT THE START CODON AND ONCE IT REACHES THE STOP CODON IT
STOPS ASSEMBLING AMINO ACID AND THE COMPLETED POLYPEPTIDE
CHAIN IS RELEASED
DNA VS RNA. THE DIFFERENCES BETWEEN DNA AND RNA
DNA RNA
Composed of deoxyribose sugar Composed of ribose sugar
Has a double helix form Has a single stranded form
Has thymine that is a pyrimidine base Has uracil that is a pyrimidine bases
Adenine and Thymine pair. Guanine and Cytosine Adenine and Uracil pair. Guanine and Cytosine pair
pair
CARRIES INSTRUCTIONS FOR PROTEIN SYNTHESIS HAS 3 TYPES (MRNA, TRNA, RRNA); PLAYS A ROLE IN
AND STORES GENETIC MATERIAL AND INFO OF THE PROTEIN SYNTHESIS
ORGANISM LONG TERM
DNA AND RNA. THE SIMILARITIES OF RNA AND DNA
Both are nucleic acids that consist of nucleotides
Both have bases that pair complementary and with hydrogen bonds between the base pairs
Both are composed of the 3 nitrogenous bases: Adenine, Cytosine, Guanine
, DNA REPLICATION is the process by which a cell makes an exact copy of its DNA
DNA replication is SEMI-CONSERVATIVE; each new DNA molecule has one old strand and one new strand.
ENZYMES INVOLVED IN DNA REPLICATION
E
1)DNA IS UNWINDED
1. TOPO-ISOMERASE UNWINDS DNA, RELIEVES SUPERCOILING
2.DNA HELICASE UNWINDS THE DOUBLE
3. HELIX OF DNA, CREATING A REPLICATION FORK AND 2 STRANDS
4. SSB, SINGLE STRANDED BINDING PROTEIN PREVENTS
DOUBLE HELIX FROM REFORMING
2)COMPLEMENTARY BASE PAIRING
1. RNA PRIMER IS NEEDED FOR DNA POLYMERASE TO BE ABLE TO SYNTHESIZE STRANDS
2. DNA PRIMASE SYNTHESIZES SHORT RNA PRIMERS, RNA PRIMERS MARK THE START OF DNA SYNTHESIS
3. NEW NUCLEOTIDES ARE ALLOWED TO PAIR COMPLEMENTARY WITH THE BASES ON OLD STRANDS DNA
4. POLYMERASE PROOFREADS THE AND CORRECTS ANY MISTAKES ON THE STRANDS
3) OKAZAKI FRAGMENTS AND JOINING OF THE DNA
1. DNA POLYMERASE SYNTHESIZES NEW STRANDS AND REPLACES THE RNA PRIMERS WITH DNA
2. ON THE LEADING STRAND REPLICATION IS CONTINOUS AS REPLICATION OCCURS IN THE 5 TO 3
DIRECTION
AS DNA POLYMERASE REPLACES RNA PRIMERS WITH DNA
3. BUT ON THE LAGGING STRAND, IT IS SYNTHESIZED DISCONTINOUSLY AS IT IS IN THE OPPOSITE
DIRECTION
OF THE REPLICATION FORK, SO DNA POLYMERASE EXTENDS THE RNA PRIMERS TO FORM OKAZAKI
FRAGMENTS (SEGMENTS OF DNA SYTHESIZED DISCONTINOUSLY ON THE LAGGING STRAND)
, 4. DNA LIGASE JOINS THE OKAZAKI FRAGEMENTS, LEADING TO THE FORMATION OF 2 DOUBLE HELIX DNA
MOLECULES, IDENTICAL TO ONE ANOTHER
PROTEIN SYNTHESIS is the process by which cells creates proteins, it involves two stages. Transcription and
Translation
THE GENETIC CODE are the instructions that cells use to build proteins up.
The genetic code has 3 features:
1. Degenerate/Degeneracy
This means that most amino acids have more than one codon. There are 20 amino acids that the genetic code
has to be able to code for. This degeneracy of the code helps protect against potentially harmful mutations
2. Unambiguous
Each triplet codon has only one meaning; each codon codes for only one specific amino acid.
3. Non-overlapping
Code is read continuous starting from the stop codon to the stop codon. There is one start signal/start codon (it
is AUG) and 3 stop signals/3 stop codons (UAA, UAG, UGA)
HOW TO READ AN AMINO ACID WHEEL
1. LOOK AT THE FIRST LETTER OF THE
CODE/CODON, THE FIRST LETTERS ON THE
WHEEL IS IN THE MIDDLE. G-U-A-C
EXAMPLE A.
2. LOOK AT THE SECOND LETTER OF THE
CODE/CODON, THE SECOND LETTER YOU
READ OFF THE WHEEL FROM WHERE YOU
READ THE FIRST LETTER.
EXAMPLE: G
3. LOOK AT THE THIRD LETTER OF THE
CODE/CODON, THE THIRD LETTER YOUR
READ FROM WHERE YOU READ THE
SECOND LETTER
EXAMPLE: C
SO THE AMINO ACID IS: SERINE
AMINO ACID WHEEL
AMINO ACID CODE TABLE
UNIT 1
NUCLEOTIDE MONOMER OF A NUCLEIC ACID, CONSISTS OF 3 COMPONENTS :
NITROGENOUS BASES (PURINE OR PYRIMIDINE BASES), 5 CARBON-SUGAR
MOLECULE, PHOSPHATE BACKBONE.
NUCLEIC ACID POLYMER THAT IS MADE UP OF NUCLEOTIDES. EXAMPLES OF NUCLEIC
ACIDS ARE: DNA AND RNA
PURINE BASES NITROGENOUS BASES THAT ARE LARGE, HAS 2 RING STRUCTURE
COMPOSED OF 5 AND 6 MEMEBRED NITROGEN CONTAINING RING;
ADENINE AND GUANINE ARE EXAMPLES
PYRIMIDINE BASES NITROGENOUS BASES THAT ARE SMALLER THAN PURINE BASES AND HAVE
A SINGLE STRANDED 6 MEMEBERED NITROGEN CONTAINING RING;
URACIL, THYMINE AND CYTOSINE ARE EXAMPLES
DNA/DEOXYRIBONUCLEIC A NUCLEIC ACID THAT CARRIES GENETIC MATERIAL OF AN ORGANISM
ACID LONG-TERM AND THE INSTRUCTIONS NEEDED FOR PROTEIN
SYNTHESIS.MADE UP OF DEOXYRIBOSE SUGAR, PHOSPHATE BACKBONE,
HAS A DOUBLE HELIX AND NITROGENOUS BASES (ADENINE, THYMINE,
CYTOSINE,GUANINE)
RNA/RIBONUCLEIC ACID IS A NUCLEIC ACID THAT HAS A ROLE IN THE SYNTHESIS OF PROTEINS; IT IS
MADE UP OF RIBOSE SUGAR, PHOSPHATE BACKBONE AND NITROGENOUS
BASES (ADENINE, URACIL,CYTOSINE, GUANINE)
COMPLEMENTARY BASE REFERS TO THE SPECIFIC PAIRING OF NITROGENOUS BASES
PAIRING
GENETIC CODE IS THE SET OF INSTRUCTIONS ENCODED IN A GENE THAT IS NEEDED OF
PROTEIN SYNTHESIS
MRNA; MESSENGER RNA IS A TEMPORARY COPY OF A GENE THAT CARRIES THE GENETIC CODE FOR
PROTEIN SYNTHESIS FROM THE NUCLEUS TO THE RIBOSOMES LOCATED IN
THE CYTOPLASM. mRNA HAS CODONS.
CODONS CODONS ARE THE 3 BASE SEQUENCE THAT CODES FOR A SPECIFIC AMINO
ACID. CODONS ALSO SIGNAL THE START AND STOP OF PROTEIN
SYNTHESIS.
START CODON IS AT THE START OF EVERY GENE ,USUALLY AUG, AND IT SIGNALS THE START
OF PROTEIN SYNTHESIS
STOP CODON IS AT THE END OF EVERY GENE, USUALLY UAA/UAG/UGA, THESE 3 BASES
DO NOT CODE FOR AMINO ACID, THE SIGNAL WHERE POLYPEPTIDE CHAIN
ENDS
tRNA; TRANSFER RNA S SINGLE STRANDED BUT IS FOLDED IN THE SHAPE OF A CLOVERLEAF AND
IS HELD BY HYDROGEN BONDS; ITS ROLE IS TO CARRY AMINO ACIDS TO
THE RIBSOMES IN THE CYTOPLASM. LOCATION OF tRNA IS THE
CYTOPLASM. tRNA HAS THE ANTICODON.
, ANTICODON ANTICODON IS THE 3 BASE SEQUENCE THAT ATTACHES TO SPECIFIC
AMINO ACIDS THAT IS COMPLEMENTARY TO IT.
rRNA; RIBSOMAL RNA IS MADE IN THE NUCLEOLUS; COMBINES WITH RIBSOMAL PROTEINS TO
FORM SUBUNITS; THE LARGE SUBUNIT CARRIES THE RYBOZYME, THAT IS
NEEDED ALONG WITH ATP TO FORM PEPTIDE BONDS BETWEEN ADJACENT
AMINO ACIDS THAT ARE ASSEMBLED BY THE RIBOSOMES IN A CHAIN
RIBOSOME ORGANELLE THAT IS THE BINDING SITE FOR MRNA AND TRNA; READS
MRNA SEQUENCE AND ASSEMBLES THE AMINO ACIDS BOUGHT BY THE
TRNA MOLECULES IN A CHAIN, FORMING A POLYPEPTIDE CHAIN. BINDS TO
MRNA AT THE START CODON AND ONCE IT REACHES THE STOP CODON IT
STOPS ASSEMBLING AMINO ACID AND THE COMPLETED POLYPEPTIDE
CHAIN IS RELEASED
DNA VS RNA. THE DIFFERENCES BETWEEN DNA AND RNA
DNA RNA
Composed of deoxyribose sugar Composed of ribose sugar
Has a double helix form Has a single stranded form
Has thymine that is a pyrimidine base Has uracil that is a pyrimidine bases
Adenine and Thymine pair. Guanine and Cytosine Adenine and Uracil pair. Guanine and Cytosine pair
pair
CARRIES INSTRUCTIONS FOR PROTEIN SYNTHESIS HAS 3 TYPES (MRNA, TRNA, RRNA); PLAYS A ROLE IN
AND STORES GENETIC MATERIAL AND INFO OF THE PROTEIN SYNTHESIS
ORGANISM LONG TERM
DNA AND RNA. THE SIMILARITIES OF RNA AND DNA
Both are nucleic acids that consist of nucleotides
Both have bases that pair complementary and with hydrogen bonds between the base pairs
Both are composed of the 3 nitrogenous bases: Adenine, Cytosine, Guanine
, DNA REPLICATION is the process by which a cell makes an exact copy of its DNA
DNA replication is SEMI-CONSERVATIVE; each new DNA molecule has one old strand and one new strand.
ENZYMES INVOLVED IN DNA REPLICATION
E
1)DNA IS UNWINDED
1. TOPO-ISOMERASE UNWINDS DNA, RELIEVES SUPERCOILING
2.DNA HELICASE UNWINDS THE DOUBLE
3. HELIX OF DNA, CREATING A REPLICATION FORK AND 2 STRANDS
4. SSB, SINGLE STRANDED BINDING PROTEIN PREVENTS
DOUBLE HELIX FROM REFORMING
2)COMPLEMENTARY BASE PAIRING
1. RNA PRIMER IS NEEDED FOR DNA POLYMERASE TO BE ABLE TO SYNTHESIZE STRANDS
2. DNA PRIMASE SYNTHESIZES SHORT RNA PRIMERS, RNA PRIMERS MARK THE START OF DNA SYNTHESIS
3. NEW NUCLEOTIDES ARE ALLOWED TO PAIR COMPLEMENTARY WITH THE BASES ON OLD STRANDS DNA
4. POLYMERASE PROOFREADS THE AND CORRECTS ANY MISTAKES ON THE STRANDS
3) OKAZAKI FRAGMENTS AND JOINING OF THE DNA
1. DNA POLYMERASE SYNTHESIZES NEW STRANDS AND REPLACES THE RNA PRIMERS WITH DNA
2. ON THE LEADING STRAND REPLICATION IS CONTINOUS AS REPLICATION OCCURS IN THE 5 TO 3
DIRECTION
AS DNA POLYMERASE REPLACES RNA PRIMERS WITH DNA
3. BUT ON THE LAGGING STRAND, IT IS SYNTHESIZED DISCONTINOUSLY AS IT IS IN THE OPPOSITE
DIRECTION
OF THE REPLICATION FORK, SO DNA POLYMERASE EXTENDS THE RNA PRIMERS TO FORM OKAZAKI
FRAGMENTS (SEGMENTS OF DNA SYTHESIZED DISCONTINOUSLY ON THE LAGGING STRAND)
, 4. DNA LIGASE JOINS THE OKAZAKI FRAGEMENTS, LEADING TO THE FORMATION OF 2 DOUBLE HELIX DNA
MOLECULES, IDENTICAL TO ONE ANOTHER
PROTEIN SYNTHESIS is the process by which cells creates proteins, it involves two stages. Transcription and
Translation
THE GENETIC CODE are the instructions that cells use to build proteins up.
The genetic code has 3 features:
1. Degenerate/Degeneracy
This means that most amino acids have more than one codon. There are 20 amino acids that the genetic code
has to be able to code for. This degeneracy of the code helps protect against potentially harmful mutations
2. Unambiguous
Each triplet codon has only one meaning; each codon codes for only one specific amino acid.
3. Non-overlapping
Code is read continuous starting from the stop codon to the stop codon. There is one start signal/start codon (it
is AUG) and 3 stop signals/3 stop codons (UAA, UAG, UGA)
HOW TO READ AN AMINO ACID WHEEL
1. LOOK AT THE FIRST LETTER OF THE
CODE/CODON, THE FIRST LETTERS ON THE
WHEEL IS IN THE MIDDLE. G-U-A-C
EXAMPLE A.
2. LOOK AT THE SECOND LETTER OF THE
CODE/CODON, THE SECOND LETTER YOU
READ OFF THE WHEEL FROM WHERE YOU
READ THE FIRST LETTER.
EXAMPLE: G
3. LOOK AT THE THIRD LETTER OF THE
CODE/CODON, THE THIRD LETTER YOUR
READ FROM WHERE YOU READ THE
SECOND LETTER
EXAMPLE: C
SO THE AMINO ACID IS: SERINE
AMINO ACID WHEEL
AMINO ACID CODE TABLE
