|
|
Lecture Learning Tools Hub |
Students are required to read the textbook for the instructor to be able to teach the concepts the course encompasses. (From FOUNDATION SKILLS in the Biology Department Master Syllabus.)
Students, do not just read these notes, to succeed in this class -- at least if you wish to have a high grade, you MUST use your textbook as a LEARNING TOOL!
MAIN TOPICS OUTLINE
11.1 DNA STRUCTURE AND FUNCTION
11.11 Important properties of DNA
11.12 Nucleic Acid Structure (DNA & RNA structure)
11.2 FROM DNA TO PROTEINS
11.21 DNA Replication
11.22 DNA Transcription
11.23 DNA Translation (Protein synthesis)
11.3 MUTAGENS
LECTURE OBJECTIVES
1. Recognize the structure of DNA and RNA
2. Distinguish between DNA, chromatin, and chromosome.
3. Explain the DNA replication process.
4. Explain the DNA transcription process.
5. Explain the process of translation
6. Give examples of mutagenic agents and how they might affect DNA.
7. Define selected key terms.
Key Terms:
def. Adenine: A purine, a nitrogen base in certain nucleotides (in both DNA and RNA).
def. Chromosome: long molecule of DNA & proteins, that contains the genes, found in the nucleus of eukaryotic cells
def. Cytosine: A pyrimidine, a nitrogen base in certain nucleotides (in both DNA and RNA).
def. Gene: Unit of heredity, the portion of DNA that determines characteristics (traits)
def. Guanine: A purine, a nitrogen base in certain nucleotides (in both DNA and RNA).
def. Mutation: A rare change in the DNA that ultimately creates genetic diversity.
def. Nucleotides: Structural units (building blocks) of nucleic acids.
def. Protein Synthesis: The process whereby tRNA utilizes mRNA as a guide to arrange amino acids in proper sequence according to the genetic information in the chemical code of DNA.
def. Purine: Type of nitrogen base in a nucleotide with a double ring structure, e.g., adenine and guanine.
def. Pyrimidine: Type of nitrogen base in a nucleotide with a single ring structure, e.g., thymine, cytosine, and uracil.
def. Replication: The process of DNA duplicating itself.
def. Thymine: A pyrimidine, a nitrogen base in certain nucleotides (in DNA only).
def. Transcription: The transfer of information from DNA into an RNA molecule.
def. Translation: The transfer of information from an RNA molecule into a polypeptide, involving a change of language from nucleic acids to amino acids.
def. Uracil: A pyrimidine, a nitrogen base in certain nucleotides (in RNA only).
def. DNA (Deoxyribonucleic Acid): Double stranded, helical nucleic acid molecule capable of replicating and determining the (inherited) structure of a proteins.
def. RNA (Ribonucleic Acid): Single stranded nucleic acid molecule that functions in the protein synthesis.
11.1 DNA STRUCTURE AND FUNCTION
 |
 |
 |
 |
11.11 Important properties of DNA
i. Chemical properties of DNA
DNA can change chemically -- mutate– allows genetic variety
chemical changes on DNA can be stored– allow for a change to be retained permanently
chemical changes on DNA can be transmitted – allow changes to be passed on to future generations
DNA structure is universal (the genetic code is universal)– allows us to understand evolutionary relationships
ii. Properties (processes) involving the Genetic Code
DNA can be replicated (the molecule can be duplicated)
– allows for cell division
DNA can be expressed (the information stored in DNA can be communicated so that it has meaning)a. DNA can be transcribed (the information stored in DNA transfered to RNA)– allows the message from the code to reach the locations in the cytoplasm where proteins are madeb. DNA can be translated (the information stored in the nucleic acid molecule can be converted into information with meaning in protein molecules "translated from a nucleotide language to an amino acid language).– allows protein synthesis |
 |
 |
11.12 Nucleic Acid Structure (DNA & RNA structure)
i. The Molecules (building blocks)
1. DNA (made and functions in the nucleus)
Double molecule (two comb-like, helical strands)
Building blocks: Nucleotides, which are composed of
Deoxyribose
Phosphate
Nitrogen bases: adenine, guanine, cytosine & thymine
|
|
 |
 |
 |
 |
 |
2. RNA (these molecules are made in the nucleus but function in the cytoplasm)
Single molecule (one non-helical strand)
Building blocks: Nucleotides, which are composed of
Ribose
Phosphate
Nitrogen bases: adenine, guanine, cytosine & uracil
|
 |
 |
ii. Complementary Base Pairing
In DNA and RNA the nitrogen bases always pairs the same way -- as complementary base pairs.
The Complementary Base Pairing at
REPLICATION (when DNA is duplicated)
TRANSCRIPTION (when RNA is made)
TRANSLATION (when proteins are made):
DNA: adenine -- thymine guanine -- cytosine
RNA: adenine -- uracil guanine -- cytosine
|
 |
 |
 |
|
11.2 FROM DNA TO PROTEINS
1. Replication (duplication of DNA)
2a. Transcription (portion DNA used as a template to make RNA)
2b. Translation (of mRNA -- protein synthesis)
|
|
|
-----------------------------------------------------------------------------------------------------------
11.21 DNA REPLICATION
Minimum Reading Assignment: Replication of DNA (Mader ed. 7, p. 226 + Fig. 14.7, or Mader ed. 8, p. 230 + Fig. 13.7, or Mader Lab Manual Molecular Genetics Chapter [the introductory pages]) (The above is the absolute MINIMUM suggested by your instructor.)
NOTE: Students are required to read the textbook for the instructor to be able to teach the concepts the course encompasses. (From FOUNDATION SKILLS in the STCC Biology Department Master Syllabus.) To succeed in this class -- at least if you wish to have a high grade, you MUST use your textbook as a LEARNING TOOL!
All cells must have a complete set of DNA, therefore, before a cell can divide it must duplicate the DNA, so that each new daughter cell also will have a complete set of DNA after going through cell division. This process of duplicating the DNA is called:
-- REPLICATION.
The replication process uses the process called Complementary Base Pairing and the already existing bases on the original DNA as a template for the new DNA.
The replication process occurs in the S stage of the cell cycle and gives two identical DNA molecules in the cell, which makes for a typical duplicated chromosome as it appears in the M stage of the cell cycle.
Human cells has 46 chromosomes, consisting of about 5 million base pairs.
Yet there is only as few errors as
5 errors / cell.
The replication process is therefore considered almost error free. However, there may be some serious or even deadly errors.
|
|
 |
|
|
-----------------------------------------------------------------------------------------------------------
11.22 DNA TRANSCRIPTION
Minimum Reading Assignment: Replication of DNA (Mader ed. 7, p. 238 + Fig. 15.6 and Fig. 15.12, or Mader ed. 8, p. 242 + Fig. 14.6 and Fig. 14.12, or Mader Lab Manual Molecular Genetics Chapter [the introductory pages]) (The above is the absolute MINIMUM suggested by your instructor.)
NOTE: Students are required to read the textbook for the instructor to be able to teach the concepts the course encompasses. (From FOUNDATION SKILLS in the STCC Biology Department Master Syllabus.) To succeed in this class -- at least if you wish to have a high grade, you MUST use your textbook as a LEARNING TOOL!
The synthesis of proteins is under genetic control. The nucleus contains genes (on the DNA molecule) which code for the synthesis of specific proteins, which in turn determines physical and chemical characteristics of an organism.
• The information from DNA is inside the nucleus
- cannot be taken out
- but info must somehow be conveyed to the cytoplasm
where the protein synthesis occurs.
There is:
One (1) DNA molecule
DNA -- long, double stranded -- contain instructions for synthesizing all proteins needed by the cells
There are:
Three (3) RNA molecules
mRNA -- A short, single stranded copy of specific sections of DNA -- can pass through the pores in the nuclear envelope hook up with a ribosome in the cytoplasm or on the Endoplasmic reticulum
tRNA -- clover shaped short, single stranded -- finds specific Amino Acids (building blocks of proteins) and deliver them to the correct position when a protein is being synthesized.
rRNA -- -- short, single stranded part of the ribosomes
The mRNA, tRNA & rRNA are made in the nucleus but perform their functions in the cytoplasm. This process of making RNA is called:
-- TRANSCRIPTION.
|
|
|
|
|
|
-----------------------------------------------------------------------------------------------------------
11.23 DNA TRANSLATION (Protein Synthesis)
Minimum Reading Assignment: Replication of DNA (Mader ed. 7, p. 237 [first paragraph] + Fig. 15.5, p. 240 + Fig. 15.9, Fig. 15.10 and Fig. 15.12, or Mader ed. 8, p. 241 [first paragraph] + Fig. 14.5, p. 244 + Fig. 14.9, Fig. 14.10 and Fig. 14.12, or Mader Lab Manual Molecular Genetics Chapter [the introductory pages]) (The above is the absolute MINIMUM suggested by your instructor.)
NOTE: Students are required to read the textbook for the instructor to be able to teach the concepts the course encompasses. (From FOUNDATION SKILLS in the STCC Biology Department Master Syllabus.) To succeed in this class -- at least if you wish to have a high grade, you MUST use your textbook as a LEARNING TOOL!
• Messenger RNA attached to ribosomes “translate” genetic information to make proteins.
- The information on mRNA is a copy of the Code (DNA) -- written in nucleotide language (The building blocks of nucleic acids: nucleotides)
- The information is used to synthesize proteins -- translation from a nucleotide language to a protein language. (The building blocks of proteins: amino Acids)
• Proteins are made of amino acids
- There are 20 amino acids used to construct all proteins.
• The construction site of proteins are on the ribosomes where mRNA meet tRNA.
-- tRNA carry an amino acid
-- which amino acid depends on the anticodon -- 3 bases on the tRNA, which match with a codon -- 3 bases on the mRNA
• Definitions:
1. a triplet nucleotide sequence on DNA: code (the genetic code)
2. a triplet nucleotide sequence on mRNA: codon
3. a triplet nucleotide sequence on tRNA,
complementary to the codon: anticodon
This process of making proteins is called:
-- TRANSLATION.
The proteins may be utilized in the cell (for various cellular functions), or may be transported through the Endoplasmic Reticulum and the Golgi Apparatus where they may undergo final processing and packaging into secretory vesicles and eventually become incorporated into the plasma membrane or be secreted (exported out of the cell).
|
|
 |
 |
|
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
• The following received the Nobel Price in 1963 for finding the structure of DNA in 1952-53:
James Watson, Francis Crick, and Maurice Wilkins, (Rosalind Franklin also credited but died in 1958)
|
|
|
|
|
|
|
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
11.3 MUTAGENS
def. Mutagens: An environmental agent that can permanently modify the structure of a DNA molecule.
def. Mutation: A heritable change in the DNA.
• If a DNA sequence is altered, the protein made will also be altered. A completely different protein may be formed.
Some changes may result in heritable changes -- mutations.
Some mutations are good, some are bad. If these changes occur in the sex cells (sperms and eggs) they can be passed on to the next generation.
• Mutagenic Agents: Chemicals that can alter DNA.
UV-rays (e.g., sunlight)
radiation (e.g., X-rays)
pesticides
nicotine
"street drugs" (e.g. LSD)
viruses
|
|
|
 |
 |
-------------
QUESTION: Do we all have the same DNA?
• Every living organism reproducing sexually -- except identical twins -- has unique DNA
-- identical twins (same egg, identical DNA -- clones, same sex)
-- fraternal twins (different eggs, different DNA, may be different sex)
-- DNA fingerprinting
• Each species has different but similar DNA
|
 |
 |
|
 |
 |
 |
 |
 |
4_GB_11_LabEx_1