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GENETIC MATERIAL Nucleic Acids: DNA & RNA
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CELL DIVISION
WHY DO CELLS UNDERGO CELL DIVISION?
1. The Cell Becomes Too Large• DNA/Information Overload• Exchange with the environment (traffic/diffusion
problems).2. Repair and Growth 3. Reproduction
• Asexual Reproduction
GENETIC MATERIALNucleic Acids: DNA & RNA
THE NUCLEIC ACIDS
• Store and transmit hereditary, or genetic, information.
• Contain hydrogen, carbon, nitrogen, oxygen, and phosphorus.
• The monomers of nucleic acids are nucleotides, which contain three parts: a 5-carbon sugar, a phosphate group, and a nitrogen base.
• Examples: Deoxyribonucleic Acid and Ribonucleic Acid
COMPARING DNA & RNADNA RNA
NAME: Deoxyribonucleic Acid Ribonucleic Acid
STRAND: Double Stranded (Helical)
Single-Stranded (Helical)
NITROGENOUSBASES:
Adenine (A), Guanine (G), Cytosine (C) &
Thymine (T)
Adenine (A), Guanine (G), Cytosine (C), & Uracil (U)
SUGAR: Deoxyribose Ribose
PHOSPHATE GROUP:
YES YES
OTHER: In Eukaryotes, DNA associated with Protein
Messenger RNA (mRNA), Transfer RNA (tRNA),
Ribosomal RNA (rRNA)
DNA & RNA STRUCTURE GAME(S)
17 Things You Should Know About DNA
EUKARYOTIC VS PROKARYOTIC DNA
EUKARYOTES PROKARYOTESDNA is found within a nucleus
DNA is confined to the nucleoid region
DNA is associated with proteins called histones.
“Naked” DNA
DNA REPLICATION
DNA REPLICATION INVOLVES “UNZIPPING”
• DNA Replication is the process by which DNA copies itself. We would say that DNA is ‘self-replicating.’ DNA copies DNA.
• The process of DNA Replication involves a number of important enzymes . . . We will focus on DNA Helicase and a group of enzymes called DNA Polymerases.
• DNA Replication is considered ‘Semi-Conservative.’
DNA REPLICATION IS A SEMI-CONSERVATIVE PROCESS
• DNA Replication results in two identical copies of DNA.
• Half of a pre-existing DNA molecule is always saved (conserved).
FORMATION OF TWO COMPLIMENTARY STRANDS
• DNA replication will occur during cell division (interphase) within the nucleus.
• Replication requires free nucleotides that form the new DNA strands.
With the help of the enzyme DNA Helicase, the original double-stranded DNA molecule will “unzip”. Helicase will break the hydrogen bonds holding complimentary base pairs
together.(A2T, G3C).
. . . .FORMATION OF COMPLIMENTARY STRANDS
• As soon as the DNA becomes ‘unzipped’, free-floating nucleotides will be covalently bonded to nucleotides on the template strands.
• Another enzyme, DNA polymerase, will catalyze this reaction (dehydration synthesis). DNA polymerase will operate on both strands but in opposite directions.
• This process can occur at multiple points (origin of replication or replication bubble) along the DNA strand.
DNA & DNA REPLICATION TUTORIALS
CELL DIVISION
LIFE SPAN OF HUMAN CELLS
Cell Type Life Span Cell DivisionEsophageal 2-3 days Can divideIntestinal (small) 1-2 days Can divideIntestinal (large) 6 days Can divideRed Blood Cells <120 days Can’t DivideWhite Blood Cells 10 hrs-decades Many don’t
div.Smooth Muscle Long-lived Can divideHeart Cells Long-lived Can’t DivideSkeletal Muscle Long-lived Can’t DivideNeurons Long-lived Most don’t
div.
CELL DIVISION: AN OVERVIEW
INTERPHASE
PROPHASE, METAPHASE, ANAPHASE, TELOPHASE
CYTOKINESIS IN ANIMALS AND PLANTS
MITOSIS ANIMATION(S)
• http://outreach.mcb.harvard.edu/animations/cellcycle.swf
• http://www.youtube.com/watch?v=7hQ5xXJSmK4&feature=related
• http://www.youtube.com/watch?v=VGV3fv-uZYI
REGULATING THE CELL CYCLE
The cell cycle is controlled by dozens of regulatory proteins inside and outside the cell:
1. Internal regulators: proteins that respond to signals inside the cell. (ex. Cyclins)
2. External regulators: proteins that respond to signals outside the cell. Growth factors are important in wound healing and embryonic development.
• http://outreach.mcb.harvard.edu/animations/checkpoints.swf
Cancer cells are your own body cells that divide Cancer cells don’t respond to signals regulating the cell cycle.
Cancer risk is increased through: genetics, tobacco use, radiation exposure, ultraviolet radiation, poor diet, viral infections,
chemicals, pollution, etc.
WHAT IS CANCER?
WHAT ARE TUMORS?A tumor (neoplasm) is an abnormal growth of tissue that can
be:
Malignant: An unusually fast-growing, sometimes fatal tumor that invades surrounding tissue and sheds cells that spread throughout the body, creating new tumors. Cancerous.
Benign: A well-defined, slow-growing mass with smooth boundaries that simply grows in diameter. Not harmful unless it’s size compresses surrounding tissues. Benign tumors are non-cancerous.
Cells may break away from malignant tumors and spread throughout the body (Metastasis or Secondary Cancer)
HOW DO WE TREAT CANCER?• Biopsy: Surgical removal of cells/a mass for
identification.• Surgery (Removal of a malignant tumor)• Radiation Therapy (kills cells)• Chemotherapy with anti-mitotic drugs)• But . . . Sometimes there is no treatment.
What are some of the Side Effects of Cancer Treatment?(Sterility, Hair Loss, Pain Destruction of non-cancerous cells, Nausea,
Vomiting, Depression . . . )