CELL CYCLE, DNA REPLICATION AND MITOSIS Amoeba Sister: Cell Cycle https:// www.youtube.com/watch?v=gwcwSZIfKlM
CELL CYCLE, DNA REPLICATION AND MITOSIS
Amoeba Sister: Cell Cycle
https://www.youtube.com/watch?v=gwcwSZIfKlM
The Cell CycleP M A T Cyto-
kinesis
G1 – 1st period of growth 1. Increase in size2. Makes new proteins and
organelles.
CELL CYCLE, DNA REPLICATION AND MITOSIS
Reasons why cells divide:
1. Repair
2. Replace old or damage cells
3. Reproduction
Cellular GrowthCopyright © McGraw-Hill Education
Cell Size Limitations
Ratio of surface area to volume
• Smaller cells can transport substances more easily
• Diffusion is inefficient over longer distances
• Cytoskeleton less efficient when cells are larger
• Cellular communication more efficient in smaller cells
Works
Better
Cellular GrowthCopyright © McGraw-Hill Education
The Cell Cycle
• Three main stages of the cell cycle:
• Interphase: stage during which the cells grows, carries out cellular
functions, and replicates its DNA.
• Mitosis: the cell’s nucleus and nuclear material divide; has four
substages.
• Cytokinesis: cell’s cytoplasm divides, creating two new cells.
CELL CYCLEIS THE SERIES OF EVENTS THAT TAKE PLACE IN A CELL LEADING TO ITS DIVISION AND DUPLICATION (REPLICATION) THAT PRODUCES TWO DAUGHTER CELLS.
G0
The Cell Cycle
Eukaryotic cells divide via the
cell cycle.
Prokaryotic cells divide via
binary fission.
CELL CYCLE
The sequence of growth and division of a cell
An average cycle may be 22 hours
Two general periods:
1. growth phase (interphase)
2. division phase (mitosis)
INTERPHASE (GROWTH PHASE)
Most of the cell’s life is spent in interphase
Longest phase –(90% of cell’s growth)
Centrioles – help to organize cell division
Chromatin – DNA bound protein within the nucleus
The Cell CycleP M A T Cyto-
kinesis
G1 – 1st period of growth 1. Increase in size2. Makes new proteins and
organelles.
INTERPHASE (GROWTH PHASE)
G1 – 1st period of growth
1. Increase in size.
2. Makes new proteins and
organelles.
G0 – Resting Phase
1. If cells don’t go into this phase it could
cause cancer (tumor)
S – DNA is synthesized or replicated
1. Chromosomes are replicated.
2. New DNA molecules are made.
G2 – final cell growth
1. Shortest phase
2. Prepares cell for mitosis
Not a part of Interphase
Mitosis –Cell Division
Cytokinesis- Division on the cytoplasm (2 new cells)
New DNA is formed during 4 phases:
The Cell CycleP M A T Cyto-
kinesis
G1 – 1st period of growth 1. Increase in size2. Makes new proteins and
organelles.
CELL CYCLE
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WHERE HAVE SCIENTISTS BEEN?A BRIEF HISTORY
Oswald Avery (1944) Discovered that the
nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next
ERWIN CHARGAFF (1950)
Discovered a relationship in the nitrogenous bases
Adenine (A) = Thymine (T)
Guanine (G) = Cytosine (C)
ALFRED HERSHEY & MARTHA CHASE (1952)
Concluded that the genetic material of the bacteriophage was DNA, not protein.
Used radioactive phosphorous and sulfur.
ROSALIND FRANKLIN (1952)
Took an x-ray of the DNA structure so the patterns could be seen.
The x-rays show that DNA is twisted around each other like a helix and has two strands.
(1953)Watson and Crick proposed that DNA is made up of 2 chains of nucleotides held together
by nitrogenous bases & that the 2 strands are twisted together in a shape called a double helix.
DNA REPLICATION: AMOEBA SISTERS
https://www.youtube.com/watch?v=5qSrmeiWsuc&index=26&list=PLvLzbk8R9i4go1-xj7jLqELF2WhbZ4XlM
1. What is the name of this monomer?
2. What is the name of the polymer or
macromolecule to which this monomer
belongs?
REVISIT PRI0R KNOWLEDGE
THE STRUCTURE OF DNA
DNA is a polymer made up of repeating monomers of nucleotides.
DNA determines an organism’s traits by controlling the manufacturing of proteins.
The sequencing of nucleotides forms unique genetic information.
OVERVIEW OF DNA
Order from smallest to largest
DNA Double Helix-Nucleosome-Coils-Supercoils-Chromosome
Eukaryotic chromosomes contain DNA wrapped around proteins called Histones.
Chromosome
Solenoid
Histone Proteins
DNA Double Helix
Each nucleotide is
constructed of 3
parts:
a PHOSPHATE group,
a SUGAR molecule
&
1 of 4 nitrogen bases
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Purines
Pyrimidines
DNA REPLICATION
Copying process by which a cell duplicates its DNA
DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing
Each strand of the double helix of DNA serves as a template for the new strand
Enzyme (Helicase) unzips DNA by breaking the hydrogen bonds between the base pairs, which produces two replication forks
DNA polymerase
Joins individual nucleotides to make a new strand.
Proofreads each new strand.
Joins the hydrogen bonds
Ligase: Enzyme creating the covalent bond that connect the sugar phosphate backbone.
Because of the
hydrogen bonds,
Adenine can only
bond with Thymine
& Guanine can only
bond with Cytosine
*A purine is always paired with a
pyrimidine.
Thymine
Adenine
Cytosine
Guanine
G2 PHASE
G2 – final cell growth1. Shortest phase2. Prepares cell for mitosis3. Check for no mistakes in the chromosomes4. Repairs any Mistakes
TERMS TO KNOW
Chromosome – contains genetic information (DNA) passed from one generation to the next
Spindle – microtubule that helps separate chromosomes
A – Centromere:
center of chromosome
B – Chromatids: two
identical “sister” parts
of the chromosome
MITOSIS(DIVISION PHASE OF BODY CELLS)
4 Phases:
(PMAT)
1)Prophase
2)Metaphase
3)Anaphase
4)Telophase
MITOSIS ACRONYM
Mitosis only
Passed (prophase)
My (metaphase)
Algebra (anaphase)
Test (telophase)
All cell cycle
I (interphase)
Passed (prophase)
My (metaphase)
Algebra (anaphase)
Test (telophase)
Corrections (cytokinesis)
CYTOKINESIS
Animal cells
The cell membrane is drawn inward forming a cleavagefurrow until the cytoplasm is pinched into 2 nearly equal parts
Plant cells
A cell plate gradually develops into a separating membrane.
CELL CYCLE AND CANCER
https://www.youtube.com/watch?v=IeUANxFVXKc&list=PL3Tg4mErzFVdvHixfoagIBFUWHGNoIgZ4
CANCER
Cancer is a disorder where the cell has uncontrolled growth. (Does not go into the G0 phase
Cancer cells do NOT respond to regulators that control timing of cell cycle (cyclins).
This causes the cells to form masses called tumors, which can damage surrounding tissues.
Growing out of control, cancer cells produce malignant tumors
Cancer cells do not respond normally to the cell cycle control system
Divide excessively
Can invade other tissues
May kill the organism
If an abnormal cell avoids destruction by the immune system, it may form a tumor
Benign: abnormal cells remain at original site
Malignant: abnormal cells can spread to other tissues and parts of the body
Metastasis: spread of cancer cells through the circulatory system
Cancers are named according to location of origin
Carcinoma: external or internal body coverings
Sarcoma: tissues that support the body
Leukemia and lymphoma: blood-forming tissues
Radiation and chemotherapy are effective as cancer treatments because they interfere with cell division
METASTASIZING CANCER CELL
LUNG CANCER CELLS