Unit 5 Part B Cell Growth, Division and Reproduction
Cell Size Are whale cells the same size as sea stars cells? Yes!
Cell Size Limitations Cells that are too big will have difficulty diffusing materials through the cell. - Nutrients, water, and air must enter cell at an efficient rate and cells need to remove wastes from the cell quickly or else they will build up toxins Cytoskeleton cannot support the cell organelles Cellular communication decreases and is less efficient DNA will a limit a cell s size If cell is too big then DNA cannot make enough proteins to support the cell
Large Cell It takes more time for the nutrients to reach the center of this cell
Smaller cell It takes less time for the same nutrients to reach the center of this cell
Cell Size Limitations Ratio of surface area to volume Works Better Copyright McGraw-Hill Education Cellular Growth
How do cells solve this problem? As cell size increases too much- it can lead to death of a cell. It is important for cells to stay small so it can function properly by transporting materials in & out faster. ANSWER: Cells divide before they get too big!
CELL CYCLE IS THE SERIES OF EVENTS THAT TAKE PLACE IN A CELL LEADING TO ITS DIVISION AND DUPLICATION (REPLICATION) THAT PRODUCES TWO DAUGHTER CELLS. G 0 The Cell Cycle Eukaryotic cells divide via the cell cycle. Prokaryotic cells divide via binary fission.
Cell Division in Prokaryotes (No Nucleus) 9
Cell Division in Prokaryotes Prokaryotes such as bacteria divide by the asexual process of binary fission Parent cell Chromosome doubles Cell splits 2 identical daughter cells
Binary Fission Advantages for prokaryotes: Only requires a single organism to start Reproduce quickly and increase in population. Less energy usage Disadvantages: All new cells are clones (identical) so the only source of genetic variation is mutation 11
The Cell Cycle Process by which a cell grows and divides to produce IDENTICAL new cells All cells go through cell division. Cells divide before they become too big Average cycle for a cell is 22 hours.
Cells grow and divide SO that YOU can grow and Human life cycle reproduce
What are the TWO main phases of the cell cycle? Cell Cycle includes Interphase Mitosis is divided into is divided into G 1 phase S phase G 2 phase Prophase Metaphase Anaphase Telophase G 0 phase
Interphase: LONGEST (90%) phase of the cell cycle (G 1, G 0, S, G 2 Phase) Interphase: G 1 1 st growth cell increases size carries out normal life activities Ribosomes makes proteins
Cell Cycle Phases: G 0 G O Phase Resting phase No division Some cells never leave G O phase ex. Nerve cells (once it s gone- it s gone) Some cells never enter G O phase ex. Skin cells (constantly renewed) G 0
Interphase: S DNA Synthesis DNA Replication process by which DNA is copied to make 2 identical DNA molecules. Double the amount of chromosomes in cell (you must give new cells a copy of ALL the instructions)
Interphase: G 2 G 2 phase: The 2nd growth Cell prepares to divide (mitosis) cell s organelles are reproduced ex. Mitochondria, vacuole, golgi, chloroplast Needed proteins are produced to build.
Not a part of Interphase Mitosis Division of Cell Nucleus Cytokinesis- Division on the Cytoplasm (2 new cells)
Oswald Avery (1944) Discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next WHERE HAVE SCIENTISTS BEEN? A BRIEF HISTORY
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.
Deoxyribonucleic Acid (DNA) Words related to DNA: Nucleic Acids Chromosome Chromatin Chromosomal Genetic material Hereditary information Genes Alleles
Function of DNA: The master copy of an organism s information code that contains the instructions (blueprint) used to make proteins Determines how an organism looks and acts (traits)
Coiled (twisted) DNA Gene Trait Protein
DNA Structure A gene is a section of DNA that codes for a protein. Each unique gene has a unique sequence of bases. This unique sequence of bases will code for the production of a unique protein. It is these proteins and combination of proteins that give us different physical traits.
DNA Structure DeoxyriboNucleic Acid The DNA shape looks like a twisted ladder and is called a Double Helix. DNA is a polymer made up of millions of tiny monomers (subunits) called nucleotides. Each nucleotide has 3 parts: 1. Phosphate group 2. Deoxyribose sugar 3. 1 of 4 Nitrogenous bases
Draw and Label a nucleotide. Phosphate Nitrogenous Base Deoxyribose Sugar
Nucleotides The phosphate (P) and deoxyribose sugar (S) form the outside of the DNA molecule. P S P S P S P S P S P S P S P S P S P S N N N N N N N N N N S P S P S P S P S P S P S P S P S P S
Nucleotides The nitrogenous bases form the inside of the DNA molecule. P S P S P S P S P S P S P S P S P S P S N N N N N N N N N N S P S P S P S P S P S P S P S P S P S There are four types of nitrogenous bases.
Nucleotides A Adenine (Purine) T Thymine (Pyrimidine) C Cytosine (Pyrimidine) G Guanine (Purine)
Nucleotides Each base will only bond with one other specific base held together with hydrogen bonds. Adenine (A) Thymine (T) A = T Cytosine (C) Guanine (G) C = G Form a base pair. If there are 5 A s, how many T s are 5 there? Form a base pair. If there are 82 G s, how many C s 82 are there?
Because of the hydrogen bonds, Adenine can only bond with Thymine & Guanine can only bond with Cytosine Adenine Thymine *A purine is always paired with a pyrimidine. Guanine Cytosine
This is known as COMPLEMENTARY base pairing
A C T C T G A G A G T C T A
DNA Structure Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand. A G G - C T C - A A G - T C C - T A G T C C - G A G - T T C - A G G - A T C
DNA VIDEO: what is it and how does it work
DNA Replication (to copy) DNA has to be copied before new cells can be made in cell division. DNA Replication happens during the S phase or synthesis phase of the cell cycle All new cells have to be given a complete set of DNA instructions!
Without replication, new cells would NOT have a complete set of DNA instructions & the organism would not function.
DNA Replication Replication is semi-conservative (one strand is old, one strand new) This is to help prevent mistakes (mutations) in DNA. Think* You want to copy of Mickey Mouse. Is it easier to draw or trace?
Semi-Conservative= Tracing!
General Process of DNA Replication Step 1: Separation of strands. DNA has to unwind and unzip. DNA separates in the middle (weak hydrogen bonds). Helicase is the enzyme speeds the breaking of hydrogen bonds.
Step 2: Base pairing & Bonding of bases The free floating bases in the cytoplasm will attach to bases to the exposed DNA.
Step 2: Base pairing & bonding Remember bases bond A=T, C=G. Free nucleotides continue to pair up until the entire double strand of DNA has been copied DNA polymerase is the enzyme that builds and joins the nucleotides DNA is made out of an original strand with a new strand. This is called semi-conservative.
Step 3: Results of replication. Replication produces 2 IDENTICAL molecules of DNA. The polymers will twist back up. Now new daughter cells can be made!
Video
Whew- end of S phase BACK TO THE CELL CYCLE!!!
Mitosis and Cytokinesis
Mitosis Overview Shortest phase of Cell Cycle A eukaryotic cell divides to produce two daughter cells that are genetically identical to the parent cell. Parent cell Daughter cells have the SAME number of chromosomes as the parent cell
Mitosis is divided into 4 phases 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase
Prophase PREPARE Centrioles move to the opposite sides Spindle fibers form Visible chromatids (DNA) Nuclear envelope breaks down
Sister Chromatids are held together by a Centromere
Metaphase MIDDLE The sister chromatids line up across the MIDDLE (equator) of the cell *no more nucleus Sister chromatids is connected to a spindle fiber at its centromere.
Anaphase AWAY Sister chromatids separate and move AWAY from each other. What happens if the chromatids break? Mutations!
Telophase TWO The chromosomes move to opposite sides of the cell. Two new nuclear membranes will form around the sets of chromosomes. *nucleus reforms in each cell
MITOSIS IS OVER! *remember only PMAT for mitosis M-Phase continues with CYTOKINESIS
Cytokinesis CUT Cell membrane CUTS inward to create 2 cells Each cell has its own nucleus with identical chromosomes
CYTOKINESIS IN PLANT CELLS Cell plate forms prior to the cell wall appearing
Mitosis Let's watch the whole process now. *many of these stages overlap when occurring constant process Source: http://highered.mcgraw-hill.com/olc/dl/120073/bio14.swf
Identify the different stages of the cell cycle:
PUT in ALL together: Cell Cycle Interphase Prophase (Two Identical Daughter Cells) (New Cell) Metaphase Anaphase Telophase Cytokinesis I Passed My Algebra Test Corrections
MITOSIS (ASEXUAL) Video- stop at 4:03 Parent Cell has 4 chromosomes Chromosomes replicate = 8 chromosomes Cell divides producing 2 identical daughter cells each with 4 chromosomes
EUKARYOTIC REPRODUCTION MITOSIS (ASEXUAL) If the Parent Cell has 16 chromosomes instead of 4 How many chromosomes would you have after replication? 32 chromosomes How many chromosomes would each Daughter Cell have? 16 chromosomes
CELL CYCLE: WHAT STAGE OF INTERPHASE IS A? WHAT STAGE IS B?
Video Review Amoeba sisters: Mitosis
Regulating the Cell Cycle Cell growth and cell division are carefully controlled inside an organism. Most nerve and muscle cells do not divide once they have developed (G 0 phase) Cells that make blood, skin, and hair divide rapidly throughout life
Regulating the Cell Cycle Cell division is controlled by: Cyclins regulates timing of cell division Regulator Proteins including growth factors Apoptosis: when a cell is programmed to die What happens if cell division is NOT regulated???
Cell Cycle Disorder: CANCER Cancer - the uncontrolled division (mitosis) of cells (cells can t stop making more cells; divides rapidly) Due to mutation in DNA Cells lose the ability to control their growth rate Cells no longer respond to signals that regulate growth of most cells.
Cell Cycle Disorder: CANCER Cancer cells form masses of cells called tumors and cause damage to other cells and tissues a. Benign tumor: does not spread to surrounding healthy tissue b. Malignant tumor: invade and destroy other tissue (*move) Tumor in liver
Causes of Cancer Smoking Radiation exposure Defective genes Viral infections Treatment of Cancer Surgery Radiation Chemotherapy
Cell cycle and Cancer Amoeba SISTERS: Cell Cycle and Cancer