Centrioles

1. Small, hollow cylinders composed of _______________. • Found in pairs perpendicular to one another. • Visible during cell division near nuclear envelope in the ____________ (cell center). • Help to organize __________ __________ during cell division. • May also form bases of cilia and flagella (known as ________ ________). Centrioles

2. Control center or “_______”of the cell. • Primary functions: • 1) maintain __________ information of the species • 2) control cellular activities through _________ synthesis. • Some cells may have one nucleus, some may be multi-nucleated, while others are anucleated. • Anatomy is divided into four parts: • Nuclear Envelope or membrane • Nucleoplasm • Chromatin • Nucleoli Nucleus

3. Nucleus is separated from cytosol by a nuclear ___________ composed of two lipid bilayers • Outer layer is continuous with the ER. • Covered in ____________. • Contains nuclear ________ - channels through envelope. • pores are large and not too selective. • Allow transport of protein in and RNA out of nucleus. • ______________ - gelatinous substance that fills the nucleus and is similar to cytosol. Nuclear Envelope and Nucleoplasm

4. Small, dark, spherical patches contained within the nucleus. • Not bound by a membrane. • Where ___________ ___________ are made (before they are sent to the cytoplasm and become functional). • Contain DNA that governs synthesis of __RNA. Nucleoli

5. _____________- made up of DNA and globular proteins called histones. • Histones decide which segments of DNA (genes) will go on to produce proteins (gene regulation). • DNA winds around 8 histone molecules to form a ________________. • Nucleosomes are joined together by linker DNA. • The chromatin condenses into super-coiled x-shaped structures called ________________ during cell division. • two chromatids held together by a protein called a centromere. DNA, RNA and Chromatin

6. Process of making mRNA • Occurs in the nucleus • Helicase separates the double helix into single strands of DNA by breaking H bonds • RNA polymerase connects free floating RNA nucleotides to their coordinating DNA nucleotides. • Once transcription ends, RNA polymerase detaches, mRNA is released, and the DNA forms a double helix again. • Splicesomes edit mRNA before it leaves the nucleus TRANSCRIPTION

7. Process of building protein • Information on mRNA is translated from nucleotides to amino acids. • rRNA wraps around the strain of mRNA in the area of the first codon. • rRNA also has an active site where tRNA can attach. • As each codon of mRNA is read, tRNA with a corresponding anticodon brings the appropriate amino acid to the mRNA. • A peptide chain is formed as amino acids link together and is eventually released Translation

8. Errors that occur in the genetic code during the many replications of DNA • Examples of mutations: • sections of DNA may be left out • nucleotide mismatching • Mutations may be so severe that cell dies, but may also cause no issues whatsoever. • Mutations in an unborn fetus are more severe than those in adults. Genetic Mutations

9. The progressive acquisition of individual characteristics by cells to enable them to perform different functions. • The temporary or permanent inhibition of genes that may be active in other cells. • No one cell can contain all of the metabolic and structural machinery needed to perform all processes that are required for homeostasis in the body. • The genetic material tells the cell what type of protein to make and what functions to perform. Cell Differentiation and Development

10. Two major periods: • _______________ • When new cell is growing, maturing, and differentiating. • DNA replication occurs here. • Cells spend majority of time in this phase. • ________________ phase • When cell is actively dividing into two equal daughter cells. Life Cycle of the Cell

11. Period between cell divisions (cell is not at rest) • Nucleus and nucleoli are visible and chromatin is loosely arranged in the nucleus. • Three subphases: • ___________ 1 (G1)- intense metabolic activity and cell growth; cell size and number of organelles doubles • ___________ (S)- DNA replication • ___________ 2 (G2)- very brief; synthesis of proteins needed for mitosis Interphase

12. DNA Replication • During S phase of Interphase • DNA must be replicated before the cell can divide into two identical copies. • Chromatin uncoils, histones separate from DNA, and a helicase enzyme separates the helix into 2 nucleotide chains • A replisomemakes a short chain of RNA, called a primer, to match the uncoiled DNA template • DNA polymerase III matches free floating nucleotides with the exposed nucleotides on the unwrapped DNA chain

13. DNA Polymerase I replaces the RNA primer with DNA nucleotides. • Finishing touches are put on the 2 new identical DNA helixes. Histones wrap around them, before they supercoil into paired chromatids held together by a centromere.

14. G1- Growth • S- Growth and DNA replication • G2- Growth and making of proteins needed for cell division • Mitosis: • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis- Division of cytoplasm Cell cycle

15. Finishing touches put on chromosomes • Cytoplasm becomes more viscous • Microtubules disassemble • Spindle apparatus appears • Centrioles have just finished replicating and each pair moves from being near the nucleus (centrosome) to being at opposite poles of the cell. • Microtubules called spindle fibers extend from centrioles to the center of the cell • Nuclear envelope disintegrates Mitosis: Prophase

16. Chromosomes are lined up in center of spindle (cell) called the equator to form the metaphase plate. • Centromere of each chromosome is attached to a spindle fiber. Mitosis:Metaphase

17. Centomeres split apart and sister chromatids separate as the spindle fiber pulls them away from each other toward the centrioles. • Cell elongates and cytoplasm constricts along metaphase plate. Mitosis:Anaphase

18. Final stage of mitosis • Begins when chromosomal movement stops and unraveling begins • New nuclear envelope appears as well nucleoli. • Microtubules that were spindle fibers disassemble • Cytokinesis (division of cytoplasm) occurs after telophase. • New daughter cells enter interphase. Mitosis:Telophase

19. Cell division is important not only for growing animals, but also for adults that need their older cells replaced. • FACTORS INFLUENCING CELL DIVISION: • Normal cells stop dividing when they come into contact with surrounding cells(CONTACT INHIBITION) • Cells may release growth-inhibiting signals once their numbers are sufficient. • Cells have checkpoints (proteins) that control whether or not they enter into the mitotic phase Control of Cell Division

20. The Cellular Environment • Body Fluids • Composed primarily of water • _________________fluid found inside cell. • ___________________fluid outside cell. • ___________________extracellular fluid contained in the tissues. Cell Physiology

21. In order to maintain homeostasis cell must select what it needs from ______cellular fluid and bring it into ______cellular environment. • Electrolytes, fatty acids, vitamins, amino acids, hormones, gases • Must excrete waste products or transport resources needed in other parts of the body to the ______cellular compartment. • Processes may be _______________ (do not require ATP) OR ___________ (do use ATP). Membrane Processes

22. No Energy Required • 4 Passive Processes: • Diffusion • Facilitated Diffusion • Osmosis • Filtration Passive Transport Processes

23. movement of molecules from _________ concentration to _____________concentration • driven by a ____________ ____________- the difference between the concentration of one area and the concentration of another. • Will continue until the molecule is evenly dispersed throughout the solution Diffusion

24. Determining factors for Diffusion through a cell membrane: • _________________– small can move through • 2. _________________– lipids can pass lipid bilayer • 3. _________________– ions move through special channel proteins • 4. _________________– faster in hot solution Diffusion

25. Selective _______ proteins assist in movement of molecules from higher to lower concentration • speed of diffusion is limited by the ___________ of carrier molecules. Facilitated Diffusion

26. Passive movement of __________ through a semi-permeable membrane from a dilute solution to a concentrated solution. • Similar to diffusion, but here, we are referring to the movement of water molecules rather than solute. • The force of water moving from one side of the membrane to the other is the __________ pressure. Osmosis

27. The passage of a fluid by _______________ through a semipermeable membrane that allows the ____________ portion to pass through but not cells and large molecules. • Liquids/small molecules are pushed through the membrane when the pressure on one side is greater than that on the other side. • the force that pushes the liquid is the _______________ pressure. Filtration

28. ________________ : Extracellular fluid has same concentration of dissolved substances as intracellular fluid • ___________________: Cytoplasm (inside) of cell is more concentrated than extracellular (outside) fluid • __________________: Extracellular fluid is more concentrated than cytoplasm Tonicity Terminology

29. Active Membrane Processes • Require Energy (ATP) • Some molecules are unable to enter the cell via passive routes because: • some molecules are not lipid soluble, too large for protein pores, or are on the wrong side of the concentration gradient • Does not require a concentration gradient • Active Transport • Cytosis • Endocytosis, Exocytosis

30. Active movement of molecules by specific carrier protein with a binding site for ATP; molecules may move against concentration gradient. • __________ system– substances are moving in the same direction • __________ system– substances are moved in opposite directions Active Transport

31. ____________________ • Cells engulf solid substances • _____________________ • Cells engulf liquid substances • _______-________ endocytosis • Specialized protein receptors bind to ligands. • Ligand-small molecules that bind to receptors or larger molecules. Endocytosis

32. Exporting substances from the intracellular to the extracellular environment • Excretion of waste products and secretion of manufactured substances. • Packaged in secretory vesicles which fuse with cell membrane and are ejected to extracellular space. • _____________- exocytosis of wastes • _____________- exocytosis of manufactured molecules Exocytosis