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Unit 2 Cells. Watching Youtube Videos When you click on the video it will play within the power point Once you’ve viewed the video you must click somewhere.

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Presentation on theme: "Unit 2 Cells. Watching Youtube Videos When you click on the video it will play within the power point Once you’ve viewed the video you must click somewhere."— Presentation transcript:

1 Unit 2 Cells

2 Watching Youtube Videos When you click on the video it will play within the power point Once you’ve viewed the video you must click somewhere on the slide outside of the video box to advance to the next slide

3 History 1660’s Microscopes developed Allowed for the observation of cells for the first time Robert Hooke examined cork under the microscope Saw a honeycomb – called them cellulae (latin for small rooms) 1830’s Matthias Schleiden and Theodor Schwann examined plant and animal tissues under the microscope From this OBSERVATION, came up with the HYPOTHESIS that all living organisms are made up of cells

4 Cell Properties 1. Import Raw materials 2. Ability to produce energy 3. Synthesize macromolecules (carbohydrates, proteins, lipids) 4. Organized pattern of growth 5. Respond to stimuli 6. Communication 7. Reproduction

5 Prokayrotic Cells Single celled organisms Bacteria No membrane bound nucleus Cell wall on outside of cell membrane Most primitive of cell types

6 Eukaryotic Cells Membrane bound organelles DNA located in membrane bound nucleus Possess subcellular organelles

7 Animal Cell

8 Plant Cell

9 Web links Here’s an interactive animation to learn the parts of cells /animations/cell_structure/cell_stru cture.htm /animations/cell_structure/cell_stru cture.htm

10 Plasma Membrane All cells are surrounded by a semi permeable plasma membrane Membrane is composed of a phospholipid bilayer Hydrophillic on the outside and hydrophobic on the inside Phosphate group is hydrophillic Lipid tails are hydrophobic

11 Subcellular Organelles Nucleus Command center Surrounded by nuclear membrane Nuclear ores in this membrane allow for transport between nucleus and cytoplasm of cell Chromosomes located here Nucleolus Darker staining region of nucleus High concentration of RNA Ribosome RNA subunits synthesized here Subunits transported to cytoplasm via pores Subunits combined to form ribosomes in the cytoplasm

12 Subcellular Organelles Ribosomes Protein synthesis for cell Consist of a large and a small subunit Located throughout the cell as free ribosomes or are bound to the Endoplasmic Reticulum Endoplasmic Reticulum Series of channels and interconnected tubules within the cytoplasm Surface of E.R. is the site for carbohydrate and lipid synthesis Rough Endoplasmic Reticulum has ribosomes attached for synthesis of those proteins for export

13 Subcellular Organelles Golgi Apparatus (body) Flattened sacks Collection, packaging and distribution of materials throughout cell Receive materials from the ER Modify these contents by adding carbohydrate groups if warranted Often located near the nucleus Cisternae are special folds at the ends of golgi bodies Vesicles are formed by pinching off at the cisternae Vesicles will go to different areas of the cell or to the plasma membrane for extracellular transport Vesicles can fuse with the plasma membrane to dump their contents to the outside of the cell

14 Subcellular Organelles Lysosomes Vesicles which contain enzymes that break down macromolecules Fuse with endocytotic vesicles to break down what the cell engulfs Peroxisomes Smaller vessicles than lysosomes Eukaryotic cell detoxification organelles Enzymes are received directly from free ribosomes Enzymes here also convert fats into carbohydrates

15 Subcellular Organelles Mitochondria Energy production for the cell Oxidative metabolism occurs here ATP produced here Double membrane organelle – has both an outer membrane and an inner folded membrane Contains its own DNA separate from the nucleus Folded internal membrane called CRISTAE Cristae provide additional surface area for reactions to take place Filled with a fluid matrix

16 Subcellular Organelles Centrioles Each cell contains a single pair These direct the assembly of microtubules which provide structural support for the cell Involved in cell division

17 Subcellular Organelles Chloroplasts Found in plants and algae Capture energy from the sun Larger than mitochondira Inner membrane folded to form closed vesicles called Thylakoids Photosynthesis occurs in the thylakoids Thylakoids are stacked to form granna Fluid stroma fills the chloroplast Have their own DNA separate from the nucleus

18 Subcellular Organelles Cell Mobility / Motility Cilia and Flagella A single cell will NOT have both Organization of microtubules for locomotion Cilia are short and numerous Create movement by beating in a coordinated manner Flagella are long and few in number Create movement by whipping action

19 Subcellular Organelles – Plants Only Central Vacuole Filled with water and other molecules Functions as storage and controls surface to volume ratio of cell Can increase the surface area by filling the central vacuole with fluid Cell Wall Protection and support of plant cell Made of fibers and cellulose Strong and rigid

20 Transport Mechanisms Overview

21 Solutes and Solvents A solute is dissolved into a solvent In a solution there will be more solvent molecules than solute molecules Example – salt water; Solute is Salt, Solvent is Water

22 Diffusion Molecules by random motion will move from an area of higher concentration to an area of lower concentration Passive process – requires no expenditure of energy Channels in the cell membrane function as gate keepers by their size Allow only molecules smaller than the pore size to pass through Molecules will travel down their concentration gradient ie from high concentration to lower concentration

23 Diffusion

24 Diffusion Facilitated diffusion Relies upon a carrier protein to bind to the molecule to help it cross the membrane Molecule still traveling down its concentration gradient Still NO energy required

25 Diffusion

26 Osmosis Specifically the diffusion of water through a semi-permeable membrane Semipermeable Membrane Cell wants to keep some things in and keep other things out Water will move from an area of high water concentration to an area of low water concentration

27 Osmosis

28 Active Transport Requires the expenditure of energy Often transporting molecules against their concentration gradient Channels are opened or closed in response to cellular signals Example – Na / K pump Cell pumps Na out of the cell while pumping K into the cell Creates a concentration gradient which is used by the cell to bring other molecules into the cell

29 Active Transport

30 Active Transport Endocytosis Infolding of the membrane to create a membrane bound vesicle containing the target Phagocytosis – cell eating – large invagination Pinocytosis – cell drinking – small invagination Exocytosis Extracellular transportation Vesicle fuses with the membrane and releases contents to the extracellular space

31 Active Transport

32 ATP: The Energy Currency of Cells Energy currency of all cells Used for all active processes Energy stored in the bonds between the phosphate molecules Break the bond between P2 and P3 releases the most energy Couple the hydrolysis of ATP with energy requiring reactions Utilize the energy released by ATP hydrolysis to ‘run’ the energy requiring reactions ATP  ADP + Pi + Energy

33 Cellular Metabolism: The Reactants Glucose ADP – adenosine –di-phosphate P – free phosphate Electron Carriers NAD + FAD O 2 - oxygen

34 Cellular Metabolism: The Products ATP – adenosine –tri-phosphate The energy currency of all cells CO 2 – carbon dioxide H 2 O - water

35 Cellular Metabolism: Overview Glycolysis Occurs in the cytoplasm Krebs Cycle Occurs in the mitochondrial matrix Electron Transport Chain Occurs on the cristae of the mitochondria

36 Glycolysis Occurs in the cytoplasm Splits glucose into 2 pyruvate molecules Requires 2 ATP to get started Generates 4 ATP and 1 NADH Net ATP Gained = 2

37 Glycolysis

38 Glycolysis Energy Investing StepsEnergy Harvesting Steps

39 The Krebs Cycle Pyruvate is transported into the matrix of the mitochondria The Krebs cycle is a series of chemical reactions which sequentially strip electrons from the pyruvate Electrons are given to the electron carriers NAD and FAD Electrons will be taken to the Electron Transport Chain For each original glucose molecule 2 ATP are produced here Carbon dioxide is also produced here

40 The Krebs Cycle

41 Krebs Cycle

42 The Electron Transport Chain Located on the Cristae of the mitochondria NADH and FADH 2 bring electrons here from the Krebs cycle Electrons travel down the chain of special proteins releasing their energy along the way Oxygen is the final electron acceptor This cellular metabolism of the krebs cycle and the electron transport chain is why we need O 2 and produce CO 2.

43 The Electron Transport Chain

44 Electron Transport Chain

45 Photosynthesis: The Players Reactants: Light Energy H 2 O (for electrons) CO 2 NADP + Specialized pigments Products: Glucose O 2 ATP

46 Photosynthesis: Overview Light reactions Occur on the thylakoid membranes of chloroplasts Dark reactions Occur in the fluid stroma of the chloroplast

47 Photosynthesis: Light Reactions Require light and water Produce ATP and O2 Take place on the thylakoid membranes of the chloroplast Light energy is used to make ATP

48 Light Reactions … How is Light energy absorbed?? Special Pigments! Chloroplasts contain special molecules called pigments Pigments have electrons which can use light energy to jump to a higher orbit Energy is released when the electron falls back to its original orbit Each pigment has a specific wavelength of light its electrons respond to White light is made up of light wavelengths ranging from nanometers Chlorophyll absorbs all wavelengths EXCEPT Chlorophyll reflects wavelengths nm Our eyes see the reflected light which is green Carotenoids absorb nm but reflect all others

49 The Light Reactions

50 Light Reactions Wow this looks a lot like the Electron Transport Chain in mitochondria!

51 The Dark Reactions Also called the Calvin Cycle Does not require light Occur in the stroma of the chloroplast Use the ATP produced during the light reactions to make glucose from CO 2

52 Cell Cycle All cells have a life cycle Checkpoints throughout the cell cycle ensure the cell divides in an appropriate manner Gap 1 - Resting cell G1 Check point decides if cell should divide Synthesis phase when DNA is duplicated (synthesized) Gap 2 – Make more organelles G2 Check point DNA duplication assessed Mitosis Check point assesses the success of cell division

53 Cell Cycle

54 Cell Cycle and Cancer Protein p53 “The guardian angel” Monitors the integrity of DNA Signals repair enzymes to address damaged DNA Tags cells for destruction if their DNA is damaged beyond repair Without this protein, damaged cells could proliferate leading to cancer

55 DNA Synthesis DNA is a double stranded helix Each strand is said to be complimentary to the other The 4 bases pair in specific couples Complimentary Base Pairing Adenine (A) only pairs with Thymine (T) Guanine (G) only pairs with Cytosine (C) DNA Polymerase enzyme synthesizes DNA Replication is semi conservative - Each daughter double helix will consist of one original and one new strand of DNA

56 DNA Synthesis

57 Mitosis Cell Division Make two EXACT daughter cells from one parental cell Divided into 4 separate stages DNA is already duplicated when mitosis begins

58 Mitosis

59 Prophase, Metaphase Prophase Nuclear membrane breaks down Chromosomes condense and coil tightly around histone proteins Centrioles duplicate and form the spindle apparatus of microtubules Metaphase Chromosomes aligned at the midline of the cell by the spindle apparatus Duplicated chromosome pairs now duplicate their centromeres

60 Anaphase, Telophase, Cytokenisis Anaphase Chromosome pairs pulled apart toward opposite poles of cell by their centromeres Telophase Chromosomes begin to unwind as the nuclear membrane is reformed Cytokinesis Cytoplasm is divided into the two cells by the pinching of the cell membrane to create two separate cells

61 Mitosis Recap

62 Meiosis For GAMETE (sex cell) production ONLY Most organisms live as diploid creatures meaning they possess two copies of each chromosome In order to maintain proper chromosome number, the DNA must be reduced by 50% in the gametes Meiosis produces 4 genetically unique Haploid cells for reproduction (eggs and sperm) Haploid cells have one copy of each chromosome

63 Meiosis

64 Meiosis 1 Prophase I Cross over between homologous pairs of chromosomes Centrioles duplicate Spindle apparatus forms Metaphase I Pairs of duplicated chromosomes line up at midline Anaphase I Individual pairs of duplicated chromosomes pulled to opposite poles of cell Telophase I Cleavage furrow separates cell into two

65 Meiosis 2  Prophase II  Centrioles duplicate  Spindle apparatus reforms  Metaphase II  Chromosome pairs line up at midline  Anaphase II  Sister chromatids now separated and pulled toward opposite poles of cell  At this point DNA is reduced by 50%  Telophase II  Cleavage furrow forms  Results in a total of 4 haploid daughter cells from 1 parental cell  Each one is genetically unique due to crossing over in Prophase I

66 Meiosis Recap Meiosis IMeiosis II


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