Unit A: Cells. Ch. 4 A Tour of the Cell

Transcription

1 Unit A: Cells Ch. 4 A Tour of the Cell

2 Standards By the end of this unit you should be able to: Recognize and explain the function of each organelle Look at micrographs/diagrams/pictures and correctly ID each organelle Write/work with/explain the balanced chemical equation for cellular respiration Relate the role of an organelle to a specific part of the body Explain how the endomembrane system functions to compartmentalize the cell and move materials through it

3 Big Picture in case you did not know!!! Life = Cells Cell Intro Cells=prokaryotic (bacteria) OR eukaryotic (all other) How do you recognize????

4 Cells EVERYWHERE!!! Staphylococcus aureus Human Red Blood Cells Apoptosis in a Leukemia Cell Cell Suicide Escherichia coli

5 How big is a cell???? Cells Everywhere!!! How many cells in your body??? 50 million million (50 trillion) cells stretched end to end they would stretch around the Earth 47 times if you could count one cell per second it would take you 2600 years!!! Inner Life of Cell

6 What cells can you see??? Hummingbird Egg 0.02 ounces Beluga sturgeon Eggs - $700 per ounce Human Egg Thousands of dollars per egg - 25G s

7 Electron microscope Light microscope Unaided eye 10 m Human height 1 m Length of some nerve and muscle cells What cells can Cells vary in size and shape 100 mm (10 cm) 10 mm (1 cm) 1 mm Chicken egg Frog egg you see??? Most cells are microscopic 100 m 10 m 1 m Most plant and animal cells Nucleus Most bacteria Mitochondrion Mycoplasmas (smallest bacteria) 100 nm Viruses Ribosome 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms Figure 4.2A

8 Surface area to volume ratio The microscopic size of most cells ensures a sufficient sur face area Across which nutrients and wastes can move to service the cell volume A small cell has a greater ratio of sur face area to volume than a large cell of the same shape 30 m 30 m 10 m 10 m Surface area of one large cube 5,400 m 2 Figure 4.2B Total surface area of 27 small cubes 16,200 m 2

9 Colorized TEM 15, Prokaryotic cells are structurally simpler than eukaryotic cells Recall: there are two kinds of cells Nucleoid region A. Prokaryotic and eukaryotic, which is which and how do you know? Prokaryotic cell Nucleus B. Eukaryotic cell Organelles Figure 4.3A

10 Prokaryotic cells are small, relatively simple cells That do not have a membrane-bound nucleus You should recall all the bits from Gr 11 microbiology (bacteria) Prokaryotic Cells Ribosomes Prokaryotic flagella Capsule Cell wall Plasma membrane Nucleoid region (DNA) Pili Figure 4.3B

11 Eukaryotic Cells 4.4 Eukaryotic cells are partitioned into functional compartments (organelles) All other forms of life (anything not bacteria) are composed of more complex eukaryotic cells Distinguished by the presence of a true nucleus Membranes form the boundaries of and within many eukaryotic cells Compartmentalizing the interior of the cell into organelles and facilitating a variety of metabolic activities

12 There are two types of Eukaryotic cells: animal and plant A typical animal cell contains a variety of membranous organelles Types of Eukaryotic Rough endoplasmic reticulum Smooth endoplasmic reticulum Nucleus Cells Flagellum Not in most plant cells Lysosome Centriole Peroxisome Golgi apparatus Ribosomes Cytoskeleton Microtubule Intermediate filament Microfilament Mitochondrion Plasma membrane Figure 4.4A

13 Types of Eukaryotic Cells A typical plant cell has some structures that an animal cell lacks Such as chloroplasts, a rigid cell wall and a central vacuole Nucleus Golgi apparatus Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Microtubule Not in animal cells Central vacuole Chloroplast Cell wall Intermediate filament Microfilament Cytoskeleton Mitochondrion Peroxisome Plasma membrane Figure 4.4B

14 Plant and Animal Differences: The 4 C s! Plant Cell Cell wall Chloroplasts Central Vacuole Animal Cell Centrioles

15 All other organelles found here Defined by cell membrane & envelope Cytoskeleton maintains cell s shape Cytoplasm

16 4.5 The Nucleus The nucleus is the cell s genetic control center Its the largest organelle which is separated from the cytoplasm by the nuclear envelope The nucleus is the cellular control center It contains the cell s DNA, which directs cellular activities Nucleolus Chromatin Nucleus Two membranes of nuclear envelope Pore Rough endoplasmic reticulum Ribosomes Figure 4.5

17 i) Nuclear Envelope 2 membranes with pores Nuclear Structure ii) Chromatin thread like Becomes chromosomes* (condensed) during cell division *Contains genetic material (DNA): Meaningful parts = genes Made of - DNA & proteins iii) Nucleolus dark center Makes rrna (ribosomal RNA)

18 4.6 Endomembrane System Many cell organelles are connected through the endomembrane system a collection of membranous organelles that manufactures and distributes cell products Nucleus, RER, SER, Golgi, Vesicles, Vacuoles

19 TEM 45, SER Smooth endoplasmic reticulum (SER) has a variety of functions Synthesizes lipids Processes toxins and drugs in liver cells Stores and releases calcium ions in muscle cells Smooth ER Rough ER Nuclear envelope Figure 4.7 Smooth ER Ribosomes Rough ER

20 Rough endoplasmic reticulum (RER) makes membrane and proteins Ribosomes on the surface of the RER Produce proteins that are secreted, inserted into RER membranes, or transported in vesicles to other organelles 4.8: RER And Ribosomes 4 stages of protein synthesis??? Figure 4.8

21 ER interconnected membrane, tubular canals, begin at nuclear envelope ER Comparison RER Studded with ribosomes Synthesize proteins for export (use outside of the cell) Ex - insulin SER NO ribosomes Synthesize lipids (ex. Male testes make testosterone a lipid steroid so lots of SER) Help liver in detox. process

22 2 Types of Ribosomes Free Floating Make proteins for cell use (internal) Embedded in RER Make proteins for export out of cell (external)

23 TEM 130, Golgi Apparatus The Golgi apparatus finishes, sorts, and ships cell products Stacks of membranous sacs receive and modify ER products then ships them to other organelles or the cell surface Receiving side of Golgi apparatus Transport vesicle from ER Golgi apparatus Golgi apparatus New vesicle forming Shipping side of Golgi apparatus Transport vesicle from the Golgi Figure 4.9

24 4.10 Lysosomes Lysosomes are digestive compartments within a cell Sacs of hydrolytic enzymes that function in hydrolysis (digestion) within a cell Double membrane bound and made by GA Function in autodigestion EX: tadpole tail, finger webbing Rough ER 1 Transport vesicle (containing inactive hydrolytic enzymes) Plasma membrane Golgi apparatus Food 2 3 Engulfment of particle Lysosomes Lysosome engulfing damaged organelle Food vacuole 4 Digestion 5 lysosomes clip Figure 4.10A

25 TEM 8,500 TEM 42,500 Lysosomes in white blood cells Destroy bacteria that have been ingested 4.10 Lysosomes Lysosome containing two damaged organelles Lysosomes also recycle damaged organelles Abnormal lysosomes can cause fatal diseases (Lysosomal storage diseases) which interfere with various cellular functions Lysosome Figure 4.10C Mitochondrion fragment Peroxisome fragment Nucleus Figure 4.10B

26 LM 650 Colorized TEM 8, Vacuoles Vacuoles function in the general maintenance of the cell Plant cells contain a large central vacuole which has lysosomal and storage functions as well as support functions Some protists have contractile vacuoles that pump out excess water Nucleus Nucleus Chloroplast Central vacuole Figure 4.12B 4.12A Contractile vacuoles

27 The various organelles of the endomembrane system are interconnected structurally and functionally A review of the endomembrane system Rough ER Transport vesicle from ER to Golgi Transport vesicle from Golgi to plasma membrane Plasma membrane Nucleus Vacuole Figure 4.13 Lysosome Smooth ER Nuclear envelope Golgi apparatus

28 TEM 9,750 ENERGY- CONVERTING ORGANELLES 4.14 Chloroplasts convert solar energy to chemical energy Chloroplasts, found in plants and some protists, convert solar energy to chemical energy in sugars (glucose) Contains chlorophyll Chloroplast Stroma Inner and outer membranes Granum Figure 4.14 Intermembrane space

29 4.15 Mitochondria harvest chemical energy from food Mitochondria carry out cellular respiration which uses the chemical energy in food (glucose) to make ATP for cellular work TEM 44,880 ENERGY- CONVERTING ORGANELLES OXYGEN + GLUCOSE ---- CARBON DIOXIDE + ATP + WATER Double membrane bound, has own DNA Mitochondrion Outer membrane Intermembrane space Inner membrane Figure 4.15 Cristae Matrix

30 The cell s internal skeleton helps organize its structure and activities A network of protein fibers make up the cytoskeleton. Microfilaments of actin Enable cells to change shape and move 4.16 Cytoskeleton Intermediate filaments Reinforce the cell and anchor certain organelles Microtubules give the cell rigidity And provide anchors for organelles and act as tracks for organelle movement Figure 4.16 Actin subunit Microfilament 7 nm Fibrous subunits 10 nm Intermediate filament Tubulin subunit Microtubule 25 nm

31 Colorized SEM 4,100 LM Cilia and Flagella Cilia and flagella move when microtubules bend Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells Clusters of microtubules drive the Flagellum Electron micrographs whipping action of these organelles of cross sections: Outer microtubule doublet Central microtubules Radial spoke Dynein arms Plasma membrane Basal body (structurally identical to Figure Figure 4.17A4.17C centriole) Figure 4.17B Flagellum Basal body TEM 206,500 TEM 206,500

32 4.19 CELL SURFACES AND JUNCTIONS Cell surfaces protect, support, and join cells Cells interact with their environments and each other via their surfaces. Plant cells Are supported by rigid cell walls made largely of cellulose Connect by plasmodesmata, which are connecting channels Vacuole Walls of two adjacent plant cells Plasmodesmata Figure 4.18A Layers of one plant cell wall Cytoplasm Plasma membrane

33 4.19 CELL SURFACES AND JUNCTIONS Animal cells Animal cells are embedded in an extracellular matrix which binds cells together in tissues Tight junctions can bind cells together into leak-proof sheets Anchoring junctions link animal cells into strong tissues Gap junctions allow substances to flow from cell to cell Tight junctions Anchoring junction Gap junctions Figure 4.18B Extracellular matrix Space between cells Plasma membranes of adjacent cells

34 FUNCTIONAL 4.19 CATEGORIES Eukaryotic organelles OF ORGANELLES comprise four functional categories Eukar yotic organelles fall into four functional groups Manufacturing Breakdown Energy processing Suppor t, movement, and communication between cells Table 4.19