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Basic Unit of Life: The Cell

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Presentation on theme: "Basic Unit of Life: The Cell"— Presentation transcript:

1 Basic Unit of Life: The Cell
Chapter 3 Basic Unit of Life: The Cell

2 All Organisms are made up of cells
Eukaryotes- Moth Juniper Protozoans Ciliates in water on plant Prokaryotes Bacteria in insect gut and on surface of insect and tree

3 Cell theory All living organisms are made up of cells
All cells come from other cells Theory refers to the body of knowledge that has been developed through scientific inquiry Human body has 60 trillion cells that all started from a single fertilized egg. How many divisions is that? Elephant bird extinct in 1600’s Madagascar

4 Two Cell Categories Prokaryote Eukaryote Cell membrane Cytoplasm
DNA (in a loop) Ribosomes (for creating proteins) Cell wall Very small DNA is loose in cytoplasm Cell membrane Cytoplasm DNA (in strands) Ribosomes Many other organelles Cell wall in plants Variable size – larger than prokaryotes Nucleus holds DNA Greek for before kernel and good kernel; Prokaryote cells were first type to evolve. Eukaryotes evolved from prokaryote cells. We’ll learn more about prokaryotes later in course.

5 The organisms that cause colors in the hot springs of Yellowstone are single celled and have been around since the beginning of life on this planet. Would these organisms be prokaryotes or eukaryotes? Would their cells have a nucleus? A. Prokaryotes, yes B. Prokaryotes, no C. Eukaryotes, yes D. Eukaryotes, no meheat/yellowstone.html

6 Basic Cell Structures Cell Membrane
Nuclear double membrane around nucleus Mitochondria for energy Processing and packaging organelles Lysosomes – digestion Cytoskeleton - support Eukaryote

7 Plasma Membranes Separates cell from its environment so it can have reactions that are different and controlled.

8 Bilayer Structure

9 Molecules Found in the cell Membrane
Cholesterol increases membrane flexibility Tertiary structure of proteins important part of holding them in a certain position in the membrane.

10 Types of Membrane Proteins
1. Receptor proteins – Bind to external molecules which cause reactions in cell Ex. Target cells can detect hormones in blood – regulate development of secondary sexual characteristics 2. Recognition proteins Typically have attached carbohydrate chains Give the cell identity – other cells can recognize them Ex. During development cells interact & work together to develop structures. Recognition is essential. Ex. Autoimmune disease = faulty self-recognition 1. Heart rate and adrenaline; 2. immune response and id’ing self

11 Visual examples Receptor proteins Recognition proteins

12 Types of Membrane Proteins
3. Transport proteins Move other molecules across the cell membrane Transmembrane proteins only Ex. Nerve cell fire – Na ions moved across 4. Enzymatic proteins Increase rate of chemical reactions associated with the cell membrane Ex. cAMP formation regulated – internal messenger created

13 Visual Examples Transport proteins Enzymatic proteins
Can have proteins working together – recognition of hormone – triggers enzymatic protein action within cell. Animation – have set up.

14 Why is the cell membrane considered a fluid mosaic?
It’s primarily made up of water with dispersed fats and proteins in a mosaic pattern Proteins move back and forth through the membrane from inside to outside of the cell and back in a fluid mosaic pattern. It’s made up of several different types of molecules, like a mosaic, and many of those molecules float around in the lipid bilayer.

15 Cell Structure and Function
Cells are factories Need raw materials to enter the cell Need to eliminate wastes Need to export products produced in the cell Need to keep up-to-date on needs of surrounding cells and tissues Cell membrane is very busy

16 Endocytosis Phagocytosis = endocytosis of large particles or other cells

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18 Exocytosis Also waste removal

19 Animation of endocytosis and exocytosis
hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535 ::535::/sites/dl/free/ /120068/bio02. swf::Endocytosis%20and%20Exocytosis

20 Other means of movement
Passive Transport Active Transport Requires no input of energy Diffusion Osmosis (diffusion of water across a membrane) Requires energy input to move molecules across the cell membrane or around in the cell Primary – uses ATP Secondary

21 Diffusion Key: Molecules tend to move from an area of
high concentration to an area of low concentration When moving across a membrane – diffusion may be facilitated by a transport protein Why is water a good solvent

22 Osmosis

23 Irrigation problems Irrigation can lead to a build up of soil salinity
If soil develops a similar (or higher) salt content than the plant cells, water doesn’t flow as easily into plant roots. Soil salt concentrations make plants and soil more alike in fluid concentration (isotonic) - so water doesn’t flow across the cell membranes into the plant roots. Soil salinity creates drought like conditions in which plants can’t get water Western Montana has this problem.

24 Passive Transport

25 Active Transport Acidity of stomach increases when you eat. pH can drop from 3-4 to as low as 1.

26 The object depicted in the figure:
A) is a bacterial cell. B) could be either a plant or an animal cell. C) is a ribosome. D) is an animal cell. E) is a plant cell.

27 Cell Wall Not found in animals
A major component of the cell wall is the complex carbohydrate, Cellulose

28 If the concentrations of a particular molecule are equal on both sides of the membrane, facilitated diffusion will: A) insure that the molecule becomes concentrated outside the cell. B) insure that the molecule stays impermeable to the membrane. C) insure that the molecule becomes concentrated inside the cell. D) insure that the concentrations inside and outside the cell are both increased. E) be ineffective.

29 Connections Between Cells: 1
Connections Between Cells: 1. Tight Junctions > hold cells in place > keep fluids from passing around edges of cells blood brain barrier lining of gut

30 Connections Between Cells: 2. Desmosomes > throughout body

31 Connections Between Cells: 3
Connections Between Cells: 3. Gap Junctions >Allows small molecules, but not large proteins and organelles to move between cells. Heart muscle

32 Why not bigger? Cell Size Chicken egg = 40-60 mm
(1mm = 1/1000 m) Paramecium caudatum = 60X 230 um (1 um = 1/1000 mm) Red blood cell = um Bacteria um Why not bigger?

33 What limits the size of cells?
Much of what occurs in a cell depends on the movement of materials in and out of the cell through the plasma membrane Rate of production and waste removal is dependent on cell volume Rate of movement across the membrane depends on surface area of cell As cell size increases, volume increases as a cubed unit while surface area as a square unit.

34 Surface to volume ratio
Radius 1 cm 2 cm 3 cm Surface area (cm2) 12.57 50.26 201.06 Volume (cm 3) 4.19 33.51 268.08 SA/V 3 1.5 0.75 Eggs can get large because much of activity is dormant (yolk is just stored material) and cell is not requiring materials for synthesis and does have waste materials to eliminate. As soon as fertilized, it starts to divide – increasing surface area rapidly.

35 Nucleus and chromosomes

36 Cytoskeleton Cell is not just a bag of loose stuff Made up of protein fibers that can expand, contract, move past one another.

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38 Microfilaments underlie the cell membrane and cytoskeletal elements can break down and reform to allow changing shape in Amoeba.

39 Cell locomotion: Protein microtubules and filaments have function in locomotion as well as cell shape and transport.

40 Mitochondria – have own DNA!
Free ribosomes in matrix (like bacteria) Circular DNA present. Mitochondria divide independently of cell. Folds of inner membrane = cristae (sing: crista)

41 Mitochondria con’t Number in a cell may vary
Cells with high energy demands like muscles have more than other cells Process known as aerobic respiration (Kreb cycle & electron transport phosphorylation) takes place here. Sugar (C6H12O6) + 6H2O + 6O2 => 6 CO water (H2O) + Energy Breaks down sugar to release the energy in the chemical bonds Oxygen is used and Carbon dioxide is a waste biproduct.

42 Chloroplasts Only in Plant Cells and Single-celled Algae Have own DNA!
Similar in some ways to bacteria that do photosynthesis – especially DNA

43 Evolution of Eukaryote Cells
Why they have double membranes around the outside and their own circular DNA like bacteria. Play animation about organelle evolution.

44 Lysosomes – Waste removal
Produced by ER and Golgi apparatus. Filled with enzymes. Fuse with vesicles containing waste and enzymes break down to components that are recycled in the cell. Rest is eliminated by exocytosis. (Microbodies are sacs of enzymes that transform products from the Golgi body into other molecules and transport these to where they are needed) Up to 50 different types of enzymes!

45 Endoplasmic Reticulum

46 Smooth Endoplasmic Reticulum
Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum

47 Golgi Apparatus

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49 Vacuoles Large in plant cells

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51 Cells can be Single-celled Organisms
Euglena can engulf other organisms or do photosynthesis to get food for building blocks and energy. Eyespot Flagellum Contractile Vacuole

52 Cells Specializations Within a Multicellular Organism
All cells have the same genetic material. Cells specialize because some genes are turned off and others are turned on. Ex. Lining of small intestine Ex. Nerve cell

53 Design Organelle Analogies
Analogy Includes similes and metaphores Similes compare things using words “as” or “like” Ex. You are as stubborn as a mule. Ex. Life is like a box of chocolates. Metaphores compare 2 unlike things for secondary meaning Ex. The gum was bursting with flavor. Ex. The relationship between them began to thaw.

54 The organelle in the figure is found in:
A) animals only. B) plants only. C) plants, animals, and bacteria. D) plants and animals. E) bacteria only. What is it?

55 The lysosomes in a human cell contain approximately ________ different type(s) of digestive enzymes.
A) 1 B) 500 C) 10 D) 4 E) 50 E

56 According to the theory of endosymbiosis, the origin of chloroplasts probably involved:
A) the formation of cell walls around the photosynthetic pigments. B) the formation of colonies of cyanobacteria. C) the engulfing of small photosynthetic prokaryotes by larger cells. D) the accumulation of free oxygen in ocean waters. E) All of the above are correct.

57 Read chapter 4 on Energy


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