Life is Cellular Section 7.1

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1 Life is Cellular Section 7.1

2 Objectives Understand Cell theory Distinguish between prokaryotes and eukaryotes Understand different types of microscopy, and how they work in more detail

nobody cared about cells if you couldn t see it it didn t matter!

3 What is a Cell? The smallest part of a living organism that can be considered alive Pre 1500s nobody cared about cells if you couldn t see it it didn t matter! In 1665, in Britain cork was analyzed under a microscope, first cells discovered Bacteria first identified in Holland around the same time Anton Van Leeuwenhoek

4 After Van Leeuwenhoek s discovery, it became clear that cells are the basic units of life 1838, decided that all plants are made of cells Mattias Schleiden 1839 all animals made of cells as well Theodor Schwann 1855 Shown that cells can reproduce Rudolf Virchow

5 Cell Theory All living things are made of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells

6 Staining microscope slide Many living cells are transparent Stains allow us to see a number of features Can use stains that only pick out specific structures

7 Electron microscopes Two types scanning and transmission

8 Prokaryotes vs Eukaryotes Prokaryotes Eukaryotes No Nucleus Nucleus separates genetic material from the rest of the cell Small and simple Often contain dozens of structures and internal membranes Although simple, fulfil al criteria to be alive Large amount of variety Example - Bacteria Protists live as unicellular organisms Can form multicellular organisms plants, animals and fungi Both come in a range of shapes and sizes Eurkaryotes tend to be more complex

10 Cell Structure Section 7.2

11 Objectives Describe the roll of the cell nucleus? What are the functions of vacuoles, lysosomes and the cytoskeleton? What organelles help make and transport proteins? What does the cell membrane do?

12 Eukaryotic cells

13 The Nucleus Contains all of the DNA m and with it the instructions for making everything that the cell needs Nuclear pores allow material to move in and out of nucleus Proteins, RNA and other molecules move Chromosomes are found in the nucleus Nucleolus where ribosome assmebly begins

smaller vacuoles found in some animal cells rare Some specialized vacuoles can pump excess water

14 Organisms that store, clean up and support Vacuole Act as storage area for materials Example water, salt, protein and carbohydrates Single central vacuole common in plants Provide structure Some smaller vacuoles found in some animal cells rare Some specialized vacuoles can pump excess water out of cells Vesicle Store and move materials between organelles Also move material to and from cell surface

common in animal cells Cytoskeleton Network of protein filaments

15 More organelles Lysosome Clean up crew sell janitors Filled with enzymes that break down macromolecules into constituent parts More common in animal cells Cytoskeleton Network of protein filaments maintain cell shape Can also aid in transport of material Can aid in cell movement Flagella

crawl Microtubules Hollow structures made of tubulins Maintain shape Assist in cell division Form

16 Cytoskeleton continued Microfilaments Threadlike structures made of protein called actin Extensive tough, flexible framework Assembly and disassembly allows amoebas and other cells to crawl Microtubules Hollow structures made of tubulins Maintain shape Assist in cell division Form centrioles in animal cells Help organize cell division Form projections from surface that allow cells to swim

synthesis Endoplasmic Reticulum Where lipids of the cell membrane are made smooth ER Rough ER has

17 Building proteins Ribosomes Ribosomes assemble proteins Small particles of RNA and protein found in cytoplasm Produce proteins by following instructions produced by DNA More ribosomes = more protein synthesis Endoplasmic Reticulum Where lipids of the cell membrane are made smooth ER Rough ER has ribosomes stuck to surface proteins for export New proteins inserted into rough ER where they can be modified

18 Golgi apparatus Acts as sorting depot Proteins are modified, sorted and packed for storage or released from cell Made of Stack of flattened membrane

Mitochondria Convert chemical energy from food into compounds more convenient for

19 Capturing and releasing energy Chloroplasts Biology s solar power plants Where photosynthesis takes place Capture solar energy and turn it into chemical energy Mitochondria Convert chemical energy from food into compounds more convenient for cell use All mitochondria comes from your mother Has it s own DNA descended from unique microorganisms

Cell walls are outside of cell membrane Porous enough for water, oxygen and

20 Cellular boundaries All cells are surrounded by a barrier known as a cell membrane Prokaryotes and plants also have an additional barrier cell wall Cell walls are outside of cell membrane Porous enough for water, oxygen and CO2 to flow in and out of cell wall Provide support For examples, makes up wood

layer Creates oily layer that makes it hard for water to

21 Cell membranes Lipid by-layer, with water loving (hydrophillic) and water hating (hydrophobic) middle layer Creates oily layer that makes it hard for water to enter or leave Transport proteins allow passage of larger molecules

22 Cell transport Section 7.3

23 Objective Know processes involved in active transport Know processes involved in Passive transport

24 What is passive transport? Diffusion! Solute particles will move from a high concentration to a low concentration Like adding sugar to tea or coffee Diffusion is the driving force for many things crossing cell membrane Even at equilibrium particles are still moving across Same number in both directions Depends on random particle motion When no energy is used to move across cell membrane this is passive transport

25 Diffusion explained

Facilitated diffusion Only small uncharged molecules can pass through the lipid bilayers Ions such as Cl-, or molecules such as glucose still pass through quickly, how?

26 Facilitated diffusion Only small uncharged molecules can pass through the lipid bilayers Ions such as Cl-, or molecules such as glucose still pass through quickly, how? Proteins act as conduits/ channels allowing diffusion to occur Facilitated diffusion There are hundred of different types that allow particular substances to move Although fast and specific it is still diffusion it uses no energy

allow transport of water Water channel protein Osmosis diffusion of water

27 Osmosis facilitated diffusion Water requires facilitated diffusion why? Water can not cross the oily layer inside cell membrane Instead Aquaporins allow transport of water Water channel protein Osmosis diffusion of water through selectively permeable membrane Water molecules move from high to low concentration

28 Isotonic vs Hypertonic vs hypotonic

29 Osmotic pressure Osmotic pressure can cause cells to shrink or expand Cells are always hypertonic in fresh water Very rare that cells are in contact with fresh water Cell walls can also help prevent cells from expanding/shrinking too much

30 Active transport The movement of materials against a concentration gradient It requires energy Carried out by transport proteins or pumps Common for Ca, Na, K Allows particular substances to concentrate Alternative endocytosis or exocytosis Bulk transport

example White blood cells eat damaged cells Exocytosis

32 Bulk transport Endocytosis Stuff enters the cell through in folding of cell membrane Phagocytosis example White blood cells eat damaged cells Exocytosis Membrane of vacuole fuses with cell membrane Contents are expelled

33 Homeostasis and cells Section 7.4

environment, transform energy and reproduce Bacteria

34 How do individual cells maintain homeostasis? Unicellular organisms can grow, respond to the environment, transform energy and reproduce Bacteria are highly adaptable Many processes are the same as in multicellular organisms

for specific tasks, and communicate with one

35 How can cells work together to maintain homeostasis? Cells in multicellular organisms are interdependent They can each become specialized for specific tasks, and communicate with one another to maintain homeostasis Some can move Some can react to the environment Some produce substances the organism needs

Connective tissue Each tissue performs an essential task Organs complete specialized

36 Levels of organization Cells are organized into tissues Groups of tissues are called organs Each muscle in your body is an individual organ Muscle Tissue Nerve tissue Connective tissue Each tissue performs an essential task Organs complete specialized tasks Organs come together to form organ systems Division of labor allows organisms to maintain homeostasis

Cellular communication Cells can communicate through chemical signals passed from one cell to another Signals can

Certain cells form cellular junctions Some hold cells together Others small messengers to pass through A cell

signal that causes heart to start contracting is the pacemaker Ions carry the signal from pacemaker over millions

37 Cellular communication Cells can communicate through chemical signals passed from one cell to another Signals can speed up or slow down the activities of cells that receive them Can cause a cell to change what it is doing Certain cells form cellular junctions Some hold cells together Others small messengers to pass through A cell must have a receptor to respond to a signal Can be on the cell membrane or in the cytoplasm Example electrical signal that causes heart to start contracting is the pacemaker Ions carry the signal from pacemaker over millions of heart cells, causing them to contract simultaneously Other junctions hold the heart cell together, so the heart does not rip

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

chapter 7 Test Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Who was one of the first people to identify and see cork cells? a. Anton van