A FACT, A CONCEPT. The cell is THE fundamental unit of living organisms

Transcription

1 A FACT, A CONCEPT The cell is THE fundamental unit of living organisms

2 CELL THEORY HISTORY Robert Hooke observed cork and saw this: 2

3 IMAGINE Some world made up of free moving materials Under some conditions, linked materials may survive better than when free and independent 3

4 NECESSITIES TO SURVIVE AND PROLIFERATE Separation from environment Integrity Energy source Reproduction

5 NECESSITIES TO SURVIVE AND PROLIFERATE Separation from environment Integrity Energy source Reproduction

6 2 ND LAW OF THERMODYNAMICS All natural systems or processes move toward disorder or randomness (entropy)

7 ENERGY SOURCES Internal - storage problems OR External - acquisition problems

8 ENERGY-SOURCE PROBLEMS Internal Storage Diffusion Size effects

9 ENERGY-SOURCE PROBLEMS External Requires a permeable membrane but this can cause leakage Energy needs to maintain integrity Surface to volume problems Waste

10 A SURFACE TO VOLUME PROBLEM A 1 cm cube gives 6 1x1 cm surface = 6 cm 2 and 1x1x1 cm volume = 1cm 3 6:1 surface to volume

11 SURFACE TO VOLUME CONTINUED A 2 cm cube gives 6 2x2 cm surface = 24 cm 2 and 2x2x2 cm volume = 8 cm 3 24:8 surface to volume

12 WHY IS SURFACE TO VOLUME IMPORTANT? Cell content volume increase at a faster rate than the surface through which materials must be brought in to support contents

13 A FACT Whenever you observe a cell with exaggerated surface area you can assume that it has a limited surface problem

14 WHY IS SURFACE TO VOLUME IMPORTANT IN GENERAL? Limited surface area can constrain many reactions

15 ENERGY-SOURCE PROBLEMS External Energy needs to maintain integrity Surface to volume problems Requires a permeable membrane but this can cause leakage Waste

16 NECESSITIES TO SURVIVE AND PROLIFERATE Separation from environment Integrity Energy source Reproduction

17 REPRODUCTION To increase representation in the population reproduction is essential "It's the first self-replicating cell on the planet that's parent is a computer, Craig Venter

18 REPRODUCTION He has not created life, only mimicked it, Dr. Baltimore said.

19 THE CELL THEORY All living organisms are composed of cells Life-dependent chemical reactions occur within cells Cells arise from other cells Hereditary information is passed from mother to daughter cell

20 COMPARISON PROKARYOTES EUKARYOTES Localized Nucleus Distinct Small Size Large Always Cell Wall Sometimes

21 A FACT 1 kilogram of fertile soil may contain more than 1 trillion individual prokaryotes!

22 ENERGY USERS Autotrophs - do NOT require external sources of organic materials. They obtain energy from light or inorganic materials Heterotrophs - Require external sources of organic materials for energy and building block materials.

23 SOMETHING TO KEEP IN MIND Form and function

24 A FACT All living cells are surrounded by a plasma membrane

25 PLASMA MEMBRANE COMPONENTS Lipid bilayer Cholesterol (in animals) Integral proteins Peripheral proteins Glycolipids

26 IMPORTANT FACT Phospholipids will spontaneously form bi-layers when immersed in water.

27 MORE KITCHEN PHYSICS WATER TENDS TO LOWER POTENTIAL IN 3 WAYS: Gravity wise Pressure wise Concentration wise

28 TWO EXTREMES Dilution Dehydration Fresh Water Lake Ocean

29 A FACT Diffusion requires random, independent movement of particles.

30 A THOUGHT EXPERIMENT Open a perfume bottle. If more perfume particles are inside the bottle at the outset there should be a net flow (to or from?) the bottle based on chance alone?

31 A FACT Water moves DOWN a concentration gradient, the steeper the faster.

32 OSMOSIS Diffusion of water across a semipermeable membrane Hypotonic Hypertonic

33 HOW TO OVERCOME OSMOTIC TENDENCY IN FRESH WATER - Use a water pump to maintain hypertonic condition IN SEA WATER - (1) Use salt pump to maintain hypotonic condition or (2) maintain isotonic condition.

34 3 WAYS TO GET MATERIALS IN AND OUT OF CELLS Osmosis Carrier assisted - passive or active Vesicular

35 ANOTHER IMPORTANT FACT The rate of facilitated diffusion depends upon the number of protein facilitators and the rate of movement through them

36 2 TYPES OF VESICULAR TRANSPORT Exocytosis - out of cell Endocytosis - into cell 36