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The Living Cell

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The Living Cell Life is based on chemistry, and chemistry takes place in cells – PowerPoint PPT presentation

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Title: The Living Cell


1
The Living Cell
Life is based on chemistry, and chemistry takes
place in cells
2
Outline
  • The Nature and Variety of Cells
  • How Does a Cell Work?
  • Metabolism Energy and Life
  • Cell Division

3
The Nature and Variety of Cells
4
The Cell Theory
  • All living things are composed of cells
  • The cell is the fundamental unit of life
  • All cells arise from previous cells

5
Observing Cells The Microscope
6
How Does a Cell Work?
7
Cell Membranes
  • Cell Membranes
  • Isolate cell
  • Separates cell parts
  • Transport
  • Individual molecules
  • Specific materials
  • channels
  • Receptors
  • Bind molecules
  • Cell Wall
  • Plants

8
Plant Cell
9
There are two types of cells on Earth
Prokaryotic and Eukaryotic. The former appeared
first, and strong evidence indicates that the
latter evolved from the former via endosymbiotic
relationship. Prokaryotic cells include all
bacteria and the blue-green algae. Fossil
evidence shows that they have lived on earth for
at least 3.8 billion years. The DNA in
prokaryotic cells is not enclosed within a
membrane-bound nucleus as is the DNA in
eukaryotic cells.
10
Schematic of a Eukaryotic Cell The
information required for producing all of the
constituents of a cell is contained in the DNA in
the chromosomes in the nucleus
11
The Nucleus
  • Nucleus
  • Contains genetic material
  • Prokaryotes
  • No nucleus
  • Eukaryotes
  • Nucleus
  • Double Membrane

12
Cell, the factories of life
  • You have about 10 trillion cells.
  • Factories have
  • Front office- paperwork
  • Building- Bricks and Mortar- loading docks
  • Production Units
  • Power Plant

13
Cell, the factories of life
  • Paperwork- the plan- DNA
  • Building- cell walls.
  • Protein Receptors- loading dock

14
Cell, the factories of life
  • Production- organelles- perform the chemical
    functions
  • Power Plant- Mitochondria receive carbohydrates,
    fats and proteins and burn to produce energy
  • Synthesis- site of protein synthesis (controlled
    by RNA next chapter)

15
Photograph of a cell of maize rust. The dark
boundary is the cell wall, made from cellulose.
The nucleus takes up almost half the area of the
central part of the cell.
16
Mitochondria
  • Sausage shaped organelles (specialized
    structures in cells) where molecules derived from
    glucose react to produce the cells energy

17
An organelle- mitochondria.
18
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19
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20
The Energy Organelles Chloroplasts and
Mitochondria
  • Organelle
  • Specialized structure in cell
  • Chloroplasts
  • Energy transformation
  • chlorophyll
  • Plant cells only
  • Double membrane
  • Mitochondria
  • Produces cells energy
  • Double membrane
  • Own DNA

21
Cytoskeleton
  • Cytoskeleton
  • Gives cell shape
  • Anchors
  • Allows movement
  • Transport system
  • Within cell
  • Structure
  • Strong filaments
  • Complex web

22
Metabolism Energy and Life
23
Cells Energy
  • Cells store energy in various ways.
  • The most common is in a molecule adenosine
    triphosphate or ATP.
  • Making ATP is endothermic so cells can make ATP
    and then release that energy when its needed.

24
The Cells Energy Currency
  • Adenosine triphosphate (ATP)?
  • Provides energy
  • Structure
  • 3 phosphate groups
  • Sugar molecule
  • ribose
  • adenine
  • Function
  • Removal of phosphate group provides energy

25
The ATP reaction
The tri-phosphate becomes a di-phosphate
26
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27
Photosynthesis
  • Photosynthesis
  • Convert sunlight to energy
  • Process
  • Energy CO2 H2O ?carbohydrate O2
  • Colors

28
Glycolysis The First Step in Energy Generation
in the Cell
  • Respiration
  • Oxidation of carbohydrate
  • Retrieves energy in glucose
  • Aerobic
  • Process
  • Glycolysis
  • Split glucose
  • Result
  • Pyruvic acid
  • 2 ATP
  • 2 energy carriers
  • Convert energy carriers to 2-3 ATP
  • 1 molecule glucose 6-8 ATP

29
Fermentation A Way to Keep Glycolysis Going
  • Fermentation
  • Anaerobic
  • Inefficient
  • Yeast
  • alcohol
  • Animal cells
  • Lactic acid

30
The Final Stages of Respiration
  • Krebs cycle
  • Glucose broken down
  • CO2 produced
  • ATP
  • Energy-carrying molecules
  • Result
  • 36-38 ATP

31
Cell Division
32
Mitosis
  • Mitosis
  • Cell division
  • Not for sexual reproduction
  • Chromosomes
  • Process
  • Copy chromosomes
  • Spindle fibers
  • Migration of chromosomes
  • Nuclear membrane reforms

33
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34
Meiosis
  • Meiosis
  • Sexual reproduction
  • 1 cell forms 4 gametes
  • Gametes are genetically unique
  • Process
  • Copy chromosomes
  • Crossing over
  • Segregation
  • Segregation again
  • Result
  • 4 daughter cells
  • ½ normal chromosomes

35
Meiosis
36
VIRUS Virus occupy a twilight zone between the
worlds of living and nonliving things. Criteria
commonly applied for living things include (1)
independent motility, (2) irritability (the
ability to respond to certain environmental
stimuli), (3) the ability to reproduce, and (4)
the ability to specify the genetic composition of
progeny.
37
Viruses can have a wide variety of shapes and
sizes. This diagram of a bacterial virus shows
the protein coat containing DNA at the head. The
tail fibers at the bottom attach the virus to the
cell wall. DNA is then injected into the cell
through the cylindrical core.
38
A diagram of the HIV virus. The reverse
transcriptase is the enzyme that initiates
reverse transcription in the virus.
39
THE AIDS VIRUS Human immunodeficiency virus (HIV)
was shown in 1984 to be the cause of the dreaded
condition called immune deficiency syndrome
(AIDS). In 2004 40 million people lived with it
(1.1 million Americans) 5 million people
acquired HIV 3.1 million people died of it
40
The central dogma of molecular biology
41
HIV is a human retrovirus, the third such virus
to be identified. Retroviruses (retro--from Latin
means "turning back" are named after the crucial
step in their growth cycle that involves the
reversal of transcription, the first half of the
"central dogma of biology"
42
Organic Molecules
43
Four Basic Characteristics
  • Most molecules based on chemistry of carbon
  • Organic molecules
  • Lifes molecules form from few elements
  • H, O, C, N?97.5 of body weight
  • Molecules composed of simple building blocks
  • Arranged differently
  • Shape determines behavior
  • Determines ability for bonding

44
Chemical Shorthand
  • No H atoms or bonds to H are shown
  • C atoms are not shown explicitly

Shorthand
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