The Cell in Action

1
The Cell in Action

• Life Science
• Chapter 4

2
Cells The unit of Life

• You will learn how cells
• grow and divide
• transport materials
• Obtain energy

3
Exchange with the Environment

• Takes place with the help of the cell membrane

4
Function of Cell Membranes

• Materials need to move in and out of the cell
• Function like gatekeepers, letting some molecules
  through, but not others ? Selectively Permeable

5
Diffusion

• The spread of molecules from areas of high
  concentration, to areas of low concentration.
• The cell does not need energy for this diffusion
  to take place

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Moving Small Particles

• Small particles like water, oxygen can diffuse
  directly through the cell membrane
• Certain other particles have to move through
  protein channels or doorways by Passive Transport
  or Active Transport

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Passive Transport

• Diffusion of particles through proteins without
  the use of energy
• Particles move from an area of high concentration
  to an area of low concentration

8
Active Transport

• Diffusion of particles through proteins with the
  use of energy
• Particles move from an area of low concentration
  to an area of high concentration

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Diffusion of Water Osmosis

• The diffusion of water (across a membrane)
• Water will move in the direction where there is a
  high concentration of solute and low water
  concentration

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Osmosis

• Dissolved molecules ( ions, organic molecules,
  etc) are called solutes
• Most solutes cannot cross membranes
• As solute increases free H2O decreases
• Hypertonic? high solute
• Hypotonic ? low solute

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Water Balance in Animal Cells

• Net water flow into the cell which can burst
  (Hemolysis)

• Water flow equal in both directions

Net water flow out of cell which
shrinks (Crenation)
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Isotonic- means the same
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Hypotonic- less solute
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Hypertonic- high solute
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Moving Large Molecules

• Large molecules have to be packaged to be
  transported in and out of the cell
• Vesicles (membranes sacs) are formed to move the
  substances
• Exocytosis
• Endocytosis

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Exocytosis
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Endocytosis
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Exocytosis Endocytosis
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How Cells get Energy

• Chapter 4 Section 2

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Energy from Sunlight
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Photosynthesis

• The use of sunlight to make food
• Takes place in the chloroplast of leaves

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Chloroplasts

• Special organelles that can capture the energy of
  the sun
• Present in the mesophyll layer of leaves
• Stomata? tiny pores also present in leaves? CO2
  enters and O2 exits

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Overview of Photosynthesis

• Plants take CO2 from the air
• Veins carry water and nutrients from the plants
  roots to the leaves
• 6CO2 6H2O ? C6H12O6 6O2

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Getting Energy from Food

• All organisms break down food to convert the
  energy it contains into a more usable form
• Usable form of energy for all cells is ATP
• Food is broken down by
• Cellular Respiration
• Fermentation

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RESPIRATION

• Harvesting of the chemical energy of food.
• Food Glucose

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RESPIRATION (cont)

• Takes place in the mitochondria of cells
• Mitochondria energy harvesting units

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Cellular Respiration Breathing

• Respiration Breathing
• Respiration ? exchange of gases
• Organisms? O2 from env.? gives off CO2

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Cellular Respiration

• Breathing Cellular Respiration are very closely
  related
• Cellular Respiration ? main function is to
  harvest energy from food

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Cellular Respiration

• Takes place in the mitochondria
• Food is broken down into CO2 and H2O
• The energy that is released is stored as ATP
• ATP is later used by the cell for different
  activities

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General Reaction

• C6H12O6 6O2
• Glucose Oxygen
• ? 6CO2 6H2O E
• Carbon Dioxide Water

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RESPIRATION

• Reactants
• C6H12O6 6O2
• Products
• 6CO2 6H2O Energy

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Photosynthesis vs. Respiration

• Photosynthesis is the opposite of respiration
• End Product of Photosynthesis
• Reactants of Respiration

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Photosynthesis vs. Respiration

• In Photosynthesis, sugars are formed and O2 is
  released.

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Photosynthesis vs. Respiration

• In Respiration, sugars are broken down and CO2 is
  released.

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CO2 O2 Cycle
O2
chloroplast
CO2
mitochondria
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CO2 O2 Cycle
O2
CO2
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Fermentation

• Cells in the absence of oxygen ferment sugars and
  other foods
• The products formed depends on the type of cells

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Muscle Cells

• Lactic acid is produced when muscle cells lack
  oxygen
• Glucose? 2 pyruvic acid? 2 lactic acid
• Lactic acid causes muscles to ache? stop take
  deep breaths

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Yeast Cells

• Alcohol is produced, CO2 is also released
• Process is used in the beer wine industry
• Also used in bread making
• Glucose? 2 pyruvic acid? ethyl alcohol
  (evaporates while baking), CO2 released makes
  bread rise

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The Cell Cycle

• Chapter 4
• Section 3

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How Cells Divide

• 1955 ? R. Virchow
• All cells come from pre-existing cells
• Cell division ? essential for life

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Purpose of Cell Division

• Repair? replacement of lost or damaged cells
• Skin cells are constantly being replaced
• Growth? cells divide and increase in size, so
  that organism can grow
• Infant? Baby? Child? Adult

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Types of Cell Division

• Asexual Reproduction
• Sexual Reproduction

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Asexual Reproduction

• Production of offspring from a single parent
• Offspring is identical to parent
• Ex bacteria, yeast, unicellular organisms some
  multicellular organisms

45
Budding? Yeast
46
Binary Fission? Bacteria
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Sexual Reproduction

• Two parents are involved
• Genetic material from each parent combines
• Offspring is different from parent

48
Eukaryotic Cells

• Division of the nucleus plus cytokinesis, ?
  produces two identical daughter cells
• Stages
• Prophase
• Metaphase
• Anaphase
• Telophase

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Eukaryotic Cells

• Chromosomes contain DNA and Protein
• The number of Chromosomes is different in
  different organisms
• Fruit flies have 8
• Humans have 46 or 23 pairs of Homologous
  Chromosomes

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Chromosomes and Cell Division

• Chromatin? fibers of DNA and protein
• Chromosomes? Chromatin fibers condense and become
  visible compact structures
• Sister Chromatids? before the cell divides the
  DNA duplicates and forms identical copies

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Prophase 1st Stage

• Chromosomes condensed and visible
• The nucleoli disappear
• The mitotic spindle begins to form
• breakdown of the nuclear membrane

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Metaphase 2nd Stage

• Chromosomes gather in the a plate across the
  middle of the cell
• Mitotic spindle is fully formed
• All chromosomes are attached to the spindle fibers

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Anaphase 3rd Stage

• The sister chromatids suddenly separate from
  their partners.
• Each chromatid ? daughter chromosomes move toward
  the poles

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Telophase 4th Stage

• The chromosomes reach the poles of the spindle.
• This processes is the reverse of prophase?
  Mitosis, the division of one nucleus into two
  genetically identical daughter nuclei

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Cytokinesis

• Division of the cytoplasm
• Occurs along with telophase
• Two daughter cells separate
• Difference in animal and plant cells
• Animal Cell ?cell membrane pinches off to form a
  cleavage furrow
• Plant Cell ?Cell plate is formed to divide cell
  into two

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Animal Cell
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Plant Cell