Bio211

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Mariebs Human Anatomy and Physiology Ninth
Edition
Marieb w Hoehn
Chapter 3 Cells The Living Units Lecture 6
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Lecture Overview

• Mitochondria
• Intro to Cellular Respiration
• The cell nucleus
• The cell cycle
• Mitosis Meiosis
• Cell Death
• Stem Progenitor Cells

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Cytoplasmic Organelles (contd) - Mitochondria

• Mitochondria
• membranous sacs with inner partitions
• contain their own DNA
• generate energy

Figure From Marieb Hoehn, Human Anatomy
Physiology, 9th ed., Pearson
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A Closer Look at Mitochondria
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
(Impermeable to charged or polar molecules)
Strategically placed in cell where ATP demand is
high
Concentration of enzymes in the matrix is so high
that there is virtually no hydrating water.
Enzyme-linked reactions and pathways are so
crowded that normal rules of diffusion do not
apply!
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Overview of Cellular Metabolism
Metabolism All the chemical reactions that
occur in an organism
ETS
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Overview of Glucose Breakdown
NAD
NAD
NADFAD
Figure from Holes Human AP, 12th edition, 2010
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Overview of Cellular Respiration
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
Anaerobic
Cellular respiration (aerobic)
ATP
e-
Most ATP from here
e-
ETS
e-
ATP
e-

• Structural Functional Relationship - Inner
  membrane
• Contains Matrix where TCA cycle takes place
• Has enzymes and molecules that allow Electron
  Transport System to be carried out

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Anaerobic Glycolysis Lactic Acid
During glycolysis, if O2 is not present in
sufficient quantity, lactic acid is generated to
keep glycolysis going so it continues to generate
ATP (even without mitochondria)
Figure from Holes Human AP, 12th edition, 2010
NOTE what happens with and without O2 being
available
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Overview of Catabolism
Figure from Martini, Visual Anatomy
Physiology, Pearson, 2011
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Cell Nucleus

• control center of cell

• nuclear envelope (membrane)
• porous double membrane
• separates nucleoplasm from cytoplasm
  (eukaryotes only)

• nucleolus
• dense collection of RNA and proteins
• site of ribosome production

• chromatin
• fibers of DNA and proteins
• stores information for synthesis of proteins

Figure From Marieb Hoehn, Human Anatomy
Physiology, 9th ed., Pearson
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The Cell Cycle

• series of changes a cell undergoes from the time
  it forms until the time it divides
• stages
• interphase
• mitosis
• cytoplasmic division
• differentiation

Figure From Marieb Hoehn, Human Anatomy
Physiology, 9th ed., Pearson
Differentiated cells may spend all their time in
G0 (neurons, skeletal muscle, red blood cells).
Stem cells may never enter G0
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Why the Cell Cycle Must Have Controls

• 1. DNA/Cell replication must not proceed unless a
  signal to proceed is received
• 2. DNA must be completely and correctly replicate
  before mitosis takes place otherwise it should
  not occur.
• 3. Chromosomes must be correctly positioned
  during mitosis so they are separated correctly

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What are the Controls of the Cell Cycle?

• cell division capacities vary greatly among cell
  types
• skin and bone marrow cells divide often
• liver cells divide a specific number of times
  then cease

• chromosome tips (telomeres) that shorten with
  each mitosis provide a mitotic clock (cell
  senescence)

• cells divide to provide a more favorable surface
  area to volume relationship

• growth factors and hormones stimulate cell
  division
• hormones stimulate mitosis of smooth muscle
  cells in uterus
• epidermal growth factor stimulates growth of new
  skin

• contact inhibition

• Cyclins and Cyclin-dependent kinases provide
  central control

• tumors are the consequence of a loss of cell
  cycle control

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The Cell Cycle and Mitosis

• Review from Biology
• What is the cell cycle? Why does mitosis happen?

INNKEEPER, POUR ME ANOTHER
TEQUILA!
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The Cell Cycle and Mitosis

• INNKEEPER (INTERPHASE)
• POUR (PROPHASE)
• ME (METAPHASE)
• ANOTHER (ANAPHASE)
• TEQUILA (TELOPHASE/CYTOKINESIS)

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Interphase and Mitosis (IPMAT)
Interphase
Early Prophase
Late Prophase
Metaphase
Anaphase
Telophase/Cytokinesis
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Mitosis and Meiosis
Figures from Martini, Anatomy Physiology,
Prentice Hall, 2001
Mitosis production of two identical diploid
daughter cells Meiosis production of four
genetically varied, haploid gametes
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Chromosome Crossing Over

• mixes up traits
• different colors represent the fact that one
  homologous chromosome comes from the individuals
  father (paternal) and one from the mother
  (maternal)

Tetrad
Figure from Holes Human AP, 12th edition, 2010

• the genetic information in sperm cells and egg
  cells varies from cell to cell

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Cell Death

• Two mechanisms of cell death
• Necrosis
• Programmed cell death (PCD or apoptosis)
• Necrosis
• Tissue degeneration following cellular injury or
  destruction
• Cellular contents released into the environment
  causing an inflammatory response
• Programmed Cell Death (Apoptosis)
• Orderly, contained cell disintegration
• Cellular contents are contained and cell is
  immediately phagocytosed

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Necrosis vs. Apoptosis
Necrosis
Apoptosis
Figure from Alberts et al., Essential Cell
Biology, Garland Press, 1998
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Cellular Pathways of Apoptosis
Figure from http//www.ambion.com/tools/pathway/p
athway.php?pathwayCellular20Apoptosis20Pathway
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Failure of Apoptosis - Syndactyly
Photo from http//en.wikipedia.org/wiki/Apoptosis
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Stem and Progenitor Cells

• Stem cell
• can divide to form two new stem cells
• can divide to form a stem cell and a progenitor
  cell
• totipotent can give rise to any cell type
  (Embryonic stem cells)
• pluripotent can give rise to a restricted
  number of cell types

• Progenitor cell
• committed cell further along differentiation
  pathway
• can divide to become any of a restricted number
  of cells
• pluripotent
• not self-renewing, like stem cells

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Figure from Holes Human AP, 12th edition, 2010
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Summary Table of Cell Respiration
GLYCOLYSIS TCA ETC

Where it takes place Cytoplasm Mitochondria Mitochondria
Products Produced ATPNADHPyruvate ATPNADH,FADH2CO2 ATPNAD,FADH2O
Purpose Breakdown of glucose (6 carbons) to 2 molecules of pyruvate (3 carbons) Generation of energy intermediates (NADH, FADH2, ATP) and CO2 Generation of ATP and reduction of O2 to H2O (Recall that reduction is the addition of electrons)
What goes on 1. Glucose is converted to pyruvate, which is converted to acetyl CoA when there is sufficient O2 present. 2. Acetyl CoA enters the TCA cycle. 3. If O2 is not present, pyruvate is converted to lactic acid to replenish the supply of NAD so glycolysis can continue to make ATP 1. The energy in acetyl CoA is trapped in activated carriers of electrons (NADH, FADH2) and activated carriers of phosphate groups (ATP). 2. The carries of electrons that trap the energy from acetyl CoA bring their high energy electrons to the electron transport chain. 1. Chemiosmosis (oxidative phosphorylation) uses the electrons donated by NADH and FADH2 to eject H from the matrix of the mitochondria to the intermembrane space. 2. These H then flow down their concentration gradient through a protein (ATP synthase) that makes ATP from ADP and phosphate. 3. During this process, the H that come through the channel in ATP synthase are combined with O2 to make H2O.
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Review

• Cellular respiration
• The metabolic processes by which ATP is produced
• Major cellular steps
• Glycolysis
• Cytoplasm
• Anaerobic
• TCA (Krebs, Citric Acid) cycle
• Mitochondria
• Aerobic
• Electron Transport Chain
• Mitochondria
• Aerobic
• Most ATP produced here

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Review

• The goal of metabolism
• provide the cell with energy (via catabolism
  breakdown) and
• materials for the manufacture of cellular
  components (via anabolism synthesis, building
  up)
• Cell Nucleus
• Nuclear envelope (membrane)
• porous double membrane
• separates nucleoplasm from cytoplasm
  (eukaryotes only)
• Nucleoli RNA organizing centers
• Chromatin combination of DNA and RNA

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Review

• The Cell Cycle
• series of changes a cell undergoes from the time
  it forms until the time it divides
• stages can include
• interphase (G1, S, G2)
• mitosis (PMAT)
• cytoplasmic division (cytokinesis)
• differentiation (G0 exit from cell cycle)

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Review

• Cell Death occurs by two processes
• Necrosis
• Sudden insult to cell causing rapid death
• Causes inflammation in surrounding tissues
• Programmed Cell Death (apoptosis)
• Planned, orderly shutdown of cell
• Ubiquitous in normal cellular processes
• Does not cause inflammation of surrounding tissues

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Review

• Mitosis
• Identical daughter cells
• Diploid number of chomosomes
• Meiosis
• Used by sex cells
• Genetically varied daughter cells
• Haploid number of chomosomes
• Stem cells can produce many, if not all, other
  cell types
• Progenitor cells can produce only a limited
  number of cell types