BIOLOGY 2401 ANATOMY AND PHYSIOLOGY PART I CHAPTER 3

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BIOLOGY 2401ANATOMY AND PHYSIOLOGYPART
ICHAPTER 3

• Cells The Living Units

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Cell Theory

• Basic structural functional unit of life
• Need a cell to make more cells
• no spontaneous generation
• Activity of body depends on activity of cells
• Activities of cells dictated by subcellular
  structure

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Topics of Cells

• Border
• Plasma membrane structure
• Membrane transport
• Cytoplasm
• Organelles mitochondria, ribosomes, ER, Golgi,
  lysosomes,etc.
• Nucleus
• Chromosomes
• Cell cycle
• Protein synthesis

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Border Plasma Membrane

• Bilayer of phospholipids with embedded, dispersed
  proteins
• Fluid Mosaic Model
• Semi-permeable membrane

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Phospholipid bilayer
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Cholesterol
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Embedded protein
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Glycoprotein

Glycolipid
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Plasma membranes are permeable

• Focus first on Passive transport
• Also known as Diffusion spreading out of
  molecules down their concentration gradient
• Osmosis Specifically, spreading out of water

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Plasma membranes are permeable

• Focus now on Active transport - moving molecules
  against their concentration gradient
• Takes energy ATP
• Example of Primary Active Transport
• Sodium-Potassium pump

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Topics of Cells

• Border
• Plasma membrane structure
• Membrane transport
• Cytoplasm
• Organelles mitochondria, ribosomes, ER, Golgi,
  lysosomes, etc.
• Nucleus
• Chromosomes
• Cell cycle
• Protein synthesis

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Cytoplasm

• Cytoplasm material between plasma membrane and
  the nucleus
• Cytosol largely water with dissolved protein,
  salts, sugars, etc.
• Cytoplasmic organelles metabolic machinery of
  the cell

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Cytoplasmic Organelles

• Specialized cellular compartments
• Membranous
• Mitochondria, peroxisomes, lysosomes, endoplasmic
  reticulum, and Golgi apparatus
• Nonmembranous
• Cytoskeleton, centrioles, and ribosomes

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Mitochondria

• Double membrane structure with shelflike cristae
• Provide most of the cells ATP via aerobic
  cellular respiration
• Contain their own DNA and RNA

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Mitochondria
Figure 3.17
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Ribosomes

• Made of protein and rRNA
• Site of protein synthesis
• Free Bound

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Endoplasmic Reticulum (ER)

• Interconnected tubes and parallel membranes
  enclosing cisternae
• Continuous with the nuclear membrane
• Two varieties rough ER and smooth ER

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Endoplasmic Reticulum (ER)
Figure 3.18a and c
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Rough (ER)

• External surface studded with ribosomes
• Manufactures all secreted proteins
• Makes membrane proteins and phospholipids for
  cell membranes

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Signal Mechanism of Protein Synthesis
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Signal Mechanism of Protein Synthesis
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Signal Mechanism of Protein Synthesis
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Signal Mechanism of Protein Synthesis
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Signal Mechanism of Protein Synthesis
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Signal Mechanism of Protein Synthesis
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Smooth ER

• Tubules arranged in a looping network
• Catalyzes a variety of reactions in various
  organs of the body

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Golgi Apparatus

• Stacked and flattened membranous sacs
• Functions in modification, concentration, and
  packaging of proteins
• Transport vessels from the ER fuse with the Golgi
  
• Secretory vesicles leave the Golgi stack and move
  to designated parts of the cell

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Role of the Golgi Apparatus
Figure 3.21
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Lysosomes

• Spherical membranous bags containing digestive
  enzymes
• Digest ingested bacteria, etc
• Degrade nonfunctional organelles

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Endomembrane System Recap

• System of organelles that function to
• Produce, store, and export biological molecules
• Degrade potentially harmful substances
• System includes
• Nuclear envelope, smooth and rough ER, lysosomes,
  vacuoles, transport vesicles, Golgi apparatus,
  and the plasma membrane

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Endomembrane System
Figure 3.23
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Cytoskeleton

• The skeleton of the cell
• Series of rods running through the cytosol

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Motor Molecules

• Protein complexes that function in motility
• Powered by ATP
• Attach to receptors on organelles

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Motor Molecules
Figure 3.25a
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Motor Molecules
Figure 3.25b
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Cilia

• Whiplike, motile cellular extensions on exposed
  surfaces of certain cells
• Move substances in one direction across cell
  surfaces

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Cilia
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Topics of Cells

• Border
• Plasma membrane structure
• Membrane transport
• Cytoplasm
• Organelles mitochondria, ribosomes, ER, Golgi,
  lysosomes, etc.
• Nucleus
• Chromosomes
• Cell cycle
• Protein synthesis

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Nucleus

• Contains nuclear envelope, nucleoli, chromatin
• Gene-containing control center of the cell
• Dictates the kinds and amounts of proteins to be
  synthesized

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Nucleus
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Nucleoli

• Dark-staining spherical bodies within the nucleus
• Site of ribosome production

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Chromatin

• Threadlike strands of DNA and histones
• Arranged in fundamental units called nucleosomes
• Form condensed, barlike bodies of chromosomes
  when the nucleus starts to divide

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Topics of Cells

• Border
• Plasma membrane structure
• Membrane transport
• Cytoplasm
• Organelles mitochondria, ribosomes, ER, Golgi,
  lysosomes, etc.
• Nucleus
• Chromosomes
• Cell cycle
• Protein synthesis

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Cell Cycle

• Interphase
• Growth (G1), synthesis (S), growth (G2)
• Mitotic phase
• Mitosis and cytokinesis

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Interphase

• G1 (gap 1) metabolic activity and vigorous
  growth
• G0 cells that permanently cease dividing
• S (synthetic) DNA replication
• G2 (gap 2) preparation for division

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Synthesis phase (DNA Replication)

• Each nucleotide strand serves as a template for
  building a new complementary strand
• DNA polymerase covalently adds complementary
  nucleotides to the template
• Since DNA polymerase only works in one direction
• A continuous leading strand is synthesized
• A discontinuous lagging strand is synthesized and
  spliced together with ligase
• Result One old strand and one new strand for
  each chromatid
• This process is called semiconservative
  replication

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DNA Replication
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Cell Division

• Essential for body growth and tissue repair
• Mitosis nuclear division
• Cytokinesis division of the cytoplasm

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Mitosis

• The phases of mitosis are
• Prophase - chromatin coils into chromosomes
• Metaphase chromosomes line up in center
• Anaphase sister chromatids split apart
• Telophase nuclei form, chromatin uncoils
• AFTER mitosis, cleavage furrow forms in
  Cytokinesis and cell splits

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Early Prophase
Pair of centrioles
Early mitotic spindle
Centromere
Aster
Chromosome, consisting of two sister chromatids
Early prophase
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Late Prophase
Fragments of nuclear envelope
Polar microtubules
Kinetochore
Kinetochore microtubule
Spindle pole
Late prophase
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Metaphase
Metaphase plate
Spindle
Metaphase
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Anaphase
Daughter chromosomes
Anaphase
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Telophase Cytokinesis
Nucleolus forming
Contractile ring at cleavage furrow
Nuclear envelope forming
Telophase and cytokinesis
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Control of Cell Division

• Surface-to-volume ratio of cells
• Chemical signals such as growth factors and
  hormones
• Contact inhibition
• Several regulatory proteins under study
• including cyclins and cyclin-dependent kinases
  (Cdks)

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Topics of Cells

• Border
• Plasma membrane structure
• Membrane transport
• Cytoplasm
• Organelles mitochondria, ribosomes, ER, Golgi,
  lysosomes, etc.
• Nucleus
• Chromosomes
• Cell cycle
• Protein synthesis

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Protein Synthesis

• DNA serves as master blueprint for protein
  synthesis
• Genes are segments of DNA carrying instructions
  for a polypeptide chain
• Triplets of nucleotide bases form the genetic
  library
• Each triplet specifies coding for an amino acid

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From DNA to Protein
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Roles of the Three Types of RNA

• Messenger RNA (mRNA) carries the genetic
  information from DNA in the nucleus to the
  ribosomes in the cytoplasm
• Transfer RNAs (tRNAs) bound to amino acids base
  pair with the codons of mRNA at the ribosome to
  begin the process of protein synthesis
• Ribosomal RNA (rRNA) is a structural component of
  ribosomes

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Gene Expression

• Transcription - Transfer of information from the
  sense strand of DNA to mRNA
• Translation use ribosome and tRNA to transfer
  information from mRNA to make protein

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Genetic Code

• RNA codons code for amino acids according to a
  genetic code

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DNA RNA Protein
Figure 3.39