Exam 2 Review Slides

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Exam 2 Review Slides

• Lectures 5-8
• Chapters 3 and 22 (Sec. 22.1-22.4)

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Cell Membranes
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Passage of Materials through the Cell Membrane
Carrier/channel proteins required for all but
fat-soluble molecules and small uncharged
molecules
oxygen, carbon dioxide and other lipid-soluble
substances diffuse freely through the membrane
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Cellular Organelles
Table 1 of 2
CELL COMPONENT DESCRIPTION/ STRUCTURE FUNCTION(S)
CELL MEMBRANE Bilayer of phospholipids with proteins dispersed throughout cell boundary selectively permeable (i.e. controls what enters and leaves the cell membrane transport)
CYTOPLASM jelly-like fluid (70 water) suspends organelles in cell
NUCLEUS Central control center of cell bound by lipid bilayer membrane contains chromatin (loosely colied DNA and proteins) controls all cellular activity by directing protein synthesis (i.e. instructing the cell what proteins/enzymes to make.
NUCLEOLUS dense spherical body(ies) within nucleus RNA protein Ribosome synthesis
RIBOSOMES RNA protein dispersed throughout cytoplasm or studded on ER protein synthesis
ROUGH ER Membranous network studded with ribosomes protein synthesis
SMOOTH ER Membranous network lacking ribosomes lipid cholesterol synthesis
GOLGI Stack of Pancakes cisternae modification, transport, and packaging of proteins
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Cellular Organelles
Table 2 of 2
CELL COMPONENT DESCRIPTION/ STRUCTURE FUNCTION(S)
LYSOSOMES Membranous sac of digestive enzymes destruction of worn cell parts (autolysis) and foreign particles
PEROXISOMES Membranous sacs filled with oxidase enzymes (catalase) detoxification of harmful substances (i.e. ethanol, drugs, etc.)
MITOCHONDRIA Kidney shaped organelles whose inner membrane is folded into cristae. Site of Cellular Respiration Powerhouse of Cell
FLAGELLA long, tail-like extension human sperm locomotion
CILIA short, eyelash extensions human trachea fallopian tube to allow for passage of substances through passageways
MICROVILLI microscopic ruffling of cell membrane increase surface area
CENTRIOLES paired cylinders of microtubules at right angles near nucleus aid in chromosome movement during mitosis
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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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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
• can divide to become any of a restricted number
  of cells
• pluripotent

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Cancer

• Two types of tumors
• benign usually remains localized
• malignant invasive and can metastasize
  cancerous

• Genes that cause cancer
• oncogenes activate other genes that increase
  cell division
• tumor suppressor genes normally regulate
  mitosis if inactivated they will not regulate
  mitosis

Oncology is the study of tumors
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Cancer
Metastasis is the spread of a cancer from its
site of origin to other areas of the body
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Lecture Review
TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION GRADIENT GENERAL DESCRIPTION EXAMPLE IN HUMANS SIGNIFICANCE
SIMPLE DIFFUSION NO HIGH TO LOW spreading out of molecules to equilibrium O2 into cells CO2 out of cells. Cellular Respiration
FACILITATED DIFFUSION NO HIGH TO LOW Using a special cm carrier protein to move something through the cell membrane (cm) Process by which glucose enters cells
OSMOSIS NO HIGH TO LOW water moving through the cm to dilute a solute maintenance of osmotic pressure of 0.9. Same
FILTRATION NO HIGH TO LOW using pressure to push something through a cm (sprinkler hose) manner in which the kidney filters things from blood removal of metabolic wastes
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Lecture Review
TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION GRADIENT GENERAL DESCRIPTION EXAMPLE IN HUMANS SIGNIFICANCE
ACTIVE TRANSPORT YES LOW TO HIGH opposite of diffusion at the expense of energy K-Na-ATPase pump maintenance of the resting membrane potential
ENDOCYTOSIS YES LOW TO HIGH bringing a substance into the cell that is too large to enter by any of the above ways Phagocytosi cell eating Pinocytosis cell drinking. Phagocytosed (foreign) particles fuse with lysosomes to be destroyed help fight infection
EXOCYTOSIS YES LOW TO HIGH expelling a substance from the cell into ECF Exporting proteins dumping waste Same
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Osmotic Pressure/Tonicity
Osmotic Pressure (Osmolarity) ability of solute
to generate enough pressure to move a volume of
water by osmosis
Osmotic pressure increases as the number of
nonpermeable solutes particles increases

• isotonic same osmotic pressure as a second
  solution
• hypertonic higher osmotic pressure
• hypOtonic lower osmotic pressure

0.9 NaCl5.0 Glucose
Crenation
The O in hypotonic
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Some Definitions
Chromatin combination of DNA plus histone
proteins used to pack DNA in the cell nucleus
Gene segment of DNA that codes for a protein or
RNA - About 30,000 protein-encoding genes in
humans - DNAs instructions are ultimately
responsible for the ability of the cell to make
ALL its components

• Genome complete set of genes of an organism
• Human Genome Project was complete in 2001
• Genomes of other organisms are important also

Genetic Code method used to translate a
sequence of nucleotides of DNA into a sequence of
amino acids
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Structure of Nucleic Acids
Purines Adenine and Guanine (double
ring) Pyrimidines Cytosine, Thymine, and Uracil
(single ring)
Figure from Alberts et al., Essential Cell
Biology, Garland Press, 1998
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Structure of DNA
5'
3'
A double-stranded DNA molecule is created by
BASE-PAIRING of the nitrogenous bases via
HYDROGEN bonds. Notice the orientation of the
sugars on each stand.
5'
3'
DNA is an antiparallel, double-stranded
polynucleotide helix
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Structure of DNA
Complementary base pairing
Base pairing in DNA is VERY specific. -
Adenine only pairs with Thymine (A-T) - Guanine
only pairs with Cytosine (G-C)
Note that there are - THREE hydrogen bonds in
G-C pairs - TWO hydrogen bonds in A-T pairs - A
purine (two rings)base hydrogen bonds with a
pyrimidine base (one ring)
Figure from Martini, Human Anatomy
Physiology, Prentice Hall, 2001
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DNA Replication
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• THINGS TO NOTE
• DNA is replicated in the S phase of the cell
  cycle
• New strands are synthesized in a 5 to 3
  direction
• DNA polymerase has a proofreading function (1
  mistake in 109 nucleotides copied!)
• Semi-conservative replication describes pairing
  of post-replication strands of DNA (1 new, 1 old)

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5
3
5
3
3
5
3
Figure from Martini, Human Anatomy
Physiology, Prentice Hall, 2001
5
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RNA

• RNA is a polynucleotide with important
  differences from DNA
• Uses Uracil (U) rather than Thymine (T)
• Uses the pentose sugar, ribose
• Usually single-stranded
• There are three important types of RNA
• mRNA (carries code for proteins)
• tRNA (the adapter for translation)
• rRNA (forms ribosomes, for protein synthesis)

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Transciption/Translation

• Transcription
• generates mRNA from DNA
• Occurs in nucleus of the cell
• Uses ribonucleotides to synthesize mRNA
• Translation
• generates polypeptides (proteins) from mRNA
• Occurs in the cytoplasm of the cell
• uses tRNA and ribosomes

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The Genetic Code

1. Codon group of three ribonucleotides found in
   mRNA that specifies an aa
2. Anticodon group of three ribonucleotides found
   in tRNA that allows specific hydrogen bonding
   with mRNA
3. AUG is a start codon and also codes for MET.
   UAA, UAG, and UGA are stop codons that terminate
   the translation of the mRNA strand.

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Find the AMINO ACID SEQUENCE that corresponds to
the following gene region on the DNA Template -gt
G A T T G A A T C Coding -gt C T A A C T T A G
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tRNAs
Transfer RNAs (tRNA) function as adapters to
allow instructions in the form of nucleic acid to
be converted to amino acids.
Figures from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Eukaryotic Genes
The template strand of DNA is the one thats
transcribed. The coding strand of DNA is used as
the complementary strand for the template strand
in DNA and looks like the codons.
Figure from Alberts et al., Essential Cell
Biology, Garland Publishing, 1998
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Eukaryotic mRNA Modification
Newly made eukaryotic mRNA molecules (primary
transcripts) undergo modification in the nucleus
prior to being exported to the cytoplasm. 1.
Introns removed2. 5' guanine cap added3.
Poly-A tail added
Figure from Alberts et al., Essential Cell
Biology, Garland Publishing, 1998
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The Fate of Proteins in the Cell

• Breakdown of proteins regulates the amount of a
  given protein that exists at any time.
• Each protein has unique lifetime, but the
  lifetimes of different proteins varies
  tremendously.
• Proteins with short life-spans, that are
  misfolded, or that become oxidized must be
  destroyed and recycled by the cell.

Enzymes that degrade proteins are called
proteases. They are hydrolytic enzymes.
Most large cytosolic proteins in eukaryotes are
degraded by enzyme complexes called proteasomes.
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Enzymes

• Enzymes are biological catalysts
• Highly specific for their substrate
• Lower activation energy needed to start a
  reaction
• Are not consumed during reaction
• May require cofactors/coenzymes
• Effectiveness is greatly affected by temperature,
  pH, and the presence of required cofactors

• Cofactors
• make some enzymes active
• ions or coenzymes

• Coenzymes
• complex organic molecules that act as cofactors
  (so coenzymes ARE cofactors)
• vitamins
• NAD

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Harnessing Energy from Carbohydrates
Electrons (H) fall in energy from organic
molecules to oxygen during cellular respiration.
That is, e- LOSE potential energy during this
process and this energy is captured to make
ATP However, electrons CANNOT be transferred
directly from glucose to the electron transport
chain. There are intermediates activated
carrier molecules
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Energy for Metabolic Reactions

• Energy
• ability to do work or change something
  (potential, kinetic)
• heat, light, sound, electricity, mechanical
  energy, chemical energy
• changed from one form to another, but NEVER
  destroyed (law of conservation of energy)
• involved in all metabolic reactions

• Release of chemical energy
• most metabolic processes depend on chemical
  energy
• oxidation of glucose generates chemical energy
• cellular respiration releases chemical energy
  slowly from molecules and makes it available for
  cellular use

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Oxidation and Reduction Revisited
Oxidation Is Loss of electrons Reduction Is
Gain of electrons OIL RIG

• Oxidation
• gain of O2
• loss of e-
• loss of H (since a H carries an electron with
  it)
• increase in oxidation number, e.g., Fe2 -gt Fe3

• Reduction
• loss of O2
• gain of e-
• gain of H
• decrease in oxidation number, e.g., Fe3 -gt Fe2

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ATP An Activated Carrier Molecule

• each ATP molecule has three parts
• an adenine molecule
• a ribose molecule
• three phosphate molecules in a chain

These two components together are called a ?

• ATP carries its energy in the form or P
  (phosphate)
• ATP is a readily interchangeable form of energy
  for cellular reactions (common currency)

High-energy bonds
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NAD(H) An Activated Carrier Molecule
NAD
NAD (and NADP) are specialized to carry
high-energy e- and H atoms
A packet of energy H
NADH H
NAD
NADH
These packets of energy will be passed to oxygen
in the electron transport chain, and their energy
used to drive the synthesis of ATP
Important carriers of e- in catabolism NADH,
FADH2
Figure from Alberts et al., Essential Cell
Biology, Garland Press, 1998
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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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Summary of Catabolism of Proteins, Carbohydrates,
and Fats
Acetyl CoA is a common intermediate in the
breakdown of most fuels. Acetyl CoA can be
generated by carbohydrates, fats, or amino
acids Acetyl CoA can be converted into fatty acids
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Pyruvate is a Key Junction in Metabolism
Pyruvate is used to synthesize amino acids and
Acetyl CoA Pyruvate can also be used to
synthesize glucose via gluconeogenesis.
?Glycogenesis
?Lipo-genesis
Glycogenolysis ?
Lipolysis ?

Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
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Carbohydrate Storage

• Excess glucose can be
• stored as glycogen by glycogenesis (liver and
  muscle cells)
• stored as fat by lipogenesis
• converted to amino acids

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Terms to Know
-olysis ? breakdown of -neo ?
new-genesis ? creation of

• Glycolysis metabolism of glucose to pyruvate
• Gluconeogenesis metabolism of pyruvate to
  glucose (making CHO from non-CHO source)
• Glycogenesis metabolism of glucose to glycogen
• Glycogenolysis metabolism of glycogen to
  glucose
• Lipogenesis creation of new triglyceride
  (lipid, fat)
• Lipolysis breakdown of triglyceride into
  glycerol and fatty acids