Biochemistry and Cell Biology 101

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Biochemistry and Cell Biology 101
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Biomolecular Quartet

• There are four primary types of biologically
  important molecules, known as the biomolecular
  quartet
• Carbohydrates (carbs)
• Fatty Acids
• Amino Acids
• Nucleic Acids

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Biomolecular Quartet

• Carbohydrates
• Sugars
• Groups called saccharides or polysaccharides
• Often 6 carbon rings
• Sometimes 6-C ladders
• Short term energy supply
• Molecular recognition

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Biomolecular Quartet

• Fatty Acids
• Fats
• Polymers are called lipids
• Lumpy head with multiple straight carbon chains
  ending with -COOH
• Long term energy storage

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Biomolecular Quartet

• Amino Acids
• Consist of a central carbon surrounded by
• A hydrogen atom
• An amine (NH3) group
• A carboxylic acid (COO) group
• A variable group
• 20 amino acids (8 or 9 are essential)
• Basic protein building block
• Amino Acid (AA), peptide, polypeptide, protein

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Biomolecular Quartet
Essential Amino Acids (cannot be made by body)

• Tryptophan
• Methionine
• Valine
• Threonine
• Phenylalanine
• Leucine
• Isoleucine
• Lysine
• Histidine

Grains
Legumes
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Biomolecular Quartet

• Nucleic Acids
• Consists of
• A pentose (5 carbon sugar)
• A phosphate group
• A purine or pyrimadine (6C ring) base

• Forms the basis of the genetic code
• DNA Adenosine, Cytosine, Guanine, Thymine
• RNA Adenosine, Cytosine, Guanine, Uracil

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Biomolecular Quartet
Alanine GCU, GCC, GCA, GCG
Cysteine UGU, UGC
Aspartate GAU, GAC
Glutamate GAA, GAG
Phenylalanine UUU, UUC
Glycine GGU, GGC, GGA, GGG
Histidine CAU, CAC
Isoleucine AUU, AUC, AUA
Lysine AAA, AAG
Leucine UUA, UUG, CUU, CUC, CUA, CUG
Methionine AUG
Asparagine AAU, AAC
Proline CCU, CCC, CCA, CCG
Glutamine CAA, CAG
Arginine CGU, CGC, CGA, CGG, AGA, AGG
Serine UCU, UCC, UCA, UCG, AGU, AGC
Threonine ACU, ACC, ACA, ACG
Valine GUU, GUC, GUA, GUG
Tryptophan UGG
Tyrosine UAU, UAC

• Amino Acids
• Coded by nucleic acid triplets in DNA/RNA
• 3 letters codon
• 3 letters of 4 types gives 64 combinations to
  encode 20 amino acids.
• A adenosine
• C cytosine
• G guanine
• U uracil

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DNA

• Two interwoven strings of nucleic acids form the
  double helix of DNA.

• 2 strands are complementary
• Adenosine pairs with Thymine
• Cytosine pairs with Guanine

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DNA

• The helix is wound on spools called histones.
• Strings of histones form chromatin fibers.
• The chromatin fibers loop and coil into
  chromatids.
• Two chromatids joined by a centromere form a
  chromosome.

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DNA

• Each chromosome
• 2 short arms (p)
• 2 long arms (q)
• Nomenclature
• TPH1 11p15.3-p14
• Chromosome 11
• p Short arm
• Region 14-15.3

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DNA Structure

• Each chromatid carries several to several
  thousand genes (about 20-30K total in humans).
• Genes control some characteristic of the
  organism. TPH1 on 11p14-15 is 21K BP (1335 BP),
  444 AAs

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DNA

• Humans normally have 23 pairs of chromosomes
  (46 total)
• 22 pairs of autosomal chromosomes
• 2 sex chromosomes XX (female) or XY (male)

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Genetics

• Monogenetic traits
• A single gene controls the presence or absence of
  the trait.
• Dominant traits One copy required to express the
  trait.
• Ex. Brown hair, Widows peak, polydactyly,
  unattached earlobes, freckles, curly hair,
  Huntingtons Disease
• Recessive traits Two copies required to express
  the trait.
• Ex Blond hair, blue eyes, colorblindness,
  albinism, PKU, sickle cell anemia, cystic
  fibrosis
• Homozygous both parental genes the same.
• Heterozygous both parental genes different.

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Genetics

• Polygenetic traits
• Several to many genes involved.
• Most human behavioral and personality traits, and
  mental health problems are polygenetic and can be
  influenced by environmental factors.
• Sex-linked traits
• reside on either the X or Y chromosomes, but X is
  usually implied since Y is so small.
• Sex-limited traits
• present in both sexes but have an effect in one
  sex only, or at least it has a much stronger
  effect in one sex than in the other. (ex breast
  size, chest hair)

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Genetics/Heritability

• Genetic does not necessarily imply heritable!
• Genes can be inherited, but
• Healthy genes can be changed by
• Random mutations
• Ionizing radiation
• Toxins
• Etc.

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Heritability

• An important question to ask is whether the
  observed differences among individuals depend
  more on differences in heredity or differences in
  environment.
• Researchers use the concept of heritability, an
  estimate of how much of the variance in some
  characteristic within some population is due to
  heredity. Range is 0 1.

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Heritability

• Twins
• Twins offer a unique opportunity to separate
  nurture (environment) from nature (genetics).
• Identical/Monozygotic/MZ both twins have exactly
  the same DNA, since they came from a single
  fertilized egg. If separated twins show the same
  trait, it is most likely genetic (nature).
• Fraternal/Dizygotic/DZ the twins have the same
  genetic similarity ( ¼ ) as any other siblings.

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Heritability

• How do researchers determine the heritability of
  a human trait?
• 1st , to compare genetics, researchers compare
  the resemblance between monozygotic (identical)
  and dizygotic (fraternal) twins.
• A stronger resemblance between monozygotic twins
  indicates higher heritability.

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Heritability

• 2nd, to examine the contribution of the
  environment, researchers examine the differences
  between adopted children and their biological and
  adoptive parents.
• Resemblance to the biological parents indicates
  high heritability resemblance to the adoptive
  parents indicates low heritability and greater
  influence of environmental factors.

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Heritability

• Personality traits 0.5
• MMPI Scales 0.26 0.62, M 0.44
• MPQ - 0.39 0.58
• Schizophrenia, Depression 0.5 0.6
• IQ about 0.7
• Bipolar Disorder 0.8
• Huntingtons 1.0

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Heritability

• Social/Antisocial
• Religiosity
• Conservatism
• Risk Taking/Harm Avoidance
• Anxiety
• Pessimism/Optimism
• Impulsive Aggression
• Persistence

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The Cell
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The Cell

• A cell is the basic structural and functional
  unit of all living organisms.
• Cells carry on all of the same life functions as
  the entire organism.
• About 50 trillion cells in the human body.

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The Cell

• Bilipid membrane
• Two lipid membrane layers tightly bound
• Hydrophobic inside, Hydrophilic outside
• The membrane is fluid
• Embedded with channel, structural and recognition
  proteins
• Maintains internal cellular environment

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Cell Membrane
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The Cell

• Nucleus
• Stores the genetic material
• Surrounded by porous nuclear envelope
• Important genes are copied and mRNA is exported
  thru the nuclear pores to the rough ER for
  protein synthesis

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The Cell

• Ribosomes
• Created in the nucleolus.
• Synthesize proteins from Aas.
• Endoplasmic Reticulum
• Rough ER
• Contiguous with nuclear membrane
• Embedded with ribosomes
• Protein synthesis
• Smooth ER
• No ribosomes
• Steroid and lipid synthesis

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The Cell

• Golgi Apparatus
• Packages proteins produced by ER into packets
  called vesicles.

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The Cell

• Mitochondria
• Energy production glucose-gtATP
• Some cells have only a few mitochrondria.
• Nerves and muscle have hundreds or more.

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The Cell

• Microtubules/ Microfilaments
• Provide cellular structure
• Protein/organelle transport
• Centrioles
• Specialized groups of microtubules.
• Helps divide cell during mitosis.

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The Cell

• Vacuoles
• Storage vesicles
• Peroxisomes
• Contain powerful enzymes for detoxification
• Lysosomes
• Contain digestive enzymes
• Destruction of old cell parts

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The Cell

• Cilia
• Move in unison to propel fluid over cell
• Flagella
• Propels the cell
• Both have a 92 structure
• 9 pairs of microtubules
• Plus a center pair

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The Cell

• Microvilli
• Hair-like projections that increase surface area
• Used for absorption in intestines, nose, lungs

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The Cell
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Cell Reproduction

• At conception there is only one cell.
• 23 chromsomes from ovum, 23 from sperm.
• All cells of the first several generations are
  exactly identical.
• Specialization starts about the 5th or 6th
  generation.
• Each generation only gets more specialized.
• Stem cells are unspecialized and can develop into
  any type of cell.

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Cell Reproduction

• Mitosis cell division
• The 46 chromosomes are duplicated, temporarily
  making 92.
• The copies are separated to opposite ends of the
  cell.
• The cell divides down the middle.
• This leaves two cells, each with 46 again.

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Cell Reproduction

• Mitosis gone bad
• The 46 chromosomes are duplicated, temporarily
  making 92.
• 45 copies move to one end, 47 to the other.
• The cell divides down the middle.
• The person is now a mosaic some cells differ
  genetically!

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Cellular Groups

• Types of attachments between cells
• Tight junctions
• Impenetrable junctions
• Found in the blood-brain barrier
• Gap junctions
• Loose junctions that allow substances to pass
• Important embryonically, before circulation
• Often have connexions, intercellular tubes
• Desmosomes (adhesion junction)
• Structural connection proteins, gap junctions

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Tissues

• A group of connected cells performing a similar
  function is called a tissue.
• Only 4 types of tissue
• Epithelial (surface) tissue
• Connective tissue
• Muscle
• Nerves
• A group of related tissues which perform a given
  function is called an organ.

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The Nerve Cell

• Several specializations from a normal cell
• No centrioles nerves cannot replicate!
• Long life (must last a lifetime)
• Long and narrow vs. round-ish
• Nissl bodies, specialized rough ER
• To handle neurotransmitter synthesis
• Extremely high metabolic rate
• Many more mitochondria than normal cells
• Create action potentials, electrical pulses

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The Nerve Cell

• Cell body
• Biosynthetic center
• Dendrites
• Receptive regions
• Axon
• Arises from the axon hillock
• Impulse generation and transmission
• Ends in telodendria and terminal buttons

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The Nerve Cell

• Classifications
• Multipolar many processes (dendrites axon)
• Most abundant type in body CNS
• Bipolar 2 processes
• Rare, mostly sensory
• (Pseudo)unipolar one process
• Form as bipolar and then the proximal processes
  merge into one
• Mostly found in the PNS

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Types of Neurons
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The Nerve Cell

• Helpers (glial cells)
• Help during migration
• Schwann cells oligodendrocytes
• Speed transmission
• Astrocytes (CNS)
• Hold nerves in place, anchor to blood supplies
• Microglia
• Monitor nerve health, phagocytosis