Transcript Cells Bio and Biochemistry

Biochemistry and
Cell Biology 101
Biomolecular Quartet
• There are four primary types of biologically
important molecules, known as the
biomolecular quartet:
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Carbohydrates (“carbs”)
Fatty Acids
Amino Acids
Nucleic Acids
Biomolecular Quartet
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Carbohydrates
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Sugars
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Often 6 carbon rings
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Groups called saccharides
or polysaccharides
Sometimes 6-C ladders
Short term energy supply
Molecular recognition
Biomolecular Quartet
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Fatty Acids
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Fats
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Polymers are called lipids
Lumpy head with
multiple straight carbon
chains ending with COOH
Long term energy
storage
Biomolecular Quartet
• Amino Acids
– Consist of a central carbon surrounded by:
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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
Biomolecular Quartet
Essential Amino Acids (cannot be made by body)
Grains
Tryptophan
Methionine
Valine
Threonine
Phenylalanine
Leucine
Isoleucine
Lysine
Histidine
Legumes
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
Biomolecular Quartet
• 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.
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A = adenosine
C = cytosine
G = guanine
U = uracil
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
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
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.
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
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
DNA
• Humans normally
have 23 pairs of
chromosomes
(46 total):
– 22 pairs of autosomal
chromosomes
– 2 sex chromosomes:
XX (female) or
XY (male)
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, Widow’s peak, polydactyly, unattached earlobes, freckles,
curly hair, Huntington’s 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.
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)
Genetics/Heritability
• Genetic does not necessarily imply heritable!
• Genes can be inherited, but
• Healthy genes can be changed by:
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Random mutations
Ionizing radiation
Toxins
Etc.
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.
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.
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.
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.
Heritability
• Personality traits – 0.5
– MMPI Scales – 0.26 – 0.62, M = 0.44
– MPQ - 0.39 – 0.58
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Schizophrenia, Depression – 0.5 – 0.6
IQ – about 0.7
Bipolar Disorder – 0.8
Huntington’s – 1.0
Heritability
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Social/Antisocial
Religiosity
Conservatism
Risk Taking/Harm Avoidance
Anxiety
Pessimism/Optimism
Impulsive Aggression
Persistence
The Cell
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.
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
Cell Membrane
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
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
The Cell
• Golgi Apparatus
– Packages proteins produced by ER into packets
called vesicles.
The Cell
• Mitochondria
– Energy production: glucose->ATP
– Some cells have only a few mitochrondria.
– Nerves and muscle have hundreds or more.
The Cell
• Microtubules/
Microfilaments
– Provide cellular structure
– Protein/organelle transport
• Centrioles
– Specialized groups of
microtubules.
– Helps divide cell during
mitosis.
The Cell
• Vacuoles
– Storage vesicles
• Peroxisomes
– Contain powerful enzymes for detoxification
• Lysosomes
– Contain digestive enzymes
– Destruction of old cell parts
The Cell
• Cilia
– Move in unison to propel
fluid over cell
• Flagella
– Propels the cell
• Both have a 9+2 structure
– 9 pairs of microtubules
– Plus a center pair
The Cell
• Microvilli
– Hair-like
projections that
increase surface
area
– Used for
absorption in
intestines, nose,
lungs
The Cell
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.
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.
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!
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
Tissues
• A group of connected cells performing a
similar function is called a tissue.
• Only 4 types of tissue:
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Epithelial (“surface”) tissue
Connective tissue
Muscle
Nerves
• A group of related tissues which perform a
given function is called an organ.
The Nerve Cell
• Several specializations from a normal cell:
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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
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
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
Types of
Neurons
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