Transcript 2_DNA_structure

DNA
Nucleus
DNA Packaging Inside Nucleus
Nucleosome
Supercoil
Chromosome
Protein
Scaffold
Double Helix (Partially Disrupted)
2 nanometers
1 turn =
10 base pairs =
3.4 nanometers
Minor Groove
Major Groove
NUCLEOTIDES
Phosphate
Base
Sugar
TRIPLET CODONS
GENETIC CODE
Initiation Codon
Termination Codons
U
U
First
Base
in
Codon
C
A
G
C
A
G
UUU
Phe
UCU
Ser
UAU
Tyr
UGU
Cys
UUC
Phe
UCC
Ser
UAC
Tyr
UGC
Cys
UUA
Leu
UCA
Ser
UAA
UAA
UGA
UUG
Leu
UCG
Ser
UAG
UGA
UGG
Trp
CUU
Leu
CCU
Pro
CAU
His
CGU
Arg
CUC
Leu
CCC
Pro
CAC
His
CGC
Arg
CUA
Leu
CCA
Pro
CAA
Gln
CGA
Arg
CUG
Leu
CCG
Pro
CAG
Gln
CGG
Arg
AUU
Ile
ACU
Thr
AAU
Asn
AGU
Ser
AUC
Ile
ACC
Thr
AAC
Asn
AGC
Ser
AUA
Ile
ACA
Thr
AAA
Lys
AGA
Arg
AUG
AUG
Met
ACG
Thr
AAG
Lys
AGG
Arg
GUU
Val
GCU
Ala
GAU
Asp
GGU
Gly
GUC
Val
GCC
Ala
GAC
Asp
GGC
Gly
GUA
Val
GCA
Ala
GAA
Glu
GGA
Gly
GUG
Val
GCG
Ala
GAG
Glu
GGG
Gly
Third
Base
in
Codon
CELL MEMBRANE
•Controlling what goes in and out of the cell.
•Anchoring of the cytoskeleton to provide shape to the cell
•Attaching to the extracellular matrix to help group cells together in the formation of
tissues
•Transportation of particles by way of ion pumps, ion channels, and carrier proteins
•
•Containing receptors that allow chemical messages to pass between cells and systems
•Participation in enzyme activity important in such things as metabolism and
immunity
CELL MEMBRANE
The cell mem consists of three classes of amphipathic lipids: PHOSPOLIPIDS, GLYCOLIPIDS, STEROIDS
Membrane is held together via weak non-covalent interaction of hydrophobic tails
Structure is fluid and not fixed rigidly in place.
Phospholipid molecules are “fluid”: free to diffuse and exhibit rapid lateral diffusion along the layer they are
present in.
The FATTY ACID chains in phospholipids and glycolipids usually contain an even number of
carbon atoms, typically between 14 and 24. The 16- and 18-carbon fatty acids are the most
common.
In animal cells, cholesterol is found dispersed in varying degrees throughout cell membranes,
where it confers a stiffening and strengthening effect on the membrane. It resides in the irregular
spaces between the hydrophobic tails of the membrane lipids.
polar, hydrophilic heads
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7nm
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hydrophobic tails
SELECTIVE TRANSPORT OF MOLECULES ACROSS MEMBRANE
Nutrients: in
Waste: out
Gate Keepers: Transmembrane PROTEINS
Create: ion channels, proton pumps, etc.
Extremely important to cell: e.g. a third of the genes in yeast code specifically for them
Again: chicken and egg
Need DNA to code for membrane proteins but
Need membrane proteins to create selective membrane to allow cell to exist.