Proteins

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Proteins

• Most abundant type of molecules in cells
• Several hundred thousand in our bodies!
• Responsible for most biological functions

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Proteins are worker molecules that are necessary
for virtually every activity in your body
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Proteins during Development
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Unique Structures Unique Functions

• Collagen in our cartilage and tendons gains its
  strength from its three-stranded, rope-like
  structure.
• Found outside and inside the cell.

• Antibodies are immune system proteins that rid
  the body of foreign material, including bacteria
  and viruses.
• The two arms of the Y-shaped antibody bind to a
  foreign molecule.
• The stem of the antibody sends signals to recruit
  other members of the immune system.
• Found in blood and other body fluids

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Unique Structures Unique Functions

• Some proteins latch onto and regulate the
  activity of our genetic material, DNA.
• Some of these proteins are donut shaped, enabling
  them to form a complete ring around the DNA.

DNA polymerase III

• Enzymes - proteins that facilitate chemical
  reactions
• often contain a groove or pocket to hold the
  molecule they act upon. Shown here (clockwise
  from top) are luciferase, amylase, and reverse
  transcriptase

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GFP
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Protein Basics

• Proteins are polymers assembled from amino acids
• 20 different amino acids are used
• Bond between amino acids is called the "Peptide
  Bond".
• Peptide Bond is formed between the carboxyl group
  of one amino acid and the alpha amino group of
  another amino acid.

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The green fluorescent protein (GFP) is composed
of 238 amino acids, originally isolated from the
jellyfish Aequorea victoria that fluoresces green
when exposed to blue light.   You have become a
mad scientist with a mission to make a human
being glow. You and your colleagues have in your
hands the protein sequence of green fluorescent
protein (GFP). What steps do you take to make
this twisted dream come true?  
Amino Acid Sequence of GFP MetSerLysGlyAlaLeuIleV
alProSerTyrPheProThrThrSTOP
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(No Transcript)
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RNA

• Single stranded
• Ribose
• U instead of T
• Same base pair rules apply
• Generally unstable and degrades easily
• If have the amino acid sequence, can figure out
  the sequence of the mRNA

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Amino Acid Sequence of GFP MetSerLysGlyAlaLeuIleV
alProSerTyrPheProThrThrSTOP
How do you get the mRNA sequence?
AUG
AGU
AAG
GGA
Now you finish it!
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AUG AGU/C AAA/G GGU/C/A/G GCU/C/A/G CUU/C/A/G
AUU/C/A GUU/C/A/G CCU/C/A/G UCU/C/A/G UAU/C UUU/C
CCU/C/A/G ACU/C/A/G ACU/C/A/G
What can be done with this to make your baby glow?
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DNA

• Double stranded
• Deoxyribose
• T instead of U
• Same base pair rules apply
• Passed from one cell to the next
• If have the mRNA sequence, can figure out the
  gene sequence!

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Lets make a gene!
mRNA sequence
DNA sequence
AUG AGC AAG GGA GCC CUG AUU GUA CCG UCG UAC UUU
CCA ACU ACC
TAC TCG TTC CCT CGG GAC TAA CAT GGC AGC ATG AAA
GGT TGA TGG
ATG AGC AAG GGA GCC CTG ATT GTA CCG TCG TAC TTT
CCA ACT ACC
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Since GFP protein can be produced in EVERY cell
via the gene, we now have a glowing baby!!!!
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How is the GFP gene passed on to the next cell?

• DNA replication occurs before mitosis
• Occurs when chromosomes duplicate (make copies)
• An exact copy of the DNA is produced with the aid
  of the enzyme DNA polymerase
• Hydrogen bonds between bases break and enzymes
  unzip the molecule
• Each old strand of nucleotides serves as a
  template for each new strand
• New nucleotides move into complementary positions
  are joined by DNA polymerase

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Two New, Identical DNA Strands Result from
Replication
Video
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Central Dogma How it happens in the cell!
Animation!
Animation!
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Human Genome

• 3.2 million DNA base pairs
• 1.5 encode proteins lt gt 98.5 not protein
  encoding
• 31,000 genes encoding 100,000 - 200,000
  proteins
• How are 100,000 to 200,000 proteins produced from
  31,000 genes?
• What is the 98.5 of the human genome that does
  not encode proteins?

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RNA Processing
Video
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Translation In the Cell