Protein Synthesis
Modern Molecular Genetics
University of Maryland College Park
LFSC 620
Lesson Objectives
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DNA structure
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Nucleotide
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Proteins and Cell structure
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Nitrogen bases
mRNA
tRNA
The DNA-Protein connection
DNA (Deoxyribonucleic acid)
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Structure
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Made up of subunits called nucleotides
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2 strands of nucleotides
Nucleotides contain
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Deoxyribose sugar
Phosphate group
Nitrogen bases
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Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
http://nobelprize.org/educational_games/medicine/dna_double_helix/readmore.html
The Double Helix
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Bases are bonded together by a hydrogen bond
Base are complimentary to each other
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A-T
C-G
http://www.elmhurst.edu/~chm/vchembook/582dnadoublehelix.html
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RNA (Ribonucleic acid)
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There are several types of RNA
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Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
There are several differences between RNA and
DNA
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1 strand
Ribose sugar
Thymine (T) is replaced by Uracil (U)
Proteins and Cell Functioning
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The work of the cell is carried out by many
types of molecules called proteins.
Proteins are made up of subunits called
Amino Acids.
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There are 20 different amino acids that are
arranged in specific sequences to form many
different proteins.
Amino Acids and proteins
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The sequence of amino acids determines the shape of
the protein
The peptide bond that forms between them causes it
to fold and bend in a particular shape.
The shape of the protein enables it to carry out its
function.
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Enzymes- regulate chemical reactions
Hormones-cell communication
Proteins are found in the cell membrane
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Channels
Receptors
markers
http://www.pbs.org/wgbh/aso/tryit/dna/protein.html
The DNA-Protein connection
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Proteins are made at the ribosomes according
to the directions stored in the cell’s DNA code
Offspring inherit genetic information from
their parents which make these proteins
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Making many of the same proteins causes both
parent and offspring to form same structures that
give them similar features.
If the parent’s DNA carries a code for a protein
that does not function properly, the children may
also make the defective protein
Protein synthesis
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Begins in the nucleus (animation)
DNA code of a particular protein is read and
used to produce mRNA.
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This process is called transcription
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The nucleotides are organized in groups of three.
The sequence of bases found in mRNA is called a
codon
Each codon codes for a particular amino acid.
Code is determined from the DNA code.
Transcription
http://www.scientificpsychic.com/fitness/transcription.gif
mRNA codon-amino acid table
http://www.biology.iupui.edu/biocourses/N100/images/13translation.gif
tRNA
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Every three bases are called anticodons
tRNAs job is to pick up and transfer amino
acids to the ribosome.
Translation
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tRNA molecules carry
the amino acids to the
ribosome to make the
protein. The process of
the mRNA codon
matching its bases with
the tRNA anticodon is
called translation.
This process verifies the
genetic code for the
appropriate protein.
http://www.accessexcellence.org/RC/AB/WYW/wkbooks/PAP/PAPg/act1translation.gif
Animated protein synthesis websites
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http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302
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http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter15/animations.html#
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http://learn.genetics.utah.edu/content/begin/dna/