Download Proteins - Mr. Vickers

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IF YOU WERE A SPY, HOW WOULD YOU
W R I T E A M E S S A G E T O H E A D Q U A RT ERS
IN A WAY THAT IF THE ENEMY
INTERCEPTED IT, THEY WOULD NOT
KNOW WHAT THE MESSAGE SAID?
Why are Codes Important?
Nucleus
(“Control Center”)
What structures are found in the nucleus?
Chromosomes
What are chromosomes made of?
DNA wrapped around proteins
What are located on chromosomes?
Genes
GENES AND CHROMOSOMES WORK TOGETHER TO
DECODE THE GENETIC CODE!!
How is genetic information passed on in such exact form?
DNA
(Deoxyribonucleic Acid)
The Structure of DNA
 DNA consists of 3 parts:
 1. Sugar = Deoxyribose
Deoxyribose
 2. Phosphate Group
 3. Nitrogen Bases
Nitrogen Base
The Structure of DNA
Deoxyribose (Sugar) + Phosphate Group + Nitrogen Base =
NUCLEOTIDE
The Structure of DNA: 4 Kinds of Nitrogen Bases
 Adenine (A)
 Guanine (G)
 Thymine (T)
 Cytosine (C)
The Structure of DNA: Scientists Contributions
 Rosalind Franklin
Used X-ray crystallography to study DNA structure
The Structure of DNA: Scientists Contributions
 James Watson and Francis Crick
Discovered the structure of DNA by building 3D
models.
The Watson and Crick DNA Model: Double Helix
 Double Stranded
 Resembles a LADDER
 Uprights =
Sugar+Phophate
 Rungs = nitrogen bases
joined together by
chemical bonds
The Watson and Crick DNA Model: Nitrogen Base Pairs
 Adenine – Thymine
(A-T)
 Cytosine – Guanine
(C-G)
DNA Replication
 Replication- DNA copying process that allows new
cells to have a complete set of DNA.
 Carried out by enzymes
 DNA polymerase- joins nucleotides to make a
DNA molecule
DNA Replication Steps
 1. DNA untwists from the double helix.
 2. DNA unzips- the chemical bonds between the
bases break and the 2 strands separate.
 3. Exposed nitrogen bases are allowed to join with
other bases using the rules of base pairing.
 4. 2 new identical DNA strands are produced.
DNA Replication
What are Proteins?
 Proteins- organic molecules made up of different
combinations of amino acids.
 Order of amino acids varies greatly from protein to
protein.
 Proteins have many functions in cells. (i.e. enzymes,
carrier molecules, etc.
How are Genes and Proteins related?
 Genes control the synthesis of proteins.
Protein Synthesis: RNA
 RNA= Ribonucleic Acid
 RNA is single stranded.
 Made up of 3 parts:
 1. Sugar = Ribose
 2. Phosphate Group
 3. Nitrogen Bases
RNA Base Pairs
 Adenine-Uracil
 (A-U)
 Note: In RNA, Thymine
is replaced with Uracil
 Cytosine-Guanine
 (C-G)
3 Types of RNA
 1. Messenger RNA (mRNA)- carries instructions
for assembling amino acids into proteins.
 2. Ribosomal RNA (rRNA)- found on ribosomes
 3. Transfer RNA (tRNA)- transfers amino acids to
the ribosomes
Protein Synthesis: Transcription
 Transcription- DNA code is transferred to RNA
code
 1. RNA polymerase unzips DNA molecule.
 2. Exposed bases pair up with mRNA bases using the
rules of base pairing.
 3. mRNA leaves nucleus and goes to ribosomes.
How do we interpret the mRNA code?
 Codon- 3 bases that
represent an amino acid
CGA TTT ATA CAG (DNA)
GCUAAAUAUGUC (mRNA)
Alanine
Tyrosine
Valine
Lysine
Protein Synthesis: Transcription
 1. Match DNA base pairs with the corresponding
mRNA base pairs.
 2. Separate mRNA base pairs into codons.
 3. Decode codons into amino acids with The Genetic
Code.
 4. Order of amino acids determines the type of
protein.
Protein Synthesis: Translation
 Translation- decoding of mRNA message into
protein (polypeptide chain).
 Takes place in the ribosomes
 Process is continuous. Different parts may happen at
once.
Translation Steps
 1. Ribosome moves along mRNA strand.
 2. tRNA brings amino acid to mRNA.
 3. Amino acid joins mRNA.
 4. mRNA codons, UAG, UAA, UGA, stop the
elongation process
 5. Amino acids link together by peptide bonds.
Proteins are made of polypeptides.
 Polypeptide- amino acid chain