nucleus structure: surrounded by nuclear envelope with pores; contains genetic information (dna)...
TRANSCRIPT
Nucleus• Structure: Surrounded by
nuclear envelope with pores; contains genetic information (DNA)
• Function: Contains the genetic information that gives the cell instructions to make proteins
The way the nucleus gives instructions to cells is called Central Dogma
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Central Dogma
RNA
Protein
DNA
• Describes the flow of information in a cell:
1. Genetic information is stored in DNA 2. It is transferred into individual
transportable copies, made of RNA (mRNA=messenger RNA)
3. Each mRNA copy transfers the information to make one particular protein.
• Central Dogma was proposed by Crick (1958)
Central Dogma
RNA
Protein
DNA deoxyribonucleic acid
Player #1: DNA
DNA structure: key to the central dogma
• DNA is double stranded• The two DNA strands
run in opposite directions
• Uses 4 bases – A, G, C, T
• Fixed base-pairing rules– A-T– G-C
• Each strand is complementary to the other:
ATGGATTACCTA
Central Dogma
RNA
Protein
DNA
ribonucleic acid
Player #2: RNA
RNA
• Single stranded molecule• Uses 4 bases
– A, G, C, U
• Can fold on itself• Base pairing rules:
G-CA-U
• RNA has 3 types of RNA:– mRNA (messenger RNA)– tRNA (transfer RNA)– rRNA (ribosomal RNA)
• Each type has a different job
Player #3: Proteins
• Chains of amino acids (aa)
• 20 different aa can be used
• Different order of aa= different functions for proteins
Central Dogma
RNA
Protein
DNA
Antibodies (www.biology.arizona.edu/.../ graphics/ribbons.gif)
Insulin
Examples of Proteins made through Central Dogma:
Transcription
• The process by which a new RNA molecule is formed from DNA.
RNA
Protein
DNA
Transcription
Central Dogma: Step #1
Transcription1. The two strands of DNA are opened up
2. One strand is used as a template
3. A new RNA molecule is formed on the template
RNADNA
RNApolymerase
Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)
Copyright Pearson Edication Inc.
Analogy: Original handwritten precious grandma’s chocolate recipe (1 DNA strand )
Your new handwritten copy to bring home (RNA)
12 2
3
Translation
• The process by which the information carried by the RNA is used to make proteins at the Ribosomes.
RNA
Protein
DNA
Transcription
Translation
Central Dogma: Step #2
mRNA
Ribosome
Methionine
Phenylalanine tRNALysine
Translation• The cell uses information from
the RNA to produce proteins.• The “code” is read in triplet form
called a codon: every three bases on mRNA has information for only one amino acid.
• The 3 types of RNA have different jobs at this point:– mRNA brings the message– tRNA brings the amino acid– rRNA + other proteins forms
the ribosome where translation happens
Codon Charts:
• I prefer this one: • But this is one seen in many textbooks:
Genetic Code
• The Central Dogma dictionary: – from “DNA/RNA language” to “protein
language”– Use the Codon Chart
• An analogy of this is:– Grandma’s special recipe is in German and
when it is being rewritten it is translated into Spanish.
– Use the dictionary
www.stanford.edu/.../ f_ae01centralDogma.gif
Summary of Central Dogma