DNA, RNA, and Protein Synthesis

http://faculty.uca.edu/~johnc/mbi1440.htm

http://www.wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/mRNA.gif

Biochemical reactions occurring in all cells are catalyzed by enzymes.

Collision model: Molecules must collide with enough kinetic at the proper orientation to break bonds

Enzymes are catalyst that lower activation energy.

In order to react must collide with enough KE to break bonds – the activation energy

With a lower activation energy, more collisions will have enough KE to react.So the reaction is faster.

Enzymes increase the rate of the reaction at the same temperature

Enzymes are proteins.

• Glycolysis is one of the simplest biochemical pathaways.

• Each of the ten steps is catalyzed by a unique enzyme

• Each of those enzymes is synthesized in each cell

• Each enzyme is coded for in the DNA of the cell

Proteins – a string of amino acids

SERINE – one of 20 amino acids

Proteins – a string of amino

acids

Peptide bonds

form between amino acids

Hydrogen bonds

Sugar-phosphate backbone

Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

Structure of DNASection 12-1

DNA – base pairs carry the genetic code for the sequence of the amino acids Nucleotide

Nucleotides in the DNA strand carry the code for

proteins

Image by: Riedell

Purines(2 rings)

Pyrimidines

(1 ring)

A

G

C

T

Phosphate group

Deoxyribosesugar

 Nitrogen bases =“Steps of ladder”

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A

G

C

T

Phosphate group

Deoxyribosesugar

 Nitrogen bases =“Steps of ladder”

© Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

ADENINE

GUANINE

CYTOSINE

THYMINE

CHARGAFF’S RULES

A = T G = C

Image from: http://evolution.berkeley.edu/evosite/evo101/images/dna_bases.gif

_________ _________At time no one knew why…

now we know its becauseAdenine always bonds across with____________

Guanine always bonds across with ____________

THYMINE

CYTOSINE

RNA and PROTEIN SYNTHESIS

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DNA is safely stored in the nucleus. mRNA (messenger RNA) brings a copy of the code out to the cytoplasm.

RNADNA

RNApolymerase

Transcription - Making a copy of the DNA code Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

Enzyme called RNA polymerase separates strands of DNA, then uses one strand as a template to assemble an mRNA copy.mRNA will carry the “script” out of the nucleus to the cytoplasm

RNA- the Other Nucleic Acid

Also made of nucleotides

Sugar is ribose insteadof deoxyribose.

RNA is single stranded, instead of doubled stranded.

Contains uracil instead of thymine.

http://images2.clinicaltools.com/images/gene/dna_versus_rna_reversed.jpg

MASTER PLAN DNA stays safe in nucleus TRANSCRIPTION (DNA→ RNA)& PROCESSING (remove interons)takes place in nucleus

TRANSLATION (RNA→ proteins)takes place on ribosomes in cytoplasm

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“Blueprints” of master plan are carried to building site

http://www.home-improvement-resource.com/images/architect.jpg

Translation - Translating the base pair codes into an amino acid sequence

mRNA – the copy of the code

sequence of base pairs

tRNA – carries the amino acid to the ribosome as coded for in the mRNA – codons code for specific amino acids.

___________ on tRNA

matches up with________ on mRNA

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ANTICODON

CODON

EACH tRNA carries onlyone kind of_____________amino acid

HOW CAN JUST 4 BASES GIVE DIRECTIONS TO MAKE 20 AMINO ACIDS?

Message is read in groups of 3 = _________

UCGCACGGU UCG-CAC-GGU

CODON

Codons represent different amino acids

Serine- Histidine- Glycine

 The m-RNA Code

64 possible codons

Some amino acidshave more than onecodon.

START= _______

3 codons for _____

AUG

STOP

Translation - Translating the base pair codes into an amino acid sequence

Translation (continued)

Summary of protein synthesis

DNA strand in nucleus

RNA message copied from DNA Occurs in the nucleus

Occurs in the cytoplasm at the ribosome

mRNA moves out to cytoplasm

A graphic to show you translation to sequence the protein

ribosome

codon

carries a specific amino acid depending upon its code