3. dna

I. Review Biological CompoundsA. Types

category monomer polymerCarbohydrate glucose starch

Lipids glycerol, fatty acid fat, oil

Protein amino acid protein

Nucleic Acid nucleotide DNA, RNA

B. Protein

A sequence of amino acids held together

by peptide bonds

There are 20 different types of amino acids

and the different arrangements of bonding

determines the protein

B1. Structure

1.Primary Structure

Sequence of amino acids = chain

2. Secondary Structure

Folds & bends due to amino acid interactions

3. Tertiary Structure

3-D shape (usually functional enzyme)

4. Quaternary Structure

More than one chain of amino acids

C. Nucleic Acids

1.TypesMonomer Polymer

DNA Nucleotide DNA

RNA Nucleotide RNA

2. Components of nucleotides

a. Phosphate Group – symbol

O-

|

H - O - P = O |

O-

b. 5 – Carbon Sugar

Deoxyribose Ribose C5 C5

O O C4 C1 C4 C1

C3 C2 C3 C2

HO H HO OH

c. Nitrogen Base

DNA RNA

Purines Adenine (A) Adenine (A)

(2 rings) Guanine (G) Guanine (G)

Pyrimidine Thymine (T) Uracil (U)

(1 ring) Cytosine (C) Cytosine (C)

3. Base Pairing

A = T A = U

C = G C = G

D. Definitions

1.DNA – A double-helix molecule made of

DNA nucleotides.

2. Gene – A segment of the DNA molecule

that codes for a specific trait.

3. Chromosome – A structure made up of

either 1 or 2 DNA molecules (each

is a double helix)

1 DOUBLE HELIX 2 DOUBLE HELIX

II. DNA Structure

A.Nucleotides

Monomer (4 different types)

Bacteria has millions

Plants/animals has billions

purine (A), (G)

= 2 rings

5

4 1

pyrimidine (T)(U)(C)

3 2 = 1 ring

N - BASE

B. Double Helix Polymer

1.Backbone

The of one nucleotide (5’) binds with deoxyribose sugar of another nucleotide (3’).

Covalent bond between the of one nucleotide and 3rd carbon of another nucleotide.

2. N-Bases – N base of one nucleotide H bonds to another N base on a separate nucleotide

DOUBLE HELIX

Nucleotides N bases paired

2 nm

III. DNA ReplicationCopy the DNA strand (Genetic info) so thatwhen a cell divides (mitosis, meiosis) they get an exact copy.

1. SEMICONSERVATIVE REPLICATION

A. General 3’ 5’ 3’ 5’ 3’ 5’ A T A T A T T A T A T A

G C GC G C

C G CG C G T A T A T A 5’ 3’ 5’ 3’ 5’ 3’ Parental DNA Enzyme reads template 3’ to 5’Double Helix synthesizes new DNA 5’ to 3’

3’ 5’ 5’ 3’STEP 1 DNA Helicase separates helix

by breaking the hydrogen bonds DNA Helicase between the N-bases.

replication fork

3’ 5’

5’ 3’

STEP 2DNA Polymerase

1. 2 Enzymes bond = 1 to each strand

2. Each enzyme reads the original 3’ to 5’

3. Each enzyme makes new DNA 5’ to 3’

4. Pairs free DNA nucleotides with parent strand

5. Bonds P to sugar to form backbone of new strand

5’ 3’ 5’ 3’

5’

3’

1.As drawn, upper DNA Polymerase synthesizes new strand as it follows helicase.

2.As drawn, lower DNA Polymerase detaches as come to unwound DNA helix

5’

3’ 5’ 3’

5’ 5’

3’

Lower DNA Polymerase synthesize

fragments and the DNA Polymerase

detach off fragments.

3’ 5’

5’ 3’

3’ 5’

5’ 3’

STEP 3 DNA Ligase - Joins the

backbone of the strands

Centromere – specific sequence of DNA that joins two DNA molecules together.

DNA Polymerase proofreads as goes along (only 1 mistake/10, 000 pairs but enzymes find and repair the mistakes).

END RESULT

3’ 5’

5’ 3’

3’ 5’

5’ 3’

I. Central DogmaOne gene one protein (really = polypeptide)

General:

1. A functional protein may be > 1 chain

2. Not all proteins are enzymes

3. 1 gene = 100’s-1000’s of nucleotides

4. 1000’s genes per chromosome

5. Start Stop on mRNA

AUG UAG, UAA, UGA

A. Nucleus 3’ 5’

DNA

5’ 3’

TRANSCRIPTION copy information from

DNA gene into mRNA

A U G G A U G C C

mRNA 5’ 3’

T A C C T A C G G’

A T G G A T G C C

B. Cytoplasm – the mRNA leaves the nucleus

by pores & goes to ribosome in the cytoplasm

rRNA –

makes up part of the ribosome

TRANSLATIONtRNA -

carries specific amino acids Amino Acid

Converts the information from

mRNA into a protein

primary structure of a protein

secondary structure of a protein

tertiary structure of a protein

II. Protein SynthesisA. DNA vs. RNA

double strand single strand

thymine uracil

deoxyribose ribose

B. RNA types

1.mRNA (messenger RNA)

Copy (where U replaces T) of DNA template gene (carries DNA code to the ribosme).

Enzyme reads the DNA 3’ to 5’ but lays the new nucleotides down 5’ to 3’ = makes mRNA 5’ to 3’

mRNA (messenger RNA)start stop

5’ A U G G A U G C C U A G 3’

CODON (corresponds to one amino acid)

Start codon Stop codon

AUG UAG

UGA

UAA

2. rRNA = Ribosomal RNA

Make ribosomes by combining two subunits (small and large)

Where protein synthesis occurs.

Ribosome structure (two subunits)

small subunit

large subunit 1st binding site 2nd binding site

catalytic site

3. tRNA = Transfer RNA

Brings amino acids to mRNA/rRNA

Anticodon = three consecutive nucleotides

on tRNA and pair to the codon on mRNA

Codon = AUG

Anticodon = UAC

Amino Acid = Met = methionine

Structure anticodon

U A C

Amino Acid

TRANSCRIPTION

1. Where Occurs nucleus

2. General DNA mRNA

Only one side of DNA Helix is copied into mRNA (not always the same side for different genes).

3. Parts of Transcription

INITIATION

a. RNA Polymerase binds to a promotor

(TATA*****), which tells the enzyme that the

gene starts on the complimentary strand of

the DNA Helix.

CONTINUE INITIATION

b. RNA Polymerase reads the template 3’ to 5’

but bonds new nucleotides for mRNA 5’ to 3’

PROMOTOR

5’ 3’

T A T A A T G C A A C T A T A A

3’ A T A T T A C G T T G A T A T T 5’

RNA Polymerase (enzyme)

ELONGATION

a. RNA Polymerase unwinds DNA Helix

b. RNA Polymerase moves along the DNA Helix

and reads the template 3’ to 5’

c. RNA Polymerase adds (bonds together) free

RNA nucleotides 5’ to 3’

d. Continues until enzyme reaches stop on DNA

C A A

GU

A

A T A T T A C G T T G A T A T T

T A T A A T G C A A C T A T A A

5’ 3’

3’ 5’

The RNA Polymerase (blue) is reading the DNA gene (bottom black) from 3’ to 5’ but adding new nucleotides (RNA) from 5’ to 3’. As it does this it is producing the mRNA (RED) 5’ to 3’.

5’

3’

The RNA Polymerase continues to add RNA nucleotides until it reaches a stop.

U A A

AUCAACGUA

5. Termination

a. Once the RNA Polymerase reaches this

point it detaches from the DNA (which

reforms the double helix). What is formed is

called a transcription unit.

b. RNA SPLICING

1.Need to remove introns

2.Need to bond together exons

3.Need to add cap and tail

4.Then have mRNA

DNA

mRNA5’ GPPP A U G C A A C U A U A A AAAAAA3’

TRANSLATION

Where: Cytoplasm

General:

mRNA moves into the cytoplasm.

Ribosomes “read” the mRNA.

Produce a protein.

1. INITIATION

Use:

tRNA-aa complex

Ribsomes

mRNA

A U G C A A C U A U A A

5’ 3’

U A C

AA1

LARGE SUBUNIT

SMALL SUBUNIT

mRNA

tRNA

1ST tRNA enters the site in the large subunit of the ribosome.

Bonds to the mRNA with the small subunit.


5’ 3’

U A C

AA1

G U U

AA2

2nd tRNA bonds to the second site in the ribosome.


5’ 3’

U A C

AA1

G U U

AA2

In the catalytic site AA1 is bonded to AA2.


5’ 3’

U A C

G U U

AA1 AA2

Ribosome moves toward the 3’ end of the mRNA.

Causes the 1st tRNA to leave and the 2nd site to be open.


5’ 3’

U A C

G U U

AA1 AA2

3rd tRNA enters the open site on Ribosome.

G A U

AA3


5’ 3’

U A C

G U U

AA1 AA2

The AA1-AA2 bond to AA3.

G A U

AA3


5’ 3’

U A C

G U U

AA1 AA2

Ribosome moves down mRNA toward the 3’ end.

G A U

AA3


5’ 3’

U A C

G U U

AA1 AA2

Causes 3rd tRNA to move in 1st site and 2nd tRNA leave ribosome sites.

Reaches stop codon on the mRNA.

G A U

AA3


5’ 3’

U A C

G U U

All detach.

G A U

AA1 AA2 AA3

3. dna

Documents