DNA Basics

Organisms are made up of cells

The nucleus of the cell contains DNA

3’C

5’ end

5’C

3’C

5’C

3’ endOH

Figure 5.26

O

O

O

O

Nitrogenousbase

Nucleoside

O

O

O

O P CH2

5’C

3’CPhosphategroup Pentose

sugar

(b) NucleotideFigure 5.26

O

DNA is a linear polymer made up of repeating units

DNA is very stable; the data is backed up.

DNA is a double helix

But start to get used to thinking about DNA sequence like this...

1 ctcctagtcc agacgccatg ggtcatttca cagaggagga caaggctact atcacaagcc 61 tgtggggcaa ggtgaatgtg gaagatgctg gaggagaaac cctgggaagg ctcctggttg 121 tctacccatg gacccagagg ttctttgaca gctttggcaa cctgtcctct gcctctgcca 181 tcatgggcaa ccccaaagtc aaggcacatg gcaagaaggt gctgacttcc ttgggagatg 241 ccataaagca cctggatgat ctcaagggca cctttgccca gctgagtgaa ctgcactgtg 301 acaagctgca tgtggatcct gagaacttca agctcctggg aaatgtgctg gtgaccgttt 361 tggcaatcca tttcggcaaa gaattcaccc ctgaggtgca ggcttcctgg cagaagatgg 421 tgactggagt ggccagtgcc ctgtcctcca gataccactg agctcgctgc ccatgatgca 481 gagcttcaag gataggcttt attctgcaag caatacaaat aataaatcta ttctgctaag 541 agatc

DNA sequence

Genetic Basics

Central Dogma

The DNA double helix unzips

Transcription:

A messenger RNA (mRNA) copy of the gene is made

RNA has ribose instead of deoxyribose, has uracil instead of thymine, and is single stranded.

DNA RNA protein: information flow

Translation:

The messenger RNA copy of the gene is “cranked” through a ribosome.

The codons of the mRNA are read as a template to make a protein.

DNA RNA protein: information flow

Translation by Codon

• The linear DNA code is read in sets of 3 bases, called codons.

• AUG is the start codon.

• UAA, UAG and UGA are “stop” codons.

• The code is redundant; more than one codon encodes the same protein.

We will talk about proteins like this...

1 mshtasscqe lvencavhva gmaqedsrrg qvpssfyhga nqeldlstkv ykresgspys 61 vlvdtkmskp hlheteeqpy fretravsdv havkedrens ddteeeeeev sykreqiive 121 vnlnnqtlnv skgekgvssq sketpvlkts seeeeeesee eatddsndyg enekqkkkek 181 iv

The previous DNA sequence had 546 nucelotides.

How many proteins should be in this sequence?

Protein Sequence

Protein strings fold into 3D structures

Lysozyme protein– 2 models

Figure 8.16

Substate

Active site

Enzyme

(a)

Hexokinase protein modifying a glucose molecule in its active site

3D proteins do the cell’s work

Figure 8.16 (b)

Enzyme- substratecomplex