DNA (deoxyribonucleic acid)- a nucleic acid which stores genetic traits in the proteins it codes for.

All living things contain DNA. DNA is a nucleic acid. Nucleic acids are made of

nucleotide subunits hooked together.

Nucleotides- subunits of DNA made of:

1. Phosphate (PO4)

2. Sugar (deoxyribose).

3. Nitrogen base.

Nucleotides

Four different nitrogen bases makes four different nucleotides:– Guanine– Cytosine– Adenine– Thymine

These four nucleotides make up the DNA of almost every single living thing.

Nitrogen Bases

Nucleotides

Chargaff’s Rule He measured amounts of each base

in various organisms and found: % of adenine (A) = % thymine (T)

% of cytosine (C) = % guanine (G) Chargaff’s rule told us that A bonds

to T and C bonds to G If 20% of strand is A, what %T?

%C?

Structure of DNA Discovered by Watson and Crick Double helix- 2 spiral strands of nucleotides

bonded together

Structure of DNA

Siderail backbone is the sugar and phosphates of nucleotidesRungs are the nitrogen bases of nucleotides

–A----T –C----G

Hydrogen bonds between bases hold two strands together

What is DNA Replication? Replicate = make “exact” copies. DNA replication- copying of DNA so that a cell

made divide All DNA must be

replicated before a cell can divide. Why?

Enzymes and Replication

Helicase- enzyme that unwinds DNA

DNA polymerase-enzyme that moves along each strand and brings in bases for new strand copy

DNA Replication Can be a mistake in replication Mutations-change in DNA Mutagens- substances that cause mutations

– X-rays – Toxins– Drugs– UV light, etc.

Mutations

3 types of mutations that can occur during DNA replication: – Insertions -extra

nucleotides– Deletions –missing

nucleotides– Substitutions –placement

of wrong nucleotides Can be helpful or harmful

mutations.

Insertion

Deletion

Substitution

Most Destructive Mutation?

The bases, A, C, G, and T can be equated to letters of a “DNA sentence”

THE DOG WAS HOT IN THE SUN Substitution:

THE DOG WAS NOT IN THE SUN Insertion?

THE DOG NWA SHO TIN THE SUN Deletion? THE DOG ASH OTI NTH ESU N Why should I care?

How Much DNA Is In OUR Cells?

Chromosome-strands of DNA coiled tightly Human cell has 46 (23 pairs)

23 from Mom 23 from Dad

Other organisms

have different

numbers of

chromosomes

2 Types of Cells

Somatic cells –all body cells except sex cells Diploidchromosomes are in pairs 46=23 pairs for humans 1 set (23) from mom, 1 set (23) from dad

Gametes - sex cells Egg & sperm Haploid no pairs (only 23 single chromosomes)

If all body cells contain the same # of chromosomes, why are all cells so different?

Different cells make different proteins due to different “active” segments of DNA.– Heart cells make proteins needed for the heart

to work properly– Brain cells make proteins needed for the brain

to work properly

What is the Purpose of DNA?

DNA stores the genetic information that codes for proteins.

ALL CELL FACTORIES MAKE PROTEINS!

What is the Purpose of DNA?Gene- a segment of DNA that codes for a protein.DNA has 1000’s of genes to make many different types of proteins.Why are proteins important?

Protein - polymer of amino acids

aa—aa—aa—aa—aa—aa—aa—aa = protein

What is the Purpose of DNA?

RNA (Ribonucleic acid)

Stores the genetic code in the nucleus

Double stranded

Sugar of DNA nucleotides = deoxyribose

A, C, G, T

“DNA is DNA”

Found in nucleus only

Transmits the genetic code to the rest of the cellSingle strandedSugar of RNA nucleotides is riboseA, C, G, U (uracil) NO T!Different forms: mRNA, rRNA, tRNAFound all over cell

_____DNA____ vs._____RNA___

DNA vs. RNA

Part 1of Protein Synthesis: Transcription

Transcription- copying of DNA to mRNA that occurs in the nucleus.

DNA complementary to mRNA ATA-CGG-AAT (DNA)

transcription in nucleus

UAU-GCC-UUA (RNA)

Transcription

Translation

cytoplasm

Part 2 of Protein Synthesis: Translation:

Translation- converting mRNA to protein which occurs at ribosomes in the cytoplasm

mRNA codons

translation by ribosomes

a.a.---a.a---a.a (protein)

cytoplasm

Part 2 of Protein Synthesis: Translation:

Codon-three bases of mRNA that code for an amino acid UAU-GCC-UUA (3 mRNA codons)

translation by ribosomes

a.a.---a.a---a.a. (protein) mRNA needs the help of tRNA to bring in the amino acids to be hooked together

cytoplasm

Whole Process ATA-CGG-AAT (DNA)

transcription in nucleus

UAU-GCC-UUA (3 mRNA codons)

translation in cytoplasm at ribosomes

a.a.-a.a-a.a. (protein)

How do we know what amino acid results?

The Codon Wheel!!!

Part #1Transcription

Part #2Translation

cytoplasm

The Codon Wheel***How do we use the wheel? There are 2 clues.

The Codon Wheel

Whole Process DNA: ATA-CGG-AAT

transcription in nucleus

mRNA: UAU-GCC-UUA(3 codons)

translation in cytoplasm

protein: a.a.-a.a-a.a.

tyrosine-alanine-leucine

Protein Synthesis Animation!

How do we know what amino acid results?

The Codon Wheel!!!

Amino Acids Where do our cells get

these amino acids to build the proteins?

From FOOD! We eat proteins, then these

proteins are broken down (metabolized) into amino acids in our stomach.

We reuse these amino acids to build other proteins.