Replication Replication Transcription Transcription TranslationTranslation

DNA1.Its structure is a Double Helix

2. Made up of nucleotides which consist of a phosphate group, a sugar, and a nitrogenous base

3. Hydrogen Bonds hold the Nitrogenous Base Pairs

4. Complimentary bases pairs bond Adenine-Thymine and Guanine-Cytosine

GeneGene

• A gene is a segment of DNA

• A gene is a sequence of nucleotides that codes for a functional product (usually a protein)

• 1 gene = 1000’s of base pairs

• 41000 possibilities of combinations

A Gene is a Segment of DNA

When a gene is expressed, DNA is transcribed to produce RNA and RNA is then translated to produce proteins.

Genotype and PhenotypeGenotype and Phenotype

• Genotype- the letters

1. Genetic Composition of an Organism

2. Represents the Potential Properties

• Phenotype- the actual organism

1. The Expression of the Genes

2. What You See

ReplicationReplication• Replication occurs before

a cell divides so that each new cell formed can have a copy of the DNA

• Occurs in the nucleus of the cell

• 1 Strand 2 Complementary Strands

• The primary enzyme in this process is DNA Polymerase

One More Time!

thymine

adenine

cytosine

guanine

phosphate

deoxyribose sugar

DNA nucleotide

Deoxyribose sugar

phosphate

Nitrogenous base (guanine)

RNA nucleotide

ribose sugar

phosphate

Nitrogenous base (uracil)

Sugar / phosphate “strand”Nitrogenous base “rung”

Hydrogen bond(H-bonds)

Step 1: Hydrogen bonds between complimentary bases break

DNA “unzips”

Step 2: DNA strandspull apart from each other

Step 3: DNA nucleotides in the cellmatch up with each side of the “unzipped” DNA

each “unzipped’ strands forms a template for a new strand

Step 4: Each “old’ strandforms a template for a “new” strand

two identical DNA molecules form

“old” (original) strand

“new” strand, identicalsequence to the original

TranscriptionTranscription• The process of DNA

making a complimentary strand of RNA.

• Occurs in the nucleus of the cell

• 1 Strand DNA 2 Strands RNA

• The primary enzyme involved in this process is RNA Polymerase

DNA                     RNA                            

                                

 

Label the Following

One More Time!

Step 1: Hydrogen bonds between complimentary bases break

DNA “unzips”

Step 2: DNA strandspull apart from each other

Step 3: RNA nucleotides in the cell match up with only one side of the “unzipped” DNA

each “unzipped’ strands forms a template for a mRNA strand

RNA nucleotide

Step 4: RNA nucleotides continue to match up with “unzipped” DNA

until the message is completelytranscribed

mRNA strand

One side of DNA strand

Step 4: mRNA strand breaks off from the DNA strand

mRNA strand

One side of DNA strand

Step 5: mRNA strand leaves the nucleus for the ribosome

Step 6: Once the mRNAleaves, the DNA “zips”back together

TranslationTranslation• The process in which

an amino acid chain is made from mRNA template

• 1 Strand RNA Amino Acid Chain Protein

• This occurs in the cytoplasm with the help of ribosomes

The problem: How does a particular sequence of nucleotides specify a particular sequence of amino acids?

By means of transfer RNA molecules, each specific for one amino acid and for a particular triplet of nucleotides in mRNA called a codon. The family of tRNA molecules enables the codons in a mRNA molecule to be translated into the sequence of amino acids in the protein.

RNA and Protein SynthesisRNA and Protein Synthesis

• RNA is a Single Stranded Nucleic Acid and has Uracil instead of thymine

• RNA Acts as a Messenger between DNA and Ribosomes

• Process Takes Amino Acids and Forms Proteins

Why Is It Necessary?Why Is It Necessary?

• DNA is in the Nucleus

• Ribosomes are in the Cytoplasm

• This requires a Messenger to go between the nucleus and the cytoplasm

DefinitionsDefinitions• Codon

1. Three-base segment of mRNA that specify amino acids.

• Anticodon1. Three-base segment of tRNA that dock with a codon.2. Docking results in depositing of amino

acid which is added to a chain .

Protein Synthesis

• Proteins are coded directly from the mRNA with 3 bases (one codon) for each amino acid. What’s up with that?

MutationMutation

• A change in the nitrogenous base sequence of DNA; that causes a change in the product coded for by the mutated gene.

Mutations

What happens when you get insertions or deletions of bases in the DNA sequence?

Usually you end up with a mess.

THE BIG FAT CAT ATE THE RAT AND GOT ILL

Deletion of one base

THE IGF ATC ATA TET HER ATA NDG OTI LL

And its all pops and buzzes.

Sickle-Cell Anemia

DefinitionsDefinitions• Carcinogens

Substances and preparations which, if they are inhaled or ingested or if they penetrate the skin; may induce cancer or increase its incidence and can affect any cells or tissues

• Mutagensmay induce hereditary genetic defects or increase their incidence and effect the germ cells (gonads)

• Teratogensmay induce non-hereditary congenital malformations or increase their incidence and effect the growing fetus

MutagensMutagens

• Tobacco products• Nitrous Acid• Mold Toxins• X-rays• Gamma Rays• UV Radiation• Some Artificial Sweeteners