DNA Form and FunctionDNA Form and Function

Prokaryote CellProkaryote Cell

Eukaryotic CellEukaryotic Cell

What is DNA?What is DNA? Deoxyribonucleic acid –DNADeoxyribonucleic acid –DNA There are 3 parts to DNAThere are 3 parts to DNA

Phosphate groupsPhosphate groups Sugar (deoxyribose) Sugar (deoxyribose) Nitrogenous base (A,T,C,G)Nitrogenous base (A,T,C,G)

The bases form the rungs of a ladder The bases form the rungs of a ladder when they base pair (chemically bond when they base pair (chemically bond with Hydrogen bonds)with Hydrogen bonds)

DNA StructureDNA Structure

Nucleotides Make up Nucleotides Make up Nucleic AcidNucleic Acid

nucleotide= nitrogenous base + nucleotide= nitrogenous base + phosphate group + sugar phosphate group + sugar

Bases DNA= A,T, G, C (Adenine, Bases DNA= A,T, G, C (Adenine, Thymine, Guanine and Cytosine)Thymine, Guanine and Cytosine)

Bases RNA= A, U, G, C (Same Bases RNA= A, U, G, C (Same except Uracil)except Uracil)

Pairs A-T(U), G-C Pairs A-T(U), G-C

What Does DNA Do?What Does DNA Do? DNA in humans contain about 3 billion base DNA in humans contain about 3 billion base

pairs, and more than 99 percent of those pairs, and more than 99 percent of those bases are the same in all people. Why?bases are the same in all people. Why?

If you unwound all the DNA is one cell and If you unwound all the DNA is one cell and placed it end to end, it would measure about placed it end to end, it would measure about 6 feet long.6 feet long.

Humans have 20,000- 25,000 different Humans have 20,000- 25,000 different genes among these 3 billion base pairs.genes among these 3 billion base pairs.

What is a gene and what does it ultimately What is a gene and what does it ultimately do?do?

Central Dogma TheoryCentral Dogma Theory DNA replication- DNA replication- DNA to DNADNA to DNA DNA transcription- DNA transcription- DNA to RNA DNA to RNA

(transcribe genes into RNA, junk (transcribe genes into RNA, junk DNA does not need to transcribe or DNA does not need to transcribe or gets deleted after transcription)gets deleted after transcription)

TranslationTranslation- RNA into protein (uses - RNA into protein (uses 3 types of RNA to get proteins 3 types of RNA to get proteins made!)made!)

ReplicationReplication DNA is copied before cells divide, so DNA is copied before cells divide, so

that the new cell has all of the DNA that the new cell has all of the DNA as it’s parent cell. as it’s parent cell.

This allows organisms to grow (if (if you are a multicellular, eukaryotic you are a multicellular, eukaryotic organism) or reproduce if you are an organism) or reproduce if you are an asexual prokaryotic or eukaryotic asexual prokaryotic or eukaryotic organism.organism.

DNA Replication is semi-DNA Replication is semi-conservativeconservative

When DNA is copied, 1 of the old When DNA is copied, 1 of the old strands is the template for the new strands is the template for the new strand.strand.

Therefore, each new double helix of DNA has 1 old and 1 new strand of DNA.

DNA Genes are the DNA Genes are the Template for Template for

Transcription (DNA to Transcription (DNA to RNA)RNA) DNA is unzippered at the site of a DNA is unzippered at the site of a

gene and 1 strand is copied into gene and 1 strand is copied into messenger RNA (so mRNA is a messenger RNA (so mRNA is a single strand and contains the base single strand and contains the base U instead of T).U instead of T).

mRNA leaves the nucleus and goes mRNA leaves the nucleus and goes to a ribosome in order to make a to a ribosome in order to make a proteinprotein

mRNA is the template for mRNA is the template for amino acids and protein amino acids and protein

buildingbuilding mRNA is organized so that every 3 base mRNA is organized so that every 3 base

pairs codes for a different amino acids.pairs codes for a different amino acids. Amino acids combine in a chain and eve

ntually fold and combine to make complex proteins!

Those proteins is what makes us what Those proteins is what makes us what we are!we are!

The genes that code for these proteins, The genes that code for these proteins, whether they conserved among all whether they conserved among all humans, or different among individuals humans, or different among individuals can be inherited.can be inherited.

Genetic Code Determines Genetic Code Determines Amino AcidAmino Acid

DNA Mutations can be DNA Mutations can be detrimental, neutral or detrimental, neutral or occasionally beneficial occasionally beneficial

Detrimental-cancers, birth defectsDetrimental-cancers, birth defects Neutral-mutations in non-coding DNA Neutral-mutations in non-coding DNA

has no effecthas no effect Beneficial- gives organisms the ability to Beneficial- gives organisms the ability to

adaptadapt

Think Evolution and Natural Selection- Think Evolution and Natural Selection- DNA mutations are necessary for this to DNA mutations are necessary for this to occur!occur!