DNA and RNA DNA stands for Deoxyribonucleic Acid

DNA and RNA

DNA stands for Deoxyribonucleic Acid • In 1953, James Watson and Francis Crick developed the model called the Double Helix used to represent DNA. • But what about Rosalind Franklin?

Rosalind Franklin • Photograph 51 is the nickname given to an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952, working as a Ph. D student under the supervision of Rosalind Franklin, at King's College London in Sir John Randall's group. It was critical evidence in identifying the structure of DNA.

What is inside of the Nucleus? • Chromosomes are threadlike structures that contain genetic information that is passed on from one generation of cells to the next. • Chromosomes are made up of DNA • Chromosomes are only visible during cell division. Otherwise genetic information is known as chromatin.

Chromatin

Parts of the chromosome • Centromere - the part of a chromosome that links sister chromatids • Chromatid - one copy of a duplicated chromosome, which is generally joined to the other copy by a single centromere. • Gene segment – segment of DNA that codes for a trait

Chromosomes

Where is Your DNA? DNA is coiled up to make chromosomes found in the nucleus. A segment of DNA is a gene that codes for a certain trait. (skin tone, eye color)

Regents Practice Question # 1 Which model best represents the relationship between a cell, a nucleus, a gene, and a chromosome? 12

Regents Practice Question # 1 (Answer) Which model best represents the relationship between a cell, a nucleus, a gene, and a chromosome? Correct Answer 13

Regents Practice Question # 2 Which diagram represents the relative sizes of the structures listed below? 14

Regents Practice Question # 2 (Answer) Which diagram represents the relative sizes of the structures listed below? Correct Answer 15

DNA • DNA is called the blueprint of life because it contains the instructions for building an organism and ensuring that organism functions correctly.

Structure of DNA • DNA belongs to the class of biochemical molecules known as nucleic acids • This Twisted Ladder is made of nucleotides • The sides of the ladder are composed (made) of alternating deoxyribose sugars and phosphates. • The rungs of the ladder are composed of nitrogenous bases.

A Nucleotide is the building block of nucleic acids. An organic compound made of one phosphate, nitrogenous base, and a sugar.

Nitrogenous Base Pair • Adenine pairs to Thymine • Guanine pairs to Cytosine

Your Turn ATTCGCGAATTG TAAGCGCTTAAC TGGATCCGTGAA ACCTAGGCACTT

DNA is Important • It carries genetic information from one generation to the next • DNA sequences create genes which then determine inherited traits • DNA can be easily copied during the creation of new cells

DNA REPLICATION • Replication is the process where DNA makes a copy of itself. WHY? • During cell division the genetic information needs to be passed to the daughter cells

DNA Replication Process • DNA separates into 2 strands unzipping itself with an enzyme called Helicase • One half of the old strand is always kept as a template for the new strand. DNA polymerase is an enzyme that matches nucleotides to old strand. • 2 daughter strands each consisting of an old DNA and a new DNA strand

DNA Replication in Use

DNA Fingerprinting or Gel Electrophoresis A process used to compare DNA samples from different sources.

DNA Fingerprinting (Gel Electrophoresis) Steps of DNA fingerprinting 1. DNA is cut using restriction enzymes, then fragments are placed in gel well 2. Electricity is applied to gel 3. DNA molecules move from negative to positive charged ends of gel 4. Smaller DNA segments move faster and farther than larger DNA segments

Uses of DNA Fingerprinting • Solve crimes • Determine Paternity • Establish Evolutionary Relationships

Proteins Synthesis • Genes control the production of proteins which occurs in the ribosomes. • Proteins are in every cell, tissue, muscle and bone – two million proteins in your body. • DNA can’t leave the nucleus but it needs to send instructions to the ribosomes so proteins can be made. • DNA sends a messenger out to the ribosome that carries the instructions for making the proteins.

What is RNA? • Ribonucleic Acid - RNA is the messenger that carries the instructions to the ribosomes so proteins can be made. • Three Types of RNA m. RNA-messenger t. RNA-transfer r. RNA-ribosomal

Structure of RNA • Single stranded • It has uracil for a nitrogenous base instead of thymine • Complimentary base pairs are: – Cytosine-Guanine – Adenine-Uracil

Making A Protein starts with Transcription • Transcription is the process where a DNA molecule makes the messenger RNA molecule in the nucleus so genetic instructions can leave the nucleus. • Done by copying part of the base sequence of the DNA into a strand of RNA • RNA polyermase unzips the DNA strand matches up the nucleotides.

Translation happens when m. RNA arrives at the ribosome • Translation allows the cell to use information from m. RNA to produce proteins that are built from amino acids • DNA m. RNA Transcription Translation Protein

Genetic Code • A codon consists of 3 nitrogenous bases that code for a single amino acid that is to be added to the growing protein chain. • Codons are located on the m. RNA • There are just 22 different amino acids that exist.

MUTATIONS • Mutations are changes in the DNA sequence that affect genetic information. • Mutations provide genetic variations in a species • Not all mutations are harmful, some give an advantage to a species

Three Types of Mutations can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. – Substitution – Deletion – Insertion

Substitution • Occurs when one nitrogenous base is substituted in place of another one

Insertion • Occurs when one extra nitrogenous base is added into the DNA sequence

Deletion • Occur when one nitrogenous base is missing from the sequence

Causes of Mutations • Two ways DNA can be mutated: – Mutations can be inherited – Mutations can be acquired • Environmental damage • Mistakes when DNA is copied

Karyotype • A photograph of an organism’s chromosomes Typical Karyotype

Mutagens from our Environment • Mutagens are environmental factors that cause mutations. They include but are not limited to: 1. High Temperature 2. Toxic chemicals (pesticides) 3. Radiation (nuclear and solar)

Nature vs Genetic Engineering

Selective Breeding • There are different ways of moving genes to produce desirable traits. For both plants and animals, one of the more traditional ways is through selective breeding. • Selective breeding is a method of improving species by allowing only those organisms with desirable traits to produce the next generation.

Examples of Selective Breeding • •

• Uses of selective breeding

Genetically Modified Organisms (GMOs)

What are GMO’s • any organism whose genetic material has been altered using genetic engineering techniques. • Also called transgenic organism – transfer of genes

Real or Photoshop?

Real or photoshop

Real or photoshop?

Real or Photoshop?

Example of GMO technique

Recombinant DNA

What the heck is Recombinant DNA? A series of procedures that are used to join together (recombine) DNA segments. A recombinant DNA molecule is constructed from segments of two or more different DNA molecules. Under certain conditions, a recombinant DNA molecule can enter a cell and replicate there, either on its own or after it has been integrated into a chromosome. For example: Insulin + Bacterial DNA Antifreeze from fish + tomato DNA Growth Hormone + Bacterial DNA Human + (other) Human DNA

Why Make Recombinant DNA? Recombinant DNA Technology May Allow Us To: • Cure or treat disease • Genetically modify our foods to increase flavor, yield, nutritional value or shelf-life • Better understand human genetics • Clone cells or organs

Why use Prokaryotes-Bacteria? • They’re relatively simple organisms. • They reproduce very quickly and asexually (this means that the “daughter” cells will contain the exact same DNA as the “parent” cell). • It’s pretty easy to get DNA back into the bacteria after you’ve changed it.

Recombinant DNA The foreign DNA is first joined to a small circular DNA molecule found in bacteria known as a plasmid

Restriction enzymes A restriction enzyme (RE) is a specialized protein that cuts DNA in a very specific place. Molecular scissors

Step to Recombinant DNA

Steps to Recombinant DNA Step 1: • Isolate (find) the human gene responsible for producing insulin and decide where you want to put it. • In this case, we decide to put our human DNA into the plasmid of E. coli, a very common bacterium.

Step 2: • Get the bacterial (plasmid) DNA out of the E. coli. We do this by basically exploding them. Step 3: • Cut your human DNA and bacterial DNA with the same restriction enzyme

Step 4: • Mix the cut human DNA, which contains the insulin gene, with the cut bacterial DNA. • They’ll stick together because they were cut with the same restriction enzyme.

Step 5: Get your new recombinant plasmid back into the bacteria. Glue with DNA ligase (enzyme) This is easy because bacteria will take in DNA that’s floating around near them. We call this “transformation”.

Voila!! Now your Prokaryote-Ecoli will use its new DNA to make human insulin! Because they reproduce so quickly, you’ll soon have thousands, millions, or billions of human insulin making machines. By filtering out the bacteria after they’ve made insulin, you’ve got clean human insulin that can be packaged and given to diabetic patients.

Cloning is the process that produces exact copies of a single cell or organism

Types of Cloning • Gene cloning- produces copies of genes or segments of DNA (Recombinant DNA) • Reproductive cloning - produces copies of whole animals • Therapeutic cloning - produces embryonic stem cells for experiments aimed at creating tissues to replace injured or diseased tissues.

Reproductive Cloning

Steps for Reproductive Cloning • • A body cell is taken from a donor animal A An egg cell is taken from a donor animal B The nucleus is removed from the egg. The body cell and egg are fused by electricity The fused cell begins dividing-embryo Embryo implanted into the uterus of foster mother. The embryo develops into cloned animal of A.

Therapeutic cloning • Therapeutic cloning involves creating a cloned embryo for the sole purpose of producing embryonic stem cells with the same DNA as the donor cell. • These stem cells can be used in experiments aimed at understanding disease and developing new treatments for disease • The richest source of embryonic stem cells is tissue formed during the first five days after the egg has started to divide.