Biotechnology Bell Ringers for September 24th, 2010

Biotechnology Bell RingersSeptember 27th, 2010

1. What are some differences between plant cells and animal cells?

2. What two resources were used to examine different examples of cells?

3. Bacteria are prokaryotes. What is a prokaryote?

Biotechnology Objectives September 27th, 2010 (EB04.03)

We will explore the structure of DNA

We will explore DNA’s relationship to the cell

We will Extract DNA from a Strawberry

Time permitting, we will go over some Biotechnology current events

Genetics and DNA

1860s, Gregor Mendel discovered that “factors” determine inheritance in pea plants

He observed that many traits control these factors

Genetics and DNA

1903, researcher William Sutton made connection between Mendel’s “factors” and chromosomes-microscopic structures in the cell nucleus that carry genetic material

Genetics and DNA

The genetic material itself, known as DNA, was discovered by Johann Miescher in Switzerland in 1869

Genetics and DNA

Yet, it wasn’t until two researchers, Francis Crick and James Watson, proposed a double-helix structure for the molecule that we began to understand how this material carries the genetic code of life

Early drawing by Watson and Crick of the DNA Double-helix

Genetics and DNA A gene is a unit of

information that can be passed on to offspring

They are a power influence on physical and mental characteristics

They aren’t just found in people, they are found in all living things

Genetics and DNA As powerful as genes are,

however, it’s important to remember that environment also helps shape organisms

The interactions between a living thing and its environment affect how it will turn out

Domineering Genes

With few exceptions, every organism has two of each kind of gene

Genes are usually either dominant or recessive

Domineering Genes

A dominant gene is expressed in the offspring no matter what gene the other parent contributes

A recessive gene is expressed in the offspring only if both parents contribute recessive genes

Domineering Genes

BROWN/BROWN BROWN/blue

blue/BROWNblue/blue

Mutations Rule Over billions of years the

earth has been around, plants, animals, and other living things have evolved through the changing of genes

Genes have been transferred, deleted, and mutated between generations

Mutations Rule Mutation has produced the

countless variations of living things we see around us

Many mutations are neutral and have no effect at all

Some mutations place a living thing at a disadvantage

Some mutations, however, give an individual a better chance of survival

This makes them more likely to survive to have offspring

Over time, this mutant gene will likely become established in the gene pool (the genes of a breeding population

Mutations Rule

Secret Codes DNA holds the secret code

to make and maintain proteins (long chains of molecules that help living things grow and function

But how does this secret code move from the nucleus to the protein-making factories in the cells?

Secret Codes Rather than move the

DNA out of the nucleus, the cell makes a copy of the gene(s) and sends it to the protein assembly site outside the cell nucleus

The copy is messenger RNA (ribonucleic Acid)

Secret Codes

RNA is a single-stranded copy of a single cell of a single gene

It carries codes from the DNA to the protein assembly sites outside the nucleus

Genes Across the Ages In nature, genes generally

are transferred between members of the same species

Some new studies, however, suggest that genes also move between unrelated organisms

For the most part, such “horizontal” gene transfer takes place among bacteria and viruses

Genes Across Ages Today, horizontal gene

transfer also can occur through genetic engineering

DNA can be transferred via direct injection or by inserting the DNA into bacteria or viruses that carry it into the cells they infect

This means that traits determined by single genes can be transferred from one kind of organism to another

Genes Across Ages Characteristics coded for

by more than one gene are much harder to transfer, since the contributing genes must all first be identified, found, and isolated

Many human diseases are thought to result from interactions of multiple genes