The Bio Miracle

This is a miracle

How did Griffith contribute to the function and structure of DNA

In 1928, Frederick Griffith experimented with two strains of bacteria- harmless and pathogenic.

In a series of experiments on mice, he killed the pathogenic bacteria, mixed it with harmless one, and found the harmless one converted to pathogenic and killed the mice.

He called this process transformation, because one type of bacteria had been changed permanently into another.

Because the ability to cause disease was inherited by the offspring of the transformed bacteria, Griffith concluded that the transforming factor had to be a gene.

How did Hershey & Chase contribute to the function and structure of DNA

In 1952, Alfred Hershey and Martha Chase performed experiments on E. coli using viruses.

A bacteriophage (phage for short) is a virus that attacks bacteria.

The Hershey-Chase experiment showed that certain viruses reprogram host cells to produce more viruses by injecting their DNA.

How did Chargaff contribute to the function and structure of DNA

discovered the percentage of adenine always matched the percentage of thymine, and same for guanine and cytosine.

How did Franklin contribute to the function and structure of DNA

used X-ray crystallography to show DNA as a helix or coil.

How did Crick and Watson contribute to the function and structure of DNA

worked out the three-dimensional structure of DNA in 1953.

List the components of DNA

Made of long chains of nucleotide monomers containing the sugar deoxyribose.

Results in a sugar-phosphate backbone, with the nitrogenous bases arranged like ribs that project from the backbone.

DNA has four kinds of nitrogenous bases.

Adenine (A), Thymine (T), cytosine (C), and Guanine (G)

RNA is also a nucleic acid:

But has a slightly different sugar (ribose).

And has uracil (U) instead of T.

Structure of DNA

Consists of two polynucleotide strands wrapped around each other in a double helix.

Hydrogen bonds between bases hold the strands together.

Each base pairs with a complementary partner.

A with T, and G with C

Describe the difference between 5' and 3' ends of DNA:

3' carbon atom is attached to an OH group

5' carbon atom is attached to a phosphate group.

Explain where in the cell cycle DNA replication occurs:

DNA replication occurs during the S (synthesis) phase of interphase.

Describe DNA replication

DNA replication starts with the separation of DNA strands.

Then enzymes use each strand as a template to assemble new nucleotides into complementary strands.

DNA replication is a complex process.

Due in part to the fact that some of the helical DNA molecules must untwist.

Enzymes Involved in DNA replication (describe)

Using the enzyme DNA polymerase the cell synthesizes one daughter strand as a continuous piece.

Leading strand.

The other strand is synthesized as a series of short pieces called Okazaki fragments, which are then connected by the enzyme DNA ligase.

Lagging strand

End result of DNA replication (describe)

two DNA nearly identical DNA double helix molecules. Each DNA is made up of one DNA strand from the original DNA and a newly created strand.

List 3 types of RNA and briefly describe their functions:

Messenger RNA (mRNA)

-Instructions copied from DNA.

Transfer RNA (tRNA)

-Brings amino acids to the ribosome.

Ribosomal RNA (rRNA)

-Part of the ribosome.

Compare and contrast DNA and RNA:

DNA:

-Deoxyribonucleic Acid

-Double-stranded

-Contains thymine, not uracil

-Contains deoxyribose (sugar)

RNA:

-Ribonucleic Acid

-Single-stranded

-Contains uracil, not thymine

-Contains Ribose (sugar)

Similarities:

-Both polymers called nucleic acid

-Both contain nucleotides

-Both contain adenine, guanine, and cytosine

Explain function of RNA polymerase:

attaches to a DNA sequence called the promoter.

Then RNA nucleotides line up along one strand of the DNA, following the base pairing rules.

RNA nucleotides are bound together by RNA polymerase.

Explain process of transcription and where it occurs:

Process:

is a process that creates mRNA from a gene within the DNA.

Location:

Nucleus

Describe how mRNA is "edited":

As the single-stranded messenger RNA (mRNA) peels away from the gene the DNA strands rejoin.

Eukaryotic RNA is processed before leaving the nucleus

Noncoding segments called introns are cut out and exons are rejoined - called RNA splicing.

And a cap and a tail are added to the ends.

Describe how a protein is made and where:

How Protein Is Made:

Translation (creating proteins from RNA) takes place in the cytoplasm (attaches to a ribosome - where the proteins are created).

Location:

Cytoplasm

Describe tRNA's role in protein synthesis:

When a ribosome attaches to the mRNA, it translates its message into a specific polypeptide aided by tRNA.

Brings amino acids to the ribosome.

Know what proteins are made of:

molecules made up of sequences of amino acids bound by a peptide bond.

Explain gene expression

The activation of a gene that results in transcription and the production of mRNA

Nucleotide

is the basic building block for DNA

base pairing

adenine with thymine (uracil); cytosine with guanine

Adenine

pairs with thymine (or uracil)

Guanine

pairs with cytosine

Thymine

pairs with adenine

Cytosine

pairs with guanine

Deoxyribose

sugar (DNA)

Nitrogenous bases

adenine, guanine, thymine (or uracil), and cytosine

DNA polymerase

enzyme used in DNA replication

Translocation

As mRNA moves, tRNA separates and the polypeptide grows

Uracil

pairs with adenine

Genes

the basic unit of heredity; made up of DNA

Transcription

is a process that creates mRNA from a gene within the DNA

RNA polymerase

an enzyme in transcription that attaches to a DNA sequence called the promoter

mRNA

(messenger RNA) - Instructions copied from DNA.

rRNA

(ribosomal RNA) - Part of the ribosome.

tRNA

(transfer RNA) - Brings amino acids to the ribosome.

Transformation

one type of bacteria had been changed permanently into another.

Intron

are portions of RNA that are cut out and discarded.

Exon

are spliced together to make the final mRNA.

Bacteriophage

is a virus that attacks bacteria

Amino acid

are organic compounds that combine to form proteins

Protein

are molecules made up of sequences of amino acids bound by a peptide bond

Codon

The "words" of the DNA "language" are triplets of bases; determine the amino acid chain of a polypeptide

Start codon

are specific codons that signal to the ribosome that the translation commences at that point

Stop Codon

signal the end of the amino acid chain

Translation

creating proteins from RNA) takes place in the cytoplasm (attaches to a ribosome - where the proteins are created)

Anticodon

Each tRNA molecule is a folded molecule bearing a base triplet

Polypeptide

chains of amino acids