Biology- Chapter 12

What are the enzymes involved in DNA replication and what are their functions?

-Helicase -polymerase -nucleotides -ligase

What did Watson and Crick discover?

-They discovered the shape of the double helix -antiparallel -How DNA replicates

The 2 strands of a DNA molecule are related how?

-antiparallel -complementary

What 3 things is the nucleotide made up as?

-sugar -phosphate -nitrogen bases

What is a Helicase?

1. the (unzipper) it unzips and unwinds the double helix

What is a primase?

2. (initiator) adds short RNA primers to start "initiate" the new strand.

What is a DNA Polymerase?

3. (Builder) adds complementary nucleotides and builds the new strands in 5' ---> 3' direction.

What is DNA ligase?

4. (Gluer)- Makes Bonds to connect Okazaki Fragments into one strand

What type of bonds hold two strands of DNA together?

A hydrogen bond between base pairs holds two strands of DNA together.

What is the base pairs? *TACGTTAC*

ATGCAATG

What nitrogen bases are purine?

Adenine and Guanine

What are the nitrogen base bonding rules?

Adenine to Thymine (A-T) Cytosine to Guanine (G-C)

Describe Avery's experiment.

Avery and his team continued work on Griffith's experiment. They extracted a mixture of various molecules from the heat- killed bacteria and treated it with enzymes that destroyed proteins, lipids, carbohydrates and other molecules. They found that transformation still occured. When the bacteria was treated with enzymes that destroyed DNA they found that transformation did not occur.

What is Chargaff's Rule?

Chargaff's Rule states that the in a sample of DNA, the amount of A is generally equal to the amount of T and the amount of G is generally equal to the amount of C.

In DNA, _______ always forms hydrogen bonds with guanine (G)

Cytosine

What nitrogen bases are pyrimidine?

Cytosine and Thymine

By what process does DNA copy itself?

DNA Replication

Why did Hershey and Chase grow viruses in cultures that contained both radioactive phosphorus and radioactive sulfur?

DNA contains phosphorus but no sulfur. Protein contains sulfur but no phosphorus. By growing viruses in separate cultures, they ensured that one sample had only radioactive DNA while the other had radioactive protein. This would allow them to conclude which material was injected by the virus into the bacterium.

Why did Hershey and Chase use radioactive phosphorus and radioactive sulfur in their bacteriophage experiments?

DNA contains phosphorus but no sulfur. Protein contains sulfur but no phosphorus. By growing viruses in separate cultures, they ensured that one sample had only radioactive DNA while the other had radioactive protein. This would allow them to conclude which material was injected by the virus into the bacterium.

unwinds the double helix

DNA helicase

What are the chemical components of DNA?

DNA is a nucleic acid made up of a long chain of nucleotides joined into long strands by covalent bonds. These covalent bonds form between the sugar of one nucleotide and the phosphate group of another. Each nucleotide is made up of a phosphate group, a deoxyribose sugar molecule, and a nitrogenous base.

What is the role of DNA in heredity?

DNA is reponsible for storing, copying and transmitting the genetic information in a cell.

Summarize the process of transformation.

During transformation, harmless bacteria can be genetically altered, or changed, by the transfer of DNA from another bacterial cell.

Summarize the events of DNA replication.

Enzymes unzip a molecule of DNA by breaking the hydrogen bonds between base pairs and unwinding the two strands of the molecule. Each strand serves as a template for the attachment of complementary bases. DNA polymerase is the principal enzyme that joins individual nucleotides to produce a new strand of DNA. DNA polymerase also proofreads each new DNA strand, so that each molecule is a near- perfect copy of the original.

How did Rosalind Franklin's work contribute to the understanding of the structure of DNA?

Franklin used X-ray diffraction to study DNA. First she purified a large amount of DNA, then she stretched the DNA fibers in a thin glass tube so that most of the strands were parallel. Next, she aimed a powerful X-ray beam at the concentrated DNA samples and recorded the scattering pattern of the X-rays on film. Her work suggested that DNA had a helix shape, with two strands and the nitrogenous bases at the center.

What did Griffith observe in his experiment?

He observed a transformation of a change in a harmless bacteria that became harmful.

What was the conclusion of Avery's experiment?

He repeated Griffith's experiment and concluded that *DNA* was the *transforming factor*

What was Avery able to conclude from his experiment.

He was able to conclude that DNA was the transforming factor. In other words, genes were made up of DNA.

What was Griffith able to conclude from his experiment?

He was able to conclude that genes from the harmful bacteria transferred to the harmless bacteria, and transformed them.

How did Hershey and Chase use bacteriophages to confirm Avery's results?

Hershey and Chase used radioactive isotopes to label a bacteriophage. In one trial, they used radioactive phosphorus- 32 to label the DNA core of the bacteriophage and in another they used radioactive sulfur- 35 to label the protein coat of the bacteriophage. After allowing the bacteriophage to infect the bacteria, the presence of radioactive phosphorus in the bacteria confirmed that DNA was the genetic material found in genes.

Why is it important for DNA to be copied carefully?

If DNA is not copied correctly, genetic information may become lost. This may result in very serious genetic disorders. This is why the proof-reading mechanism of DNA polymerase is important.

Describe Griffith's experiment.

In Griffith's experiment, he mixed heat-killed S-strain bacteria with live, harmless bacteria from the R-strain. When this mixture was injected into mice, the mice developed pneumonia, died.

What is a bacteriophage?

It is a type of virus that infects bacteria. It has a head that is filled with DNA (nucleic acid) and it covered in a protein coat. https://farm6.staticflickr.com/5023/5586595514_6e1763e1e1.jpg

What makes up the "rungs" of the DNA ladder?

Nitrogen bases

What was Rosaline Franklin's contribution to the discovery of DNA?

She used x-ray diffraction (photo 51) to study DNA.

Describe the similarities and differences between DNA replication in prokaryotic cells and eukaryotic cells.

Similarities: DNA replication in both eukaryotes and prokaryotes proceeds identical strands of DNA. Differences: Prokaryotic DNA replication occurs in the cytoplasm and begins at a single

What makes up the sides (backbone) of the DNA?

Sugars & Phosphate

What did Watson and Crick contribute to the understanding of the structure of DNA?

Watson and Crick used the image taken of DNA by Franklin in their work to figure out the structure of DNA. They built a model of DNA in which two strands are wound together around each other mking a double helix. The two strand are antiparallel, meaning that they run in opposite directions. This allowed for the base pairs to form hydrogen bonds at the center of a strand of DNA.

a nucleotide

What is this?

a phosphate

What is this?

deoxyribose, a sugar

What is this?

nitrogen bases: Adenine and Thymine

What is this?

nitrogen bases: Guanine and Cytosine

What is this?

______, guanine (G), cytosine (C), and thymine (T) are the four _________in DNA

adenine (A) Nitrogenous bases

DNA supercoils to make up the structure known as __________

chromosomes

the DNA of prokaryotes

circular DNA

How does a leading strand replicate?

continuously

The twisted ladder shape of DNA is called a

double helix

The purine bases have a ________ structure

double-ring

unwinds in multiple areas as DNA is replicated

eukaryotic DNA

DNA is the __________ of all organisms

genetic material

How does a lagging strand replicate? what is it composed of?

it builds in fragments called Okazaki fragments

elongates as DNA unwinds and is replicated continuously

leading strand

DNA and RNA are the two __________ found in living cells.

nucleic acids

What monomer makes up DNA?

nucleotide

The sequence of ________ carries the genetic information of an organism.

nucleotides

Chargaff's data states that the number of ______ bases equals the number of pyrimidine bases in DNA.

purine

What is the process that produces molecules with one parent strand and one new strand?

semi-conservatitive replication

parental strands separate and serve as templates for new strands of DNA

semiconservative replication

The pyrimidine bases have a _______ structure.

single-ring

keep the strands of DNA separate during replication

single-stranded binding proteins

What holds together the 2 DNA strands?

weak hydrogen bonds