18.1 DNA Structure and Replication

Question 1

Who coined the term Nucleic Acid?

Answer 1

Friedrich Meischer

Question 2

What is DNA (deoxyribonucleic acid)?

Answer 2

The nucleic molecule that governs the process of heredity in all plant and animal cells

Question 3

What is Ribonucleic Acid (RNA)?

Answer 3

A nucleic acid that plays a role in gene expression and protein synthesis

Question 4

What did Levene prove about chromosomes?

Answer 4

That they were made up of DNA and proteins

Question 5

What experiment did Frederick Griffith conduct?

Answer 5

In order to study the bacteria responsible for pneumonia, he injected live and non-live bacteria into mice

Question 6

What were the results of Frederick Griffith’s experiment?

Answer 6

The dead pathogenic bacteria some had somehow passed on their disease-causing properties to live, non-pathogenic bacteria

Question 7

What is the Transforming Principle?

Answer 7

Discovered y Frederick, the ability of dead pathogenic bacteria to pass on their disease-causing properties to live, non-pathogenic bacteria

Question 8

What provided evidence that DNA played a role in the transformation principle?

Answer 8

When they treated the heat-killed pathogenic bacteria with a protein destroying agent, the transformation still occurred. When they treated the heat-killed pathogenic bacteria with a DNA destroying agent, the transformation did not occur

Question 9

How did Martha Clause show that genes are made of DNA?

Answer 9

She used a virus that consists of a protein coat surrounding the length of DNA. The virus injects its genetic information in the cell. They labelled the protein coat using radioactive sulfur and the DNA with radioactive phosphorus. It then showed that Viral DNA and not viral protein enters the cell

Question 10

What are Nucleotides?

Answer 10

The individual units that make up the long chains of DNA and RNA

Question 11

What is each DNA Nucleotide composed?

Answer 11

A five carbon sugar, a phosphate group, and one of the 5 nitrogen containing bases

Question 12

What are the 4 nitrogen containing bases found in DNA nucleotides?

Answer 12

Guanine
Cytosine
Adenine
Thymine

Question 13

What nitrogen containing base does RNA nucleotides contain?

Answer 13

Uracil (U) instead of thymine. But the rest are all the same

Question 14

What are the Nucleic Acids made of?

Answer 14

Long Chains of Nucleotides strung together

Question 15

What is Chargaff’s rule?

Answer 15

The idea that Guanine and Cytosine are present in equal amounts. And Adenine and Thymine are present in equal amounts

Question 16

What did Franklin determine about DNA through X-ray photography?

Answer 16

DNA has a helical structure with two regularly repeating patterns

Question 17

What are the inside and outside portions of DNA made of?

Answer 17

The nitrogenous bases are located on the inside and the sugar phosphate backbone is located on the outside

Question 18

Who published a paper describing the double helix model?

Answer 18

Watson and Crick

Question 19

What remains constant in a DNA molecule?

Answer 19

The distance between the sugar phosphate handrail even the nitrogenous bases are different sizes

Question 20

What are Adenine and Guanine derived from?

Answer 20

A family of compounds known as purines which have a double ring structure

Question 21

What are Thymine and Cytosine derived from?

Answer 21

Pyrimidines which have a single ring structure

Question 22

What are the complementary base pairs?

Answer 22

A-T and C-G

Question 23

What are the complementary base pairs held together by?

Answer 23

Hydrogen Bonds

Question 24

What does Antiparallel mean in terms of DNA?

Answer 24

The phosphate bridges run in opposite directions in the two strands

Question 25

Where are DNA and RNA found?

Answer 25

In most bacteria and the Nuclei of most Eukaryotic cells

Question 26

What are the 3 structural differences between DNA and RNA?

Answer 26

- The sugar component of RNA is ribose rather than deoxyribose - RNA does not have the nucleotide Thymine, instead it has Uracil - RNA is single stranded, although a single strand can sometimes fold back on itself to produce regions of complementary base pairs

Question 27

What is a Gene?

Answer 27

A functional sub-unit of DNA that directs the production of one or more polypeptides (protein molecules)

Question 28

What is the Genome of an organism?

Answer 28

The sum of all the DNA that is carried in each cell of the organism

Question 29

What is replication?

Answer 29

The process of creating an exact copy of a molecule of DNA

Question 30

What does it mean that DNA replication is Semi-conservative?

Answer 30

It means that each new molecule of DNA contains one strand of the original complementary DNA molecule and one new parent strand

Question 31

What is the Replication Origin?

Answer 31

A specific nucleotide sequence that replication starts at. There can be many spots on a DNA where this occurs

Question 32

What are Helicases and what do they do?

Answer 32

They are a group of enzymes that bind to DNA at the replication origin creating y shaped areas of separated nucleotides

Question 33

What is the Replication Bubble?

Answer 33

The opened up, seperated, region of DNA that the Helicase creates

Question 34

What is the Replication fork?

Answer 34

Two unwound strands of DNA that branch into unpaired (but complementary) single strands

Question 35

What serves as templates for the new strands of DNA?

Answer 35

The unwound strands of DNA at the replication fork

Question 36

What does DNA polymerase do?

Answer 36

Inserts into the replication bubble and begins to add nucleotides

Question 37

What is elongation?

Answer 37

The process of joining nucleotides to extend a new strand of DNA

Question 38

Where does DNA polymerase attach new nucleotides?

Answer 38

To the free 3' end of an existing chain

Question 39

What are the two conditions for elongation?

Answer 39

It can only take place in the 5' to 3' direction and a short strand of RNA known as primer must serve as a starting point for the attachment of new nucleotides

Question 40

What is the RNA primer?

Answer 40

A short strnad that serves as a starting point for the attachment of new nucleotides

Question 41

What is the Leading strand?

Answer 41

The strand that is replicated continuously in the 5' to 3' direction

Question 42

What is the Lagging strand?

Answer 42

The strand of DNA that is replicated in short segments in the 5' to 3' direction

Question 43

What are Okazaki fragments?

Answer 43

The DNA that gets replicated in the 5' to 3' direction but in short segments

Question 44

What does DNA Ligase do?

Answer 44

Splices together the Okazaki fragments

Question 45

What is needed to construct the RNA Primer?

Answer 45

An enzyme called Primase

Question 46

What happens one the Primer is in place?

Answer 46

DNA polymerase extends each fragment by adding new nucleotides and it also removes the RNA primer by eliminating the nucleotides in the 5' to 3' direction and fills in the space by extending the neighboring DNA strands

Question 47

What is another important function of DNA polymerase?

Answer 47

It proofreads by recognizing whether a hydrogen bond is taking place and between the new base and its complement on the original strand. If there is no hydrogen bond, there is a mismatch between bases

Question 48

What is the replication machine?

Answer 48

The complex of polypeptides and DNA that interact act the replication fork

Question 49

What is Termination?

Answer 49

The completion of the new DNA strands and the dismantling if the replication machine

Question 50

What is DNA sequencing?

Answer 50

The process of identifying the precise nucleotide sequence in a DNA fragment

Question 51

What was the Human Genome Project?

Answer 51

A monumental effort to sequence the entire human Genome