Chapter 11

Question 1

Molecular genetics studies?

Answer 1

The structure and function of DNA

Question 2

When Griffith (1928) injected a mixture of dead smooth-type Strep pneeumonie and living rough type strep pneumonia into mice, what happened to the mice!

Answer 2

They died

Question 3

In the context of the experiments of Griffith (1928) and Avery, Macleod, and McCarty, what is transformation?

Answer 3

The ability of a molecule to confer new characteristics on an organism that acquires that molecule

Question 4

What types of macromolecules are present in the T2 bacteriophage?

Answer 4

DNA and protein

Question 5

What are the 3 parts of a nucleotide?

Answer 5

A phosphate group
A nitrogenous base
A 5 carbon sugar

Question 6

Which criteria from the list can be used to discriminate between purine and pyrimidine base?

Answer 6

The ring structures of the bases

Question 7

How can nucleotides found in RNA be discriminated from those found in DNA?

Answer 7

RNA may contain uracil, contains ribose, and don’t contain thymine

Question 8

What is a nucleoside

Answer 8

A base attached to either a ribose or deoxyribose sugar

Question 9

A nucleoside composed of the base cytosine attached to ribose is called?

Answer 9

Cytidine

Question 10

What is a nucleotide?

Answer 10

A nucleoside with an attached phosphate group

Question 11

What are some of the key characteristics needed by genetic material?

Answer 11

1. Must contain information that is inherited 2. Must be passed from parent to offspring 3. Must be able to be replicated 4. Must have variation among traits

Question 12

What is DNA?

Answer 12

DNA is a molecule that carries genetic material and is responsible for heredity

Question 13

What is DNA molecular structure?

Answer 13

Double helix

Question 14

Who discovered DNA had a double helix?

Answer 14

Watson and Crick

Question 15

What are the subunits of DNA?

Answer 15

DNA is made of repeating sequences called nucleotides

Question 16

What are the 3 main components that make up DNA?

Answer 16

A phosphate group
A five-carbon sugar called deoxyribose
A nitrogenous base (one of four types)

Question 17

What are the 4 nitrogenous bases in DNA?

Answer 17

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

Question 18

What did Chargaff do?

Answer 18

He proposed the A=T and C=G theory and found that in other species the proportions of these were different showing DNA composition was different species to species

Question 19

What did Griffith do?

Answer 19

He showed through 2 strains of bacteria that genes ccould be transferred from one organism to another, that he coined “transformation”

Question 20

What did Avery, MacLeod, and McCarty do?

Answer 20

They identified DNA as the genetic material being transferred between bacteria

Question 21

What did Hershey & Chase do?

Answer 21

They confirmed DNA was the genetic material and not proteins.

Question 22

What did Linus Pauling do?

Answer 22

Discovered alpha helix and beta sheet structures, and introduced the triple helix theory of DNA (which was wrong but led to the right theory being developed)

Question 23

What did Rosalind Franklin & Maurice Wilkins do?

Answer 23

Both used Xray crystallography to photograph DNA, helped to later confirm the double helix structure of DNA

Question 24

What did Watson and Crick do?

Answer 24

They confirmed DNA’s double helix structure

Question 25

In DNA what does a phosphodiester bond link?

Answer 25

the bond forms between the 3' carbon of the sugar (deoxyribose) of one nucleotide and the 5' carbon of the sugar in the adjacent nucleotide through a phosphate group

Question 26

What do hydrogen bonds link together?

Answer 26

link the nitrogenous bases of the two complementary DNA strands together, forming the "rungs" of the double helix ladder

Question 27

How many hydrogen bonds link the different nitrogen bases?

Answer 27

Adenine (A) pairs with Thymine (T), forming two hydrogen bonds. Cytosine (C) pairs with Guanine (G), forming three hydrogen bonds.

Question 28

What are the purine bases?

Answer 28

Adenine and guanine (5 ring structure)

Question 29

What are the pyrimidine bases?

Answer 29

Thymine, cytosine, and uracil (single ring structure)

Question 30

Nucleoside

Answer 30

is a structure in which a base is attached only to a sugar, with no phosphate attached to the sugar

Question 31

Phosphodiester linkage

Answer 31

DNA or RNA strand, a linkage in which a phosphate group connects two sugar molecules

Question 32

Directionality

Answer 32

DNA and RNA, the 5' to 3' arrangement of nucleotides in a strand

Question 33

why do purines have to be pared with pyrimidines?

Answer 33

maintain a consistent and stable double-helix structure

Question 34

what would happen if 2 purines paired?

Answer 34

If two purines were to pair, they would create a bulge because their combined structure would be too wide.

Question 35

What would happen if two pyrimidines paired?

Answer 35

if two pyrimidines paired, they would create a gap because their combined structure would be too narrow

Question 36

What does it mean when DNA is described as antiparallel?

Answer 36

it means that the two strands of the DNA double helix run in opposite directions (5' to 3' and 3' to 5')

Question 37

What does it mean when base pairing is described as complementary?

Answer 37

it means that each nitrogenous base on one DNA strand specifically pairs with a corresponding base on the opposite strand (A=T and C=G)

Question 38

Nucleosome

Answer 38

A nucleosome is the basic unit of DNA packaging in eukaryotic cells. It consists of a segment of DNA wound around a core of histone proteins. Nucleosomes help organize and compact DNA within the cell nucleus while also playing a role in gene regulation.

Question 39

Chromatin fiber

Answer 39

is a higher-order structure of DNA organization in eukaryotic cells, where nucleosomes are further compacted to form a more condensed and organized fiber.

Question 40

Chromatid

Answer 40

one of two identical halves of a duplicated chromosome

Question 41

Levels of organization, from smallest to largest structure, of DNA, Chromatid, chromatin fiber, nucleosome, and chromosome

Answer 41

DNA>Nucleosome>Chromatin fiber>chromatid>chromosome

Question 42

Histones

Answer 42

proteins that play a key role in DNA packaging within eukaryotic cells. They serve as the structural core around which DNA wraps to form nucleosomes, enabling efficient organization, compaction, and regulation of genetic material in the cell nucleus

Question 43

What is the structure of RNA?

Answer 43

Single stranded, Ribose sugar + Phosphate group + Nitrogenous base (A, U, G, C)

Question 44

Compare and contrast DNA and RNA

Answer 44

DNA: Double stranded, Deoxyribose sugar, A,T,C,G nitrogenous bases, typically longer in length RNA: Typically single stranded, Ribose sugar, A, U, C, G, and typically shorter in length

Question 45

What is supercoiling?

Answer 45

refers to the over- or under-twisting of a DNA molecule, which causes it to coil further into a compact, twisted shape. This phenomenon helps cells efficiently package large amounts of DNA into a confined space

Question 46

what is the difference between heterochromatin and euchromatin?

Answer 46

Heterochromatin is densely packed, transcriptionally inactive, and gene-poor, often serving structural and regulatory roles. Euchromatin is loosely packed, transcriptionally active, and gene-rich, allowing genes to be accessed and transcribed as needed.

Question 47

how are bacterial chromosomes and eukaryotic chromosomes the same?

Answer 47

Carry Genetic Information: Both contain DNA that encodes the genes essential for cellular functions and the organism's characteristics. Undergo Replication: Both must replicate before cell division to ensure each daughter cell receives a complete set of genetic information. Use DNA as Genetic Material: Both consist of double-stranded DNA molecules that store genetic information in the form of nucleotide sequences. Have Organized Structures: Both are organized in ways that allow the DNA to be compacted and regulated, although the structures differ in complexity

Question 48

how are bacterial chromosomes and eukaryotic chromosomes different?

Answer 48

Structure: Bacterial chromosomes are typically circular and usually consist of a single chromosome. Eukaryotic chromosomes are linear and usually occur in multiple pairs. Location: Bacterial chromosomes are located in the cytoplasm in a region called the nucleoid (no nucleus). Eukaryotic chromosomes are contained within a nucleus. Packaging: Bacterial chromosomes are less complexly packaged, usually using proteins but not histones (except in some archaea). Eukaryotic chromosomes are highly organized and compacted around histone proteins into nucleosomes and further into chromatin. Size: Bacterial chromosomes are generally smaller with fewer genes. Eukaryotic chromosomes are typically larger and contain more genetic material.