DNA Replication (Wilson Lecture 1)

Question 2

What does DNA store?

Answer 2

Genetic information.

Question 3

How is genetic information organized?

Answer 3

In genes, similar to words in text.

Question 4

What does turning on a gene cause?

Answer 4

An effect on the organism.

Question 5

What controls gene expression?

Answer 5

Gene regulation.

Question 6

Who demonstrated that molecules can transfer genetic information in 1928?

Answer 6

Frederick Griffith.

Question 7

What organism did Griffith study in his experiment?

Answer 7

Streptococcus pneumoniae.

Question 8

What were the two strains of Streptococcus pneumoniae in Griffith’s experiment?

Answer 8

• A virulent strain * A nonvirulent strain.

Question 9

What happened when debris of dead virulent cells was mixed with nonvirulent cells?

Answer 9

Some nonvirulent cells became virulent.

Question 10

What did Griffith conclude about the molecule in the debris?

Answer 10

It carried genetic information for virulence.

Question 11

Who followed up Griffith’s experiments in 1944?

Answer 11

Avery, MacLeod, and McCarty.

Question 12

What molecule was found to be responsible for transforming nonvirulent bacteria?

Answer 12

DNA.

Question 13

What is a phosphodiester bond?

Answer 13

The C—O—P—O—C linkage connecting two nucleotides.

Question 14

What does the polarity of a DNA strand refer to?

Answer 14

One end differs from the other.

Question 15

What are the ends of a DNA strand called?

Answer 15

5’ end and 3’ end.

Question 16

Who announced the structure of DNA in 1953?

Answer 16

James Watson and Francis Crick.

Question 17

What key image led to the discovery of DNA’s structure?

Answer 17

Photograph 51.

Question 18

What did Rosalind Franklin’s studies imply about DNA?

Answer 18

DNA molecules form a helix.

Question 19

What is the correct model for DNA replication according to Meselson and Stahl?

Answer 19

Semiconservative DNA Hypothesis.

Question 20

What was used to differentiate between heavy and light DNA strands in Meselson and Stahl’s experiment?

Answer 20

Isotopes of nitrogen.

Question 21

What is the role of telomerase in eukaryotic cells?

Answer 21

To replace missing nucleotides at telomeres.

Question 22

What is a telomere?

Answer 22

A repeating sequence at the end of eukaryotic chromosomes.

Question 23

What is the sequence of the human telomere?

Answer 23

5’-TTAGGG-3’.

Question 24

What is cell division?

Answer 24

The process by which cells make more cells.

Question 25

What are the two stages of the cell cycle in eukaryotes?

Answer 25

* M phase * Interphase.

Question 26

What type of cell division occurs in prokaryotes?

Answer 26

Binary fission.

Question 27

What type of cell division occurs in eukaryotes?

Answer 27

Mitosis.

Question 28

What are eukaryotic gametes produced by?

Answer 28

Meiosis.

Question 29

What is the purpose of DNA replication?

Answer 29

To duplicate DNA for daughter cells.

Question 30

What is the main difference between the leading and lagging strands during DNA replication?

Answer 30

Leading strand is continuous; lagging strand is discontinuous.

Question 31

What are Okazaki fragments?

Answer 31

Short pieces of DNA synthesized on the lagging strand.

Question 32

What is the function of DNA ligase?

Answer 32

To join DNA fragments together.

Question 33

What is DNA proofreading?

Answer 33

The correction of errors by DNA polymerases during replication.

Question 34

What is an origin of replication?

Answer 34

A point where DNA replication is initiated.

Question 35

What occurs at the replication bubble during DNA replication?

Answer 35

The double helix opens and grows until it fuses with another bubble.

Question 36

How does telomere shortening affect cell division?

Answer 36

Cells can only divide a limited number of times before telomeres are too short.

Question 37

What are eukaryotic gametes produced by?

Answer 37

Meiosis

Question 38

What is the structure of DNA in eukaryotic cells?

Answer 38

Organized with histones and other proteins into chromatin

Question 39

What is a karyotype?

Answer 39

The portrait formed by the number and shapes of chromosomes representative of a species

Question 40

How many chromosomes do most human cells contain?

Answer 40

46 chromosomes (23 pairs)

Question 41

What do homologous chromosomes carry?

Answer 41

The same set of genes, one from the mother and one from the father

Question 42

What are the sex chromosomes in humans?

Answer 42

X and Y chromosomes

Question 43

What is the largest compressed form of DNA?

Answer 43

Chromosome

Question 44

What is mitosis followed by?

Answer 44

Cytokinesis

Question 45

What characterizes prophase?

Answer 45

Appearance of visible chromosomes

Question 46

What is assembled outside the nucleus during prophase?

Answer 46

The mitotic spindle

Question 47

What is the role of centrosomes in animal cells?

Answer 47

Microtubule-organizing centers that migrate to opposite poles

Question 48

What happens during prometaphase?

Answer 48

The nuclear membrane breaks down and microtubules attach to chromosomes

Question 49

What are kinetochores?

Answer 49

Protein complexes associated with centromeres for microtubule attachment

Question 50

What is the arrangement of kinetochores during mitosis?

Answer 50

Each sister chromatid is attached to a microtubule radiating from one of the poles

Question 51

What occurs during metaphase?

Answer 51

Chromosomes are lined up in a single plane equidistant from spindle poles

Question 52

What happens during anaphase?

Answer 52

Sister chromatids separate and travel to opposite poles

Question 53

What are the key changes during telophase?

Answer 53

Complete set of chromosomes arrives at a spindle pole and nuclear envelopes re-form

Question 54

What begins as mitosis ends?

Answer 54

Cytokinesis

Question 55

How does cytokinesis occur in animal cells?

Answer 55

A contractile ring forms and pinches the cytoplasm

Question 56

What structure forms in plant cells during cytokinesis?

Answer 56

Cell plate

Question 57

What guides vesicles containing cell-wall components to the middle of the cell in plant cells?

Answer 57

Phragmoplast

Question 58

What are the five phases of mitosis?

Answer 58

* Prophase * Prometaphase * Metaphase * Anaphase * Telophase

Question 59

In which phase do chromosomes condense and become visible?

Answer 59

Prophase

Question 60

In which phase do chromosomes attach to the mitotic spindle?

Answer 60

Prometaphase

Question 61

In which phase do chromosomes align?

Answer 61

Metaphase

Question 62

In which phase do sister chromatids fully separate?

Answer 62

Anaphase

Question 63

In which phase do nuclear envelopes re-form around newly segregated chromosomes?

Answer 63

Telophase