Lecture 2

Question 1

What identifies chromosomes as the carriers of genes?

Answer 1

Chromosome theory of inheritance and Mendel’s studies

Question 2

Why are proteins more complex?

Answer 2

Because proteins have 20 amino acids

Question 3

What are chromosomes made of?

Answer 3

Proteins and DNA

Question 4

What did Fred Griffith study?

Answer 4

Pneumonia

Question 5

What does Streptococcus pneumonia form?

Answer 5

A diplococcus where a pair of cells remain attached due to incomplete cell division

Question 6

What changed in Griffiths experiment?

Answer 6

Rough looking colonies of diplococcus

Question 7

What is the characteristics of the Smooth strain of of Pneumonia?

Answer 7

• Smooth colonies form pneumonia
• Kill mice
• glycocalyx protects bacteria from mouse immune system

Question 8

What are the characteristics of the Rough strain of Pneumonia?

Answer 8

• Rough colonies do not cause pneumonia
• not virulent because they lack the protective glycocalyx
• Look rough because they look glycocalyx

Question 9

What is Griffiths experiment killed the mice?

Answer 9

The S-strain and the heat killed S strain combined with the R strain

Question 10

what was the conclusion of Griffiths experiment?

Answer 10

That there was something in the heat inactivated S-cell bacteria that was taken up by the R strain that restored the virulence to the R strain that now looked like the S strain. This is called the transforming principle

Question 11

What does DNA competence?

Answer 11

It means that a cell has the right facilities to accommodate the DNA

Question 12

How can researches change bacteria in the lab?

Answer 12

A researcher can modify the bacteria to be competent by adding receptors and then add DNA

Question 13

How did Avery figure out what was responsible for the transforming principle?

Answer 13

He destroyed different parts of the bacteria and repeated the experiment

Question 14

What substance is responsible for the transforming principle?

Answer 14

DNA

Question 15

How does Bacteria replicate?

Answer 15

Bacteriophages injects itself in the bacteria and replicate which produces more bacteriophages

Question 16

How did Hershy and Chase confirm the transforming principle?

Answer 16

By marking the DNA is phages before they infect bacterium and seeing which one was injected inter the bacteria

Question 17

what are the things that DNA must be able to do if it is the hereditary material?

Answer 17

Replicate
Carry information
Control cell activity
Mutate

Question 18

What are the components of DNA?

Answer 18

Nucleotide

Question 19

What are the components of a nucleotide?

Answer 19

A phosphate group
A pentose sugar
A nitrogenous base

Question 20

What are the two types of Nitrogenous bases?

Answer 20

Purines (double ring)

Pyrimidines (single ring)

Question 21

Which Nucleotides are Purines?

Answer 21

Adenine

Guanine

Question 22

Which nucleotides are Pyrimidines?

Answer 22

Thymine
Uracil
Cytosine

Question 23

What are the two types of sugars in nucleotides?

Answer 23

Ribose and Deoxyribose

Question 24

How are Nucleotides attached to all its components?

Answer 24

A phosphate group attaches to the 5th carbon on the sugar and the nitrogenous base attaches to the first carbon on the sugar

Question 25

how are the 5' end and the 3' end of two nucleotides joined?

Answer 25

Through a condensation reaction producing water and a covalent bond

Question 26

What is the charge of the phosphate group?

Answer 26

Negative

Question 27

How are the sugar groups able to be inverted?

Answer 27

The covalent bond between the nitrogen and the sugar is complete rotatable

Question 28

Which part of the DNA has inverted orientation?

Answer 28

The sugar phosphate back-bone but not the nucleotides. Meaning that they are upside down

Question 29

What is responsible for the 5' 3' ends of DNA?

Answer 29

The fact that the sugar phosphate backbone that is in opposite directions

Question 30

What is Strand Directionality based on?

Answer 30

The orientation of sugar molecules

Question 31

Who discovered the structure of DNA?

Answer 31

Watson and Crick with the help of Rosalind Franklin

Question 32

What is Helical Pitch?

Answer 32

The distance between two equivalent positions on the double helix

Question 33

What is the difference between the Minor Groove and the Major Groove?

Answer 33

The size

Question 34

How wide is the Double Helis?

Answer 34

2nm wide

Question 35

What is the Double Helix made of?

Answer 35

Two anti parallel nucleotide polymer strands

Question 36

What connects nucleotides?

Answer 36

Covalent bonds between phosphates and sugars

Question 37

How many base pairs per a helical turn?

Answer 37

10.4 base pairs

Question 38

What connects the two base pairs together?

Answer 38

Hydrogen bonds

Question 39

How does the Conservative model of DNA replication work?

Answer 39

The parental model conducts replication of an entirely new double stranded molecule

Question 40

How does the Semi-conservative model of DNA replication work?

Answer 40

The new DNA molecules are composed of a parental strand and a daughter strand (new

Question 41

How does the Dispersive model of DNA replication work?

Answer 41

The two parental strands are distributed randomly between the daughter molecules

Question 42

What is the Pulse Chase experiment?

Answer 42

Following molecules through a system by marking them with radioactive markers

Question 43

What was the Meselson-Stahl approach to proving semi-conservative replication?

Answer 43

He marked the DNA with N15 then brought it back to its normal environment where it duplicated so that half of the DNA was N15 and half was N14 (normal) then separated the DNA strands based on their density using caesium chloride in water

Question 44

How were DNA bands visualized?

Answer 44

By ultraviolet absorption photography. DNA absorbs light at 260nm