Theme 1- Module 4 (Nucleic Acids)

Question 1

True or false: bacterial cells have a cell membrane but no cell wall

Answer 1

False

They have a cell membrane AND a cell wall

Question 2

True or false: all genetic material in the bacterial cell is contained in the chromosomes

Answer 2

False

Also contained in plasmids

Question 3

What are plasmids?

Answer 3

Small, circular DNA molecules that carry only one or two genes (such as those that contribute to anti-biotic resistance)

Question 4

What causes the rapid spread of genes (i.e. antibiotic resistance) in bacterial populations?

Answer 4

Caused by plasmids replicating independently of the core genome and transferring from one cell to another

Question 5

What are chromosomes?

Answer 5

Word that describes the organization of double-stranded DNA in its association with proteins and RNAs

Question 6

What is the difference between prok chromosomes and euk chromosomes?

Answer 6

Prok chromosomes = small, circular

Euk = large, linear

Question 7

True or false: mitochondria have their own chromosomes

Answer 7

True

Question 8

E.Coli chromosomes are a 1000 times longer than the diameter of the cell, and yet it is able to fold up within the nucleoid. How?

Answer 8

The circular chromosomes are able to SUPERCOIL into many loops and associate with proteins to compact the DNA into the nucleoid region

Question 9

True or false: only euk DNA have a double helix structure

Answer 9

False

Prok DNA are also in double helixes

Question 10

What is supercoiling?

Answer 10

Coiling that occurs in addition to the coil of the helical DNA structure

Question 11

Why is supercoiling advantageous?

Answer 11

Preserves the double helix

Compacts DNA

Question 12

True or false: chloroplasts AND mitochondria contain their own genomes

Answer 12

True

Question 13

Streptococcal bacteria reside where?

Answer 13

Human upper respiratory tract

Question 14

True or false: virulent strains of Streptoccal bacteria are harmless and not associated with any disease symptoms

Answer 14

False

Benign strains = harmless
Virulent = dangerous

Question 15

Who found out that there were two diff strains of Streptococcus pneumon? How did he find out?

Answer 15

Fred Neufeld

Inserted two diff strains of bacteria into mice. One strain did nothing (Benign) and the other caused death by pneumonia (virulent)

Question 16

Describe Griffith’s hypothesis and how he came about it

Answer 16

Heated the virulent bacteria in order to kill them (all macromolec still there, the cell is just dead)

Inserted the dead strain into mouse; did not die

Hypothesis: all info that makes a cell virulent was still present, but the cell carrying that information had been killed

Question 17

Describe Griffith’s experimental setup

Answer 17

Set up three control mice (injected one with virulent, one with benign, one with killed virulent bacteria)

In fourth mouse, he killed virulent strain and incubated remains with living cells of benign bacteria.

Question 18

Describe Griffith’s results and his conclusions

Answer 18

The fourth mouse died, indicating that the benign cells were now virulent

Concluded that the benign cells had acquired the ability to be virulent from the dead cells via transformation

Question 19

What is transformation?

Answer 19

A change in cell behaviour resulting from the incorporation of genetic material from outside of the cell

Question 20

Describe Oswald’s experimental setup

Answer 20

Build on Griffith’s experiment; find out which macromolecule is responsible for carrying hereditary info

One control flask with protein, RNA, and DNA

Three other flasks with non-virulent bacteria

• Protein + DNA, protein + RNA, RNA + DNA
• Selectively eliminated each type of macromolecule from cell extracts (i.e. eliminated RNA with RNAase)

Then added killed virulent bacteria in each flask

Question 21

Describe Oswald’s results and conclusion

Answer 21

Results: All of the flasks (three in total) that had DNA had the bacteria turn from non-virulent to virulent (underwent transformation. The one flask without the DNA still had non-virulent bacteria

Conclusion: transformation requires the presence of DNA; the macromolecule that det the characteristics of the cell was contained in DNA

Question 22

What did Rosalind Franklin do?

Answer 22

Rosalind Franklin was the first to use a technique called x-ray diffraction to aim x-rays at DNA to create images based on the diffraction of the x-rays by the atoms of the DNA molecule

Question 23

What is the significance of Photo 51?

Answer 23

From this image that the helical nature of DNA was identified

Question 24

What are the three components of a nucleotide?

Answer 24

Phosphate group

5-carbon deoxyribose sugar (H on bottom)

Nitrogenous base

Question 25

Diff between pyrimidines and purines?

Answer 25

Pyrimidines = single ring Purines = two rings (pyrimidine ring fused to an imidazole ring) = larger

Question 26

Cytosine, Adenine, Thymine, Guanine. Sort these into pyrimidines and purines

Answer 26

Pyrimidines = Cytosine = Thymine Purines = Adenine = Guanine

Question 27

What is the bond between two nucleotides called?

Answer 27

Phosphodiester bond

Question 28

Describe how the nucleotides are linked along the phosphoribose backbone

Answer 28

Phosphate group on 5' carbon on deoxyribose forms a bond with the HYDROXYL GROUP on the 3' carbon on the next

Question 29

Which way does DNA run, 5' -> 3' or 3' -> 5'?

Answer 29

5' -> 3'

Question 30

True or false: new nucleotides are added to the 5' end of the strand

Answer 30

False Added to 3' end

Question 31

What are Chargaff's rules?

Answer 31

DNA from any cell of all organisms should have a 1:1 ratio of pyrimidines and purines A pairs with T C pairs with G

Question 32

True or false: covalent bonds form between the nucleotide bases (i.e. A-T)

Answer 32

False Hydrogen bonds

Question 33

How many hydrogen bonds exist between thymine and adenine?

Answer 33

2

Question 34

How many hydrogen bonds exist between guanine and cytosine?

Answer 34

3

Question 35

True or false: the two strands of DNA run parallel

Answer 35

False Run antiparallel

Question 36

What does RNA polymerase II do?

Answer 36

Transcribes DNA into RNA

Question 37

What are the different categories of RNA?

Answer 37

Messenger RNA Ribosomal RNA Transfer RNA RNA Polymerase

Question 38

What's the difference between the deoxyribose sugar and the ribose sugar?

Answer 38

Ribose has a hydroxyl group (-OH) on the carbon 2 Deoxyribose has a hydrogen (-H) on the carbon 2 DNA has A, T, G, C RNA has A, U, G, C (Uracil replaces the Thymine)

Question 39

What's the difference between uracil and thymine?

Answer 39

Uracil has a hydrogen (-H) where Thymine has a methyl (-CH3) group

Question 40

Is uracil a pyrimidine or a purine?

Answer 40

Pyrimidine

Question 41

What types of bonds are formed in the RNA backbone?

Answer 41

Phosphodiester bonds

Question 42

True or false: new ribonucleotides are added to the 5' end of the polymer

Answer 42

False Added to 3' end

Question 43

What are ribosomal RNAs (or rRNAs)?

Answer 43

Forms (along with proteins) the functional ribosome complexes that perform translation of mRNAs into proteins

Question 44

True or false: most of the RNA in the cell are rRNAs

Answer 44

True

Question 45

Which rRNAs comprise the large ribosomal subunit and which comprise the small subunit?

Answer 45

23S RNA + 5S RNA = large subunit 16S RNA = small subunit

Question 46

How are DNA molecules organized in euk cells?

Answer 46

DNA molecules are linear and organized around proteins (histones) to form chromatin fibres. Chromatin fibres coil more and make chromatids.

Question 47

What is a nucleosome?

Answer 47

Length of DNA coiled around a core of histones

Question 48

What is the difference between euk DNA and prok DNA?

Answer 48

Euk chromosome is much greater than prok nucleoid Euk genome is greater than the prok genome

Question 49

What's similar between the euk DNA and prok DNA?

Answer 49

Same nucleotides, same double helix, similar gene codings for proteins (i.e. RN A polymerase)