2.1- STRUCTURE OF RNA AND DNA

Question 1

What are nucleic acids?

Answer 1

group of most important molecules of which best known are RNA and DNA

Question 2

What does RNA stand for?

Answer 2

ribonucleic acid

Question 3

What does DNA stand for?

Answer 3

deoxyribonucleic acid

Question 4

What structure of DNA makes it immediately recognisable?

Answer 4

double helix structure

Question 5

What does DNA do?

Answer 5

carries genetic information

Question 6

What is DNA made up of?

Answer 6

nucleotides that have just three basic components

Question 7

How many components does each nucleotide have?

Answer 7

three components

Question 8

What are the three components of a nucleotide?

Answer 8

pentose sugar
phosphate group
nitrogen-containing organic base

Question 9

Why is a pentose sugar called a pentose sugar?

Answer 9

it has 5 carbon atoms

Question 10

What are the nitrogen-containing organic bases?

Answer 10

cytosine C, thymine T, uracil U, adenine A and guanine G

Question 11

What is the pentose sugar, phosphate group and organic base joined as a result of?

Answer 11

condensation reactions

Question 12

When the pentose sugar, phosphate group and organic base are joined by condensation reactions what does it form?

Answer 12

mononucleotide

Question 13

How can two mononucleotides be joined?

Answer 13

through a condensation reaction

Question 14

Where does the condensation reaction happen between two mononucleotides?

Answer 14

between the deoxyribose sugar and the phosphate group of another

Question 15

What is the bond called that is formed between two mononucleotides?

Answer 15

phosphodiester bond

Question 16

What is the new structure called when two mononucleotides are bonded?

Answer 16

dinucleotide

Question 17

What does the continued linking of mononucleotides form?

Answer 17

a long chain known as a polynucleotide

Question 18

What is ribonucleic acid?

Answer 18

polymer made up of nucleotides

Question 19

Two characteristics of ribonucleic acid?

Answer 19

single, relatively short

Question 20

What is always the pentose sugar of a ribonucleic acid?

Answer 20

always ribose

Question 21

What are the organic bases of RNA?

Answer 21

adenine, guanine, cytosine and uracil

Question 22

What does one type of RNA do?

Answer 22

transfers genetic information from DNA to the ribosomes

Question 23

What are the ribosomes themselves made up of?

Answer 23

made up of proteins and other types of RNA

Question 24

What is the third type of RNA involved in?

Answer 24

protein synthesis

Question 25

What did James Watson and Francis Crick do in 1953?

Answer 25

worked out the structure of DNA

Question 26

What did Rosalind Franklin do?

Answer 26

pioneering work on the X-ray diffraction patterns of DNA

Question 27

What is always the pentose sugar in DNA?

Answer 27

deoxyribose

Question 28

What are the organic bases on DNA?

Answer 28

adenine, guanine, thymine and cytosine

Question 29

How many strands of nucleotides is DNA made up of?

Answer 29

two

Question 30

What is the length like of each of the strands on DNA?

Answer 30

extremely long

Question 31

How are the two strands on DNA joined?

Answer 31

by hydrogen bonds formed between certain bases

Question 32

What is the base pairing for adenine?

Answer 32

adenine and thymine

Question 33

What is the base pairing for guanine?

Answer 33

guanine and cytosine

Question 34

What is adenine said to be to thymine, and guanine to cytosine?

Answer 34

complementary

Question 35

What are the quantities of thymine and adenine like?

Answer 35

same

Question 36

What are the quantities of cytosine and guanine like?

Answer 36

same

Question 37

How is the two polynucleotide strands of DNA twisted?

Answer 37

uprights of phosphate and deoxyribose wind around one another

Question 38

What is formed when the uprights of phosphate and deoxyribose wind around each other?

Answer 38

double helix

Question 39

What importance does the phosphate and deoxyribose have?

Answer 39

form structural backbone of DNA molecule

Question 40

How is DNA a stable molecule? (2)

Answer 40

phosphodiester backbone protects more chemically reactive organic bases inside double helix hydrogen bonds link organic base pairs forming bridges between phosphodiester uprights.

Question 41

How many hydrogen bonds are there between cytosine and guanine?

Answer 41

three hydrogen bonds

Question 42

What would a higher proportion of C-G pairings mean?

Answer 42

more stable the DNA molecule

Question 43

What else is there between the base pairs holding the molecule together?

Answer 43

other interactive forces

Question 44

What is the function of DNA?

Answer 44

hereditary material responsible for passing genetic information from cell to cell and generation to generation

Question 45

In the DNA of a typical mammalian cell, what is approximately the total number of base pairs?

Answer 45

3.2 billion pairs

Question 46

What does the vast number of base pairs in a typical mammalian cell mean?

Answer 46

there's an almost infinite variety of sequences of bases along the length of a DNA molecule

Question 47

What does the variety of sequences of bases along the length of a DNA molecule provide?

Answer 47

genetic diversity within living organisms

Question 48

How is the DNA molecule adapted to carry out its functions? (5)

Answer 48

very stable two separate strands only joined with hydrogen bonds extremely long molecule base pairs within helical cylinder of deoxyribose-phosphate backbone base pairings leads to DNA being able to replicate + transfer information as mRNA

Question 49

Why is DNA being very stable good?

Answer 49

normally passes from generation to generation without change- rarely mutates

Question 50

Why is the two strands of DNA being joined by hydrogen bonds only good?

Answer 50

allows them to separate during DNA replication and protein synthesis

Question 51

Why is DNA being an extremely long molecule good?

Answer 51

means it carries an immense amount of genetic information

Question 52

Why is the base pairs within the helical cylinder of the deoxyribose-phosphate backbone good?

Answer 52

genetic information is to some extent protected from being corrupted by outside chemical and physical forces

Question 53

What does the function of DNA depend on?

Answer 53

sequence of base pairs that is possesses

Question 54

Why is the sequences of base pairs the DNA possesses important?

Answer 54

sequence is important to everything it does and to life itself