DNA

Question 1

What is DNA?

Answer 1

DNA is a molecule that contains all the instructions (genetic information) to put an organism together and make it work

Question 2

Where is DNA found?

Answer 2

DNA is found in the nucleus of living cells
In really long molecules called chromosomes
(Chromosomes are made up of coiled up DNA)

Question 3

What is uncoiled DNA known as?

Answer 3

• CHROMATIN

Question 4

How many metres of DNA does every cell in the body contain?

Answer 4

Every cell in the body contains about 2 metres of DNA therefore it has to be coiled and tightly packed

Question 5

What does DNA stand for?

Answer 5

Deoxyribonucleic-acid

Question 6

What gives a DNA molecule its spiral double helix shape?

Answer 6

• the DNA molecule consist of 2 ‘polynucleotide strand’ that look like a twisted ladder

Question 7

Why do all of the body’s cells contain exactly the same DNA?

Answer 7

• all of the body’s cells contain exactly the same DNA because the DNA is copied exactly every time the cell divides

Question 8

What are the sides of DNA made up from?

Answer 8

The sides (backbone) is made of sugar (deoxyribose) and phosphate

Question 9

What are the 4 bases that make the ‘steps’ of the double helix ladder?

Answer 9

• ADENINE (A)
• THYMINE (T)
• CYTOSINE (C)
• GUANINE (G)
  Bases are the basic building blocks of DNA

Question 10

What do all of the ORGANIC bases contain?

Answer 10

All 4 bases contain nitrogen hence their other name NITROGENOUS BASES

Question 11

How many classes can the 4 bases be split into? And what are the names of the two classes?

Answer 11

The 4 bases can be split into 2 classes PURINES and PYRIMIDINES

Question 12

Name 2 purines:

Answer 12

1. ADENINE
2. GUANINE

THINK OF ‘OH PURE ADELAIDE’

Question 13

Name 2 pyrimidines:

Answer 13

1. THYMINE

2. CYTOSINE

Question 14

What are purines?

Answer 14

• bases that form double rings

Question 15

What are pyrimidines?

Answer 15

• bases that have one ring

Question 16

Why is DNA a polymer?

Answer 16

• DNA is a polymer because it’s made up of many repeated units called nucleotides

Question 17

What groups do ALL nucleotides contain:

Answer 17

1. Phosphate group
2. Pentose - 5 carbon sugar
3. Nitrogenous base e.g. A T C G

Question 18

What do nucleotides form?

Answer 18

• nucleotides form the MONOMERS of nucleic acids DNA and RNA

Question 19

In DNA what is the nucleotide pentose sugar?

Answer 19

• in DNA the nucleotide pentose sugar is DEOXYRIBOSE

Question 20

In RNA what is the nucleotide pentose sugar?

Answer 20

• in RNA the nucleotide pentose sugar is RIBOSE

Question 21

What reaction joins nucleotides together and what is the product of this reaction?

Answer 21

• Nucleotides join together by a CONDENSATION reaction to form a POLYNUCLEOTIDE chain

Question 22

What is the covalent bond between the sugar residue and phosphate group in a nucleotide known as?

Answer 22

• The covalent bond between the sugar residue and the phosphate group in a nucleotide is called a PHOSPHODIESTER group

Question 23

Why are the 2 polynucleotides strands described as ANTIPARALLEL?

Answer 23

• The 2 strands run in opposite directions so they are described as ANTIPARALLEL

Question 24

What is the direction of a polynucleotide based on?

Answer 24

• the ‘opposite direction’ of the 2 strands refers to the direction that the 3rd and 5th carbon molecule on the 5 carbon sugar, deoxyribose are facing

Question 25

What is the 5'end of the molecule referring to?

Answer 25

- the 5'end of the molecule is referring to where the phosphate group is attached to the 5th carbon atom of the deoxyribose sugar

Question 26

What is the 3'end of the molecule referring to?

Answer 26

- the 3'end of the molecule is referring to where the phosphate group is attached to the 3rd carbon atom of the deoxyribose sugar

Question 27

What do the 2 polynucleotide strands twist around one another to form?

Answer 27

- the 2 polynucleotide stands twist around one another to form the double helix

Question 28

Why do the 4 bases join together and form complementary pairs?

Answer 28

- they form complementary pairs because they always join in a very specific way

Question 29

What base does the PURINE ADENINE always join to? And how many hydrogen bonds form between them?

Answer 29

- ADENINE always joins to the PYRIMIDINE THYMINE | - 2 hydrogen bonds

Question 30

Which base does the PURINE GUANINE always form with? And how many hydrogen bonds form between the bases?

Answer 30

Guanine always forms with the PYRIMIDINE CYTOSINE | 3 Hydrogen bonds

Question 31

Why do hydrogen bonds join the bases in DNA?

Answer 31

- because the hydrogen bonds are very weak and so can easily be broken for transcription and DNA replication

Question 32

What bonds hold the 2 antiparallel polynucleotide strands together?

Answer 32

- the two antiparallel strands are held together by hydrogen bonds

Question 33

Are there other types of nucleotide molecules?

Answer 33

YES

Question 34

What do you call a nucleotide which contains more than 1 phosphate?

Answer 34

When nucleotides contain more than 1 phosphate they are said to have become PHOSPHORYLATED - phosphor y lated - nucleotides

Question 35

Give 2 examples of 2 phosphoylated nucleotides:

Answer 35

1. ATP | 2. ADP

Question 36

What does ATP stand for?

Answer 36

ATP = ADENOSINE TRIPHOSPHATE

Question 37

What is Adenosine triphosphate?

Answer 37

- Adenosine triphosphate is an energy-rich END PRODUCT of most energy releasing bio chemical processes - and it is used in many energy requiring metabolic processes

Question 38

What does ADP stand for?

Answer 38

ADENOSINE DIPHOSPHATE

Question 39

What is adenosine diphosphate?

Answer 39

- Adenosine diphosphate is another molecule that plays an important role in the process in which CELLS GENERATE ENERGY

Question 40

What makes an adenosine?

Answer 40

ADENINE + RIBOSE = ADENOSINE