1B - More Biological Molecules

Question 1

Name two types of nucleic acid.

Answer 1

DNA and RNA.

Question 2

Where are DNA and RNA found and what do they do? (Brief)

Answer 2

In all living cells and they both carry genetic information.

Question 3

What is the full name of DNA and what is its function?

Answer 3

DeoxyriboseNucleic Acid It is used to store genetic information, that’s all the instructions an organism needs to grow and develop from a fertilised egg to a fully grown adult.

Question 4

What is the full name of RNA and what is its function? How do they interact with ribosomes?

Answer 4

RiboseNucleic Acid It is similar in structure to DNA. One of its main functions is to transfer genetic information from the DNA to the ribosomes. Ribosomes are the body’s ‘protein factory’, they read the RNA to make polypeptides in a process called translation.

Question 5

What is a nucleotide and what is it made from?

Answer 5

A type of biological molecule. It’s made from: -A pentose sugar (That’s a sugar with 5 carbon atoms) -A nitrogen-containing organic base -A phosphate group

Question 6

What are nucleotides?

Answer 6

The monomers that make up DNA and RNA.

Question 7

Describe the structure of a DNA nucleotide.

Answer 7

-The pentose sugar in a DNA molecule is called deoxyribose. -Each DNA nucleotide has the same sugar and a phosphate group. The base on each nucleotide can vary. -There are four possible bases, Adenine (A), Thymine (T), Cytosine (C) and Guanine (G).

Question 8

Describe the structure of an RNA nucleotide.

Answer 8

-RNA contains nucleotides with a RIBOSE sugar -Like DNA, and RNA nucleotide also has a phosphate group and one of four different bases. -In RNA though, Uracil (U), REPLACES Thymine as a base!!

Question 9

What is a “polynucleotide”?

Answer 9

A polynucleotide is a polymer of nucleotides. (Both DNA and RNA nucleotides form polynucleotides).

Question 10

Describe how a polynucleotide is formed.

Answer 10

Both DNA and RNA nucleotides form polynucleotides. - The nucleotides join up via a condensation reaction between the phosphate group of one nucleotide and the sugar of another - This forms a PHOSPHODIESTER BOND (consisting of one phosphate group and two ester bonds). - The chain of sugars and phosphates is known as the sugar-phosphate backbone.

Question 11

Briefly explain the length of an RNA polynucleotide chain

Answer 11

RNA is made from a single polynucleotide chain (not a double one). It’s much shorter than most DNA polynucleotides.

Question 12

Explain how a sugar phosphate backbone is formed

Answer 12

-A polynucleotide is a polymer of nucleotides. Both RNA and DNA nucleotides form polynucleotides -The nucleotides join up via a condensation reaction between the phosphate group of one nucleotide and the sugar of another. -This forms a phosphodiester bond (consisting of one phosphate group and two ester bonds) -The chain of sugars and phosphates is known as the sugar-phosphate backbone

Question 13

Draw the structure of a single polynucleotide strand, identifying:

• The sugar phosphate backbone
• Phosphodiester bond
• Ester Bond

Answer 13

Question 14

What bond joins two DNA polynucleotide strands together?

Answer 14

Hydrogen Bonding

Question 15

What is ‘complementary base pairing’?

Answer 15

Each base can only join with one particular partner

A AND T

C AND G

Question 16

Name the four bases in DNA

Answer 16

Adenine

Guanine

Thymine

Cytosine

Question 17

What does complementary base pairing mean for the amount of each base in a DNA molecule?

Answer 17

There are equal amounts of cytosine and guanine and then equal amounts of adenine and thymine

Question 18

How many hydrogen bonds form between the complementary bases?

Answer 18

C and G = 3 hydrogen bonds

A and T = 2 hydrogen bonds

Question 19

Define antiparallel

Answer 19

running in opposite directions

Question 20

What twists to form the DNA double-helix

Answer 20

Two antiparallel polynucleotide strands twist to form the DNA double helix

Question 21

When was DNA first discovered?

What did lots of scientists say at the time?

Answer 21

In the 1800’s

Lots of scientists doubted that it could carry the genetic code because it has a relatively simple chemical composition. Some argued that genetic information must be carried by the proteins.

Question 22

What happened in 1953, (regarding DNA)?

Answer 22

In 1953, experiments had shown that DNA was the carrier of the genetic code. This was also the year in which the double-helix structure, which helps DNA to carry out its function, was determined by Watson and Crick.

Question 23

Draw and label the structure of two joined polynucleotide strands and how they twist to form a double helix

Answer 23