1.5.1 structure of DNA and RNA

Question 1

DNA defintion

Answer 1

Is a double helix with 2 polynucleotide chains held together by HB between specific complementary base pairs

Question 2

What is the function of DNA?

Answer 2

holds genetic information.

Question 3

What is the function of RNA?

Answer 3

RNA transfers genetic information from DNA to the ribosomes.

Question 4

Ribosomes are formed from

Answer 4

RNA and proteins

Question 5

Nucleotide is the monomer.
What is the polymer?

Answer 5

Nucleic acids (DNA or RNA)

Question 6

What is DNA and RNA a polymer of

Answer 6

nucleotides

Question 7

What is a DNA nucleotide made up of?

Answer 7

• a deoxyribose sugar
• a phosphate group
• a nitrogenous base

Question 8

What are the 4 bases of DNA?

Answer 8

Adenine + Thymine and Guanine + Cytosine

Question 9

What is an RNA nucleotide made up of?

Answer 9

• a ribose sugar
• a phosphate group
• a nitrogenous base

Question 10

What are the 4 bases of RNA?

Answer 10

Adenine + Uracil and Cytosine + Guanine

Question 11

What bonds join together each nucleotide?

Answer 11

phosphodiester bonds

Question 12

What are the 2 strands of DNA joined together by?

Answer 12

hydrogen bonds between complementary base pairs

Question 13

What is the sugar-phosphate backbone?

Answer 13

The chain of alternating phosphate groups and pentose sugars, produced as a result of many phosphodiester bonds.

Question 14

what are the three types of RNA

Answer 14

mRNA and tRNA and rRNA

Question 15

What is the difference between DNA molecules and RNA molecules? (2)

Answer 15

DNA molecules are double stranded but RNA molecules are single stranded
DNA is longer than RNA

Question 16

What makes DNA compact?

Answer 16

double helix structure

Question 17

what protects the base pairs

Answer 17

sugar phosphate backbone

Question 18

What reaction joins DNa and RNA necleotides together and what bond is formed

Answer 18

condensation reaction and a phosphodiester bond

Question 19

Why is there a very large variability/range of genes that DNA can code for?

Answer 19

sequence of bases has (almost) infinite variability

Question 20

Why can DNA carry a lot of code?

Answer 20

it is an extremely large molecule

Question 21

Structure of DNA

Answer 21

Base sequence
allows info to be stored
codes for amino acids and proteins

Double helix
compact

Long and large
can store lots of info

Hydrogen bonds
Easily broken between bases
enables DNA replication to occur

Sugar phosphate backbone
Strength and flexibility

DOuble stranded
enables semi conservative Replication to occur

Question 22

If 20% of the bases in a DNA molecule are adenine, what percentages do the other bases hold?

Answer 22

Thymine = 20%
Guanine = 30%
Cytosine = 30%

Question 23

How many hydrogen bonds are formed in a C-G pairing?

Answer 23

3

Question 24

How many hydrogen bonds are formed in an A-T pairing?

Answer 24

2

Question 25

Suggest how PNA (binds to DNA) affects the transcription of the section of DNA

Answer 25

PNA is complementary to DNA PNA forms base pairs with DNA Preventing/ reducing RNA polymerase activity/ bonding Reducing/ stopping transcription

Question 26

What group is attached to the 3' carbon in a DNA nucleotide?

Answer 26

hydroxy

Question 27

What group is attached to the 5' carbon in a DNA nucleotide?

Answer 27

phosphate

Question 28

How does DNA replicate

Answer 28

via semi - coservative Replication

Question 29

Describe the structure of DNA and structure of a chromosomes

Answer 29

- polymers of nucleotides - nucleotides consist of deoxyribose phosphate and organic nitrfogneous base - Phosphodiester bonds between nucleotides - DNA double helix held by H bonds - 2 strands held by hydrogen bonds - adenine, thymine, cyotsine and guanine - DNA is associated with histones/ proteins - During mitosis/ when visible chromsomeoes cons tis of two chromatids joined at a centromere

Question 30

Describe the structure of DNA (5)

Answer 30

- polymer of nucleotides - each nucleotide is formed from deoxyribose, a phosphate group and an nitrogenous base - phosphodiester bonds - double helix held together by hydrogen bonds - H bonds between: adenine + thymine, and also cytosine + guanine

Question 31

Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule. (2)

Answer 31

- Condensation reaction - between phosphate and deoxyribose - catalysed by DNA polymerase