M1:07 DNA

Question 1

In what two forms does nucleic acid come in?

Answer 1

DNA and RNA that hold the coded information that build an organism

Question 2

What does DNA stand for?

Answer 2

deoxyribonucleic acid

Question 3

What does RNA stand for?

Answer 3

ribonucleic acid

Question 4

Where is DNA usually found in eukaryotic cells?

Answer 4

in the nucleus

Question 5

What are the three forms of RNA used for?

Answer 5

• to read and translate the information in order to produce the various proteins required to make a living, functioning organism.

Question 6

What is a nucleotide?

Answer 6

a monomer of all nucleic acids

Question 7

What are single nucleotide made up of?

Answer 7

• one phosphate group - one organic nitrogenous base -one sugar molecule

Question 8

What are the three subunits of a nucleotides bonded together with?

Answer 8

covalent bonds

Question 9

How many different nucleotides make up the code carrying the instructions to make proteins in all living things.

Answer 9

4

Question 10

Describe, in detail the make up on a nucleotide

Answer 10

• the phosphate group in all nucleic acids is always the same - the sugar molecule is a 5-carbon sugar, either deoxyribose (in DNA) or ribose (in RNA) -There are 5 possible bases, ATGCU

Question 11

What does T G U A and C stand for?

Answer 11

Thymine Guanine Uracil Adenine Cytosine

Question 12

How are long chains of nucleotides formed?

Answer 12

The condensation reaction between the phosphate group of one nucleotide and the sugar of another nucleotide joins two together, with this repeating it forms a long chain.

Question 13

What does the backbone of nucleotides consist of?

Answer 13

consists of repeating sugar-phosphate chain

Question 14

What are chains of nucleotides bonded together known as ?

Answer 14

nucleic acids

Question 15

Which nucleotides bond together to form nucleic acids? and what does this mean about the description of the nucleic acid?

Answer 15

Those carrying the same sugar moleculeso they can either be describe as RNA when the sugar is ribose, or DNA when the sugar is deoxyribose

Question 16

How are the 5 organic bases grouped?

Answer 16

Three are called pyrimidines (T U C) and two are called purines (A G)

Question 17

What is smaller, pyrimidines or purines?

Answer 17

pyrimidines

Question 18

What is produced when excess purines are broken down in the liver?

Answer 18

uric acid, which is excreted into the urine

Question 19

What happens if someone has too much uric acid in their blood?

Answer 19

The uric acid is insoluble at lower temperatures and forms crystals that are deposited in joints at the extremities, such as the toes. Then the toes become painful and swollen, a condition called gout.

Question 20

What do organic bases conatin and what should they always be referred to as?

Answer 20

nitrogen, always referred to as nitrogenous bases.

Question 21

What do nucleic acids and amino acids contain?

Answer 21

nitrogen

Question 22

What is DNA?

Answer 22

a long-chain polymer of nucleotide monomers called a polynucleotide

Question 23

When does DNA molecules form?

Answer 23

When two polynucleotide strands come together, forming what looks like a ladder- the sugar phosphate backbones of two chains form the uprights, and the bases project towards each other to form the rungs.

Question 24

What strengthens the DNA strands?

Answer 24

hydrogen bonds form between the bases in opposite uprights

Question 25

Why is it vital that DNA are very stable structures?

Answer 25

As it carries the instructions to make an organism, and if it was unstable then the instructions could go wrong too easily.

Question 26

Why is the term 'anti-parallel' used to describe two DNA strands?

Answer 26

As they run parallel to each other and the space between them is taken up by nitrogenous bases projecting inwards, but the strands run in oppositions to each other, so the sugars are pointing in opposite directions

Question 27

Why are purines and pyrimidines sizes vital in DNA?

Answer 27

Where a pyrimidines appear on one side, purines occur on the other

Question 28

Which nitrogenous pairs link up?

Answer 28

A-TC-G

Question 29

How is the base pairing described as?

Answer 29

complementary

Question 30

What is the double helix?

Answer 30

the complete DNA structure , where the anti-parallel chain twists to form the final structure

Question 31

What point does DNA replication take place?

Answer 31

interphase

Question 32

Describe DNA replication

Answer 32

- the double helix is untwisted-hydrogen bonds between the bases are broken apart to unzip the DNA, which exposes the base - free DNA nucleotides are hydrogen-bonded onto the exposed according to the base-pairing rules. - covalent bonds are formed between the phosphate of one nucleotide and the sugar of the next to seal the backbone.

Question 33

What is the process of DNA replication described as? why?

Answer 33

semi-conservative replication , as each new DNA molecule consists of one conserved strand plus one newly built strand.

Question 34

Describe the connection between structure and function of DNA

Answer 34

- The sequences of bases is an example of information, the information is in the form of codes to build proteins. -The molecules are long, so a large amount of information can be stored- The base-pairing rules mean that complementary strands of information can be replicated- The double helix structure gives the molecule stability- hydrogen bonds allow easy unzipping for copying and reading information

Question 35

How is RNA differently structured to DNA?

Answer 35

-the sugar molecule that makes up the nucleotides are ribose - the nitrogenous base uracil is found instead of the organic base thymine.- the polynucleotide chain is usually single stranded - three forms of molecule exist

Question 36

Which bases are complementary in RNA?

Answer 36

U-AC-G

Question 37

Why is it important that the base-pairing rule means RNA can be complementary to DNA ?

Answer 37

As exposed DNA nucleotides can have free RNA nucleotides hydrogen-bonded to them and then the sugar phosphate back bone is sealed up to form a chain of RNA nucleotides

Question 38

What is transcription?

Answer 38

copying the genetic code of the DNA base sequence.

Question 39

What are the three forms of RNA?

Answer 39

mRNA (messenger) rRNA (ribosomal) tRNA ( transfer)

Question 40

What is mRNA made for?

Answer 40

as a strand complementary to one strand of the DNA nucleotide (template strand) , making it a copy of the other DNA strand of the double helix.

Question 41

where is rRNA found?

Answer 41

in the ribosomes

Question 42

what is the role of tRNA?

Answer 42

to carry amino acids to the ribosomes, where they are bonded together to form polypeptides

Question 43

What happens to amino acids in the ribosomes?

Answer 43

they are bonded together to form polypeptides

Question 44

How are instructions in the DNA carried out to form proteins ?

Answer 44

- the sequence coding for a particular protein is exposed by splitting the hydrogen bonds that hold the double helix together -RNA nucleotides form a complimentary strand (mRNA) which is a copy of the DNA - The mRNA peels away from the DNA and leaves the nucleus through a nuclear pore -mRNA attaches to the ribosome -Then tRNA molecules bring amino acids to the ribosome in the correct order, according to the base sequence of the mRNA -The amino acids are joined together by peptide bonds to give a protein with a specific primary structure (which then gives rise to the secondary and tertiary structures)