Topic 1- 1.3 Biological Molecules 2

Question 1

Describe the structure of a nucleotide, DRAW IT

Answer 1

A nucleotide are molecules with three parts. They have a 5-carbon pentose sugar, a nitrogen containing base and a phosphate group joined by condensation reactions

Question 2

What kind of bond holds nucleotides together?

Answer 2

Condensation reactions

Question 3

What is ATP? DRAW IT

Answer 3

Is a nucleotide which acts as the universal energy supplier of cells. It is made up of the base adenine, ribose and three phosphate groups.

Question 4

How does ATP provide us with energy? DRAW ADP

Answer 4

The third phosphate bond is broken In a hydrolysis reaction, this is catalysed by the enzyme ATPase, the products of this reaction is ADP.
One bond is broken in ATP which consumes energy however two bonds are made to form ADP which releases energy more than that was used.

Question 5

Describe the general structure of nucleic acids (polynucleotides)

Answer 5

They are polymers which are made of many nucleotide monomer units. The information takes the form of a code in the molecule of DNA.

Question 6

Draw a polynucleotide chain

Answer 6

….

Question 7

Which bases are Purine?

Answer 7

Guanine, adenine

Question 8

Which bases are pyrimidine?

Answer 8

Cytosine, thymine and uracil

Question 9

How do pyrimidine bases and purine bases bond?

Answer 9

A purine base will always bond with a pyrimidine base

Question 10

Which bases make up DNA? And which bonds with which?

Answer 10

Cytosine
guanine
These bond

Adenine
Thymine
These bond

Question 11

Which bases make up RNA? And which bonds with which?

Answer 11

Cytosine
Guanine
These bond

Adenine
Uracil
These bond

Question 12

How are hydrogen bonds involved in the structure of DNA?

Answer 12

Hydrogen bonds form between the amino groups of the nucleotides. There are 3 bonds between C and G There are two bonds between A and T

Question 13

What is a phosphodiester bond?

Answer 13

Is a bond formed between the phosphate group of one nucleotide and the sugar of the next nucleotide in a condensation reaction

Question 14

What are nucleic acids?

Answer 14

Are polymers made up of many nucleotide monomer units that carry all the information needed to form new cells

Question 15

What was Matthew meselson and franklin stahls experiment?

Answer 15

They took E-coli and grew it in a medium contains only 15N nitrogen atoms.
They moved this E-coli too a medium containing only 14N nitrogen atoms.
They found that each DNA unzips into two strands and each of those strands duplicate.
They were able to come up with this conclusion because of the different densities of the nitrogen isotopes

Question 16

Describe how DNA copies itself.

Answer 16

The DNA double helix is unzipped and unravelled by DNA helicase causes the hydrogen bonds to break and unravel.
The exposed bases attract free nucleotides
DNA polymerase catalysed the linking up of these nucleotides
DNA helicase catalyses the formation of phosphodiester bonds between the strands of DNA
The results is two new strands of DNA identical to the original

Question 17

Describe/define the genetic code

Answer 17

The genetic code is based on genes, these genes are made of codons each codon codes for a specific amino acid. The genetic code is a triplet code which is non overlapping and degenerative as well.

Question 18

What does it mean that DNA is non-overlapping?

Answer 18

It means that a code like this ATGCTACCG can only code for ATG CTA and CCG rather than ATG TGC etc. It’s less economical however it means that a mutation doesn’t affect more than just three nucleotides.

Question 19

What does it mean that DNA has a degenerate code?

Answer 19

DNA contains more genetic information than is needed however it acts as a safety mechanism as if the last base for a codon mutates then it could still code for the same amino acid.

Question 20

Describe messenger RNA and its function

Answer 20

Is the RNA formed in the nucleus that is created where RNA polymerase unravels and transcribes complementary codons. These codons are then fused through phosphodiester bonds again catalysed by DNA polymerase.
The MRNA leaves through a nuclear pore carrying the complementary code of the DNA strand it copied held together by phosphodiester and hyrdogen bonds

Question 21

Describe transfer RNA (tRNA)

Answer 21

tRNA carries amino acids to the ribosomes as each triplet(codon) is read tRNA deposits the corresponding amino acid. The anticodon is responsible for identifying the corresponding codon.

Question 22

What is rRNA?

Answer 22

rRNA is responsible for making up 60% of the structure of ribosomes

Question 23

DNA Helicase’s function?

Answer 23

Unzips the DNA strands and breaks the hydrogen bonds between the bases of the strands

Question 24

DNA Polymerase’s function?

Answer 24

Adds new nucleotides to new strand and pairs complementary bases

Question 25

DNA Ligase function?

Answer 25

Joins the phosphate groups to the deoxyribose of growing strand to form phosphodiester bonds

Question 26

RNA polymerase function?

Answer 26

Is the enzyme which polymerises units to form RNA in a sequence determined by the antisense strand of DNA

Question 27

Describe the entire process of the production of a polypeptide amino chain from the DNA of the nucleus.

Answer 27

Transcription take place. The DNA separate at one one gene. mRNA strand copies from the antisense strand, this process is catalysed by RNA polymerase enzyme.
The mRNA strand leaves the nucleus and moves to a ribosome in the cytoplasm .
tRNA carries amino acids to ribosomes
The ribosome moves up the chain of mRNA reading the codon, the codon of mRNA attract the appropriate amino acid
The ribosome puts these amino acids together forming a completed polypeptide functional protein.

Question 28

What are the three types of point mutation?

Answer 28

Substitutions- where one base substitutes for another.
Deletions- where a base is completely lost in a sequence
Insertions- when an extra base is added

Question 29

What is a chromosomal mutation?

Answer 29

When a chromosome is lost or gained or lost during meiosis and mitosis causing Down’s syndrome etc..