Module 2-Nucelotides and nucleic acids

Question 1

What are the 2 main types of nucleic acids?

Answer 1

DNA and RNA

Question 2

What is a genome?

Answer 2

cells entire genetic content

Question 3

What is DNA?

Answer 3

Genetic material of a living organism

Question 4

Where is DNA found in eukaryotes?

Answer 4

Mainly in nucleus but can also be found in chloroplasts and mitochondria

Question 5

Where is DNA found in prokaryotes?

Answer 5

It is found in the cytoplasm as not enclosed in any membranous envelope

Question 6

What is RNA mainly involved in?

Answer 6

Ribo nucleic acid is mostly involved in synthesising proteins

Question 7

What are ribosomes formed from?

Answer 7

RNA and proteins

Question 8

How does DNA transfer genetic material to the rest of the cell?

Answer 8

It uses messenger RNA to transfer genetic information out of the nucleus

Question 9

What bond is formed between two nucleotides?

Answer 9

Phosphodiester

Question 10

What does each nucleotide contain?

Answer 10

A pentose sugar, nitrogenous base and a phosphate group

Question 11

Where does a phosphodiester bond form between two nucleotides?

Answer 11

Sugar group on one and phosphate group on the other

Question 12

Components of a DNA nucleotide

Answer 12

Deoxyribose sugar, phosphate group, adenine/guanine/cytosine/thymine

Question 13

Components of an RNA nucleotide

Answer 13

Ribose sugar, phosphate group, adenine/cytosine/guanine/thymine

Question 14

What 3 things is the genetic code?

Answer 14

Degenerate, non overlapping and universal

Question 15

What does degenerate mean?

Answer 15

Some amino acids are encoded from more than one codon

Question 16

What does universal mean?

Answer 16

The same 4 bases are used on the DNA of every organism. Codons in dna are transcribed into mRNA and translated into amino acids in every organism

Question 17

What does non overlapping mean ?

Answer 17

There’s no overlapping between triplet codes

Question 18

DNA structure?

Answer 18

-2 polynucleotide chains arranged in a double helix
-the sugar and phosphate lie on the outside of the helix and form the backbone of the DNA
-the nitrogenous bases are stacked in the inside of the helix
-hydrogen bonds hold base pairs together

Question 19

RNA structure?

Answer 19

-relatively short, single polynucleotide chain
-composed of ribonucleotides that are linked by phosphodiester bonds

Question 20

What is the base complementary rule?

Answer 20

DNA strands are complementary to one another
-A and G are both purines and contain a double carbon ring structure and 2 hydrogen bonds
-C and T are both pyrimidines containing single carbon ring structures and 3 hydrogen bonds

Question 21

Why is DNA replication semi conservative?

Answer 21

-when a cell divides, it forms 2 daughter cells so needs to duplicate its DNA so each daughter cell inherits a full set of DNA
-each of the 2 strands in the double helix are used as a template from which new strands are copied
-after replication the new DNA is made up of one original polynucleotide and a new complementary strand.

Question 22

Describe the process of replication

Answer 22

-DNA helicase binds to DNA and breaks the hydrogen bonds between the 2 strands
-the DNA helix unwinds and the 2 strands separate
-free floating nucleotides form hydrogen bonds with the complementary bases
-each strand is used as a template to produce complementary strands `
-DNA polymerase forms phosphodiester bonds between the nucleotides
-2 new DNA strands are synthesised

Question 23

Describe how the strands of the double helix are joined together?

Answer 23

-the phosphate residue attaches to the hydroxyl group of the 5’ carbon of one sugar and the hydroxyl group of the 3’ carbon sugar
-the bond is called the 5’-3’ phosphodiester linkage

Question 24

What enzyme catalyses the condensation reaction between the nucleotides in the DNA strand?

Answer 24

DNA polymerase

Question 25

Why is ATP called a nucleotide derivative?

Answer 25

because it is a modified form of a nucleotide

Question 26

What are the components of ATP?

Answer 26

-adenine (nitrogenous base) -ribose (5 carbon sugar) -3 phosphate groups

Question 27

What is the primary energy currency of cells?

Answer 27

ATP

Question 28

When does hydrolysis of ATP occur?

Answer 28

when a cell needs energy

Question 29

State the hydrolysis reaction of ATP

Answer 29

ATP+H2O->ADP+inorganic phosphate group+(energy)

Question 30

What is the enzyme called the catalyses the hydrolysis of ATP?

Answer 30

ATP hydrolase

Question 31

What is the energy released from the hydrolysis of ATP used for?

Answer 31

to perform work inside the cell

Question 32

What is the inorganic phosphate released in ATP used for?

Answer 32

to phosphorylate other compounds which often makes the compounds more reactive

Question 33

What enzymes catalyses the condensation of ATP?

Answer 33

ATP synthase

Question 34

Name the 2 stages of polypeptide synthesis

Answer 34

transcription and translation

Question 35

Describe the process of transcription

Answer 35

1)RNA polymerase binds to the locus of the gene to be transcribed 2)DNA helicase unwinds the double strands of DNA and breaks the hydrogen bonds between the 2 strands 3)the bases of the target gene are exposed so RNA polymerase binds free floating RNA nucleotides to the template strand (so it is complementary to the target) 4)RNA nucleotides form a strand of mRNA that is complementary to the template strand 5)RNA polymerase reaches the triplet of bases that signal stop so the RNA polymerase stops separating the DNA and producing mRNA 6)the hydrogen bonds between the 2 strands of DNA form again 7)the completed mRNA strand leaves the nucleus and enter s the cytoplasm

Question 36

Describe the process of translation

Answer 36

1)mRNA that has been produced during transcription binds to a ribosome in the cytoplasm 2)6 bases can fit inside the ribosome at one time 3)one molecule of tRNA binds to the first codon in the ribosome 4)the tRNA molecule has an anti codon that is complementary to a specific codon, this allows the anticodon to bind to the correct codon 5)each tRNA molecule carries a specific amino acid into the ribosome which is bound to tRNA using ATP 6)a second tRNA molecule binds to the second codon in the ribosome, the corresponding amino acid is brought into the ribosome 7)the 2 amino acids in the ribosome form a peptide bond and the ribosome then moves along the mRNA strand so that a new codon enters the ribosome 8)when the stop codon is reached there is no corresponding tRNA molecule and the polypeptide chain is released from the ribosome 9)the polypeptide chain has been formed