Structure of Nucleotides

Question 1

What are nucleic acids?

Answer 1

Polymers made from monomers called nucleotides

Question 2

What are all nucleotides made up of?

Answer 2

three parts which are combined by Phosphodiester bonds formed in condensation reactions

Question 3

What are the components of nucleotides?

Answer 3

-phosphate group
-A pentose sugar (deoxyribose, or river sugar)
-An organic nitrogenous base

Question 4

What are the two groups of organic nitrogenous base?

Answer 4

Pyrimidine skeleton and purine skeleton

Question 5

What bases are pyrimidine (single ring)?

Answer 5

Thymine
Cytosine
uracil(replaced timing in RNA)

Question 6

What bases are purine (double ring)?

Answer 6

Adenine
Guanine

Question 7

What does DNA stand for?

Answer 7

Deoxyribonucleic Acid

Question 8

What is DNA and where is it found?

Answer 8

-Very large and stable molecule
-Found as chromatin in the nucleus of eukaryotic cells, and small amounts are found in the mitochondria and chloroplasts

Question 9

What are the functions of DNA?

Answer 9

-It carries is the genetic code for protein synthesis
-replicates in dividing cells

Question 10

what does DNA consist of?

Answer 10

Two polynucleotide strands twisted into a double helix.

Question 11

What does DNA contain?

Answer 11

A pentose sugar (deoxyribose) and one of four nitrogenous bases: Adenine, Guanine, Cytosine, Thymine (components)

Question 12

Why are the two DNA strands said to be anti-parallel?

Answer 12

The two strands run in opposite directions

Question 13

Within each polynucleotide strand, what are the nucleotides held together by and what does this mean?

Answer 13

Bonds between the phosphate group attached to the fifth carbon atom on one pentose sugar and the third carbon atom on another- means that one end of the strength finishes on carbon five, so it’s called carbon five prime end (5’)
The other finishes on carbon three and it’s called three prime end (3’)

Question 14

What do the two sugar phosphate backbones in DNA do?

Answer 14

protect the genetic information, stored within a sequence of bases

Question 15

What do the bases face each other within the double helix according to, and what they held together by?

Answer 15

-according to the complimentary base pair rule
-Held together by hydrogen bonds

Question 16

What does guanine pair with?

Answer 16

cytosine (three h2 bonds)

Question 17

What does RNA stand for?

Answer 17

ribonucleic acid

Question 18

what is RNA and where is it found?

Answer 18

A short lived molecule (single-stranded polynucleotide), mainly found in the cytoplasm of the cell and also found in the nucleus

Question 19

what do RNA nucleotides contain?

Answer 19

A different pentose sugar (ribose) one of 4 organic nitrogenous bases- AGCU

Question 20

what is the function of RNA?

Answer 20

-It is involved in protein synthesis, and there are three types of RNA involved

Question 21

What are the three types of RNA

Answer 21

mRNA
rRNA
tRNA

Question 22

What is mRNA?

Answer 22

A single stranded molecule that carries the genetic code for a specific protein from DNA in the nucleus to ribosomes in the cytoplasm

Question 23

what is tRNA?

Answer 23

-transfers specific amino acids to the ribosome
-A single RNA strand forms a cloverleaf shape, held together by hydrogen bonds between certain base pairs

Question 24

what is rRNA?

Answer 24

this, together with protein forms a large complex molecule: ribosome
-Ribosomes translate the genetic code and joining amino acids together to form polypeptides

Question 25

How do you compare DNA and RNA?

Answer 25

-the pentose sugar for DNA is deoxyribose, whereas for RNA it’s ribose
-The Purine bases in DNA and RNA are guanine and adenine
-the pyrimidine bases in DNA are thymine and cytosine, cytosine and uracil in RNA
-DNA double stranded, RNA single stranded
-DNA= long , RNA short

Question 26

what are differences between DNA and RNA?

Answer 26

DNA is found in the nucleus bound to histone proteins whereas RNA is found in both the nucleus and the cytoplasm,
• DNA is a much longer-lived molecule than RNA and
• DNA always contains hydrogen bonds between complementary bases, whereas in RNA hydrogen bonds are only found in tRNA.

Question 27

what codes for the sequence of amino acids (primary structure) in one polypeptide?

Answer 27

sequence of DNA nucleotides (a gene)

Question 28

what 2 stages are involved in protein synthesis involve?

Answer 28

Transcription and translation

Question 29

Where does transcription occur?

Answer 29

In the nucleus

Question 30

What is transcription?

Answer 30

Occurs in the nucleus.
DNA is read by enzymes and used to make a single-stranded mRNA molecule. This then leaves the nucleus through a nuclear pore and travels to a ribosome in the cytoplasm or Rough endoplasmic reticulum.

Question 31

What is translation?

Answer 31

Occurs at a ribosome.
mRNA attaches to the ribosome, and a tRNA molecule brings a specific amino acid.
Ribosomal enzymes catalyse the formation of peptide bonds between adjacent amino acids to form the primary structure of a new polypeptide

Question 32

what is ATP (Adenosine Triphosphate) and where is it found?

Answer 32

-And nucleotide found in all living organisms

Question 33

What does ATP contain?

Answer 33

-three phosphate groups, a ribose sugar and the nitrogenous base adenine

Question 34

What is chemical energy stored in?

Answer 34

carbohydrates or lipids (like glucose)

Question 35

what does respiration do to glucose?

Answer 35

Oxidises it in a series of small reactions to release energy in the form of ATP

Question 36

what is ATP?

Answer 36

-not an energy store but an energy currency; it is synthesised as it is required

Question 37

what is ATP involved in?

Answer 37

Energy changes, carrying the energy where it is needed and releasing the energy when ATP is broken down

Question 38

What are the uses of ATP?

Answer 38

-Active transport
-Nerve impulse transmission
-Secretion (packaging molecules into vesicles for exocytosis)
-Muscle contraction
-Synthesis of complex molecules from smaller simpler molecules e.g. Proteins/nucleic acids

Question 39

What’s the formation of ATP?

Answer 39

The enzyme AT synthase combines ADP and P, (inorganic phosphate) in a condensation reaction. This requires an input of energy (30.6 kJ mol-1) in an endergonic reaction. The addition of this phosphate to ADP is called phosphorylation.

Question 40

What is the hydrolysis of ATP?

Answer 40

The enzyme ATPase hydrolyses the terminal phosphate bond releasing a small packet of energy (30.6 kJ mol-1) in an exergonic reaction. This forms ADP and Pi.

Question 41

What are the advantages of using ATP as an intermediate and providing energy compared with using glucose directly?

Answer 41

Glucose*
ATP
Many enzymes needed to release energy
Only one enzyme is needed to release energy through the breaking of one high energy bond*
Releases large quantities of energy that may not be needed, generating lots of heat.
Releases small packets of energy (30.6kJ) when and where it is needed*
Only releases energy through respiration.
Common source of energy for different chemical reactions - universal.*
Requires proteins to cross a membrane
Easily transported across membranes*

Question 42

Why is ATP called the universal energy currency?

Answer 42

it provides energy for many metabolic reactions in all living organisms

Question 43

what is ATP synthase?

Answer 43

The enzyme that synthesises ATP

Question 44

what is ATPase?

Answer 44

The enzyme on that hydrolyses ATP

Question 45

What is exergonic?

Answer 45

Reaction that releases free energy

Question 46

what is endergonic?

Answer 46

Reaction that requires energy