structure of nucleotides

Question 1

define purine

Answer 1

a double ringed organic nitrogenous base
(adenine, guanine)

Question 2

define pyramidine

Answer 2

a single-ringed organic nitrogenous base
(thymine, cytosine, uracil)

Question 3

define tRNA

Answer 3

transfer RNA
a clover leaf-shaped single RNA strand which transfers specific amino acids to a ribosome in translation

Question 4

define mRNA

Answer 4

messenger RNA
a single stranded RNA molecule which is a copy of one gene formed in transcription

Question 5

define rRNA

Answer 5

ribosomal RNA
makes up a ribosome (along with some protein)

Question 6

define universal energy currency

Answer 6

ATP is described as this because it provides energy for many metabolic reactions in all living organisms

Question 7

define ATP synthase

Answer 7

the enzyme that synthesises ATP

Question 8

define ATPase

Answer 8

the enzyme that hydrolyses ATP

Question 9

define exergeonic

Answer 9

a reaction that releases free energy

Question 10

define endergonic

Answer 10

a reaction that requires energy

Question 11

what does DNA stand for?

Answer 11

deoxyribose nucleic acid

Question 12

what are nucleotides composed of?

Answer 12

• phosphate group
• a pentose sugar (deoxyribose sugar or ribose sugar)
• organic nitrogenous base

Question 13

what are the two type of organic nitrogenous bases?

Answer 13

• pyramidine
• purine

Question 14

what bases are pyramidine and what bases are purine?

Answer 14

purine : adenine, guanine
pyramidine : cytosine, thymine, uracil

Question 15

describe pyrimidine

Answer 15

single ring

Question 16

describe purine

Answer 16

double ring

Question 17

what are the functions of DNA?

Answer 17

• it carries the genetic code for protein synthesis
• it replicates in dividing cells

Question 18

why is DNA said to be anti-parallel?

Answer 18

the two DNA strands run in opposite directions

Question 19

if the strand finishes on the fifth carbon atom, what is it called?

Answer 19

5 prime end

Question 20

what do the two sugar-phosphate ‘backbones’ do?

Answer 20

protect the genetic information stored within the sequence of bases which face each other within the double helix.

Question 21

what bond holds the bases together?

Answer 21

hydrogen bonds

Question 22

what bases pair together?

Answer 22

guanine and cytosine
adenine and thymine

Question 23

what doe RNA stand for?

Answer 23

ribose nucleic acid

Question 24

describe RNA

Answer 24

a short-lived molecule
found mainly in the cytoplasm of the cell - also found in the nucleus
single stranded polynucleotide

Question 25

what are the four organic nitrogenous bases in RNA?

Answer 25

- adenine - guanine - cytosine - uracil

Question 26

in what process is RNA involved in?

Answer 26

protein synthesis

Question 27

what are the 3 types of RNA?

Answer 27

- mRNA - tRNA - rRNA

Question 28

what is mRNA?

Answer 28

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

Question 29

what is tRNA?

Answer 29

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

Question 30

what is rRNA?

Answer 30

this, together with protein, forms a large complex molecule : a ribosome. ribosomes translate the genetic code and join amino acids together to form polypeptides

Question 31

state the differences between DNA and RNA?

Answer 31

DNA - deoxyribose sugar RNA - ribose sugar DNA - adenine, guanine,cytosine, thymine RNA - adenine, guanine, cytosine, uracil DNA - double stranded RNA - single stranded DNA - longer in length RNA - shorter in length

Question 32

where is DNA is found?

Answer 32

the nucleus bound to histone protein

Question 33

what is protein synthesis?

Answer 33

a sequence of DNA nucleotides codes for the sequence of amino acids in one polypepetide chain

Question 34

in how many stages does protein synthesis occur, and what are these stages called?

Answer 34

two stages 1. transcription 2. translation

Question 35

describe transcription

Answer 35

- occurs in nucleus - DNA is read by enzymes and is used to make single stranded mRNA. - this leaves the nucleus through a nuclear pore - this travels to a ribosome in the cytoplasm or rough endoplasmic reticulum

Question 36

describe translation

Answer 36

- occurs at a ribosome - mRNA attatches to the ribosome, and a tRNA molecule brings a specific amino acid - ribosomal enzyme catalyse the formation of peptide bonds adjacent amino acid to form the primary structure of a new polypeptide

Question 37

what does ATP stand for?

Answer 37

adenine triphosphate

Question 38

what is ATP composed of?

Answer 38

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

Question 39

what is ATP described as and why?

Answer 39

energy currency BECAUSE... it is a source of energy for many metabolic reactions in all living organisms

Question 40

what are some uses of ATP?

Answer 40

- muscle contraction for movement - synthesis of complex molecules (e.g protein, DNA) - active transport - nerve impulse transmission

Question 41

how is ATP formed?

Answer 41

the enzyme ATP synthase combines ADP and P i in a condensation reaction this is a endergonic reaction the addition of this phosphate to ADP is called phosphorylation

Question 42

how is ATP broken down?

Answer 42

the enzyme ATPase hydrolyses the terminal phosphate bond releasing a small packet of energy in an exergonic reaction. this forms ADP and P i

Question 43

what are the advantages of using ATP as an intermediate in providing energy, compared with using glucose directly?

Answer 43

ATP - only one enzyme needed to release energy through the breaking of one high energy bond GLUCOSE - many enzymes needed to release energy ATP - releases small packets of energy (30.6kJ) where it is needed GLUCOSE - releases large quantities of energy that may not be needed, generating lots of heat ATP - common source of energy for different chemical reactions GLUCOSE - only releases energy through respiration ATP - easily transported across membrane GLUCOSE - requires a specific carrier protein for transport across membrane

Question 44

what does tRNA consist of ?

Answer 44

hydrogen bonds amino acid attachment site anti-codon