2- Nucleic Acids

Question 1

DNA vs RNA (in terms of genetic info)=

Answer 1

DNA= holds genetic information
RNA= transfers genetic information from nucleus to the rest of the cell

Question 2

Ribosomes are formed from?

Answer 2

RNA & proteins

Question 3

structure of nucleotide= (3)

Answer 3

1x pentose sugar, 1x nitrogen-containing base, 1x phosphate group

Question 4

A condensation reaction between 2 nucleotides forms a __________ bond

Answer 4

phosphodiester

Question 5

DNA nucleotide vs RNA nucleotide components

Answer 5

all have a phosphate group

• All have an organic base (RNA has U & DNA has T)
• DNA has deoxyribose sugar, RNA has ribose sugar

Question 6

DNA vs RNA structure=

Answer 6

• DNA is composed of 2 nucleotide strands, RNA has 1

- RNA relatively short polynucleotide chain, DNA much longer

Question 7

DNA structure=

Answer 7

• A double helix made up of 2 polynucleotide chains held together by H bonds
• consists of a sugar-phosphate backbone
• the strands run anti-parallel

Question 8

How does the semi-conservative replication of DNA ensure genetic continuity

Answer 8

each strand of new DNA is made of ONE original polynucleotide strand & new complementary strand

Question 9

Process of SCR (5)

Answer 9

1. -DNA helicase binds to DNA &
   breaks H bonds between 2
   strands, unwinding & separating them
2. Free floating nucleotides form H bonds with complementary exposed bases
3. each strand is used as a template
4. DNA polymerase (via condensation reactions) joins adjacent nucleotides by forming phosphodiester bonds
5. 2 new DNA strands are synthesised

Question 10

Components of ATP=

Answer 10

1x adenine
1x ribose
3x phosphate group

Question 11

Hydrolysis of ATP is catalysed by enzyme_________

Answer 11

ATP hydrolase

Question 12

ATP hydrolysis can be used for: (2)

Answer 12

• energy coupling
  (Hydrolysis of ATP can be coupled to other reactions within cells that need energy)
• phosphorylation
  (The Pi released in ATP hydrolysis can be used to phosphorylate other compounds)

Question 13

ATP synthesis is catalysed by enzyme _________ during photosynthesis or respiration

Answer 13

ATP synthase

Question 14

equation for ATP synthesis

Answer 14

ADP+ Pi (+energy) > ATP + H2O

Question 15

Properties of water that make it a major component of cells= (5)

Answer 15

• metabolite
• high heat capacity
• large latent heat of vaporisation
• cohesive properties
• useful as a solvent

Question 16

water & polarity

Answer 16

O atoms in water is slightly - charged
H atoms in water are slightly + charged

Polarity means a H atom on 1 molecule is attracted to the O atom on another water molecule

Question 17

Latent heat of vaporisation=

Answer 17

amount of energy needed to change 1g of a liquid substance to gas

Question 18

Why is water’s latent heat of vaporisation so large?

Answer 18

H bonding

Question 19

why is water a good solvent?

Answer 19

• because ions and polar molecules can easily dissolve in it

- water is polar so the + end of the molecule attracts - ions & the - end attracts + ions

Question 20

Water’s cohesive properties=

Answer 20

the strong attraction between H2O molecules, due to H bonds is called COHESION
Cohesion produces surface tension which can be beneficial

Question 21

Benefit of High SHC in warm blooded animals=

Answer 21

heat can be more evenly dispersed in their bodies

Question 22

what is water’s high SHC caused by ?

Answer 22

Hydrogen bonding

Question 23

SHC=

Answer 23

amount of heat 1g of a substance must absorb or lose to change its temperature by 1 degree.

Question 24

What are inorganic ions?

Answer 24

molecules that do NOT contain carbon

Question 25

Important inorganic ions=

Answer 25

H+, Na+, Fe2+ & phosphate ions

Question 26

Inorganic ions occur in _____ & ______ of organisms

Answer 26

cytoplasm, body fluids

Question 27

Hydrogen ions (H+) and pH=

Answer 27

pH values represent the concentration of H+ in a solution

The more H+= the lower the pH

Question 28

Iron ions (Fe2+) in haemoglobin=

Answer 28

iron ions are the central part of the haem group in haemoglobin, allowing blood cells to transport O2 & CO2.

Question 29

Na+ in co-transport of glucose & AA

Answer 29

Transport of Na+ across cell membrane of cells in the intestine, allows the co-transport if glucose & AA

Question 30

Phosphate ions as components of DNA & ATP

Answer 30

for DNA= Pi are essential part of sugar-phosphate backbone of DNA molecules.
for ATP= ATP can form ADP & release a phosphate ion + energy
for ADP= ADP can store energy by gaining a phosphate ion & taking in energy