Chapter 2 Nucleic acids

three components of DNA

1. pentose sugar
2. phosphate group
3. organic base

how is a pentose sugar, phosphate group and organic base formed

through a condensation reaction

what forms in a condensation reaction of DNA

a mononucleotide

how are two mon nucleotides joined

condensation reaction

what are the bonds formed between nucleotides called

phosphodiester bonds

long chain on nucleotides

polynucleotide

RNA

polymer made up of nucleotides

pentose sugar of RNA

ribose

organic bases of RNA

* Adenine
* Guanine
* Cytosine
* Uracil

organic bases of DNA

* Adenine
* Guanine
* Cytosine
* thymine

A

T

T

A

C

G

G

C

types of RNA

types of RNA

* messenger
* transfers genetic info from DNA to ribosomes
* protein synthesis

pentose sugar in DNA

deoxyribose

DNA structure

* two strands of nucleotides
* extremely long
* joined by hydrogen bonds

bond that joins organic bases

hydrogen bonds

why are base pairings specific

quantities are always the same

double helix

the uprights of phosphate and deoxyribose wind around one another to form a double helix

A- 26%

T- 26%

C- 24%

G- 24%

C- 12%

G- 12%

A- 38%

T- 38%

how is DNA stable

* phosphodiester backbone
* hydrogen bonds

phosphodiester backbone

protects the more chemically reactive organic bases

hydrogen bonds between A and T

2

hydrogen bonds between C and G

3

adaptations of DNA

* very stable
* 2 separate strands joined only by hydrogen bonds
* extremely late molecule
* base pairs with helical structure
* able to replicate

DNA only joined by hydrogen bonds

can separate during DNA replication and protein synthesis

base pairs with helical structure

genetic info protected prom being corrupted by outside chemical and physical forces

nuclear division

process by which the nucleus divides

types of nuclear division

* meiosis
* mitosis

cytokinesis

process by which the whole cell divided

why must before a nucleus divides much the DNA be replicated

so that the daughter cells have all the genetic information to produce enzymes and other proteins they need

requirements for semi conservative replication

* 4 types of nucleotides
* both strands of DNA need to be replicated
* enzyme DNA ploymerase
* a source of chemical energy

process of semi conservative replication

1. enzyme DNA helices breaks the hydrogen bonds linking the base pairs of DNA
2. double helix separates into its two strands and unwinds
3. each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind to specific base pairing
4. joined together in condensation reaction by enzyme DNA polymerase
5. each new DNA molecule contains one new strand of DNA and one from the original

structure of ATP

* adenine
* ribose
* phosphates

phosphate groups of ATP

3

3 phosphates

* unstable
* low activation energy
* easily broken

when phosphate groups break

release considerable amount of energy

what is used to convert ATP to ADP

water

what is the conversion of ATP to ADP catalysed by

the enzyme ATP hydrolase

how does the synthesis of ATP to ADP happen

* photosynthesis
* respiration

why is ATP a good immediate energy source

* releases less energy then each glucose molecule
* released in smaller amounts
* hydrolysis of ATP is a single reaction that releases immediate energy

where is ATP made

in mitochondria

where has Many mitochondria

* muscle cells
* epithelium of small intestine

what energy requiring processes is ATP used in

* metabolic processes
* movement
* active transport
* secretion
* activation of molecules

metabolic processes

provides the energy needed to build up macromolecules from their basic units

movement

provided energy for muscle contraction

(for the filaments of muscle to slide past one another and therefor shorten the overall length of muscle fibre)

active transport

provided energy to change shape of carrier proteins in plasma membranes

secretion

provided energy needed to form lysosomes necessary for the secretion of cell products

why is ATP referred to as an immediate energy source

released very rapidly

3 roles of ATP in plant cells

* active transport
* secretions
* macromolecules

macromolecule

a large organic molecule such as carbohydrate, lipid or nucleic acid

how can ATP make an enzyme catalysed reaction take place more readily

has a phosphate that can attach to another molecule making it more reactive and so lowering its activation energy

water structure

* 2 atoms of hydrogen
* no overal charge

\

why is water dipolar

has both positive and negative charge

hydrogen bonding in water

positive pole of one water molecule attached the negative pole of another water molecule

bonding in water

hydrogen bonds

why does it take more energy to separate water

they stick together

latent heat of vaporisation in water

hydrogen bonding means it requires a lot of energy to separate water

cohesion

water sticking together

water in metabolism

* hydrolysis
* condensation reaction
* where chemical reactions take place
* raw material in photosynthesis

water as a solvent

water dissolves other substances such as oxygen and carbon dioxide, ammonia and urea, amino acids and monosaccharides and enzymes