Dna, Replication, Atp And Inorganic Ions

Front 1

What is the function of DNA?

Back 1

Store genetic information; all the instructions and organism needs to grow and develop.

Front 2

What is the main function of RNA?

Back 2

Transfer genetic information from the DNA to the ribosomes.

Front 3

What are nucleotides?

Back 3

Monomers that join together to form DNA or RNA (polymers).

Front 4

What is a nucleotide made from?

Back 4

A pentose sugar; a nitrogen organic base; a phosphate group.

Front 5

Compare the nucleotides of DNA and RNA?

Back 5

DNA contains deoxyribose sugar; RNA contains ribose sugar.

DNA contains the bases A, T, C and G; RNA replaces T with U (uracil).

DNA is made of two polynucleotide strands; RNA is only single stranded.

Front 6

How do nucleotides (monomers) join together to form DNA or RNA (polymers)?

Back 6

Condensation reactions between the phosphate group of one nucleotide with sugar of another.

Front 7

What is the chain of sugars and phosphate known as?

Back 7

The sugar-phosphate backbone.

Front 8

Outline the structure of a DNA molecule?

Back 8

Two DNA polynucleotides joined together; held together hydrogen bonding between bases.

A pairs with T and C pairs with G; complementary base pairing.

Two antiparallel polynucleotide strands twist to form double helix.

Front 9

How does DNA replicate?

Back 9

DNA replicates semi-conservatively.

Front 10

Why is DNA replication described as semi-conservative?

Back 10

One of the two strands in each new DNA molecule is from the original DNA.

Front 11

Outline the process of semi-conservative replication?

Back 11

DNA helicase breaks hydrogen bonds between complementary base pairs; helix unwinds.

Each original strand used as template; complementary base pairing free-floating DNA nucleotides attracted exposed bases on original strand.

DNA polymerase joins the nucleotides; hydrogen bonds form between complementary bases.

Each new DNA molecule contains one original and one new strand of DNA.

Front 12

Why can DNA polymerase only add nucleotides to new strand at 3' (prime) end?

Back 12

The active site of DNA polymerase is only complementary to the 3' (prime) end of newly forming DNA strand.

Front 13

\Who provided evidence for semi-conservative replication?

Back 13

Meselson and Stahl.

Front 14

What did the experiment involve?

Back 14

Two isotopes of nitrogen; light nitrogen (N14) and heavy nitrogen (N15).

Front 15

Give the structure of water molecules?

Back 15

H2O; one atom of oxygen, two atoms of hydrogen.

Front 16

Why is water a polar molecule?

Back 16

It has a partial negative charge on one side (O-) and a partial positive charge on the other side (H+).

Front 17

The slightly negatively charged oxygen atoms attract what?

Back 17

The slightly positively charged hydrogen atoms.

Front 18

What is this attraction called?

Back 18

Hydrogen bonding.

Front 19

Why is water an important metabolite; why is this useful?

Back 19

Many metabolic reactions involve condensation and hydrolysis reactions.

eg. Energy released from ATP by hydrolysis of ATP to ADP + Pi.

Front 20

Water has a high latent heat of vaporisation; what does this mean and why is it useful?

Back 20

It takes a lot of energy to break hydrogen bonds between water molecules; a lot of energy is used up when it evaporates.

eg. Humans sweat to cool down without losing too much water.

Front 21

Water can buffer (resist) changes in temperature; why is this useful?

Back 21

Hydrogen bonds can absorb a lot of energy so water has high specific heat capacity.

eg. Water inside organisms remains fairly stable temperature - helps to maintain constant body temperature.

Front 22

Water is a good solvent; explain why and how this is useful?

Back 22

Lot of important substances in metabolic reactions; ionic.

Water is polar; positive end attracted to negative ion and vice versa - ions totally surrounded by water; they'll dissolve.

Front 23

There is strong cohesion between water molecules; why is this important?

Back 23

Water molecules cohesive as they are polar; strong cohesion helps water to flow making it great for transporting substances.

eg. Water travels in columns up xylem.

Front 24

What does strong cohesion also provide?

Back 24

High surface tension.

Front 25

What molecule is immediate source of energy in a cell?

Back 25

Adenosine Triphosphate; ATP.

Front 26

How is ATP made from respiration?

Back 26

In respiration, energy released from glucose to make ATP.

Front 27

What is the structure of ATP?

Back 27

Nucleotide base - adenine; ribose sugar; three phosphate groups.

Front 28

How is the energy stored in ATP?

Back 28

In high energy bonds between the phosphate groups.

Front 29

When energy is needed by the cell, what happens to ATP?

Back 29

It is hydrolysed into ADP + Pi (inorganic phosphate); phosphate bond broken and energy is released.

Front 30

ATP can be re-synthesised; how?

Back 30

By a condensation reaction between ADP and Pi.

Front 31

When does this condensation reaction occur?

Back 31

During respiration and photosynthesis; catalysed by ATP synthase.

Front 32

What is an ion?

Back 32

An atom with an electrical charge.

Front 33

What is an ion with a positive charge called?

Back 33

A cation.

Front 34

What is an ion with a negative charge called?

Back 34

An anion.

Front 35

Iron ions (Fe2+) are an important part of which molecule?

Back 35

Haemoglobin; Fe2+ binds to the oxygen - temporarily becomes Fe3+ until oxygen released.

Front 36

Why are hydrogen ions (H+) important?

Back 36

H+ ions determine pH; the more H+ ions the lower the pH and more acidic.

Front 37

Why are sodium ions (Na+) important?

Back 37

Transport glucose and amino acids across cell membranes.

Front 38

Why are phosphate ions (PO4[3-]) important in DNA/RNA and ATP?

Back 38

In DNA/RNA; allows nucleotides join to form polynucleotide chains.

In ATP; bonds between phosphates that store energy.