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Biology > Biological molecules - Enzymes, Nucleic Acid, Water, ATP, Inorganic Ions > Flashcards

Biological molecules - Enzymes, Nucleic Acid, Water, ATP, Inorganic Ions Flashcards

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1
Q

What is the function of DNA?

A

To hold and store genetic information.

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2
Q

What is the function of RNA?

A

To transfer genetic code found in DNA out of the nucleus to carry to ribosomes in the cytoplasm.

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3
Q

What are nucleotides formed from?

A

Pentose sugar
Nitrogen containing base
Phosphate group

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4
Q

What is the difference between the 2’ positions in DNA and RNA and how does this affect their functions?

A

DNA has a hydrogen at the 2’ position and RNA has a hydroxyl group making it more subseptible to hydrolysis. Therefore RNA is shorter lived and used as a transport molecule rather than a storage molecule like DNA.

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5
Q

Name the 4 nitrogenous bases

A

Adenine
Cytosine
Guanine
Thymine

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6
Q

What are the components of an RNA nucleotide?

A

Ribose sugar with a hydroxyl (OH) group at 2’
A phosphate group
One of the 4 nitrogenous bases (A, C, G, U)

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7
Q

Which nitrogenous base is replaced in RNA and for what?

A

Thyamine replaced with Uracil

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8
Q

What does the 2’ hydroxyl group make RNA move susceptible to?

A

hydrolysis.

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9
Q

Two structural formes nitrogenous base molecules occur in?

A

Purines and pyrimides.

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10
Q

Arrange A, T, C, G, U into their structural groups.

A

A and G- Purine
C and T and U - pyramidal

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11
Q

How are seperate nucleotides joined together?

A

Condensation reactions between phosphate group of one nucleotide and pentose sugar of the next

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12
Q

What type of bond does condensation reaction between two nucleotides form?

A

Phosphodiester

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13
Q

What is the sugar phosphate backbone?

A

A chain of alternating phosphate groups and pentose sugars produced as a result of many phosphate diester bonds.

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14
Q

What is the difference between an purine and pyramidine nitrogenous base?

A

Purines have double ring structure whereas pyramidines have a single ring structure

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15
Q

What are DNA molecules made up of and held together by?

A

Two polynuclotide strands that are antiparallel held together by hydrogen bonds.

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16
Q

What are the monomers of DNA & RNA?

A

Nucleotides

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17
Q

What is the polynucleotide strand made up of in DNA?

A

Alternating deoxyribose sugars and phosphate groups bonded together to form sugar phosphate backbone

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18
Q

Which carbons numbers are used to link one phosphodiester bond to the next?

A

5 carbon to 3 carbon

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19
Q

State 4 difference between RNA and DNA

A

RNA is shorter
RNA contains ribose sugar instead of deoxyribose
RNA is made of 1 polynuclotide strand
RNA is shorter lived

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20
Q

give 3 examples of RNA

A

mRNA
tRNA
rRNA

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21
Q

Ribosomes are formed from…

A

RNA and proteins

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22
Q

Where are ribosomes found?

A

Free in the cytoplasm or attached to Rough endoplasmic rectilium in eukaryotic cells

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23
Q

How does rRNA in the ribosome help form peptide bonds in amino acids?

A

It has enzymic properties which helps catalyse formation

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24
Q

Who is the scientist credited with the discovery of DNA

A

Friedrich Miescher

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25
Q

Why did scientific researchers doubt the DNA molecule could carry the genetic code?

A

The simple chemical composition of DNA was only made up of repeating nucleotides and only composed of 3 parts.

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26
Q

Which scientists helped conclude the double helix structure of DNA?

A

Watson & Crick
Rosalind Franklin

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27
Q

By what process is DNA copied before it divides?

A

Semi-Conservative Replication

28
Q

What is the importance in retaining one DNA strand?

A

It ensure genetic continuity in generations
Genes are inherited from their parent cells
Body cells replaced and we need new one sto do the same job as the old ones

29
Q

what does the enzyme DNA helicase do in DNA replication?

A

It unwind DNA’s double helix by breaking hydrogen bonds between base pairs on two anti parallel polynucleotide DNA strands

30
Q

In the nucleus there are free nuclotides. What are the two names for these?

A

Nucleoside Triphosphate
or
Activated Nucleotides

31
Q

What is the only direction DNA polymerase can build strands?

A

5’ to 3’ direction

32
Q

How does DNA polymerase synthesis new DNA strands?

A

It combines DNA strands by catalysing condenstaion reactions between deoxyribose sugar and phosphate base to form sugar phosphate backbone of new DNA strand. It then breaks off the two extra phosphates and uses it as energy to create the phosphodiester bonds. Then hydrogen bonds form between complimentary base pairing.

33
Q

How is DNA replicated?

A

Through a process called semi conservative replication. The enzyme DNA helicase breaks hydrogen bonds between polynucleotide DNA strands causing it to unwind into single strands. Each strand acts as a template for new strands. Free floating nucleotide are attrracted to exposed complimentary bases. Condensation reactions catalysed by DNA polymerase join nucleotuides together. Hydrogen bonds form between each new strand. The DNA molecule consists of 1 new strand and 1 origional strand.

34
Q

Describe meselon and Stahls expiremnt and what it showed.

A

They had two isotopes of nitrogen broth, 15N heavy and 14N light. Two samples of bacteria were grown in the broth and nitrogen was took up from each broth by bacteria for new DNA. DNA samples were taken from each broth and put in a centrifuge. The light DNA settled at the top of the tube and the heavy settled lower down. Then the sample of DNA was put in light broth for another round of DNA replication. When it was put in the centrifuge, the DNA settled between where the light and heavy strand did showing that DNA did replicate semi-conservatively as it had its origional strand and a new light strand.

35
Q

What does ATP stand for?

A

Adeenosine triphosphate

36
Q

What makes water a good solevent?

A

Water is polar so it attracts both positive and negative ions so that they can be surrounded by water and dissolved.

37
Q

Draw a molecule of ATP

A
38
Q

What is an ATP molecule made of?

A

A ribose sugar
3 phosphate groups
Nuclotide base adenine

39
Q

How is energy in ATP stored?

A

In high energy bonds between phosphate groups.

40
Q

How is energy from ATP released?

A

ATP is broken down into ADP through a hydrolyisiks reaction catalysed by the enzyme ATP hydrolyse. When a phosphate bond is broken, energy is released.

41
Q

How can ATP be resynthesised?

A

The reaction between ADP and the inorganic phosphate (Pi) that occurs during repiration or photosynthesis. It is catalysed by the enzyme ATP synthase.

42
Q

What does it mean that ATP can be coupled to other energy requiring reactions in a cell?

A

Energy is released drectly to make reactions happen rather than be lost as heat.

43
Q

What is the inorganic phosphate released during hydrolysis of ATP used for?

A

To phosphorlyate other compounds making them more reactive

44
Q

What are the charges on a water moleule?

A

Oxygen is lightly negative and bith hydrogens are slightly positive making it a polar molecule.

45
Q

Define metabolite

A

Substance involved in a metabolic reaction

46
Q

What are ions?

A

An atom or group of atoms that have an electric charge.

47
Q

What is a metabolic reaction?

A

A chemical reaction that happens in living organisms to keep it alive.

48
Q

In the exam how do you draw hydrogen bonds between wtaer molecules?

A

As dashed lines from hydrogen to oxygen.

49
Q

What is cohesion?

A

Attraction between molecules of the same type.

50
Q

Name 2 reactions water is involved in

A

Condensation reactions
Hydrolysis

51
Q

Why is water being resistant to changes in temperature imporatnt for living organisms?

A

It means organisms can mantain a stable internal temperature and so that sea creatures have a good living temeperature in the water.

52
Q

Why is cohesion in water molecules important in plants?

A

Cohesion helps water flow and so water can efficiently travel up the xylem.

53
Q

Water has a high latent heat of vaporisation, what does this mean?

A

When water vaporises its hydrogen bonds have to be broke however, it takes a significant amount of energy to break hydrogen bonds meaning a lot of heat is required to change water from liquid to gas.

54
Q

What is a metabolic reaction?

A

A chemical reaction that happens in living organism to keep it alive.

55
Q

What is the name of an ion with a positive charge?

A

cation

56
Q

What is the name of an ion with a negative charge?

A

Anion

57
Q

What is an inorganic ion?

A

One that does not contain carbon.

58
Q

How is the role of an ion determined?

A

Whether it is found in high or low concentrations.

59
Q

Give 2 examples of ions in the body

A

Iron ions in haemoglobin
Phosphate ions in DNA & RNA
Hydrogen ions control pH of blood

60
Q

What is the role of iron in haemaglobin?

A

Fe2+ binds to the oxygen in haemoglobin and is Fe3+ until oxygen is released.

61
Q

What is the ion linked to pH?

A

H+

62
Q

What ion is involved in moving glucose and amino acids across cell membranes and what is this process called?

A

Sodium ions
Co- Transport

63
Q

Suggest how the structure of DNA relates to its functions

A

Two strands- so 1 acts as template for semi conservative replication
Hydrigen bonds between bases are weak- easily seperated for replication
Long molecule- Store lots of genetic information
Double helix -Compact
Complemenatry base pairing- Accurate replication
Many hydrogen bonds between bases- Stable molecule

64
Q

Why is semi conservative replication important?

A

Ensures genetic continuity between generations of cells

65
Q

Describe the process of semi conservative DNA replication

A

DNA helicase breaks hydrogen bonds between complementary bases unwinding the double helix
Both strands act as templates
Free DNA nucleotides attracted to exposed bases join by specific complemetary base pairing
Hydrogen bonds for between adenin- thymine & guanine-cytosine
DNA polymerase joins adjacent nucleotides on new strand by condenation reaction form phosphodiester bonds

66
Q

Use your knowledge of enzyme action to suggest why DNA polymerase moves in opposite directions along DNA strands

A

-DNA has antiparallel strands
-Shapes/arrangement of nucleotides on two ends are different
-DNA polymerase is an enzyme with a specific shaped active site
- So can only bind to substrate with complentary shape

67
Q

Why did many scientists intially doubt that DNA carried the gentic code

A

Due to the relative simplicity of DNA

Biology (11 decks)

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