Pack 5 - DNA, ATP, Mitosis Flashcards

1
Q

What are the three components of an individual nucleotide?

A
  • A pentose sugar
  • A phosphate group
  • A nitrogen containing organic base.
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2
Q

Which 4 bases does DNA contain?

A
  • Adenine
  • Thymine
  • Guanine
  • Cytosine
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3
Q

Which 4 bases does RNA contain?

A
  • Adenine
  • Uracil
  • Guanine
  • Cytosine
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4
Q

What type of reaction joins a pentose sugar to a phosphate group and an organic base in a nucleotide?

A

Condensation reaction.

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5
Q

What is the monomer of DNA and RNA?

A

Nucleotide

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6
Q

What type of REACTION joins two mono nucleotides and what BOND is formed?

What is the name of the PRODUCT?

A
  • Condensation
  • Phosphodiester Bond
  • Dinucleotide
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7
Q

What is the name for a long chain of nucleotides?

A

Polynucleotide

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8
Q

What sugar is found in RNA?

A

Ribose

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9
Q

What sugar is found in DNA?

A

Deoxyribose

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10
Q

Briefly describe three roles of RNA.

A
  • Ribosomes are made of rRNA
  • mRNA transfers genetic information from DNA to the ribosomes.
  • tRNA is involved in protein synthesis
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11
Q

What type of bonds form between complementary bases on opposite strands of DNA.

A

Hydrogen bonds.

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12
Q

How many strands does DNA have?

A

2

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13
Q

How many strands does RNA have?

A

1

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14
Q

Which base pairs with Adenine in DNA?

A

Thymine

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15
Q

Which base pairs with Thymine in DNA?

A

Adenine

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16
Q

Which base pairs with Cytosine in DNA?

A

Guanine

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17
Q

Which base pairs with Guanine in DNA?

A

Cytosine

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18
Q

If a molecule of DNA contains 20% Adenine, what is the percentage of Cytosine in this molecule?

A

30%

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19
Q

What word is used to describe the direction in which each strand of DNA runs?

A

Antiparallel - one strand runs in one direction the other is ‘upside down’ running in the other direction.

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20
Q

Give two ways that DNA is a chemically stable molecule.

A
  • Phosphodiester backbone protects the more chemically reactive bases.
  • H-bonds link base pairs. As there are 3 h-bonds between C and G , the higher the proportion of C-G pairings, the more stable the molecule of DNA.
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21
Q

What is the function of DNA?

A

It is responsible for storing and passing on genetic information about an organism from cell to cell and generation to generation.

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22
Q

Give 5 ways in which DNA is adapted to carry out its function.

A
  • Stable - information does not change/rarely mutates.
  • Two strands joined by h-bonds - allows them to separate during DNA replication and protein synthesis.
  • Large - carries a large amount of genetic information.
  • Base pairs within helical cylinder - protects genetic information from outside chemical and physical forces.
  • Base pairing - DNA can be replicated and transfer information as mRNA.
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23
Q

Describe the steps (5) of the semi-conservative replication of DNA.

A
  • DNA helices breaks the hydrogen bonds between base pairs.
  • The double helix separates into two strands and unwinds.
  • Each exposed polynucleotide acts as a template to which free nucleotides bind to their respective complementary base pair, forming hydrogen bonds.
  • DNA polymerase forms phosphodiester bonds between adjacent nucleotides, forming a polynucleotide.
  • Each new molecule contains one strand from the original molecule.
24
Q

Describe the Meselsohn Stahl experiment on bacteria.

A
  • ¹⁵N ¹⁴N
  • Bacteria grown in medium ¹⁴N as a control collected at the top of the centrifuge tube.
  • Bacteria grown in medium ¹⁵N collected at the bottom of the centrifuge tube.
  • They then placed the ¹⁵N bacteria into a ¹⁴N medium for one generation.
  • Its DNA was in the middle of the centrifuge tube as it had 1 strand of light and one strand of heavy.
  • After two generations 50% was a mixture of the isotopes DNA and and 50% was lights.
  • This is because the light strands of the mixed DNA formed new DNA with a light strand and so did the light side>
25
Q

What are the three components of ATP and what does ATP stand for?

A
  • Adenine, ribose, 3 phosphate groups

* Adenosine triphosphate.

26
Q

What is useful about the bonds between phosphate groups in ATP? (3 points)

A
  • Unstable
  • ⇒ Low activation energy
  • Considerable amount of energy released when broken.
27
Q

State the word equation of the hydrolysis of ATP.

A

ATP + H₂O → ADP + Pᵢ + Energy

28
Q

What enzyme catalyses the hydrolysis of ATP?

A

ATP Hydrolase (ATPase)

29
Q

What enzyme catalyses the synthesis of ATP?

A

ATP synthase

30
Q

What is the equation of the synthesis of ATP?

A

ADP + Pᵢ + Energy → ATP + H₂O

31
Q

What type of reaction is the synthesis of ATP?

A

Condensation reaction

32
Q

In what three ways is ATP synthesised from ADP?

A
  • in chlorophyll-containing plant cells during PHOTOSYNTHESIS.
  • during RESPIRATION.
  • in plant and animal cells when phosphate groups are transferred from donor molecules to ADP
33
Q

Why is ATP a bad long term energy source ?

A

Unstable bonds between phosphate groups.

34
Q

What kind of energy source is ATP?

A

Intermediate energy source.

35
Q

Why is ATP a better intermediate energy source than glucose?

A
  • Hydrolysis of ATP releases less energy. Energy for reactions is released in smaller more manageable quantities.
  • Hydrolysis of ATP to ADP is a single reaction. Breakdown of glucose is a series of reactions.
36
Q

Why does ATP have to be continuously made?

A

It cannot be stored in the cell.

37
Q

Where is ATP made continuously in metabolically active cells?

A

Mitochondria

38
Q

Name 5 processes where ATP is used?

A
  • Metabolic processes - provides energy needed to build macro-molecules, e.g. starch.
  • Movement - ATP provides energy for muscle contraction.
  • Active transport - ATP provides energy to change the shape of carrier proteins.
  • Secretion - ATP is used to form lysosomes necessary for secretion.
  • Activation of molecules - phosphate released can be used to phosphorylate other compounds, thus lowering the activation energy in enzyme-catalysed reactions.
39
Q

In what phase of the cell cycle does DNA divide?

A

S phase of interphase.

40
Q

What connects the two strands of identical DNA after it replicates?

A

Centromere

41
Q

Name the 4 stages of mitosis in order and the following process.

A
  • Prophase
  • Metaphase
  • Anapahse
  • Telophase
  • Cytokinesis
42
Q

Describe the stages of prophase. (5 steps)

A
  • Chromosomes become visible and shorten and fatten.
  • Centrioles move to poles of the cell.
  • Spindle fibres develop (from centrioles)
  • Nucleolus disappears; nuclear envelope breaks down.
  • Spindle fibres draw chromosomes towards the equator. Attached at the centromere.
43
Q

What is a centriole?

A

Cylindrical organelles found in animal cells from which spindle fibres develop.

44
Q

What are spindle fibres collective known as?

A

Spindle apparatus

45
Q

Describe the stages of metaphase. (3 steps)

A
  • Chromosomes are seen to be made of two sister chromatids connected at the centromere (each chromatid is identical copy of each other).
  • Microtubules attach to the centromere.
  • Chromosomes are pulled along the spindle apparatus and line up at the equator.
46
Q

Describe the stages of Anaphase. (3 steps)

A
  • Centromeres divide into two.
  • Spindle fibres pull individual chromatids apart towards the poles.
  • Mitochondria provide energy for the process by gathering around the spindle fibres.
47
Q

Describe the stages of Telophase. (4 steps)

A
  • Chromosomes reach their poles.
  • Chromosomes become longer and thinner and eventually visibly disappear.
  • Spindle fibres disintegrate.
  • Nuclear envelope and nucleolus reform.
48
Q

What is cytokinesis.

A

Following telophase, the cytoplasm divides forming two separate cells.

49
Q

What is the name of the process by which prokaryotic cells divide?

A

Binary fission

50
Q

Describe in 5 steps binary fission.

A
  • Circular DNA replicates.
  • Both copies attach to the cell membrane.
  • Plasmids replicate
  • Cell membrane grows between the two molecules (dividing the cytoplasm in two).
  • Cell wall forms between the two copies of DNA forming two daughter cells.
51
Q

Describe how viruses replicate (4 steps).

A
  • Virus attaches to host cell with attachment proteins on the surface of the cell.
  • They inject their nucleic acid into the host cell.
  • The host cells resources use the viruses genetic information to produce viral components. (e.g. nucleic acids and enzymes)
  • These are assembled into new viruses.
52
Q

If 10 out of 100 cells in view are undergoing metaphase, what proportion of the cell cycle is taken up by metaphase?

A

10%

53
Q

Give 3 uses of mitosis.

A
  • Growth
  • Repair
  • Asexual reproduction
54
Q

What are the three stages of the cell cycle?

A
  • Interphase
  • Nuclear division
  • Cytokinesis
55
Q

What causes uncontrolled cell division?

A

Mutation of genes that control cell division.