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A-Level Biology > 3 - DNA and Protein Synthesis > Flashcards

3 - DNA and Protein Synthesis Flashcards

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1
Q

Define virulent

A

Disease / has harmful effects

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2
Q

Who did the first experiment for DNA evidence?

A

Griffiths

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3
Q

Who did the second experiment for DNA evidence?

A

Avery, Macleod, McCarthy

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4
Q

Who did the third experiment for DNA evidence?

A

Hershey and Chase

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5
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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6
Q

What does DNA consists of?

A 
Phosphate group
Nitrogenous base (ATCG)
Deoxyribose sugar (5 carbon)
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7
Q

What did Chargaff et al discover?

A

Number of A = number of T

Same with C and G

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8
Q

Name the two types of bases

A

Purine and pyrimidine

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9
Q

Name the 2 purines

A

A and G

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10
Q

Name the 2 pyrimidines

A

T and C (both contain y)

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11
Q

Number of rings in purines

A

2

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12
Q

Number of rings in pyrimidines

A

1 ( 1 y 1 ring)

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13
Q

What does ATCG stand for

A

Adenine
Thymine
Guanine
Cytosine

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14
Q

What bond connects the bases

A

Hydrogen bonds

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15
Q

How many bonds connects the bases A and T

A

2

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16
Q

How many bonds connects the bases C and G

A

3 (George Clooney is 3 stars)

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17
Q

Describe a nucleotide

A

Phosphate , base , deoxyribose

             |
   O    /\ |
     |  /    \
        \ _ /
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18
Q

Which 2 directions do the nucleotides go?

A

Carbon 5-3 and Carbon 3-5

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19
Q

Which is bigger : purine or pyramidine

A

Purine as 3 hydrogen bonds

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20
Q

In which direction are the pentagons upside down?

3-5 or 5-3

A

Carbon 3-5

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21
Q

5 differences between DNA and RNA

A

Sugar Deoxyribose Ribose
Bases Thymine Uracil (pyrimidine)
Stands Double + base pairing Single
Helix Yes No
Length Big Smaller – no introns

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22
Q

Who did the DNA replication experiment?

A

Meselson and Stahl

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23
Q

What type of replication is DNA repiication?

A

Semi-conservative - half of original is bonded to new stands

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24
Q

Draw semi-conservative replication

A

11 II
1I I1
1I II II I1

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25
Q

Name the 3 types of rna

A

Messenger RNA
Ribosomal RNA
Transfer RNA

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26
Q

Describe rRNA (synthesises, found, shape, function)

A

Synthesised - nucleolus
Found - ribosomes (RER)
Shape - Globular
Function -Protein synthesis

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27
Q

Describe tRNA (synthesises, found, shape, function)

A

Synthesised - nucleolus
Found - cytoplasm
Shape - clover
Function -transfer AA

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28
Q

Describe mRNA (synthesises, found, shape, function)

A

Synthesised - nucleolus
Found - nucleus
Shape - single stranded
Function -DNA -> ribosome

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29
Q

What comes first: translation or transcription

A

Transcription - need to write script before you can translate it

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30
Q

Describe transcription (7)

A
  1. DNA helix unwinds to expose bases on template strand
  2. Template = 1 chain of DNA
  3. Catalysed by DNA helicase
  4. Break hydrogen bonds
  5. Free mRNA nucleotides oppose complementary bases
  6. RNA polymerase bonds them and copies them
  7. Leave through nuclear pores
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31
Q

What is splicing?

A

Removal of introns

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32
Q

What are introns?

A

Non-coding DNA

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33
Q

What are extrons?

A

Sequence containing coding DNA

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34
Q

Which strand is which? (sense)

A C T G

A

mRNA stand is anti-sense

Other one is sense strand

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35
Q

Summarise transcription

A

DNA to MRNA

36
Q

Summarise translation

A

MRNA to Proteins

37
Q

ATT CCG GGC
I
V
??????????????????

A

UAA GGC CCG

Codon 1 Codon 2 Codon 3

38
Q

Define codon

A

Sequence of three nucleotides which form a unit of genetic code in a DNA or RNA molecule.

39
Q

Name 3 characteristic of DNA

A

Universal coder
Non-overlapping
Degenerate

40
Q

How is DNA the universal coder?

A

The same 3 bases codes for the same protein in all organisms

41
Q

How is DNA non-overlapping?

A

Each base is only part of 1 triplet

42
Q

How is DNA degenerate?

A

An amino acid is coded for by more than one triplet of bases

43
Q

Processes in translation (7)

A
  1. Modified mRNA leaves nucleus and attaches to ribosome
  2. Ribosomes attaches to start codon
  3. tRNA molecule with complementary anticodon (to start codon) aligns opposite mRNA
  4. Ribosome moves along mRNA so others can attach
  5. Two delivered AA join by peptide bond
  6. Continue until reach stop codon
  7. Chain enters Golgi body
44
Q

Define anticodon

A

Found on tRNA and sequence of nucleotides

45
Q

Why does mitosis happen?

A

Cell growth and repair

46
Q

Name the 6 stages of mitosis

A 
Interphase
Prophase
Metaphase
Anaphase
Telophase and cytokinesis
47
Q

Describe interphase

A

Chromosomes are thread like and cant be seen individually. DNA replicates
.
. .
. .
. .
. ~~~~~~~ .
. ~~~~~~~~~ .
. ~~~~~~~ .
. .
. .
. .
.

48
Q

Describe prophase

A

DNA condenses into discrete sister chromatins held together at the centromere.
The nuclear envelope breaks down and spindles form at opposite poles.
.
. .
. .
. .
. X X .
. ⃝ X X ⃝ .
. = = .
. .
. .
. .
.

49
Q

Where are spindles formed and at what stage?

A

Centrioles - prophase

50
Q

Describe the metaphase

A

Sister chromatids are aligned at the equator
.
. .
. .
. ———— X———- .
. ⃝ ———– X ————— ⃝ .
. □ ———— X ———- □ .
. ———— X——— .
. .
. .
. .
.

51
Q

Describe the anaphase

A

Spindle fibres contract and chromatids are separated. Chromosomes are pulled to opposite poles
.
. .
. .
. —-( (—— .
. ⃝ ————( (——- O .
. □———( (———– □ .
. ——( (———- .
. .
. .
. .
.

52
Q

Describe the telophase

A

Chromosomes are condoned off into distinct new nuclei in emerging daughter cells.
.
. .
. .
. . . .
. . . . .
. . II II . . II II . .
. . . . . .
. . . . . .
. .
. .
.

53
Q

Describe cytokinesis

A

The cytoplasm splits
.
. .
. .
. .
. ~~~~~~~ .
. ~~~~~~~~~ . X2
. ~~~~~~~ .
. .
. .
. .
.

54
Q

In mitosis, which two stages happen at the same time

A

Telophase and cytokinesis

55
Q

What are the centrioles?

A

O I=I

56
Q

What is the centromere

A

Where the spindle fibres attach to the chromosome

57
Q

What are a pair of chromosomes called?

X X

A

Homologous chromosomes

58
Q

What are the ends of the chromosomes called?

X ____here

A

Sister chromatids

59
Q

Describe the process of DNA replication (9)

A
  1. DNA helicase breaks hydrogen bonds to form a replication fork
  2. Primase makes a primer
  3. DNA polymerase binds primer to make a new strand by moving along exposed bases
  4. DNA polymerase makes Okazaki fragments
  5. Primase makes a primer and DNA polymerase adds DNA in 5-3 direction
  6. Primer is added further down the strand then adds Okazaki fragments
  7. Exonuclease removes primers then DNA polymerase fills gaps with DNA
  8. DNA ligase seals strands to form a continuous strand
  9. Semi - conservative replication
60
Q

What does DNA helicase do in DNA replication?

A

Breaks hydrogen bonds between the strands

61
Q

What does primase do in DNA replication?

A

Makes primers

62
Q

What is a primer in DNA replication?

A

Small piece on RNA

63
Q

What does DNA polymerase do in DNA replication?

A

Binds the primer to synthesise a new strand and make Okazaki fragments

64
Q

What does DNA ligase do in DNA replication?

A

Seal the strands

65
Q

What does exonuclease do in DNA replication?

A

Remove the primer

66
Q

Name the phases of meiosis in order

A 
I1
P 1
M 1
A 1
T  1
P 2
M 2
A 2
T 2
67
Q

What does meiosis produce?

A

4 daughter cells that AREN’T genetically identical

68
Q

Define bivalent

A

The homologous chromosomes join

69
Q

Equation for mitotic index

A

of cells in mitosis / total # of cells

70
Q

Give 4 differences between mitosis and meiosis

A

Mitosis - Meiosis

  • 2 daughter cells - 4 daughter cells
  • Genetically identical - Not genetically identical
  • Happens everywhere - Reproductive organs
  • Diploid (23 pairs) -Haploid (23 total)
71
Q

Name the 4 stages of the cell cycle

A

G1 - Growth 1 - new organelles / proteins made
S - DNA replication
G2 - Growth 2 - cytoplasm expands
M - Mitosis

72
Q

Name two types of cancer

A

Benign

Malignant

73
Q

Give 5 characteristics of benign cancer

A
  • Grow slowly
  • Well defined capsule
  • Not invasive
  • Low mitotic index
  • Doesn’t metastasise
74
Q

Give 5 characteristics of malignant cancer

A
  • Grow rapidly
  • Not encapsulate
  • Invasive
  • High mitotic index
  • Metastasises (spread distantly)
75
Q

Name 3 types of cancer treatment

A

Inhibit spindle fibre formation
Inhibit required enzymes
Competitive inhibition of nucleotides

76
Q

Describe how MRNA is made

A

Helicase;

  1. Breaks hydrogen bonds;
  2. Only one DNA strand acts as template;
  3. RNA nucleotides attracted to exposed bases;
  4. (Attraction) according to base pairing rule;
  5. RNA polymerase joins (RNA) nucleotides together;
  6. Pre-mRNA spliced to remove introns;
77
Q

Describe the structure of proteins

A

Polymer of amino acids;
2. Joined by peptide bonds;
3. Formed by condensation;
4. Primary structure is order of amino acids;
5. Secondary structure is folding of polypeptide chain due to hydrogen
bonding;
Accept alpha helix / pleated sheet

  1. Tertiary structure is 3-D folding due to hydrogen bonding and ionic /
    disulfide bonds;
  2. Quaternary structure is two or more polypeptide chains;
78
Q

Why does DNA polymerase move in different directions on different strands (4)

A
  1. DNA has antiparallel strands
  2. Shape of the nucleotides is different / nucleotides aligned differently
  3. Enzymes have active sites with specific shape
  4. Only substrates with complementary shape / only the 3’ end can bind with active site of enzyme / active site of DNA polymerase
79
Q

Explain why the replication of DNA is described as semi-conservative. (2)

A

Two copies of the original strand are made, but each strand contains half of the original strand.

80
Q

Why is N15 further down the test tube than N14?

A

N15 is more dense.

81
Q

Describe the role of tRNA in the process of translation.

5

A

1 - tRNA attaches to an AA on one end and has an anticodon on the other
2 - Transferred to a ribosome on a mRNA molecule
3 - Anticodon pairs with complementary codon sequence on mRNA
4 - More tRNA molecules line up along mRNA
5 - AA bond through a peptide bond

82
Q

What would happen to a protein if there was a mutation in an intron?

A

Nothing - introns are removed by splicing so a protein isn’t made.

83
Q

Describe and explain the appearance of one of the chromosomes in cell X. (3)

XX

A

There is a homologous chromosome, which is made from two chromatids. They are held together by the centromere. This has happened because DNA replication has occurred.

84
Q

Identify one event that occurred during division 2 but not during division 1

A

Separation of (sister) chromatids / division of centromere

85
Q

Name two ways in which meiosis produces genetic variation.

A

1 Independent segregation

2 Crossing of the chromatids

A-Level Biology (7 decks)

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