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Y3 and Y4 IP Biology > Chapter 16: Molecular Genetics > Flashcards

Chapter 16: Molecular Genetics Flashcards

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1
Q

What is DNA?

A

A molecule that carried genetic information

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2
Q

What is DNA made up of?

A

Nucleotides

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3
Q

What are nucleotides made of?

A

1) A deoxyribose molecule (sugar)
2) A phosphate group
3) A nitrogen-containing base

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4
Q

What are the four types of nitrogen bases?

A

Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

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5
Q

How does the numbering system work in the nucleotide?

A

The 1’ carbon is bonded to the nitrogen base, the 3’ carbon is bonded to the OH group, and the 5’ carbon is bonded to the phosphate group. The numbers always follow the cloclwise direction.

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6
Q

How are the nucleotides bonded together?

A

The 5’ carbon of the most bottom nucleotide bonds to the phosphate group, which bonds to the 3’ carbon of another nucleotide. The 5’ carbon from that nucleotide then bonds to another phosphate group.

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7
Q

What are the directions of the anti-parallel nucleotide strands, and how can their directions be observed?

A

The complementary strand runs in the opposite direction of the nucleotide strand. From bottom to top, the nucleotide strand runs in the 3’ to 5’ direction, while the complementary strand runs in the 5’ to 3’ direction

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8
Q

What nitrogen bases pair together?

A

Adenine (A) and Thymine (T); 2 bonds, Cytosine (C) and Guanine (G); 3 bonds

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9
Q

What are the bonds between nitrogen base pairs?

A

Hydrogen bonds

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10
Q

What structure do the two anti-parallel strands form?

A

A double helix structure

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11
Q

What is a gene?

A

A segment of DNA

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12
Q

What determines the polypeptides formed in a gene?

A

The nucleotide sequence

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13
Q

What does a codon do?

A

Codes for one amino acid

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14
Q

What are codons made of?

A

Three nucleotides (consecutive base sequences)

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15
Q

What is a gene mutation?

A

A change in the nucleotide sequence of a gene

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16
Q

What can gene mutation cause?

A

May lead to a change in the protein product of a gene, whch may lead to an observable phenotype

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17
Q

What were the three types of DNA replication models (including the two incorrect replication models), and what do they predict?

A

Conservative: The two parent strands rejoin after duplication, to form one new and one old strand
Semiconservative: Each daughter strand contains one old strand belonging to the parent, and one new duplicated strand
Dispersive: Each strand is a mix of old and new strands

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18
Q

Which DNA replication model is accurate?

A

Semiconservative

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19
Q

How does base pairing aid in DNA replication?

A

Serves as a template for a new strand

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20
Q

How is DNA replication coordinated?

A

Via a large team of enzymes

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21
Q

What are the steps in DNA replication?

A

1) DNA replication starts at the origin of replication
2) DNA replication expands sideways
3) Continues until the replication bubbles come into contact with one another, in which case DNA replication is complete

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22
Q

What does topoisomerases do?

A

Unwind DNA to reduce torsional stress in DNA molecule during DNA replication

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23
Q

What does helicase do?

A

Seperates double strand DNA into single strands (breaks the hydrogen bonds linking nitrogen base pairings using ATP)

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24
Q

What does single strand binding proteins (SSBP) do?

A

Prevents the single stranded DNA to anneal (join) back together into double stranded DNA

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25
Q

What does RNA primase do?

A

Makes a short RNA primer, which is the building block for DNA replication

26
Q

What does DNA polymerase do?

A

Polymerises free deoxyribonucleotides (a nucleotide that contains deoxyribose) into a newly synthesised DNA strand (5’ to 3’) by reading a single strand of DNA (3’ to 5’) as a template. It also replaces RNA primer with DNA

27
Q

What does ligase do?

A

Joins DNA fragments together

28
Q

What are the 3 types of RNA?

A

Messanger RNA (mRNA)
Ribosomal RNA (rRNA)
Transfer RNA (tRNA)
Acronym: MRT

29
Q

What are mRNA used for?

A

Transcription and translation from genes to proteins

30
Q

What are rRNA?

A

Components of ribosomes in translation of mRNA

31
Q

What does tRNA do?

A

Attatches to amino acids and is used in translation of mRNA

32
Q

What does the DNA genotype do?

A

Determines traits (phenotypes) through expression of genes and protein synthesis

33
Q

What is transcription?

A

The synthesis of RNA under the direction of DNA in the nucleus

34
Q

What is translation?

A

The synthesis of proteins under the direction of RNA in the cytoplasm

35
Q

What is the source and product of information translatation?

A

Information in codons is translated into amino acids

36
Q

What is some information about genetic code?

A
  • Nearly universal (common to almost all organisms on Earth)
  • Amino acids may be coded by more than one codon, but each codon only codes for one amino acid
  • Without punctuation and is uninterrupted
37
Q

How is RNA molecules transcribed from DNA templates?

A

By a process similar to DNA replication

38
Q

What does RNA polymerase do?

A

Carries out transcription (Like DNA replication but for RNA)

39
Q

What is the DNA template also known as?

A

Antisense DNA

40
Q

How is the starting and ending of transcription marked?

A

By specific sequences of nucleotides

41
Q

What nucleotide sequence indicates the start of transcribing?

A

Promoter

42
Q

What are the 3 stages of transcription?

A

1) Initiation
2) Elongation
3) Termination

43
Q

What happens at initiation during transcription?

A

RNA polymerase attatches to promoter

44
Q

What happens at elongation during transcription?

A

RNA nucleotides form the mRNA strand

45
Q

What happens at termination during transcription?

A

Enzymes reach the ending sequence and detatch from the DNA template (antisense DNA)

46
Q

Where does the detatched mRNA move to?

A

The cytoplasm out of the nuclear pores

47
Q

What does translating of DNA mean?

A

Converts DNA code (in codons) into protein code (amino acids sequence)

48
Q

How are tRNAs differentiated?

A

By a special 3 nucleotide sequence on the tRNA called the anticodon. Anticodons are complimentary to the codons on mRNA that the amino acid is associated with

49
Q

What are the 2 stages of translation?

A

1) Initiation
2) Elongation

50
Q

What happens at initiation in translation?

A

The mRNA binds to the ribosomes, and the start signal codon binds with tRNA which holds the anticodon UAC

51
Q

What happens at elongation in translation?

A

tRNA with the complimentary anticodon to the codon on the mRNA binds within the ribosomes. A new amino acid is joined to the already existing chain with a peptide bond, and the tRNA of the previous codon (with a different anticodon) is released from the ribosomes. Ribosomes (with current tRNA still attatched) move on to the next codon

52
Q

What are some differences between DNA and RNA?

A

Sugar unit: deoxyribose vs ribose
Nitrogen-containing bases: thymine (T) vs uracil (U)
Ratio of nitrogen-containing bases: 1:1 vs no fixed ratio
Molecule type: large and insoluble vs small and soluble
Lifespan: permenant molecule in the nucleus vs temporary molecule which is made when needed

53
Q

What is a gene vector?

A

A DNA molecule that is used as a vehicle to artificially carry foreign genetic material into another cell

54
Q

What is a plasmid?

A

A small circular DNA obtained from bacteria that can be used to transfer genes (a type of vector)

55
Q

What is recombinant DNA?

A

A vector containing foreign DNA

56
Q

What is a transgenic organism?

A

An organism whose genetic material has been altered

57
Q

What is the 4-step process in genetic modification?

A

1) Human chromosome containing the insulin gene is obtained
2) A plasmid from the bacteria is obtained
3) The plasmid is mixed with the DNA fragment
4) The bacterium takes up the plasmid

58
Q

How is the human chromosome containing insulin and the plasmid from the bacteria obtained?

A

Both ends of the insulin gene / plasmid is cut from the human chromosome / bacteria using a restriction enzyme. This enzyme produces sticky ends at the ends of the gene, which can pair with complementary bases to form a double strand

59
Q

How does bacteria take up the plasmid?

A

Via heat or electric shock, which opens up the pores on the cell surface membrane

59
Q

How is the plasmid mixed with the DNA gene?

A

DNA ligase is added to join the insulin gene to the plasmid

Y3 and Y4 IP Biology (20 decks)

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