Storing and Using Genetic Information Flashcards

1
Q

What is a phenotype?

A

Physical manifestation of genotype

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2
Q

What is a genotype?

A

All of the genes in our DNA, even the ones that are not expressed

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3
Q

Why are proteins functionally different?

A

Due to their different structures

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4
Q

What does the structure of a protein depend on?

A

The primary structure (sequence of amino acids)

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5
Q

What is DNA?

A

A chain of nucleotide monomers that contains all of our genetic information

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6
Q

What does each nucleotide contain?

A

Sugar

Base

Phosphate group

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7
Q

What structure does DNA form?

A

Double helix

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8
Q

How many bases is there per turn of the helix?

A

10

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9
Q

How do polypeptide chains of DNA run to each other?

A

Antiparralel to one another

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10
Q

How are the groves in DNA described?

A

Major and minor groves which is important for the interaction of proteins

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11
Q

What is the pairing of bases called?

A

Compliment base pairing

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12
Q

What bases pair with what in DNA?

A

Thymine paires with adenine

Guanine pairs with cytosine

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13
Q

What does compliment base pairing happen?

A

Due to the structures of the bases:

Thymine pairs with ademine due to both forming 2 hydrogen bonds

Guanine pairs with cytosine due to both forming 3 hydrogen bonds

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14
Q

What bases form 3 hydrogen bonds with each other?

A

Cytosine and guanine

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15
Q

What bases form 2 hydrogen bonds with each other?

A

Thymine and adenine

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16
Q

What is the site of a cells genetic information (DNA)?

A

Nucleus

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17
Q

Where does the first step of protein production take place and what is this?

A

DNA replicaiton which takes place in the nucleus

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18
Q

What does each nucleus contain?

A

A nucleolus which can take up to 25% of its volume and is where transciption and assemble of rRNA takes place

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19
Q

Where does transcription and assemble of rRNA take place?

A

Nucleolus

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20
Q

What is DNA packaged into?

A

Thread like structures called chromosomes

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21
Q

When are chromosomes visible?

A

During cell division

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22
Q

What is a chromosome?

A

Single piece of DNA containing many genes, regulatory elements and other nucleotide sequences

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23
Q

How many chromosomes does a human have?

A

46

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24
Q

What can the structure of chromosomes be described as?

A

Highly ordered to contain vast amounts of DNA

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25
Q

What is the process of packaging chromosomes?

A

1) Chromatin is the double stranded helical structure of DNA
2) DNA is packed with histones to form nucleosomes, with each consiting of 8 histones
3) Binded with H1 histone to form chromatosome
4) Folded up and tightly coiled to produce fibre called chromatid of the chromosome

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26
Q

What is chromatin?

A

Mixture of DNA, proteins and RNA thay packages DNA within the nucleus

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27
Q

What are the 2 forms of chromatin?

A

Heterochromatin (condensed)

Euchromatin (extended)

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28
Q

What must the chromatin do for transcription and replication to occur?

A

Open up to allow enzymes to access the DNA template

29
Q

What are the 2 mechanisms for opening up chromatin to allow replication or transcription to occur?

A

Histones can be enzymatically modified

Histones can be displaced by chromatin remodelling complexes

30
Q

What should be noted about both processes of opening up chromatin?

A

They are reversible

31
Q

What does it mean that DNA replication is semi conservative?

A

Half of each new molecule is old DNA and half is new DNA

32
Q

What does it mean that DNA replication is bi-directional?

A

DNA polymerase is onlty able to add new nucleotides onto the 3’ end of the growing strand (replication occurs in the 5’ to 3’ direction)

33
Q

In what direction does DNA replication occur?

A

In the 5’ to 3’ direction

34
Q

What fragments are formed on the lagging strand and how are they koint together?

A

Okazaki fragments which are joined together by DNA ligase

35
Q

What are the 2 stages of cellular division?

A

Prometaphase

Metaphase

36
Q

When are chromosomes most compacted?

A

During metaphase where the chromatin fibres are folded into multiple loops and coils (1000 times more compact than other stages)

37
Q

What percentage of bases in people are the same?

A

99.9%

38
Q

Roughly how many genes are there in the genome?

A

22000

39
Q

What percentage of the genome codes for proteins?

A

<2%

40
Q

What are exons?

A

Coding region

41
Q

What are introns?

A

Non-coding regions

42
Q

What is a codon?

A

Set of 3 bases

43
Q

What does each codon specify?

A

A particular amino acid

44
Q

How many different codons and amino acids are there (found in proteins)?

A

64 codons

20 amino acids

45
Q

What occurs due to there being 64 codons but only 20 amino acids?

A

Degeneracy

46
Q

What is degeneracy?

A

More than one codon codes for the same amino acid

47
Q

What are codons that code for the same amino acid refered to as?

A

Synonyms which tend to be very similar

48
Q

Where do variations of synonyms tend to occur?

A

The third base

49
Q

What does degeneracy minimise?

A

The effect of genetic mutations as the change is less likely to change which protein is coded

50
Q

What do all polypeptides begin with?

A

Methionine (initiation codon)

51
Q

What is methionine?

A

Initiation codon

52
Q

What often happens to methionine (initaiton codon)?

A

Removed at a later stage

53
Q

What can single point mutations cause?

A

A dysfunctional protein

54
Q

What is an example of a single point mutation causing a dysfunctional protein?

A

Mutated haemoglobin gene causing sickle cell anaemia

55
Q

What is the major role of RNA?

A

To participate in protein synthesis

56
Q

What are the 3 kinds of RNA?

A

Messanger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

57
Q

What is mRNA?

A

Transcribed from DNA and carries genetic information for protein synthesis

58
Q

How can the same gene produce many different proteins?

A

Due to splicing which occurs after the synthesis of mRNA

59
Q

What is alternative splicing?

A

Process where exons of the RNA prdouced by transcription of a gene (primary gene transcript) are reconnected in multiple ways during RNA splicing

60
Q

What is the RNA strand before splicing occurs called?

A

Primary gene transcript

61
Q

What determines the reading frame of the RNA sequence?

A

Initiation codon

62
Q

What is the space between the start and stop codon called?

A

Open reading frame

63
Q

Where does transcription, alternative splicing, protein synthesis and post translational modifications take place?

A

Transcription in the nucleolus

Alternative splicing in the nucleus

Protein synthesis in the ribosome

Post translational modifications in the endoplasmic reticulum

64
Q

What is tRNA?

A

Major role is to translate mRNA sequence into amino acid sequence

65
Q

What are the complimentary 3 bases on tRNA refered to as?

A

Anticodon

66
Q

What is rRNA?

A

Component of ribosomes, are produced in the nucleus and transported to the cytoplasm where they form a ribosome

67
Q

What is a polysome?

A

What is produced when several ribosomes can trasnlate mRNA at one time

68
Q

What base is present in mRNA instead of what?

A

Uracil is present instead of thymine