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BMS109 Introduction to Biomedical Science > Principles of Molecular Biology > Flashcards

Principles of Molecular Biology Flashcards

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Biology 101 flashcards
1
Q

Name 3 major components of the cell.

A

DNA, RNA and proteins.

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2
Q

Name 3 characteristics of the genetic material.

A 
Codes for all necessary information within the organism.
Carefully replicated to pass onto progeny.
Regulated decoding (puberty) to suit development and environment.
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3
Q

How many amino acids exist?

A

21.

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4
Q

Describe the Hershey-Chase experiment 1952.

A

Exploited bacteriophages (virus) nature to infect and replicate in bacteria.
Some viruses with labelled DNA infected to E.coli with phosphate and some viruses with labelled proteins infected to E.coli with sulphate.
Mixed with non radioactive bacteria and radioactivity only detected with labelled DNA viruses.

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5
Q

What is the chemical composition of DNA?

A

Nucleotide monomer made of a pentose sugar, nitrogenous group and phosphate group.

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6
Q

DNA is a _____________ composed of ________.

A

Macromolecule.

Monomers.

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7
Q

What is the difference between ribose and deoxyribose?

A

Ribose has an OH group on carbon 2. Deoxyribose does not.

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8
Q

What carbon is the phosphate group attached to?

A

5.

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9
Q

What carbon is the nitrogenous group attached to?

A

1.

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10
Q

Name the purines.

A

Adenine.

Guanine.

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11
Q

Name the pyrimidines.

A

Cytosine.
Thymine.
Uracil.

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12
Q

Name 2 differences between DNA and RNA.

A

Deoxyribose and Ribose.

Thymine and Uracil.

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13
Q

How do the DNA/RNA nucleotides join together?

A

Carbon 3 of one nucleotide joins with the phosphate (carbon 5) of a second nucleotide. Forms a phosphodiester bond.

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14
Q

Why does the polynucleotide chain have polarity?

A

5’ phosphate end to 3’ hydroxyl end.

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15
Q

Explain the structure of DNA.

A

Double stranded helical structure. Right handed.
Sugar-phosphate backbone at the outside with nitrogenous bases in the middle.
Anti-parallel strands.
Complementary base pairing (A-T G-C).

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16
Q

The molecular _________ of ___ makes..

A

Structure.
DNA.
..the genetic copying process highly reliable.

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17
Q

What is the phrase to describe DNA replication.

A

Semi-conservative.

Each new double helix contains a template parent strand and a template strand.

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18
Q

What enzyme is necessary for DNA synthesis?

A

DNA Polymerase.

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19
Q

Which end can nucleotides be added to in DNA synthesis?

A

Free OH on the 3’ carbon.

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20
Q

What enzyme separates the paired strands of DNA?

A

DNA Helicase.

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21
Q

What direction does DNA synthesis occur in?

A

5’ to 3’ because nucleotides can only be added at the OH of the 3’ carbon end.

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22
Q

What is the leading strand and what is the lagging strand in DNA synthesis?

A 
Leading strand (Continuous) is synthesised in the direction of the DNA fork.
Lagging strand (Discontinuous) is synthesised opposite to this.
This is due to the antiparrallel strands.
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23
Q

What are Okazaki fragments?

A

Short, newly synthesised DNA fragments formed on the lagging strand.

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24
Q

What initiates DNA synthesis?

A

RNA primer sequence with DNA Primase (An RNA polymerase). DNA Polymerase can extend from this.

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25
Q

What are SSBS?

A

Single-stranded Binding Proteins that maintain unwound parental DNA strands to ease replication fork progression.

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26
Q

What does Ribonuclease H do?

A

Removes the RNA primer and DNA Polymerase fills the gap.

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27
Q

What does DNA Ligase do?

A

Covalently links the Okazaki fragments of the lagging strand.

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28
Q

How does a DNA sequence encode biological form and function?

A

DNA encodes heritable instructions for the synthesis of RNAs and proteins to determine cellular properties.
Different genes selectively expressed in different cell types.

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29
Q

What are the two major steps in gene expression?

A

Transcription: mRNA synthesis.
Translation: protein synthesis.

30
Q

How do the DNA sequences exhibit colinearity?

A

There is linear correspondence between the sequence of bases in DNA/RNA and sequence of amino acids in the protein product.

31
Q

How many bonds in complementary base pairing?

A

A - T/A - U have 2 H bonds.

G - C have 3 H bonds.

32
Q

Describe transcription in a typical prokaryotic cell.

A

Initiated by RNA polymerase binding to promoter region upstream of start site.
Transcript elongation by RNA polymerase yields single stranded mRNA. Read 5’ to 3’.
Termination when RNA polymerase encounters terminator region promoting dissociation.

33
Q

What limits the transcription rate in prokaryotic cells?

A

Frequency of transcript initiation.

34
Q

Describe how eukaryotic transcription differs from prokaryotic.

A

Introns are spliced out of the primary mRNA to produce mature mRNA.

35
Q

What DNA synthesis processes occur inside the nucleus and which ones occur in the cytoplasm?

A

Nucleus: Transcription and RNA processing.
Cytoplasm: Translation and Protein modification.

36
Q

What is a genome?

A

An organism’s entire DNA sequence of its chromosomes.
All somatic cells of a multicellular organism contain the same genome.
Different cell types in a multicellular organism express different sets of genes from this.

37
Q

What is a housekeeping gene?

A

Genes expressed in all cell types.

38
Q

Different cell types have different ______________ and _________.

A

Transcriptomes.

Proteomes.

39
Q

How many protein coding genes are in the human genome?

A

~21,000.

40
Q

What is the karyotype of the human genome?

A

23 pairs: 22 different autosomes and X & Y chromosomes.

41
Q

Define haploid and diploid.

A

Haploid: 23 chromosomes (germ cells).
Diploid: 23 pairs of chromosomes (somatic cells).

42
Q

What are the carriers of genes?

A

Chromosomes.

43
Q

What is a centromere?

A

Specialised repetitive DNA sequences where spindle attaches allowing chromosome segregation.

44
Q

What is a replication origin?

A

DNA sequence where DNA replication is initiated. Not at the ends of the molecule.

45
Q

What is a telomere?

A

Specialised DNA sequences at the ends of linear chromosomes which maintain chromosomal integrity.

46
Q

What is a kinetochore?

A

Protein structure in the centromere where microtubules attach during division.

47
Q

Describe DNA replication.

A

Local opening of DNA helix where RNA primers synthesise.
Leading strand DNA synthesis of both forks begins (THIS IS IN THE MIDDLE).
Lagging strand RNA primers start synthesis.

48
Q

What is the job of telomerase?

A

Maintains telomeres (repeat DNA sequences at end of linear chromosomes).

49
Q

Describe the genome of E. coli.

A

4289 protein coding genes in a single circular chromosomal DNA molecule.

50
Q

How to circular bacterial chromosomes replicate?

A

Bidirectional from the replication origin.

51
Q

What is the trend between organisms and genome size?

A

More complex organisms tend to have more genes so tend to have larger genomes.

52
Q

What is the trend between organisms and gene density?

A

Gene density generally declines as the organism becomes more complex.

53
Q

Genomes of more complex organisms have similar exon sizes but..

A

..larger intron sizes.

54
Q

Give an example of human gene size compared with another organism.

A

Human Huntingtin gene is 7.5x larger than the equivalent in the Pufferfish. Human intron is larger than the Pufferfish but exon are the same sizes.

55
Q

How much of the human genome is made up of cellular protein coding DNA sequences?

A

1.5%.

56
Q

Define retrotransposons.

A

RNA that used reverse transcription to DNA then insert into the genome at a target site - the principle behind this is not fully understood.

57
Q

Larger genomes contain more..

A

..repetitive DNA elements.

58
Q

Larger genomes contain more complex..

A

..control elements distributed over larger regions of DNA - promoter and enhancer elements.

59
Q

Who was Joseph Gottlieb Kolreuter?

A

Before Mendel and interested in species/true breeding plant varieties/hybridisation.

60
Q

What experiments did Gregor Mendel do on his premise?

A

Premise: Genes are discrete, physical entities to not give blended characters.
Experiments: Pea plants (hermaphrododitic) to give a reliable breeding programme where characteristics could be easily identified.
First experiment produced identical progeny.
Cross-bred P generation smooth and wrinkled to give all smooth - like one parent.
Cross-bred F`1 smooth and smooth to give mostly smooth and some wrinkled.
Gave the idea of alleles.

61
Q

What is Mendel’s First Law?

A

The principle of segregation.

Two alleles of a gene segregate from each other during gamete formation.

62
Q

What is Mendel’s Second Law?

A

The principle of independent assortment.

Genes controlling different characters assort into gametes independently of one another.

63
Q

What did Mendel’s experiments miss?

A

Many genes have more than 1 allele.
Not all alleles exhibit complete dominance or recessiveness.
Many genes fail to exhibit independent assortment.

64
Q

What is incomplete dominance?

A

Heterozygote phenotype which is intermediate of 2 homozygous phenotypes eg. flower colours.

65
Q

What is co-dominance?

A

Simultaneous expression of 2 phenotypes determined by alternative alleles of a single gene eg. blood group AB.

66
Q

Who was Thomas Morgan?

A

Worked on gene linkage.

67
Q

How can you find and analyse genes to dissect biological mechanisms?

A

1 Exploit natural genetic variation.
2 Create new genetic variation with chemicals/radiation to induce mutations.
3 Engineer defined changes into the genome by removing genes (targeted mutations) or adding new genes (transgenes).

68
Q

Explain gene linkage.

A

Genes that lie on the same chromosome do not tend to assort independently and show linkage.

69
Q

How does recombination affect gene linkage?

A

Can separate genes, during the formation of gametes, so they do show linkage.

70
Q

What is a complementation test?

A

Identifies whether 2 mutations conferring similar phenotypes lie in the same or different pathways.
Can identify components of biochemical pathways and protein complexes.

BMS109 Introduction to Biomedical Science (6 decks)

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