Molecular Genetics

Question 1

Chromosome

Answer 1

Condensed chromatin ready for cell division containing proteins and nucleic acid.

Question 2

Griffith's experiment

Answer 2

mixed the living non-virulent pneumococcus bacteria with a heat inactivated virulent form. He subsequently infected mice with this mixture and the mice developed pneumonia and died. Concluded that R strain inherited a transforming principal from heat-killed s strain and assumed the transforming principal was dna

Question 3

Avery, macleod and McCarthy

Answer 3

showed that DNA (not proteins) can transform the properties of cells. Treated bacteria samples with DNAase RNAase or protease. The DNAase bacteria did not kill the mice.

Question 4

Hershey-chase

Answer 4

showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Grew the bacteriophages either in radioactive sulphur or radioactive phosphate and saw which molecule is present in the bacteria.

Question 5

Chagraff's rule

Answer 5

Amount of adenine (purine) is equal to the amount of thymine (pyrimidine). Amount of guanine (purine) is equal to the amount of cytosine (pyrimidine).
Adenine and thymine form 2 hydrogen bonds. Guanine and cytosine form three hydrogen bonds.

Question 6

Central dogma

Answer 6

Genetic information flows in only one direction. From DNA to RNA to protein to phenotype.

Question 7

Beadle and Tatum's experiment

Answer 7

experimented on Neurospora, a type of bread mold, and they concluded that mutations to genes affected the enzymes of organisms, and thus what molecules it could synthesise.

Question 8

Transcription

Answer 8

Conversion of DNA into RNA.

Question 9

RNA

Answer 9

Has a different sugar (ribose), is single-stranded and has the base uracil instead of thymine. RNA has an OH group at the 2 prime position making it more reactive and less compact than DNA. Single strand can double up to create a double helix as it's tertiary structure.

Question 10

mRNA

Answer 10

carries genetic information, out of the nucleus to ribosomes where it can be translated into proteins

Question 11

tRNA

Answer 11

Small RNA molecule that acts as an adaptor converting code ons to amino acids. Consists of an anticodon that will correspond to a codon on the MRNA chain and the corresponding amino acid is attached to the other end.

Question 12

rRNA

Answer 12

Structural component of the ribosome

Question 13

Guanosine-5'-triphosphate (GTP)

Answer 13

one of the building blocks needed for the synthesis of RNA during the transcription process. energy source for the binding of a new amino-bound tRNA to the A site of the ribosome. GTP is also used as an energy source for the translocation of the ribosome towards the 3' end of the mRNA.

Question 14

Promoter region

Answer 14

region of DNA upstream of a gene where relevant proteins (such as RNA polymerase and transcription factors) bind to initiate transcription of that gene. Not transcribed into mRNA.

Question 15

ribonucleoside tri-phosphate (rNTP)

Answer 15

Building blocks used to create mRNA

Question 16

RNA polymerase 2

Answer 16

Multiprotein complex that unwinds DNA and performs transcription into mRNA

Question 17

Terminator region

Answer 17

the nucleotide sequence that determines the detachment of RNA polymerase from the DNA template strand. Not transcribed into mRNA

Question 18

Translation

Answer 18

mRNA is read by ribosome in codon units, and matched to tRNA anticodon with the corresponding amino acid to form a polypeptide chain

Question 19

Features of the genetic code

Answer 19

Universal = same for all species
Redundant = more than one codon codes for the same amino acid
Unambiguous = one codon can't code for more than one amino acid
Non-overlapping = always some distance between one gene and the next, genes don't share sections

Question 20

DNA template strand

Answer 20

The strand being transcribed into MRNA

Question 21

DNA coding strand

Answer 21

The same as the mRNA strand being formed, except for t instead of u

Question 22

Parts of the ribosome

Answer 22

Amino acyl site = site for a charged tRNA to enter the ribosome
Peptidyl site = holds the tRNA which is linked to the growing polypeptide chain and where peptide bond forms
Exit site = releases the tRNA after it loses its amino acid

Question 23

Translation initiation

Answer 23

Assembly of the ribosome on the MRNA start codon. The small subunit interacts with the MRNA and locates the closest Aug to the 5 prime end. When the large subunit attaches the met tRNA is in the p-site.

Question 24

Translation elongation

Answer 24

Entry of TRNA into a site. formation of the peptide bond via GTP. Translocation in which the ribosome is moved along the MRNA by one codon.

Question 25

Translation termination

Answer 25

Release of the completed protein when a stop codon is reached. Release factors catalyzed completed protein release.

Question 26

Signal selection

Answer 26

Promoter determines where when and how many transcripts are made.

Question 27

Signal amplification

Answer 27

Multiple MRNA molecules synthesise from.

Question 28

Transcription and translation signals

Answer 28

Transcription = promoter and Terminator region

Translation= start and stop codons

Question 29

DNA replication enzymes

Answer 29

DNA polymerase 3 = adds dNTPs in the 5' to 3' direction
DNA polymerase 1 = removes RNA primers and subs in DNA bases
helicase = unwinds double helix
Primase = catalyze the synthesis of short RNA molecules used as primers for DNA polymerases.
ligase = seals okazaki fragments and phosphate backbones

Question 30

Leading strand

Answer 30

single DNA strand that synthesised in the 5'-3' direction (same direction as the replication fork moves). DNA is added to the leading strand continuously

Question 31

Lagging strand

Answer 31

Discontinuously synthesized strand in the 3'-5' direction. Requires multiple primers to be placed so poly III can synthesise in okazaki fragments

Question 32

Point mutations

Answer 32

Silent = does not change resulting amino acid
Missense = change in one amino acid
Nonsense = change to stop codon

Question 33

Frameshift mutation

Answer 33

insertion or deletion of nucleotide bases in numbers that are not multiples of three

Question 34

Mutation examples

Answer 34

Cystic fibrosis = most common is phe508del deletion of one coding (not a frameshift) reducing function of the protein.
Huntington's disease = insertion of an extra codon (not a frameshift) for c-terminal gln causing no normal functioning of protein.
Achondroplastic dwarfism gly380ary missense mutation causing protein to be more active than normal

Question 35

FOXP2 gene

Answer 35

provides instructions for making a protein called forkhead box P2, which appears to be essential for the normal development of speech and language