BMS2062 Exam Questions With
Accurate Answers
Central dogma of molecular biology - ANSWER DNA --> RNA --> Protein --> Cellular
phenotype
Central dogma of genomics - ANSWER Genomics --> Transcriptomics --> Proteomics -->
Cellular phenotype
What is bioinformatics? - ANSWER The application of computational methods to the
storage and analysis of biological data.
What is a common use of bioinformatics? - ANSWER To look for patterns and
significance in at a, model biological systems and structures, and examine biological
relationships.
Which strand is the same sequence as RNA? - ANSWER The coding strand.
How does transcription occur? - ANSWER RNA polymerase binds to the promoter,
opens helix to expose the bases of the gene .
DNA template strand is built 3' to 5'. Read this way by RNA.
RNA polymerase assembles the new mRNA strand which is determined by the gene
sequence.
How does translation occur? - ANSWER A strand of mRNA goes to the ribosome. The
ribosome reads the message on the mRNA codon by codon by matching the anticodons
on the tRNA molecules. The ribosome forms bonds between the amino acids.
Spliceosome - ANSWER A large complex made up of proteins and RNA molecules that
splices RNA by interacting with the ends of an RNA intron, releasing the intron and
joining the two adjacent exons in the nucleus.
Start codon - ANSWER AUG (methionine)
Stop codons - ANSWER UAG, UGA, UAA
Primary structure - ANSWER The first level of protein structure; the specific sequence
of amino acids making up a polypeptide chain.
Secondary structure - ANSWER The second level of protein structure; the regular local
patterns of coils or folds of a polypeptide chain (eg. alpha helices and beta sheets)
Tertiary structure - ANSWER The third level of protein structure; the overall,
,three-dimensional shape of a polypeptide due to interactions of the R groups of the
amino acids making up the chain.
Quarternary structure - ANSWER The fourth level of protein structure; the shape
resulting from the association of two or more polypeptide subunits.
Non-polar, aliphatic R groups - ANSWER - glycine
- alanine
- proline
- valine
- leucine
- isoleucine
- methionine
Polar, uncharged R groups - ANSWER - serine
- threonine
- cysteine
- asparagine
- glutamine
Aromatic R groups - ANSWER - phenylalanine
- tyrosine
- tryptophan
Positively charged R groups - ANSWER - lysine
- arginine
- histidine
Negatively charged R groups - ANSWER - aspartate
- glutamate
Gene - ANSWER The basic unit of inheritance. Each one is a sequence that encodes the
information required for the synthesis of protein or non-coding RNA.
Genome - ANSWER The complete set of genes (and non-coding DNA) belonging to a
particular organism.
Haploid - ANSWER Prokaryotic cells; an organism or cell having only one complete set
,of chromosomes, and no nucleus.
Diploid - ANSWER Eukaryotic cells; an organism having multiple chromosomes and
typically have two copies of each. Contains a nucleus.
Alleles - ANSWER Different forms of a gene present in a diploid organism.
Promoter sequences - ANSWER DNA sequences that define where transcription of a
gene by RNA polymerase begins. Good example of DNA motifs.
Is DNA conservative or semi-conservative? - ANSWER Semi-conservative
Chargaff's Rule 1 - ANSWER Base composition of DNA varies from species to species,
but is constant within a species.
Chargaff's Rule 2 - ANSWER DNA isolated from different tissues of the same animal has
the same composition.
Chargaff's Rule 3 - ANSWER The base composition in a given species does not change
with age, nutritional state or changing environment.
Chargaff's Rule 4 - ANSWER In all cellular DNAs, the number of adenines equals the
number of thymines, and the number of guanosine equals the number of cysteine
residues.
What form is the majority of DNA in ? - ANSWER DNA duplex is in the B-form.
Chromatin - ANSWER Substance found in eukaryotic chromosomes that consists of DNA
tightly coiled around histones.
Do prokaryotes methylate their own DNA? - ANSWER Yes, and they destroy foreign DNA
that is not correctly modified.
Is cytosine commonly methylated? - ANSWER Yes, as CpG. Is is frequently
transcriptionally silent.
Codon - ANSWER A specific sequence of three adjacent bases on a strand of DNA or
RNA that provides genetic code information for a particular amino acid.
Reading frame - ANSWER The way a cell's mRNA-translating machinery groups the
mRNA nucleotides into codons. Only one carries the correct code for a particular
protein, so information is need to tell the cell where to start and finish reading the DNA
sequence.
Synonymous codons - ANSWER Codons that specify the same amino acid. Eg. GCA,
GCC, GCG and GCU all code for alanine.
, Which reading frames are located where? - ANSWER Frames 1-3 are on the coding
strand. Frames 4-6 are on the template strand.
Substitution mutation - ANSWER Mutation in which a single base is replaced, potentially
altering the gene product.
Usually results in a new codon and amino acid at a particular position. Can also result in
the generation of a stop codon, which prematurely ends and truncates the protein.
Deletion/insertion mutation - ANSWER A mutation in which one or more pairs of
nucleotides are removed/added from a gene.
1 or 2 nucleotides alters the reading frame. 3 nucleotides maintains the reading frame.
Open reading frame (ORF) - ANSWER DNA or RNA sequence which contains a run of
codons uninterrupted by a stop codon. (Or, a stretch of codons between two stop
codons).
What's the difference between a coding sequence and an ORF? - ANSWER A coding
sequence must start with a methionine (AUG) but an ORG may start with any amino acid.
- all coding sequences are ORFs
- not all ORFs are coding sequences
- a coding sequence may fall within a longer ORF
What is the chance that a stop codon will occur? - ANSWER Once every 21 codons (3
stop codons/64 total codons)
How can we tell if an ORF is part of a real protein coding sequence in prokaryotes? -
ANSWER - it needs a start codon
Accurate Answers
Central dogma of molecular biology - ANSWER DNA --> RNA --> Protein --> Cellular
phenotype
Central dogma of genomics - ANSWER Genomics --> Transcriptomics --> Proteomics -->
Cellular phenotype
What is bioinformatics? - ANSWER The application of computational methods to the
storage and analysis of biological data.
What is a common use of bioinformatics? - ANSWER To look for patterns and
significance in at a, model biological systems and structures, and examine biological
relationships.
Which strand is the same sequence as RNA? - ANSWER The coding strand.
How does transcription occur? - ANSWER RNA polymerase binds to the promoter,
opens helix to expose the bases of the gene .
DNA template strand is built 3' to 5'. Read this way by RNA.
RNA polymerase assembles the new mRNA strand which is determined by the gene
sequence.
How does translation occur? - ANSWER A strand of mRNA goes to the ribosome. The
ribosome reads the message on the mRNA codon by codon by matching the anticodons
on the tRNA molecules. The ribosome forms bonds between the amino acids.
Spliceosome - ANSWER A large complex made up of proteins and RNA molecules that
splices RNA by interacting with the ends of an RNA intron, releasing the intron and
joining the two adjacent exons in the nucleus.
Start codon - ANSWER AUG (methionine)
Stop codons - ANSWER UAG, UGA, UAA
Primary structure - ANSWER The first level of protein structure; the specific sequence
of amino acids making up a polypeptide chain.
Secondary structure - ANSWER The second level of protein structure; the regular local
patterns of coils or folds of a polypeptide chain (eg. alpha helices and beta sheets)
Tertiary structure - ANSWER The third level of protein structure; the overall,
,three-dimensional shape of a polypeptide due to interactions of the R groups of the
amino acids making up the chain.
Quarternary structure - ANSWER The fourth level of protein structure; the shape
resulting from the association of two or more polypeptide subunits.
Non-polar, aliphatic R groups - ANSWER - glycine
- alanine
- proline
- valine
- leucine
- isoleucine
- methionine
Polar, uncharged R groups - ANSWER - serine
- threonine
- cysteine
- asparagine
- glutamine
Aromatic R groups - ANSWER - phenylalanine
- tyrosine
- tryptophan
Positively charged R groups - ANSWER - lysine
- arginine
- histidine
Negatively charged R groups - ANSWER - aspartate
- glutamate
Gene - ANSWER The basic unit of inheritance. Each one is a sequence that encodes the
information required for the synthesis of protein or non-coding RNA.
Genome - ANSWER The complete set of genes (and non-coding DNA) belonging to a
particular organism.
Haploid - ANSWER Prokaryotic cells; an organism or cell having only one complete set
,of chromosomes, and no nucleus.
Diploid - ANSWER Eukaryotic cells; an organism having multiple chromosomes and
typically have two copies of each. Contains a nucleus.
Alleles - ANSWER Different forms of a gene present in a diploid organism.
Promoter sequences - ANSWER DNA sequences that define where transcription of a
gene by RNA polymerase begins. Good example of DNA motifs.
Is DNA conservative or semi-conservative? - ANSWER Semi-conservative
Chargaff's Rule 1 - ANSWER Base composition of DNA varies from species to species,
but is constant within a species.
Chargaff's Rule 2 - ANSWER DNA isolated from different tissues of the same animal has
the same composition.
Chargaff's Rule 3 - ANSWER The base composition in a given species does not change
with age, nutritional state or changing environment.
Chargaff's Rule 4 - ANSWER In all cellular DNAs, the number of adenines equals the
number of thymines, and the number of guanosine equals the number of cysteine
residues.
What form is the majority of DNA in ? - ANSWER DNA duplex is in the B-form.
Chromatin - ANSWER Substance found in eukaryotic chromosomes that consists of DNA
tightly coiled around histones.
Do prokaryotes methylate their own DNA? - ANSWER Yes, and they destroy foreign DNA
that is not correctly modified.
Is cytosine commonly methylated? - ANSWER Yes, as CpG. Is is frequently
transcriptionally silent.
Codon - ANSWER A specific sequence of three adjacent bases on a strand of DNA or
RNA that provides genetic code information for a particular amino acid.
Reading frame - ANSWER The way a cell's mRNA-translating machinery groups the
mRNA nucleotides into codons. Only one carries the correct code for a particular
protein, so information is need to tell the cell where to start and finish reading the DNA
sequence.
Synonymous codons - ANSWER Codons that specify the same amino acid. Eg. GCA,
GCC, GCG and GCU all code for alanine.
, Which reading frames are located where? - ANSWER Frames 1-3 are on the coding
strand. Frames 4-6 are on the template strand.
Substitution mutation - ANSWER Mutation in which a single base is replaced, potentially
altering the gene product.
Usually results in a new codon and amino acid at a particular position. Can also result in
the generation of a stop codon, which prematurely ends and truncates the protein.
Deletion/insertion mutation - ANSWER A mutation in which one or more pairs of
nucleotides are removed/added from a gene.
1 or 2 nucleotides alters the reading frame. 3 nucleotides maintains the reading frame.
Open reading frame (ORF) - ANSWER DNA or RNA sequence which contains a run of
codons uninterrupted by a stop codon. (Or, a stretch of codons between two stop
codons).
What's the difference between a coding sequence and an ORF? - ANSWER A coding
sequence must start with a methionine (AUG) but an ORG may start with any amino acid.
- all coding sequences are ORFs
- not all ORFs are coding sequences
- a coding sequence may fall within a longer ORF
What is the chance that a stop codon will occur? - ANSWER Once every 21 codons (3
stop codons/64 total codons)
How can we tell if an ORF is part of a real protein coding sequence in prokaryotes? -
ANSWER - it needs a start codon
