Nucleic acids and proteins Flashcards
Polypeptide
A long chain of amino
acids
Proteome
all the proteins that are
expressed by a cell or organism at
a given time
Enzyme
an organic molecule,
typically a protein, that catalyses
(speeds up) specific reactions
Carboxyl group
The functional
group on amino acid molecules
that contains a hydroxyl group
(OH) and an oxygen double bonded to a carbon atom
Amino group
The functional group
on amino acid molecules that is
made up of one nitrogen and two
hydrogens (NH2)
R-group
the variable portion of
an amino acid molecule. It can
be one of twenty variations and
determines the identity of the
amino acid
Amino acid overall structure
Central carbon (C), carboxyl group (COOH), amino group (NHH), R group (R) and hydrogen atom (H)
Hydrophobic
having a tendency
to repel and be insoluble in water
Hydrophilic
having a tendency
to be attracted to and dissolve
in water
Monomer
a molecule that
is the smallest building block
of a polymer
Polymer
a large molecule that
is made up of small, repeated
monomer subunits
Peptide bond
the chemical bond
linking two amino acids
Primary structure
refers to the sequence of amino acids
in a polypeptide chain
Secondary structure
where the amino acid chain forms either alpha-helices, beta-pleated
sheets, or random coils due to forming hydrogen bonds between AAs of different its sections
Tertiary structure
the functional 3D shape of a polypeptide chain, formed by secondary structures further folding by interactions and bonds between AAs and R-groups.
Quaternary structure
the level of protein structure where
multiple polypeptide chains bond
together, or other non-protein (prosthetic) groups are added to form a fully functional protein. E.g. RuBisCo
Alpha helix
an organised coiled
secondary structure of proteins
Beta-pleated sheet
an organised
folded secondary structure
of proteins
Random coil
an irregular secondary structure of proteins that is neither an alpha helix nor a beta-pleated sheet. Join alpha-helices and beta-pleated sheets
Disulphide bond
a strong covalent
bond occurring between two
sulphur atoms (cysteine amino acids have these), further stabilising the protein’s 3D structure
Prosthetic group
a non-protein
group bound to a protein. For
example, a vitamin or ion
Amino acid
The monomer of proteins that join together via condensation reactions to form polypeptide chains.
Nucleic acid
the class of macromolecule that includes DNA and RNA. All nucleic acids are polymers made out of nucleotide
monomers
Nucleotide
The monomer subunit
of nucleic acids. Made up of a
nitrogen-containing base, a fivecarbon sugar molecule (ribose in
RNA and deoxyribose in DNA),
and a phosphate group
DNA (deoxyribonucleic acid)
a double-stranded nucleic acid
chain made up of nucleotides.
DNA carries the instructions for
proteins which are required for
cell and organism survival
RNA (ribonucleic acid)
a single-stranded nucleic acid chain made up of nucleotides. Includes mRNA, rRNA, and tRNA
Phospodiester bond
a strong
covalent bond linking a five-carbon
sugar to a phosphate group
sugar-phosphate backbone
a strong covalently linked chain of
five-carbon sugar molecules and
phosphate groups in a nucleic
acid chain
chromosome
a structure made
of protein and nucleic acids that
carries genetic information
gene
a section of DNA that
carries the code to make a protein
antiparallel
a characteristic of
DNA strands describing how
each strand runs in an opposite
direction to the other. One strand
runs in a 3’ -> 5’ direction and the
other runs in a 5’ -> 3’ direction
double helix
the structure of
double-stranded DNA in the
nucleus of eukaryotic cells, where
each DNA strand wraps around a
central axis
nuclear DNA
DNA that is located
in the nucleus of a cell
messenger RNA (mRNA)
RNA molecules that are produced
during transcription and carry
genetic information from the
nucleus to the ribosomes
transfer RNA (tRNA)
RNA that recognises specific
codons on the mRNA strand and
adds the corresponding amino acid
to the polypeptide chain during
protein synthesis
ribosomal RNA (rRNA)
RNA that is a key structural
component of ribosomes,
which assemble proteins
transcription
the process
whereby a sequence of DNA is
used as a template to produce a
complementary sequence of mRNA
translation
the process where an
mRNA sequence is read to produce
a corresponding amino acid
sequence to build a polypeptide
triplet
the sequence of three
nucleotides in DNA coding for one
amino acid
codon
the sequence of three
nucleotides in mRNA coding for
one amino acid
start codon
the sequence of three
nucleotides in mRNA that signals
the start of translation
stop codon
the sequence of three
nucleotides in mRNA that signals
the end of translation
Universal
Nearly all living organisms use the same codons to code for specific amino acids.
Unambiguous
Each codon is only capable of coding for one specific amino acid. For example, the codon UUA only codes for
the amino acid leucine.
Degenerate
Each amino acid may be coded for by
multiple different codons.
Non-overlapping
Each triplet or codon is read independently, without overlapping from adjacent triplets or codons.
Promoter
the sequence of DNA to
which RNA polymerase binds
RNA polymerase
the enzyme responsible for constructing a pre-mRNA sequence from a DNA sequence during transcription
TATA box
a type of promoter region
introns
non-coding regions
of DNA that do not code for
proteins. They are spliced out
during RNA processing
exons
regions of DNA that code
for proteins and are not spliced out
during RNA processing
termination sequence
a sequence of DNA that signals
the end of transcription
operator
a short region of DNA
that interacts with repressor
proteins to alter the transcription
of an operon
repressor protein
a protein
coded for by a regulatory gene
that prevents gene expression by
binding to its operator
leader region
the segment of
DNA or mRNA that immediately
precedes the coding region. Also
known as the leader segment or
leader sequence
precursor messenger RNA
(pre-mRNA)
the immediate
product of transcription of a DNA
sequence. Requires modifications
before it can undergo translation
transcription factor
proteins
that bind to the promoter region
and control the functioning of
RNA polymerase
template strand
the strand
of DNA transcribed by RNA
polymerase to produce a
complementary pre-mRNA strand
coding strand
the strand of
DNA not transcribed by RNA
polymerase, contains an identical
sequence to the mRNA strand
produced (except thymine is
replaced with uracil in mRNA)
termination sequence
a sequence
of DNA that signals the end
of transcription
ribosome
an organelle made of
rRNA and protein that is the site
of protein synthesis. Can be free
in the cytosol or attached to the
rough endoplasmic reticulum
5’ methyl-G cap
a molecule added to the 5’ end of pre-mRNA during RNA processing
3’ poly-A tail
a chain of adenine
nucleotides added to the 3’ end of
pre-mRNA during RNA processing
introns
non-coding regions of
DNA that do not code for proteins.
They are spliced out during RNA
processing
splicing
process where introns are
cut out of a pre-mRNA molecule,
and exons are joined together
exons
regions of DNA that code for proteins and are not spliced out during RNA processing
spliceosome
the enzyme that
removes introns from the premRNA molecule and joins exons
together during RNA processing
alternative splicing
the process where different exons may be spliced, resulting in a single gene producing multiple different mRNA strands
codon
the sequence of three
nucleotides in mRNA coding for
one amino acid
start codon
the sequence of three
nucleotides in mRNA that signals
the start of translation
anticodon
the sequence of three
nucleotides on a tRNA molecule
that recognises a specific sequence
of three nucleotides (codon) on an
mRNA strand
peptide bond
the chemical bond
linking two amino acids
condensation reaction
a reaction where two monomers join to form a larger molecule, producing water as a by-product
stop codon
the sequence of three
nucleotides in mRNA that signals
the end of translation
