Unit 3 AOS 1 Key Terms Flashcards
Define α-helix
A type of secondary protien structure in which the polypeptide chain folds into a tight coil
Define allele
A different version of the same gene (at the same locus) determined by small difference in the DNA sequence of the gene
Define alternative splicing
A process in which one or more exons are removed with the introns to produce mRNA molecules of different length and sequence
Define amino acid
a nitrogen-containing compund that is the monomer from which proteins are built
Define anticodon
The three nucleotides in tRNA that bring to the complementary codon in mRNA according to base-pairing rules, resulting in the addition of a specific amino-acid to the polypeptide chain
Define antiparallel
Parallel but orientated in the opposite direction
Define attenuation
A mechanism for reducing expression of the 𝘵𝘳𝘱 operon when trytophan levels are hig, by preventing completion of transcription of the structual genes, not by stopping initiation of transcription by a repressor protein
Define β-pleated sheet
A type of secondary protein strucure in which segments of the polypeptide chain bond side by side into a flattened assembly
Define base pair
Two complementary nitrogen bases linked by hydrogen
Define biological funtionality
The function of a protein
Define catalyse
To speed up a biochemical equation using an enzyme
Define chromosome
A thread-like structure made of nucleic acids and proteins that encode genetic information
Define cisterna
A flattened membrane disc that makes up Golgi apparatus and endoplasmic reticulm
Define codon
A group of 3 nucleotides in mRNA that specifies an amino acid
Define complementary base pairing
The linking together of complementary nitrogen basing by hydrogen bonding; A pairs with T ( or U in RNA) and C pairs with G
Define condensation polymerisation
A reaction in which monomers are linked together into a polymer with the release of a small molecule, such as water, as a by-product
Define conformation
The proper or functional shape of a protein
Define degenerate
A property of the genetic code in which most animo acids are encoded by two or more codons
Define denature
To permanately change the molecular structure of a protein or DNA
Define deoxyribonucleic acid (DNA)
The information molecule that is the basis of an organism’s genetic material
Define DNA polymerase
The enzyme that catalyses the bonding of nucleotides to form new strands of DNA
Define endoplasmic reticulum
An organelle made up of a network of membranous tubules involved in protein synthesis and folding for secretion
Define enzyme
A specific protein catalyst that increases the rate of a biochemical reaction within the cell by lowering the amount of energy required for the reaction to proceed
Define exon
A segment of DNA or RNA containing information that codes for a polypeptide or part of a polypeptide
Define functional proteomics
The study of how proteins work together in different cells or tissues, or under different circumstances
Define gene
A segment of DNA in a chromosome that codes for a polypeptide; comprises the promoter, exons and introns
Define gene expression
The process by which the information in a gene is turned into a polypeptide
Define gene regulation
The process by which gene expression is switched on or off
Define genetic code
The complete set of mRNA codons and the corresponding amino acids they specify
Define genome
The complete sequence of DNA in a single (haploid) set of an organism’s chromosomes, including nuclear, mitochondrial and chloroplast DNA
Define Golgi apparatus
A collection of membranes that package and store substances into vesicles in preparation for their release from the cell
Define histone
A protein that binds and packages DNA in eukaryotic chromosomes
Define hydrogen bond
A weak chemical bond between a hydrogen atom on one molecule and a more electronegative element, usually an oxygen or nitrogen atom, on another molecule
Define hydrophillic
Describes substances such as polar molecules and ionic compounds that dissolve readily in water
Define hydrophobic
Describes substances such as non-polar molecules that are insoluble in water
Define inducer
A signalling molecule that switches on expression of a gene
Define intron
A segment of DNA within a gene or pre-mRNA that does not code for a polypeptide and interrupts the sequence of a gene
Define messenger RNA (mRNA)
RNA copied from DNA that conveys the instructions needed for polypeptide synthesis from the nucleus to the cytoplasm
Define non-coding region
DNA that does not encode a protein sequence
Define non-template strand
The DNA strand that has the same sequence of nucleotides as the mRNA (except it has T instead if U)
Define nucleic acid
A large, linear polymer built from nucleotide monomers bonded together; includes DNA and RNA
Define nucleosome
A histone with a length of DNA coiled around it
Define nucleotide
The monomer, or building block, of DNA and RNA, consisting of sugar, phosphate and a nitrogen base
Define operator
A segment of DNA to which a protein binds, usually to switch iff gene expression
Define operon
A group of genes that are expressed as a single unit
Define peptide bond
A chemical bond that links two nucleotides in a growing chain
Define phosphodiester bond
A chemical bond that links two nucleotides in a growing chain
Define plasmid
A small, circular DNA structure independent of the chromosome in prokaryotic cells
Define poly-A tail
A chain of 100-200 adenine nucleotides added at the 3’ end of an mRNA strand
Define polypeptide
A linear polymer built from amino acid monomers
Define polyribosome
A chain of ribosomes formed by attaching to and translating from a single mRNA strand
Define pre-mRNA
An unprocessed RNA strand that is transcribed directly from the DNA
Define primary structure
The linear sequence of amino acids that makes up a polypeptide chain
Define product
The outputs of a chemical reaction that are formed from the reactants or imputs
Define promoter region
A segment of DNA to which RNA polymerase binds to begin transcription
Define protein
A polymer made up of amino acid monomers; may consist of a single polymer chain or many polymer bonded together into a functional molecule
Define protein secretory pathway
The pathway through which cells package proteins into vesicles for release into the extracellular environment
Define proteome
The study of proteomes
Define quaternary structure
The structure formed when two or more polypeptides associate into a mature protein
Define random coil
A secondary protein structure in which the polypeptide chain does not fold into a specified arrangement
Define regulatory gene
A gene whose product switches on or switches off expression of one or more other genes
Define repressor protein
A protein that binds DNA to prevent RNA polymerase attaching or transcribing; essentially shuts off gene expression
Define ribonucleic acid (RNA)
A type of nucleic acid consisting of a single strand of nucleotides; has essential roles in protein synthesis
Define ribosomal RNA (rRNA)
An RNA strand that serves as a structural component of a ribosome
Define ribosome
A small structure consisting of RNA and proteins where amino acids are joined to form polypeptides
Define RNA polymerase
The enzyme that catalyses the synthesis of RNA
Define rough endoplasmic reticulum
Endoplasmic reticulum with ribosomes attached
Define secondary structure
The localised folding of a polypeptide chain when neighbouring amino acids bind to each other to form α-helices, β-pleated sheets or random loops
Define semi-conservative replication
The replication of DNA in which the product contains one original and one newly made strand
Define structural gene
A gene that codes for tRNA, rRNA or a polypeptide other than a regulatory molecule
Define substrate
The substances that an enzyme acts on
Define subunit
A distinct component of a biological particle; in proteins, it refers to each polypeptide that contributes to the quaternary structure
Define template
A pattern that can be used for making many more copies
Define template strand
A strand of DNA that is copied during DNA or RNA synthesis
Define tertiary structure
The overall three-dimensional shape of a completely folded polypeptide
Define transcription
The process by which DNA is copied into mRNA
Define transcription factor
A protein that binds to DNA to control the rate of transcription from a gene
Define transfer RNA (tRNA)
An RNA molecule that transports an amino acid to the ribosome for assembly into a polypeptide
Define translation
The process of turning the nucleotide sequence of mRNA into the amino acid sequence of a polypeptide
Define transport vesicle
A small membrane-bound sac containing protein that is transported from the Golgi apparatus to the plasma membrane for release into the extracellular environment
Define triplet
A set of three nucleotide codes
Define agarose gel
A gel matrix used for electrophoresis
Define annealing
A process used in the polymerase chain reaction to join seperate strands of DNA together as a result of hydrogen bonds pairing; occurs when the temperature is lowered
Define antibiotic selection
Growing bacteria in the presence of an antibiotic so only cells containing a gene for antibiotic resistance (encoded on a recombinant plasmid) can grow
Define bacteriophage
A virus that can infect bacteria and replicate
Define bioethics
The study of ethical issues emerging from advancements in biology
Define biotechnology
The use of living organisms and biological systems and processes for human benefit
Define blunt end
The end of a DNA fragment that is created following cleavage by a restriction enzyme that cuts DNA at the same position on both strands
Define Cas9 protein
An endonuclease that cuts double-stranded DNA at a target location in the genome
Define CRISPR-Cas9
A bacterial immune defence mechanism in which short RNAs target complementary sequences in viral genomes to guide Cas9 proteins to destroy an invading virus
Define crRNA (CRISPR RNA)
RNA transcribed from the CRISPR locus; guides Cas9 proteins to their complementary sequence in the invadung viral DNA genome, targeting it for destruction by Cas9
Define DNA ligase
An enzyme that catalyses the formation of a phosphodiester bond between two piece of DNA
Define DNA profiling
Comparison of individuals based on patterns of non-coding base sequences in the genome
Define frameshift mutation
A mutation in DNA caused by the addition or deletion of a nucleotide or nucleotides resulting in a change in the amino acid sequence and protein being made
Define gel electrophoresis
A technique that separates DNA fragments according to their size and charge
Define gene cloning
The process of using plasmids and bacteria to make numerous identical copies of a gene
Define genetic engineering
Manipulation of genetic material, including altering DNA in an organism to suppress or enhance a gene’s activity, or combining genetic material from different species
Define genetic modified organism (GMO)
An organism whose genome has been genetically engineered
Define guide RNA
RNA that guides the Cas9 protein to the target sequence in a genome for gene editing
Define knock-in organism
An organism in which DNA has been inserted into a specific locus
Define knock-out organism
An organism whose DNA has been modified to disable the expression or function of a gene product
Define molecular size marker
A set of pieces of DNA of known length that is used to estimate the size of another DNA fragments in a gel
Define polymerase chain reaction (PCR)
A cyclical reaction in which DNA polymerase is used to copy a DNA template, making millions of copies of the same piece of DNA
Define polymorphism
A variation in DNA sequences among individuals
Define primer
A single-stranded DNA molecule that acts as the start of the amplification process
Define recombinant DNA technology
The process of transferring a gene from a gene from a cell of one species to the cell of a different species
Define recombinant plasmid
A plasmid with foreign DNA inserted into it
Define reporter gene
A gene that enables visualisation or quantification of gene expression
Define restriction digest reaction
A reaction in which restriction enzymes are incubated with DNA to cut the DNA into fragments at specific restriction sites
Define restriction endonuclease (restriction enzyme)
An enzyme that cuts DNA at a specific restriction site
Define restriction fragment
A short fragment of DNA generated after the cutting of a longer DNA fragment by a restriction enzyme
Define restriction site
A specific nucleotide sequence (usually 4-8 bp) that is recognised as a cleaving site for a restriction enzyme
Define short tandem repeat (STR)
A short non-coding region of DNA of up to five bases that is repeated many times in the genome of an organism; the number of times an STR is repeated is variable and can be used in DNA profiling
Define sticky end
The end if a DNA fragment that is created following cleavage by a restriction enzyme that cuts DNA at different positions on each strand
Define transformation
The process by which the genetic material of an organism id changed by the addition of new genetic material
Define transgenic organism
An organism that has been modified by incorporating a piece of foreign DNA into its genome
Define vector
A vehicle used to transfer DNA sequences from one organism to another
Define wild type
The genotype or phenotype that is most common, or standard, in natural conditions, in contrast to an atypical or mutant form
