Biology Unit 3 AoS1: What is the role of proteins and nucleic acids in maintaining life?

α-helix

a secondary structure found in proteins in which the polypeptide chain folds into a tight coil

allele

an alternative form of a single gene characterised by small differences in the gene's DNA sequence

alternative splicing

a process in which one or more exons are removed with introns to produce mRNA molecules of different lengths and sequences from the same starting gene

amino acid

a nitrogen-containing compound that are referred to as the monomers or "building blocks" from which proetins are built

anticodon

a group of three nucleotides in tRNA that correspond and bind to a complementary codon in mRNA, resulting in the addition of a specific amino acid to a polypeptide chain

antiparallel

of DNA strands: running parallel to each other in opposite directions

attenuation

a mechanism for reducing the expression of the trp operon when tryptophan levels are high by preventing the completion of transcription of the involved structural genes

β-pleated sheet

a secondary structure found in proteins in which segments of a polypeptide chain bond side-by-side into a flattened assembly (or a "pleated sheet")

base pair

a pair of nitrogen containing bases linked by hydrogen bonds found in DNA

biological functionality

the function/role of a protein

catalyse

to increase the rate at which a biochemical reaction occurs, generally referring to the use of an enzyme

chromosome

a structure made of nucleic acids and proteins that encode genetic information

located in the nucleus of eukaryotic cells and in a singular circular structure found in the cytoplasm/nucleoid of prokaryotic cells

cisterna

flattened, membrane-bound compartments (tubules and sacs) that make up the Golgi apparatus and endoplasmic reticulum

codon

a group of three nucleotides found in mRNA that code for specific amino acids

complementary base pairing rules

A always pairs with T (U in RNA; specific processes)
G always pairs with C

condensation polymerisation

a reaction in which monomers are linked together into a polymer while releasing a small molecule as a by-product (generally water)

conformation

the proper or functional shape of a protein

degenerate

describes the property of genetic code in which most amino acids are coded for by two or more codons

denature

to permanently change the shape/molecular structure of a protein or DNA

DNA (Deoxyribonucleic Acid)

the double-stranded nucleic acid that carries genetic information for the development and functioning of an organism
contains deoxyribose sugar, the nitrogenous base Thymine over Uracil, and forms an antiparallel spiral between its two strands

DNA polymerase

the enzyme that catalyses the polymerisation of nucleotides to form new strands of DNA

endoplasmic reticulum

an organelle composed of several membranous tubules involved in both protein synthesis and folding for secretion

enzyme

a specific protein that acts as a catalyst to increase the rate of a biochemical reaction within cells by lowering the amount of energy required for the reaction to take place

exon

segments of DNA/RNA that code for polypeptides/parts of a polypeptide (they are "expressed")

functional proteomics

the study of how proteins work together in different cells or tissues, or under varying circumstances

gene

a segment of DNA that codes for a polypeptide; consists of the promoter, exons and introns

gene expression

the process by which the information encoded in a gene is used to produce a functional product; generally a protein or an RNA molecule

gene regulation

the processes through which cells can "turn on" and "turn off" gene expression as the need arises

genetic code

the complete set of mRNA codons and the amino acids they specify for

genome

the complete sequence of DNA in a single (haploid) set of an organism's chromosomes

Golgi Apparatus

a collection of membranes that package and store substances in vesicles for secretion from the cell

histone

protein that organises chromosomes and around which DNA wraps found in eukaryotic cells and very few prokaryotic cells

hydrogen bond

weak attraction between a hydrogen atom and another atom that is more electronegative

hydrophilic

"water loving" (polar)

hydrophobic

"water fearing" (non-polar)

inducer

a signalling molecule that triggers/turns on the expression of a gene

intron

sequence of DNA that is not involved in coding for a protein that is always cut out during RNA processing

leader region

codes for the leader sequence in mRNA including the attenuator region

leader sequence

the sequence at the 5' end of an mRNA that is not translated into protein

attenuator region

a regulatory region responsible for the termination of transcription by folding back on itself to block RNA polymerase

mRNA (messenger RNA)

RNA that contains a copy or 'transcript' of the instructions needed for protein/polypeptide synthesis transcribed from DNA

non-coding region

a region outside of that that codes a protein sequence

non-template strand

(coding strand) the DNA strand that contains the same nucleotides are mRNA after transcription with U replaced with T

nucleic acid

a large, linear polymer built from the monomers that are nucleotides (includes DNA and RNA)

nucleosome

a histone with DNA coiled around it

nucleotide

the monomers of nucleic acids that consist of a pentose (5-carbon) sugar, a nitrogenous base, and one or more phosphate groups

operator

a segment of DNA that a protein binds to, generally in order to switch off gene expression when the product that gene produces is already abundant

operon

a group of genes that are expressed as a single unit

peptide bond

a chemical bond linking two amino acids in a polypeptide chain

phosphodiester bond

a special type of ester bond that links two nucleotides between their phosphate group and third carbon in a growing chain

plasmid

a small circular DNA structure that is independent of the chromosome in prokaryotic cells

poly-A tail

a chain of 100-200 adenine nucleotides added at the 3' end of an mRNA strand during polyadenylation

polypeptide

a linear polymer built from amino acid monomers

polyribosome

a chain of ribosomes formed by attaching to and translating from a single mRNA strand

pre-mRNA

an unprocessed mRNA strand that has been transcribed directly from DNA and has yet to be altered in any way

primary structure

describes the linear sequence of amino acids that make up a polypeptide chain

secondary structure

the localised folding of a polypeptide chain when neighbouring amino acids have bonded to each other, forming α-helices, β-pleated sheets, or random loops

tertiary structure

the overall three-dimensional shape of a completely folded polypeptide

quaternary structure

the structure formed when two or more polypeptides associate into a mature protein

product

the outputs of a chemical reaction that are formed from the reactants/inputs

promoter region

a segment of DNA to which RNA polymerase binds to to begin transcription

protein

a polymer of amino acids that may consist of a single polypeptide or many bonded into a functional molecule

protein secretory pathway

the pathway through which proteins are packaged into vesicles and are sent out of the cell for different purposes

proteome

the complete set of proteins produced by a cell, tissue, or organism as a whole

proteomics

the study of the proteome

random coil

a type of secondary protein structure in which a polypeptide chain is not folded into a specified arrangement like β-pleated sheets or α-helices

regulatory gene

a gene whose product "switches on" or "switches off" the function of one or more other genes

structural gene

any gene that codes for a product that is not involved in gene regulation

repression

a mechanism for reducing the expression of the trp operon when tryptophan levels are high by blocking initial transcription

repressor protein

a protein coded for by a regulatory gene whose function is to bind to DNA to stop RNA from attaching and transcribing, shutting off gene expression

RNA (Ribonucleic Acid)

A relatively short-lived, single-stranded nucleic acid whose primary function is to synthesise proteins but can take on a variety of other roles within a cell.
Consists of ribose sugar and the nitrogenous base Uracil over Thymine

rRNA (ribosomal RNA)

an RNA strand comprising 60% of the structure of ribosomes with the other 40% being proteins

ribosome

a small structure consisting of RNA and proteins where amino acids are joined to form polypeptides

RNA polymerase

the enzyme that catalyses the synthesis of RNA

rough endoplasmic reticulum

endoplasmic reticulum with ribosomes attached

semi-conservative replication

the replication of DNA where the product consists of one original (parent) strand and one newly made (daughter) strand

substrate

the substance an enzyme acts upon

subunit

a distinct component of a biological particle

template

a pattern that can be used to make many more copies

template strand

a strand of DNA that is copied during DNA or RNA synthesis

transcribe

to copy DNA into mRNA

transcription

the process through which DNA is copied into mRNA

transcription factor

a protein that can bind to DNA to control the rate of transcription from a gene

tRNA (transfer RNA)

an RNA molecule that delivers amino acids to the ribosome for assembly into a polypetide

translation

the process of turning a sequence of nucleotides in mRNA into the amino acid sequence of a polypeptide

transport vesicle

a small membranous sac in a eukaryotic cell that is transported from the Golgi apparatus to the plasma membrane for release into the extracellular environment

triplet

a set of three nucleotide codes in DNA

agarose gel

gel matrix used for electrophoresis

annealing

a process use in the polymerase chain reaction to join separate strands of DNA together as a result of hydrogen bonds pairing; occurs when temperature is lowered

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

bacteriophage

a virus that can infect bacteria to replicate

bioethics

the study of ethical issues surrounding advancements in biology

biotechnology

the use of living organisms and biological systems and processes for human benefit

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

sticky end

the end of a DNA fragment that is created following cleavage by a restriction enzyme that cuts DNA at different positions on each strand

Cas9 protein

an endonuclease that cuts double-stranded DNA at a target location in the genome

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

crRNA (CRISPR RNA)

RNA transcribed from the CRISPR locus; gudies Cas9 proteins to their complementary sequence in the invading viral DNA genome, targeting it for destruction by Cas9

DNA ligase

an enzyme that catayses the formation of a phosphodiester bond between two pieces of DNA

DNA profiling

comparison of individuals using differences in DNA sequences; often used in criminal investigations to exclude suspects