Introduction to Molecular Biology Flashcards
What is adenine?
One of the five nitrogenous bases of nuclei acids that is a purine that pairs with thymine in DNA and uracil in RNA
What are amino acids?
An organic molecule containing both an amine group and a carboxyl group. Those that serve as building blocks of proteins are alpha amino acids, having both the amino and carboxyl groups linked to the same carbon atom
What is annealing?
When complementary sequences of single-stranded DNA or RNA pair by hydrogen bonds to form a double-stranded polynucleotide
What is anti-parallel?
When two biopolymers run next to each other but with opposite alignments
What is archaea?
One of the three domains of life that share similarities with both bacteria and eukaryotes
What is ATP?
Adenosine triphosphate: a nucleoside triphosphate composed of adenine, ribose and three phosphate groups. The principle carrier of chemical energy in cells. The terminal phosphate groups are highly reactive in the sense that their hydrolysis, or transfer to another molecule, takes place with the release of a large amount of energy
What are bacteria?
A large subgroup of unicellular microorganisms that makes up one of the three domains of life
What is a catalyst?
A substance that increases the rate of a chemical reaction by lowering the activation energy of the reaction without itself undergoing any permanent chemical change
What is chromatin?
A complex of DNA, histones, and non-histone proteins found in the nucleus of a eukaryotic cell. The material of which chromosomes are made
What is a chromosome?
A structure composed of a very long DNA molecule and associated proteins that carries part (or all) of the hereditary information of an organism. Especially evident in plant and animal cells undergoing mitosis or meiosis, during which each chromosome becomes condensed into a compact rodlike structure visible under the light microscope
What is cytosine?
One of the four bases of nucleic acids that is a pyrimidine that pairs with guanine in double stranded DNA
What does denatured mean?
To destroy the characteristic properties of a biological macromolecule by heat, acidity, or other effects that disrupt molecular conformation
What is deoxyribose?
A sugar derived from ribose that forms that backbone of DNA (along with phosphate)
What are dispersion forces?
A temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms forms temporary dipoles
What is divergence?
The process in which two or more populations of an asncestral species accumulate independent mutations through time, often after the populations have become reproductively isolated for some time
What is DNA?
Deoxyribonucleic acid: a self-replicating material present in nearly all living organisms as the main constituent of chromosomes
What is DNA replication?
The process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules
What is a domain?
A classification of organisms made up of three categories: archaea, bacteria and eukaryotes
What is dsDNA?
Double-stranded DNA
What is duplication?
A mechanism through which new genetic material is duplicated in a region of DNA that contains a gene
What is E. Coli?
A bacterium commonly found in the intestines of humans and other animals, where it usually causes no harm. Some strains cause severe food poisoning, especially in old people and children
What is electrostatic attraction?
The attractive force between two particles of opposite charges
What is a eukaryote?
A domain of organisms consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus
What is an exon?
A segment of a eukaryotic gene that consists of a sequence of nucleotides that will be represented in mRNA or in a final transfer, ribosomal, or other mature RNA molecule. In protein-coding genes, exon encode the amino acids in the protein. An exon is usually adjacent to a noncoding DNA segment called an intron
What are fatty acids?
Long-chained hydrocarbons with a carboxyl group that acts as the building blocks for larger lipid molecules
What is free energy?
The amount of energy in a system able to be utilised for a chemical reaction
What is a gene?
A distinct sequence of nucleotides forming part of a chromosome, the orders for which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell may synthesise
What is guanine?
One of the four bases of nucleic acids that is a purine that pairs with cytosine
What are homologies?
The state of having the same or similar relation between organisms due to genes
What is hybridisation?
In molecular biology, the process whereby two complementary nucleic acid strands forms a base-pair duplex DNA-DNA, DNA-RNA, or RNA-DNA molecule. Forms the basis of a powerful technique for detecting specific nucleotide sequences
What are hydrogen bonds?
A weak bond that forms between two molecules resulting from electrostatic attraction between a proton in one molecule and a highly electronegative atom in the other (FON)
What are hydrophobic interactions?
The force exerted by the hydrogen-bonded network of water molecules that brings two non-polar surfaces together by excluding water between them
What is an intron?
A non-coding region of a eukaryotic gene that is transcribed into a pre-mRNA molecule but is then excised by RNA splicing during the production of the mRNA or other functional RNA
What does lithotrophic mean?
A group of organisms that use inorganic substance to obtain energy for metabolism
What is mechanical shearing?
Physically tearing apart unusually long DNA molecules
What is metabolism?
Combined set of anabolic and catabolic process that occur in a living organism in order to maintain life
What are monomers?
A molecule that can be bonded to other similar or identical molecules to form a larger molecule known as a polymer
What are monosaccharides?
The most basic form of carbohydrates. They can be combined by condensation reaction to form polysaccharides
What is mRNA?
A type of RNA molecule that specifies the amino acid sequence of a protein. Produced in eukaryotes by processing of an RNA molecule made by RNA polymerase as a complimentary copy of DNA. It is translated into protein in a process catalysed by ribosomes
What is a mutation?
The changing of a structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion or rearrangement of larger sections of genes or chromosomes
What is non-coding DNA?
Components of an organisms DNA that do not encode protein sequences
What is a nucleoside?
A compound commonly found in DNA or RNA, consisting of a purine or pyrimidine base linked to sugar
What is a nucleotide?
A compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA
What is an operon?
L
A unit made up of linked genes that is thought to regulate other genes responsible for protein synthesis
What does organotrophic mean?
A type of organism that obtains its energy through ingesting other living things or the chemicals they produce
What is a phsophodiester bond?
A chemical bond of the kind joining successive sugar molecules in a polynucleotide
What is a phototroph?
A type of organism that obtains its energy through converting light energy into chemical energy through a process known as photosynthesis
What is a plasma membrane?
A barrier made up of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and that regulates the passage of molecules in and out of the cytoplasm
What is a polymer?
A substance made up of a large number of similar units bonded together
What is a polysaccharide?
A carbohydrate whose molecules consist of a number of sugar molecules bonded together
What is a probe?
A technique for identifying a segment of DNA, using a known sequence of nucleotide bases from a DNA strand to detect a complementary sequence in the sample by means of base pairing
What is a progeny?
The cells produced as a result of cellular replication
What are prokaryotes?
A single-celled organism that has neither a distinct nucleus with a membrane nor other specialised organelles
What is a protein?
A class of organic compound that consists of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms
What is protein synthesis?
The assembly of specific proteins as directed by DNA sequences
What are purines?
A double-ringed aromatic compound. Adenine and guanine are important purines that make up the structure of DNA
What are pyrimidines?
A single-ringed aromatic compound. Thymine and cytosine are important pyrimidines that make up the structure of DNA
What does renatured mean?
To restore a denatured biomacromolecule to an original or normal conditions
What is RNA?
Ribonucleic acid: a nucleic acid present in all living cells. It’s principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins, although some viruses use RNA rather than DNA to store their genetic information
What is RNA polymerase?
An enzyme that calluses the synthesis of an RNA molecule on a DNA template from ribonucleic triphosphate precursors
What is rRNA?
Any one of a number of specific RNA molecules that form part of the structure of a ribosome and participate in the synthesis of proteins. Often distinguished by their sedimentation coefficient
What is ssDNA?
Single-stranded DNA
What is a template strand?
A single strand of DNA or RNA whose nucleotide sequence acts as a guide for the synthesis of a complementary strand
What is thymine?
One of the four bases of nucleic acids that is a pyrimidine that binds with adenine in double stranded DNA. Thymine is not found in RNA
What is transcription?
The process by which the information in a strand of DNA is copied into a new molecule of mRNA
What is translation?
The process by which ribosomes create polypeptide chains using the information encoded in mRNA as a blueprint
What is tRNA?
A set of small RNA molecules used in protein synthesis as an interface (adapter) between mRNA and amino acids. Each type of tRNA molecule is covalently bonded to a particular amino acid
What is uracil?
A compound found in living tissue as a constituent base of RNA. In DNA it’s place is taken by thymine
What are the universal features in all cells?
- Hereditary information is stored in DNA
- DNA is replicated by template-directed polymerisation
- Sections of the DNA are transcribed into the same intermediary form (RNA)
- Proteins compose cellular machinery
- Proteins are produced by translation of RNA
- Basic mechanism of translation (protein synthesis) is the same
A segment of DNA that can produce a functional product (RNA or protein) is known as a…
Gene
True or False: Only one strand serves as a template, but it may be a different one for different genes
True
True or False: A single prokaryotic mRNA often only contains the instructions for one protein
False: A single prokaryotic mRNA often contains the instructions for several different proteins (polycistronic)
Which human cell(s) cannot produce proteins and why?
Mature red blood cells - the do not have a nucleus and therefore cannot produce mRNA to be translated into protein
What are the monomers of nucleic acids called?
Nucleotides
What are nucleotides made up of?
Sugar (RNA-ribose, DNA-deoxyribose)
Phosphate group(s)
Nitrogenous base
What is the name of the bond that connects two adjacent nucleotides?
Phosphodiester bond
What is the name of the bond that connects two opposite nucleotides
Hydrogen bond
To which end are nucleotides added?
Nucleotides are added to the 3’ end of the DNA strand
What functional group is found at the 3’ end?
-OH group
What is found at the 5’ end?
Phosphate group
Are nitrogen bases hydrophobic or hydrophillic?
Hydrophibic - responsible for the double-helix form
Between which two bases does three hydrogen binds form?
Cytosine and guanine
How many bases are there per turn of the DNA?
10-10.5
Where are chromosomes found (usually)?
In the nucleus
What are the three main types of RNA?
tRNA (transfer)
mRNA (messenger)
rRNA (ribosomal)
Which stuctural feactures of DNA determine its physical properties?
Double stranded helix Complementary base pairing Hydrogen binding Length/diameter Acidity (phosphate group)
Which properties of DNA allow it to be studied?
Solubility Viscosity UV Absorption Denaturation Stability
Why is DNA soluble in aqueous conditions?
The high negative charge of the phosphate groups makes it soluble
Is DNA soluble in alcohol? Why/why not?
No - alcohol is a non-polar solvent and DNA is charged
How is DNA viscosity decreased?
Disruption of hydrogen bonding - one method is mechanical shearing
Which part of a nucleotide absorbs UV light?
Nitrogenous bases
True or False: dsDNA absorbs more UV light that ssDNA?
False - the double helix stucture of dsDNA shields the bases, so ssDNA can absorb more
What are probes used for?
Probes are labelled DNA or RNA fragments that are used to detect specific nucleic acid sequences by hybridisation
What is DNA melting temperature dependent on?
The size of the molecule
Its GC content
The pH and ionic strength
Does melting temperature increase of decrease as the size of the strand increases?
Increase
Does the melting temperature of the DNA increase or decreases as GC content increases? Why?
Increase - GC have three hydrogen bonds and therefore require more energy to break
