Nucleic Acids and Proteins Flashcards
What is an enzyme?
It is an organic molecule, typically a protein, that catalyses (speeds up) specific reactions.
What is an antibody?
It is a protein produced by plasma cells during the adaptive immune response that is specific to an antigen and combats pathogens in a variety of ways. Also known as immunoglobulin.
What does the structure of the amino acid consist of?
It consists of the carboxyl group, amino group(NH2) and an R-group(20 variations).
Define hydrophobic
It is having a tendency to repel and be insoluble in water
Define hydrophilic
It is having a tendency to be attracted to and dissolve in water
What are some examples of hydrophilic and hydrophobic R-groups?
Alanine(hydrophobic R-group), Tryptophan(hydrophobic R-group) and tyrosine(hydrophilic R-group)
What is the Primary structure for proteins?
refers to the sequence of amino acids in a polypeptide chain
What is the Secondary structure for proteins?
the level of protein structure where the amino acid chain forms either alpha-helices, beta-pleated sheets or random coils.
What is the Tertiary structure for proteins?
refers to the overall functional 3D shape of a protein.
What is the Quaternary structure for proteins?
the level of protein structure where multiple polypeptide chains bond together, where other non-protein groups are added to form a fully functional protein.
Define Nucleic acids
They are the class of macro-molecule that includes DNA and RNA. They are classified as polymers made out of nucleotides.
Define and explain the concepts of a Nucleotide
A Nucleotide is the monomer subunit of nucleic acids. They consist of a nitrogen-containing base, a phosphate group and a five-carbon sugar.
Define DNA
It is a double stranded nucleic acid chain made up of nucelotides. It carries the instructions for proteins which are required for cell and organism survival.
Define Chromosomes
It is a structure made up of protein and nucleic acids that carry genetic information.
Explain which complimentary bases pair with one another
In the structure of DNA, the base Adenine(a) pairs with Thymine(T) and Guanine(g) pairs with Cytosine(c).
Define messenger RNA(mRNA)
It is RNA molecules that are produced during Transcription and carry genetic information from the nucleus to the ribosomes for protein synthesis.
Define transfer RNA(tRNA)
It is RNA that recognises specific codons on the mRNA strand and adds the corresponding amino acid to the polypeptide chain during protein synthesis.
Define gene
It is a section of DNA that carries the code to make a protein.
Define the process of Transcription
it is the process whereby the sequence of DNA is used as a template to produce a complimentary sequence of mRNA.
Define the process of Translation
it is the process where an mRNA sequence is read to produce a corresponding amino acid sequence to build a polypeptide.
Define a codon, start codon and stop codon
A codon is sequence of three nucleotides in mRNA coding for one amino acid. A start codon is the sequence in mRNA that signals the start of Translation. The stop codon is the sequence of three nucleotides in mRNA that signals the stop of Translation.
Define a promoter
A promoter is the sequence of DNA which RNA polymerase binds to.
Define RNA polymerase
DNA polymerase is the enzyme responsible for constructing a pre-mRNA sequence from a DNA sequence during transcription.
Define Introns and Exons
Introns are the non-coding regions of DNA that do not code for proteins. They are spliced out during RNA processing. Exons are regions of DNA that code for proteins and are not spliced out during RNA processing.
Define a termination sequence
A termination sequence is a sequence of DNA that signals the end of transcription.
Define an operator
An operator is a short region of DNA that interacts with repressor proteins to alter the transcription of an operon.
Define a repressor protein
A protein coded for by a regulatory gene that prevents gene expression by binding to its operator.
Explain a leader region
A leader region is the segment of DNA or mRNA that immediately precedes the coding region. AKA the leader sequence or the leader segment.
List the steps of Transcription
Initiation, Elongation and Termination.
Define Initiation (Transcription)
specific proteins called transcription factors bind to the promoter region to initiate transcription. RNA polymerase binds to the promoter region. This signals for the weak hydrogen bonds between the two strands of DNA to break, resulting in the bases of each strand being exposed and DNA being unzipped and unwound.
Define Elongation (Transcription)
RNA polymerase moves along the template strand of DNA, reading nucleotide sequence and uses complementary RNA to produce pre-mRNA. The pre-mRNA is synthesised so new RNA nucleotides are added to exposed 3’ end. Strand that is not read by the RNA polymerase is called the coding strand.
Define Termination (Transcription)
Transcription ends when RNA polymerase reaches the termination sequence of a gene. RNA polymerase then detaches, releasing the pre-mRNA and the DNA molecule winds up again into a double helix. Pre-mRNA is then processed to become mRNA, carrying message for protein synthesis from DNA in the nucleus to the ribosomes located in cytosol and other locations.
Define Splicing
Splicing is a process where introns are cut out of a pre-mRNA molecule, where exons join together.
Define Alternative Splicing
Alternative Splicing is the process where different exons may be spliced, resulting in single gene producing different mRNA strands.
List the steps of Transcription
Initiation, Elongation and Termination
Define Initiation (Translation)
It is when the 5’ end of the mRNA binds to ribosome and is read until the start codon(AUG) is recognised. Then, the tRNA with a complimentary anticodon(UAC) binds to the ribosome and delivers amino acid, signifiying start of Translation.
Define Elongation
It is when the first amino acid is attached, mRNA molecule is fed through the ribosome so that the next codon can be matched to matching anticodon of tRNA. The first tRNA molecule then leaves the ribosome and is free to pikc up another amino acid and next mRNA is exposed for next reaction.
Define Termination
It is when the reading of mRNA, delivery of amino acids by tRNA, and the linking of amino acids in the polypeptide chain continues until the ribosome reaches the stop codon, signalling the end of Translation.
Define Gene Regulation
Gene Regulation is the control of gene expression, achieved by switching transcription on or off.
Define Regulatory gene
A regulatory gene is a segment of DNA responsible for producing proteins that control expression of other genes.
Explain the trp operon
The trp operon is a series of genes within certain species of bacteria that encode for the production of the amino acid Tryptophan.
Define trp operon repression
trp operon repression is the mechanism for gene regulation within the trp operon whereby repressor proteins stop the initiation of transcription when tryptophan levels are high.
Define trp operon attenuation
trp operon attenuation is the mechanism for gene regulation within the trp operon whereby the premature ceasing of translation stops transcription when tryptophan levels are high.
Define a terminator hairpin
A terminator hairpin is when a loop is formed in mRNA in the presence of tryptophan that ceases transcription of the trp operon.
Define an antiterminator hairpin
An antiterminator hairpin is a loop formed in mRNA when tryptophan is not present that ensures the transcription of the structural genes in trp operon.
Define Exocytosis
Exocytosis is a type of bulk transport that moves large substances out of a cell.
Define a vesicle
A vesicle is a small fluid-filled organelle enclosed in a phospholipid membrane that moves substances around the cell.
