Covers topics such as DNA and RNA structure, replication, transcription and RNA processing, translation, regulation of gene expression, general gene expression, cell specialization, mutations, and biotechnology.
Purines
Nucleotides with a double ring structure.
IE: Adenine and guanine
Pyrimidines
Nucleotides with a single ring structure.
IE: Cytosine, thymine, and uracil
Antiparallel
The opposite of parallel; the two strands run in opposite directions.
One strand runs 5’ to 3’ and the other runs 3’ to 5’.
Plasmids
Small, circular DNA molecules that are separate from chromosomes.
Contain useful genes for a particular environment
Typically not required for survival
RNA
Ribonucleic acid (polymer that creates proteins via translation)
Single stranded
A=U and C=G
DNA
Deoxyribonucleic acid (polymer containing genetic information)
Double stranded
A=T and C=G
Origin of Replication
The origin (place) at which the sequence of replication starts and DNA is opened to form the replication fork.
Topoisomerase
An enzyme that prevents strain ahead of the replication form by relaxing supercoiling.
Helicase
An enzyme that unwinds the DNA strands at each replication fork.
Replication Fork
The active area in which DNA replication takes place.
Primase
An enzyme that initiates replication by adding primers (short segments of RNA) to the parental DNA strand.
DNAP III
An enzyme that attaches to each primer on the parental strand, moving in the 3’ to 5’ direction, adding nucleotides to the new stand in the 5’ to 3’ direction.
Leading Strand
The strand in which DNAP III follows helicase and only one primer is required.
Lagging Strand
The strand in which DNAP III moves away from helicase and requires many primers.
Okazaki Fragments
Segments of the lagging strand
DNA Ligase
The enzyme that joins okazaki fragments together to form a continuous DNA strand.
Primers
Short segments of RNA that serve as the foundation for DNA synthesis.
Telomeres
Repeating units of short nucleotide sequences that do not code for genes.
Form a cap at the end of DNA to help to postpone erosion
Added by telomerase
Telomerase
The enzyme responsible for the creation of telomeres.
Mismatch Repair
When enzymes remove and replace the incorrectly paired nucleotide(s) of a mismatch.
Nuclease
An enzyme that can remove segments of nucleotides if the segments of DNA are damaged, allowing those segments to be replaced by other enzymes.
DNAP 1
Adds nucleotides to new DNA strand and proofreads the added bases
Also repairs mismatches
Gene Expression
The process by which DNA directs the synthesis of proteins.
Transcription
The synthesis of RNA using information from DNA, which allows for the “message” of DNA to be transcribed.
Occurs in the nucleus
Translation
The synthesis of a polypeptide using information from RNA.
Occurs at the ribosome
Nucleotide sequence becomes an amino acid sequence
mRNA
Carries information from the DNA (at nucleus) to the ribosomes (in cytoplasm).
Synthesized during transcription using a DNA template
tRNA
Useful in the process of translation, with each carrying a specific amino acid. Allow information to be translated into a peptide sequence.
Can attach to mRNA via their anticodon
Anticodon
A complimentary codon to mRNA that is located on tRNA.
rRNA
Helps in forming ribosomes and linking amino acids together.
Codons
mRNA nucleotide triplets that code for amino acids.
Template Strand
The strand of DNA that is transcribed in the process of transcription.
Also known as the noncoding strand, minus strand, or antisense strand
Redundancy
In terms of genetics, this refers to the fact that more than one codon codes for each amino acid.
Reading Frame
The codons on the mRNA must be read in the correct groupings during translation to synthesize the correct proteins, so they must be read in the right frame.
5’ Cap
The 5’ end of the pre-mRNa receives a modified guanine nucleotide “cap".
Poly-A Tail
The 3’ end of the pre-mRNA receives 50-250 adenine nucleotides.
RNA Splicing
When sections of the pre-mRNA, called introns, are removed and the exons are joined together.
Alternative Splicing
When a single gene can code for more than one kind of polypeptide and splicing occurs.
Stop Codon
A codon that does not code for an amino acid, but rather signals for a release factor hydrolyzing the bond that holds the polypeptide to the P site.
When this is added and mRNA reaches the A site of the ribosome, termination occurs (step 3 of translation).
Operons
A group of genes that can be turned on or off
Consist of promoter, operator, and genes.
Promoter
The part of an operon where RNA polymerase can attach.
Operator
The part of an operon that is the on/off switch.
Genes
The part of an operon that codes for related enzymes in pathways.
Repressible
A type of operon in which transcription is usually on, but can be repressed (stopped).
Inducible
A type of operon in which transcription is usually off, but can be induced (started).
Regulatory Gene
A gene that produces a repressor protein that binds to the operator to block RNA polymerase from transcribing the gene.
Always expressed, but at low levels
Binding of a repressor to an operator is always reversible
Allosteric Activator
Substrate that binds to allosteric sites and stabilizes the shape of an enzyme so that the active sites remain open (remain in the active form).
Allosteric Inhibitor
Substrate binds to allosteric sites and stabilizes the enzyme shape so that the active sites are closed (in the inactive form).
Histone Acetylation
Adds acetyl group to histones, which loosens the DNA.
A form of eukaryotic gene expression regulation.
DNA Methylation
Adds methyl groups to DNA, which causes the chromatin to condense.
A form of eukaryotic gene expression regulation.
Control Elements
Sections of non coding DNA that serve as binding sites, where gene expression can be increased or decreased by binding of activators or repressors.
Cytoplasmic Determinants
Substances in the maternal egg that influence cells.
Induction
Cell to cell signals that can cause a change in gene expression.
Pattern Formation
A “body plan” for the organism that is influenced by both cytoplasmic determinants and induction.
Homeotic Genes
Genes that map out the body structures.
Apoptosis
Programmed cell death.
Allows structures to take their form.
Critical in cell differentiation.
Morphogenesis
The physical process that gives an organism its shape.
Differentiation
The process by which cells become specialized in their structure and function.
Epigenetic Inheritance
A form of inheritance in which a parent’s experiences, through epigenetic changes, are passed down to offspring.
Mutations
Changes in the genetic material of a cell, which can alter phenotypes.
A primary source of genetic variation
Substitution
A mutation in which one nucleotide and its partner are replaced with another pair of nucleotides.
Nondisjunction
A mutation where chromosomes do not separate properly in meiosis, which results in the incorrect number of chromosomes.
Ex: Down Syndrome - Trisomy 21
Translocation
A mutation where a segment of one chromosome moves to another.
Inversions
A mutation where a segment is reversed.
Duplications
A mutation where a segment is repeated.
Deletions
A mutation where a segment is lost / deleted.
Horizontal Gene Transfer
A form of exchange of genetic material in prokaryotes through the movement of material between different organisms (and different cells).
Transformation
The uptaking of DNA from a nearby cell.
Transduction
The viral transmission of genetic material.
Conjugation
The cell to cell transfer of DNA.
Transposition
The movement of DNA segments within and between DNA molecules.
Point Mutations
Changes in a single nucleotide pair of a gene.
Genotype
An organism’s sequence of DNA.
Phenotype
The observable expression of a genotype.
Gel Electrophoresis
A technique used to separate DNA fragments by size.
DNA is loaded into wells on one end of a gel and an electric current is applied.
DNA fragments are negatively charged so they move towards the positive electrode.
PCR (Polymerase Chain Reaction)
A method used in molecular biology to make several copies of a specific DNA segment.
Segments of DNA are amplified
Results analyzed using gel electrophoresis
DNA Sequencing
The process of determining the order of nucleotides in DNA.