What is a gene?
segment o DNA that encodes a functional product, usually a protein
What is genome?
entire DNA sequence of an organism
What is chromosome?
structure containing DNA that physically carries hereditary information, chromosomes contain genes
What is genetics?
study of what genes are, how they carry information, how information is expressed and how genes are replicated
What is phenotype?
manifestation of genotype (what you can see and test for, what proteins are made and expressed)
What is genotype?
actual genes present, information that codes for characteristics
What is structure of DNA?
Sugar-phosphate backbone, nucleotides held together by weak hydrogen bonds
What does anti-parallel mean?
sugar-phosphate backbone of one strand is upside down relative to the backbone of the other stand
What nucleotides are in DNA, and which ones pair?
Adenosine, Thymine, Guanine, Cytosine
Adenosine pairs with Thymine
Guanine and Cytosine pair
What is function of DNA polymerase?
synthesizes DNA, proofreads and repairs DNA
What is function of ligase?
makes covalent bonds to join DNA strands, joins Okazaki fragments and new segments in excision repair
What is function o RNA polymerase?
copies RNA from a DNA template
What is function of helicase?
unwinds double-stranded DNA
Where does DNA synthesis take place in Eukaryotes and Prokaryotes?
In eukaryotes takes place in nucleus in prokaryote in the cytoplasm.
What is the replication fork?
where DNA unwinds
What is role of primer?
RNA primer initiates DNA synthesis
What does semiconservative mean?
One parent strand is constantly transferred on to daughter helix of DNA
What are the leading strand and the lagging strand in DNA replication?
Leading strand is synthesized continuously by DNA polymerase, lagging strand is synthesized discontinuously
What are Okazaki fragments and where does energy come from to join them?
segments of DNA synthesized discontinuously, ligase joins fragments, energy comes from hydrolysis of phosphate bonds
What is transcription?
DNA is transcribed to make mRNA. Begins when RNA polymerase binds to promoter sequence, proceeds in 5-3" direction, stops when it reaches terminator sequence
What is difference between DNA and RNA?
DNA is genetic material, directs protein synthesis, replicates itself before cell division, sugar is deoxyribose, double strand coiled into a double helix. RNA carries out genetic instructions for protein synthesis, sugar is ribose, single strand straight or folded
What is genetic code?
nucleotide triplets of DNA and RNA molecules that carry genetic information in living cells
What does degenerate mean?
more than one codon for one amino acid
How many nucleotides are needed for amino acid?
What is a start codon?
either of two codons, AUG or GUG, that signal initiation of translation and the fist amino acid in polypeptide chain
What is a stop codon?
any of three codons in a molecule of mRNA that don't code for an amino acid and signal termination of the synthesis of protein
What is most common amino acid start codon?
What are codons?
sequence of three nucleotides that together form a unit of genetic code in DNA or RNA molecule
What are anticodons?
sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to complimentary codon in mRNA
Where are codons found?
Where are anticodons found?
found on tRNA
what is translation?
whole process by which the base sequence of a mRNA is used to order and to join amino acids in a protein
Where does translation take place Eukaryotes?
in ribosomes in nucleus
where does translation take place in prokaryote?
What does structure of prokaryote cell allow it to do regarding transcription and translation?
allows to occur at same time, lacks introns
Describe prokaryote ribosome
Large subunit with tRNA binding sites, and small subunits. first binding sit is P, second is A, they form polypeptide bond, move to E site
What is constitutive gene?
expressed at a fixed rate, needed all the time, used for major processes like glycolysis
what are operons?
linear sequences of DNA composed of a promoter sequence, followed by an operator gene, followed by one or more structural genes that act as blueprints for proteins, can be inducible (turned-on by substrate) or repressible (turned-off by a product)
What is promoter and operator?
where RNA polymerase binds, on/off switch
what is trp operon?
operon that promotes production of tryptophan when tryptophan isn't present in environment, represses gene trancription
what is lac operon?
lactose binds to repressor protein, allowing gene transcription
What does cAMP have to do with lac operon?
As concentration of glucose increases amount of cAMP decreases, as cAMP decreases amount complex decreases. Decrease in complex inactivates promoter, lac operon is turned off. positive control over the expression of lac operon
What is difference between DNA of eukaryotic and prokaryotic cells?
Prokaryotic DNA is circular and there is only one replication origin when replication starts. Eukaryotic DNA is linear, when replicated theres as many as 1000 replication origins
What is an intron?
segment of DNA or RNA molecule that doesn't code for proteins and interrupts the sequence of genes, not in prokaryotic DNA
What is exon?
segment of DNA or RNA molecule containing information coding for a protein or peptide sequence
what are snRNPs?
small nuclear ribonucleic particles are RNA-complexes that combine with unmodified pre-mRNA and various other proteins to form a spiceosomal
what is conjugation?
transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells
What is sex pili?
filament projector on surface of bacterium that are important in conjugation
What is recombinant DNA?
DNA that has been formed artificially by combining constituents from different organisms
What is mutation?
changing of structure of a gene resulting in variant form that may be transmitted to subsequent generations
What are two main kinds of mutations?
frame-shift and base substitution
what is missense mutation substitution?
creates codon for a different amino acid, may or may not affect function of protein
What is silent mutation?
base substitution may not change amino acid, common if substitution is in third nucleotide of codon
what is frame-shift mutation?
shifts reading frame for each amino acid, changes every amino acid after change
what is mutagen?
agent that causes mutations
what is carcinogen?
substance capable of causing cancer in living tissue
what are nucleoside analogs?
molecules that act like nucleosides in DNA synthesis, include antiviral products used to prevent viral replication in infected cells
what is thymine dimer?
pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by UV irradiation
what does exonuclease do?
How does ionizing radiation affect DNA?
can cause mispairing and physical breaks in chromosomes
`What does auxotrophic mean?
auxotrophic mutant is mutant with differential nutrient requirements from parent strain
what is replica plating?
Sterile velvet is pressed on grown colonies on master plate, cells from each colony transferred from velvet to new plate, plates incubated, growth on plate compared
What is vertical and horizontal gene transfer?
Vertical-occurs during reproduction between generations of cells, horizontal-transfer of genes between cells of same generation
What is Ames test?
reversion test, allows knowledge of what gene is being mutated and know exactly what type of mutation is being reverted. begin with histidine-dependent bacteria, look for revertant ability to grow on histodine negative media
what is Griffiths experiment?
demonstrated genetic transformation using encapsulated an nonencapsulated bacteria, proved recombination of bacteria DNA
what are transposons?
sequences of DNA that can move around to different positions within a genome of a single cell, process called transposition
what is a plasmid?
genetic structure in a cell that can replicate independently of chromosomes
What is DNA transfer between f+ and f- cell?
when an F factor (plasmid) is transferred from a donor (f+) to a recipient (f-), the f- cell converts to f+ cell.
what is transduction?
process of transferring genetic material from one cell to another by plasmid or bacteriophage
what is R factor?
name for plasmid that codes for antibiotic resistance
what is transformation?
process by which the genetic makeup of a organism is altered by insertion of new gene into its genome
what are competent cells?
take up foreign DNA wanted to be included in cell