Forensics Unit 5
Hunter Tysver
Chapter 9
Chapter 9
Terms
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copy deck
- tandem repeat
- A region of a chromosome that contains multiple copies of a core DNA sequence arranged one after another.
- DNA Transfer
- The deposition of just a few microscopic cells from a perpetrator onto a victim or an item at the crime scene which can be enough to allow for the development of a DNA profile.
- DNA Profiling
- The act or process of extrapolating identifying information about a person based on DNA levels in the range of one-billionth of a gram.
- hybridization
- The process of joining two complementary strands of DNA from a double stranded molecule.
- low copy number
- A sample containing fewer than eighteen DNA-bearing cells.
- Four Bases of DNA
- Adenine, cytosine, guanine, and thymine.
- polymerase chain reaction
- A technique for copying or multiplying small quantities of DNA found in crime-scene evidence outside a living cell.
- primer
- A short strand of DNA used to target a region of DNA for replication by PCR.
- chromosome
- A threadlike structure made up of DNA and protein, along which genes are located.
- multiplexing
- The concept of simultaneously extracting, amplifying, and detecting a combination of STRs.
- Mitochondrial DNA
- Located outside the cell's nucleus and inherited directly from the mother only.
- ase
- The suffix meaning enzyme.
- homologous
- Chromosomes that are not identical, but carry genes that code for the same traits.
- short tandem repeat
- Locations on the chromosome that contain sequences of three to seven base pairs that occur over and over within the DNA molecule.
- DNA backbone
- The bonds formed between the sugar of one nucleotide and the phosphate group of the next nucleotide.
- locus
- The specific site of a particular gene on its chromosome.
- agar
- An extract of sea weed used to solidify gels in electrophoresis.
- degree of discrimination
- The ability to separate the pattern under study from one produced using a random sample from the population.
- heterozygous
- An individual having two different alleles for a give trait
- the power of STRs
- What makes them so attractive to forensic scientists is that hundreds of different types are found in human genes.
- allele
- The alternate form of a gene.
- three advantages of PCR
- Best used with small fragments of DNA no longer than a couple hundred bases; short segments are more stable and less subject to degradation; it can amplify minute quantities of DNA, overcoming the limited sample size problem often associated with crime scene evidence.
- human genome
- The order of bases on all twenty-three pairs of human chromosome that can be passed down from parent to offspring.
- nitrogenous base
- Any of the five nitrogen containing molecules in a nucleotide.
- protein
- A polymer of amino acids connected in a specific order to produce a 3-D structure that allows its function.
- sequencing
- A technique used to determine the order of bases in a DNA segment.
- three
- The number of nucleotides in a codon.
- mutation
- a random change in the DNA sequence that can be inherited by succeeding generations.
- RFLP
- A large segment of DNA that contains a core sequence of 15-35 bases that repeat up to a thousand times.
- DNA at work
- DNA directs the production of proteins, which are made by combining unit molecules called amino acids.
- DNA Polymerase
- The enzyme that adds nucleotides together in DNA replication.
- ose
- The suffix meaning sugar.
- polymer
- A substance made up of repeating unit molecules.
- Y-STRs
- Short tandem repeats found on the Y chromosome used for analyzing samples containing a mix of DNA from more than one male.
- substrate control
- An unstained object adjacent to an area on which biologic material has been deposited.
- electrophoresis
- The motion of charged particles in a colloid under the influence of an electric field; particles with a positive charge go to the cathode and negative to the anode.
- Chargaff
- The individual who discovered the rules of complementary base pairing in DNA.
- negative
- The natural charge of DNA molecules.
- nucleotide
- The unit molecule of all nucleic acids.
- recessive
- The allele that is not expressed in an organism heterozygous for a particular trait.
- germ line
- Cells that ultimately produce gametes.
- RFLP analysis
- Restriction fragment length polymorphisms that form the basis for one of the first DNA typing procedures.
- sex in humans
- A characteristic determined by the presence or absence of the Y chromosome.
- gene
- A segment of DNA that codes for a specific protein.
- diploid
- Any cell having two copies of each chromosome.
- positive RFLP test
- When comparing the DNA fragment patterns of two or more specimens, one merely looks for a match between the band sets.
- replication
- The synthesis of new DNA from existing DNA.
- phenotype
- The physical appearance of an organism with regard to a trait, such as eye color or blood type.
- buccal sample
- Using a swab to collect cells from the mouth and cheek.
- probe
- A known sequence of nucleotide bases from a DNA strand used to detect a complementary sequence in the sample by means of base pairing.
- enzyme
- A biologically active protein that speeds up chemical reactions in a cell.
- nucleic acids
- Large polymers of nucleotides such as DNA or RNA in a cell.
- genotype
- All the alleles present in the chromosomes of a cell.
- phosphate
- A phosphorus atom surrounded by four oxygen atoms that gives DNA an overall negative charge.
- Combined DNA Index System
- A computer software program developed by the FBI that maintains local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and profiles of missing persons.
- restriction enzymes
- Proteins manufactured by bacteria and used by scientists to cut DNA into fragments that can later be incorporated into other DNA molecules.
- paternity testing
- DNA testing procedures that can conclusively determine who the farther is in a disputed case.
- mitochondrion
- The organelle that manufactures ATP in eukaryotic cells.
- pico
- Metric prefix meaning one-trillionth.
- dominant
- An allele that is expressed in an organism heterozygous for a particular trait.
- Standardizing STR testing
- Currently, U.S. crime laboratories utilize 13 STRs for entry into CODIS.
- sugar
- A circular molecule of ribose or deoxyribose.
- Southern blotting
- A technique used to transfer DNA bands from an electrophoresis get onto a membrane so they can be stained and compared.
- disadvantages of mDNA
- Forensic analysis is more rigorous, time consuming, and costly when compared to nuclear DNA analysis; all individuals of the same maternal lineage will be indistinguishable.
- three advantages of STRs
- They are made up of very few base pairs so they may be recovered from bodies or stains that have been subjected to extreme decomposition; they are ideal candidates for multiplication by PCR; 100 times less DNA is required for analysis than that normally required for RFLP.
- Four bases of RNA
- Adenine, cytosine, guanine, and uracil.
- individualization
- The ability to identify an evidence sample as originating from a specific person.
- complementary base pairing
- An orderly arrangement of nucleotides where A binds to T and C binds to G.
- multiplicative law
- The probability of two independent events occurring at the same time is the product of their individual probabilities.
- codon
- A series of three nucleotides in a DNA sequence which determines the shape and function of the protein.
- recombinant DNA
- The joining of DNA segments from two different sources.
- genetic code
- The relationship between the base letters on a DNA strand and the type of protein specified for manufacture by the sequence of these letters.
- trait
- The physical manifestation of an individual's genes.
- forty-six
- The number of chromosomes in each diploid human somatic cell.
- Franklin, Wilkins, Watson, Crick
- Four individuals credited with discovering the double-helix design of DNA.
- gametes
- Haploid sex cells.
- monomer
- The unit molecules of a polymer.
- somatic
- Body cells.
- Key to understanding DNA Typing
- The knowledge that numerous possibilities exist for the number of times a particular sequence of base letters can repeat itself on a DNA strand.
- the central dogma of biology
- DNA is used to make RNA which is used to make PROTEIN (helps us understand how different cells do different things)
- autosomes
- The first 22 pair of human chromosomes.
- epithelial
- Cells on body surfaces such as skin and mucus membranes.
- Key to understanding electrophoresis
- The smaller DNA fragments will move at a faster rate through the gel than the larger ones.
- primers
- Short strands of DNA used to target specific regions of DNA for replication.
- hapliod
- Any cell having a single copy of each chromosome.
- tracking dye
- A material used to visualize the movement of DNA molecules during electrophoresis.