DNA Flashcards
Describe an Exon:
- make up 1.5% of the entire human genome
- encoded DNA with direction to build proteins and other important molecules
- 24,000 genes
- scientists can identify slight variations between individuals
Describe an Intron:
- non-coding segments of DNA
- make up 98.5% of entire human genome
- “junk” DNA
- may be important in gene splicing
- vary widely from individual to individual
To avoid DNA evidence contamination, crime scene investigators should:
i. Wear disposable gloves and change them often
ii. Use disposable instruments for handling each sample
iii. Avoid talking, coughing, or sneezing over evidence
iv. Do not touch your face or body when collecting or packaging evidence
v. Air-dry evidence before packaging. If evidence cannot be dried, it may be frozen.
vi. Avoid using plastic bags to store evidence that contains DNA; use paper bags or envelopes
vii. Keep evidence cool and dry during transportation and storage. Avoid direct sunlight which can
damage DNA.
Which shape represents a phospate group in the nucleotide?
Circle
Describe STR:
- Short Tandem Repeats
- 2 - 5 bases in length
- short repeating sequences found in 12 loci on various human chromosomes
- preferred by Forensic Scientists for analysis in creating DNA profiles
Describe VNTR:
- Variable Number Tandem Repeats
- 9-80 bases in length
What does Purine match with?
Pryimidine
How accurate (percentage) is DNA fingerprinting when ruling an individual out as the father?
100
What shape represents a Deoxyribose?
Pentagon
True or False: Most lab techniques used for DNA fingerprinting were not intended for these purposes, but instead were developed for use in the medical field for diagnosis and treatment of diseases.
True
What’s true about DNA and chrmosomes?
- DNA exists as pairs of chromosomes in the nucleus
- An individual person has the same DNA in every cell of their body that contains a nucleus
- One person’s DNA is different from all other people’s DNA (except identical twins).
What is Gel Electrophoresis used for today?
- establish maternity and paternity
- identify individuals who are related
- study biodiversity of species
- identify victims of war and large scale disasters
Put the steps of DNA fingerprinting in order:
Extraction: DNA is collected from the suspect with a buccal swab
The DNA is cut with restriction enzymes.
Amplification: billions of copies are made of the isolated segment of DNA using PCR.
DNA fragments are placed into the wells in the agarose gel.
Electrical current is applied and DNA becomes negatively charged.
DNA migrates through agarose gel from negative to positive creating banding patterns in the gel. DNA is sorted by size - the smaller fragments move farther and faster.
A DNA fingerprint is created and compared to DNA fingerprints from the crime scene.
What’s the description of exponential amplification?
Millions of copies of DNA segments that investigators want analyze are created.
What’s the shape of nitrogenous bases in the nucleotide?
Rectangle
