DNA Flashcards
What is DNA?
Deoxyribonucleic Acid, the genetic blueprint for all living things
Where is nuclear DNA found?
In every cell that has a nucleus
Which human cells do not have a nucleus?
Human red blood cells
List some sources of DNA.
- Body fluids
- Blood
- Semen
- Saliva
- Urine
- Earwax
- Sweat
- Gum
- Lipsticks/balm
- Envelopes
- Contact surfaces
- Eyeglasses
- Bottles/cans
- Hamburger buns
- Hair roots
What is a nucleotide made up of?
- A nitrogenous base
- A carbohydrate
- A phosphate group
What are the nitrogenous bases in DNA?
- Adenine (A)
- Thymine (T)
- Cytosine (C)
- Guanine (G)
What forms the primary structure of DNA?
The sequence of nucleotides
Describe the secondary structure of DNA.
Two single strands of DNA are joined to form a double helix; the sugar and phosphate form the backbone, and nitrogenous bases form the rungs.
What is the base pairing rule in DNA?
A always binds to T and G always binds to C
How many hydrogen bonds form between A and T?
Two hydrogen bonds
How many hydrogen bonds form between G and C?
Three hydrogen bonds
What does it mean if two DNA bases are complementary?
If the sequence of one strand is known, the sequence of the other strand can be determined.
What is the tertiary structure of DNA?
The double helix is twisted upon itself and wrapped around proteins (histones) to form chromosomes.
How many pairs of chromosomes do humans have?
23 pairs
What are genes?
Units of inheritance that are particular sequences of nucleotides located on chromosomes.
What is a locus?
The location of a gene on a chromosome.
What are polymorphic genes?
Genes that have more than one form, known as alleles.
What is a homozygote?
An individual with two identical forms of a gene.
What is a heterozygote?
An individual with two different forms of a gene.
List environmental factors that can cause DNA damage.
- Sun/UV light
- Temperature
- Humidity
- Dirt/bacteria
- Chemicals
What is the first type of DNA analysis performed?
RFLP (Restriction Fragment Length Polymorphism)
What is the purpose of gel electrophoresis?
To separate DNA or proteins based on their size using an electric current.
What happens to DNA during electrophoresis?
DNA migrates towards the positive electrode due to its negative charge.
What is PCR?
Polymerase Chain Reaction, a method for making copies of DNA.
What are the components of PCR?
- Template DNA
- Primers
- Polymerase
- Nucleotides
- Buffer
- Magnesium ions
What are the steps in PCR?
- Denaturation
- Annealing
- Extension
What is STR in forensic DNA analysis?
Short Tandem Repeats, areas of DNA analyzed for forensic purposes.
What does the product rule in statistical analysis do?
Multiplies the frequencies of independent events to determine a combined frequency.
What is CODIS?
Combined DNA Index System, a database of genetic profiles.
What is mitochondrial DNA (mtDNA)?
DNA found in the mitochondria of cells, inherited maternally.
How many copies of mtDNA can be found per cell?
Up to 1,000 copies.
What are sequence polymorphisms?
Differences in the sequence of nucleotides identified in mtDNA.
What can mitochondrial DNA analysis be useful for?
Identifying remains, unknown soldiers, and samples without nuclear DNA.
What is the significance of Y-STRs?
Y-specific short tandem repeats are male-specific markers useful in certain forensic cases.
