DNA Structure and Replication

Flashcards about DNA structure, organization, and replication, as well as DNA profiling.

What is the hereditary molecule passed from parents to offspring?

Deoxyribonucleic Acid (DNA)

Where is DNA found in eukaryotes?

Nucleus

Where is DNA found in prokaryotes?

Cytoplasm (nucleoid)

What are chromosomes?

Discreet structures of organized DNA

How many chromosomes do humans have?

46 (23 pairs)

What determines a person's sex?

The 23rd chromosome pair (sex chromosomes)

What is the structure of DNA?

A polymer of nucleotides with a sugar (deoxyribose), phosphate group, and nitrogenous base.

What are the four nitrogenous bases in DNA?

Thymine (T), Adenine (A), Guanine (G), Cytosine (C)

How are the two strands of nucleotides held together in DNA?

By hydrogen bonds between the bases

What forms the outside 'backbone' of DNA?

Sugars and phosphates

What forms the internal 'rungs' of DNA?

Nitrogenous bases

Describe the directionality of DNA strands.

Strands of nucleotides have directionality with a 5’ end (phosphate group) and a 3’ end (sugar).

What does 'antiparallel' mean in the context of DNA structure?

The two strands of nucleotides run in opposite directions (5’ to 3’ and 3’ to 5’).

What is the complementary base pairing rule in DNA?

A pairs with T, and C pairs with G

What is a genome?

A complete set of genetic instructions encoded in the DNA of an organism

What is DNA replication?

The natural process by which cells make an identical copy of a DNA molecule

What does it mean that DNA replication is semi-conservative?

Each new DNA molecule consists of one original strand and one newly synthesized strand.

What enzyme unwinds the DNA helix during replication?

DNA helicase

What enzyme synthesizes a new DNA strand by adding complementary nucleotides?

DNA polymerase

Why is Primase important in DNA replication?

Primase adds a RNA primer (short sequence of RNA nucleotides) that DNA polymerase can use for synthesis

What are short tandem repeats (STRs)?

Sections of a chromosome in which DNA sequences are repeated in noncoding regions of DNA

What laboratory technique replicates a specific DNA segment?

Polymerase chain reaction (PCR)

What are the ingredients in PCR?

Nucleotides, DNA polymerase, Primers, and the DNA sample

What happens during each round of PCR?

The two nucleotide strands separate via heat, and DNA polymerase pairs nucleotides beginning at the primer when cooled.

What is gel electrophoresis?

A laboratory technique that separates fragments of DNA by size

How does gel electrophoresis work?

Apply an electrical current to a gel loaded with DNA causing negatively charged DNA to migrate; shorter fragments travel further

In gel electrophoresis, do shorter fragments travel further, or longer fragments?

Shorter fragments travel the furthest