chapter 7- DNA structure and replication

DNA

stores biological information necessary for building new organism

chromosome

a single long strand of DNA wrapped around proteins

• 23 pairs and 26 total

23rd chromosome

sex chromosome

• males have X and Y and females have 2 X’s

nucleotide

3 parts (sugar, phosphate group, and a base)

phosphate of one nucleotide binds to sugar of next nucleotide

double helix

spiral structure formed by 2 strands of DNA nucleotides held together by hydrogen bonds

• sugar and phosphate group form the “backbone” of helix

4 nucleotide bases

adenine (A), thymine (T), guanine (G), and cytosine (C)

DNA profile

visual representation of persons unique DNA sequence

DNA replication

natural process where cells make identical copy of a DNA molecule (cells reproduce)

1) enzyme, helicase, unwinds and unzips dNA double helix

2) enzyme, DNA polymerase, reads DNA sequence and incorporates complimentary nucleotides into a new strand

semiconservative

each DNA molecule is made of 1 og strand and 1 new

polymerase chain reaction (PCR)

similar to DNA replication, but in a test tube

• can make billions of copies in just a few hours

genome

1 complete set of genetic instructions encoded in DNA of organism

short tandem re[eat (STR)

section of chromosome where short DNA sequences are repeated

gel electrophoresis

lab technique that separates fragments of DNA by size

CODIS

combined DNA index system, criminal records