Bio Chapter 8 DNA structure and function

DNA replication

-each base pair is paired w/ complementary base in other strand -double helix can unwind to allow access (enzyme helicase) -each original strand serves as template for synthesis -yields an exact copy --dna polymerase assemble new strands -first step for all cell divisions (reproduction) --bacteria: 1 chromosome replicates simply --eukaryotes: have multiple so its more complicated

DNA molecule

-stable info storage -2 polynucleotide strands joined by hydrogen bonds -sugar-phosphate backbone -4 bases: ATGC A/T, G/C

DNA building blocks

a DNA strand is a polymer of nucleotides -each nucleotide has 3 phosphate groups, a deoxyribose sugar, and one of 4 nitrogen-containing bases

autosomes

most types of chromosomes are the same in both male and females -of a pair, they have the same length, shape, centromere location, and carry the same genes

francis collins on new drugs

new drugs (?)

nucleosomes

"beads" of DNA molecules wrapping around a core of histone proteins

chromosome structure

1) DNA in a nucleus is divided into chromosomes 2) most condensed, duplicated is packed into an X shape 3) it unravels as a single fiber (hollow cylinder formed by coiled coils) 4) ^the coils consists of a long DNA molecule and associated proteins 5) the DNA molecule wraps around a core of *histone* proteins, forming "beads" called *nucleosomes* 6) the DNA molecule has 2 strands twisted into a double helix

nucleic acid hybridization

Base pairing between a gene and a complementary sequence on another nucleic acid molecule

chromosome number

DNA is divided among a # of chromosomes that differ in length and shape. The sum of all chromosomes in a cell of a given type is the _____ (each species has a characteristic chromosome #) -humans has 46 chromosomes, but our chromosome # is diploid, so we have 23 pairs (2 types of each chromosome)

histone proteins

a core of proteins that the DNA molecule wraps around, forming "beads" called nucleosome

the 4 nucleotide bases

adenine, guanine, thymine, cytosine A=T (double bond) G=C (triple bond)

sister chromatids

after DNA replication, each chromosome consists of 2 DNA molecules, attached at a centromere (X shape), each called a ___

reproductive cloning

artificial twinning (genetically identical individuals)

chargaffs rule

complementary base pairing of DNA sequence: A=T, G=C

craig venter

cracked the human genome energy

types of chromosomes

sex and autosomes

bacteriophage

a virus that infects bacteria -theres a constant battle b/w tons of bacteriophages and viruses -viruses can do reverse transcription, making its dna the dna to be transcribed in the cell, so it produces viruses that viron (?)

chromosome

each DNA molecule is organized as this structure, containing DNA and associated proteins -carries all/part of genetic info -eukaryotic cells have a number of them -during most of cells life, each consists of ONE DNA molecule -its duplicated b4 division -after duplication, each has 2 DNA molecules (sister chromatids) (X shape) --DNA double helix wraps around spools of histone proteins (nucleosomes), spool into a coil, condense into an line (X for duplication)

DNA polymerase

enzyme that assembles new strands of DNA during replication -attaches to a primer to get started -can only go from 5' to 3' direction

karyotype

image of an individuals complement of chromosomes arranged by size, length, shape, and centromere location -reveals abnormalities in an individuals complement of chromosomes

Oswald Avery and Maclyn McCarty

in 1940s they tried to identify Griffiths 'transforming principle' -isolated lipid, protein, and nucleic acid components of S cell -then isolated RNA and DNA, and DNA prevailed to be the transforming principle

somatic cell nuclear transfer (SCNT)

lab procedure where an unfertilized eggs nucleus is replaced with a donor nucleus (from a somatic cell) -can be used for medical purposes; *therapeutic cloning*

Johannes Miescher

made a discovery of DNA function in the 1800s -nuclei contain an acidic substance composed mostly of nitrogen and phosphorus -later called deoxyribonucleic

Frederick Griffith

made a discovery of DNA function in the 1900s (can be transferred) -isolated 2 strains (types) of streptococcus pnemoniae (pnumonia bacteria): harmless Rough (R) and killer smooth (S) -dead S killer cells could transfer hereditary material into live R cells, making them S cells

directional synthesis

numbering the carbons of the sugars in nucleotides (of DNA) allows us to keep track of the orientation of DNA strands in a double helix -one side is 5' (5 prime), other end is 3' (3 prime) -dna polymerase can only work from 5' to 3' (directionaly)

mutations

permanent change in the DNA sequence of a cells chromosome -passed to descendants -can be caused by radiation, chemical/infectious agents

DNA ligase

seals any gaps in a replicated DNA sequence, so the new strands are continuous

diploid

some cells are ____, meaning they have 2 of each type of chromosome (pairs)

Hershey-Chase Experiment

tested whether genetic material injected by *bacteriophages* into bacteria is DNA, protein, or both -traced proteins containing sulfur and DNA containing phosphorus

DNA sequence

the order in which 1 nucleotide follows the next along a strand of DNA -varies tremendously among species -100s of millions of nucleotides long -attached by hydrogen bonds -all chromosomes make up your karyotype -humans have 22,333 genes, corn has 50,000 (# is irrelevant)

differentiation

the process during development, cells start using different subsets of their dna, becoming different in form and function (specialized)

semi conservative replication

the process of after DNA replication, one strand of each new molecule is parental and one is new

sex chromosomes

this pair of chromosomes differs among males and females, and those differences determine an individuals sex

DNA sequencing

uses the natural process of DNA replication in a special way to discover what the DNA sequence is -if each base had a unique color, we can see it