genome
the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes
chromosome
A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information
gene
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).
human genome project
An international collaborative effort to map and sequence the DNA of the entire human genome.
DNA
Deoxyribonucleic acid; the genetic material that carries information about an organism and is passed from parent to offspring.
base pair
two nucleotides on complementary strands of DNA that form a pair, linked by hydrogen bonds; the pattern of pairing is adenine (A) with thymine (T) and cytosine (C) with guanine (G)
genbank
sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations.
ancient dna
DNA found in archaeological contexts , preserved in ancient remains, bones, plant seeds, mummified tissue, fossils
biomolecule
large and complex molecule with spcific biological function eg lipid, carbohydrate, protein DNA
advantages of DNA versus morphology
exits in allmost all cells/tissues, identical for sam individuals but different for each person, population species, predictable inheritance pattersn , plenty of markers available
preserved DNA
relatively little bigger than 600 bp in length, some 400, mostly 300 bp and shorter are preserved,
process for analyzing aDNA
Bone containing aDNA is ground into powder, incubated, made into bone solution, DNA is extracted, DNA is amplified using PCR, amplified DNA is sequenced.
first aDNA extracted
1980 LAdy Dai preserved DNA extracted from mummified body
first aDNA analyzed
1984 - Quagga -aDNA cloned and seqenced
PCR invented
Karry Mullis 1985
first human fossil aDNA extracted from
1997 NEanderthal
2006 NEanderthal
genome sequenced
structure of DNA
double helix/double Strand, basic unit is a nucleotide with sugar phosphate backbone
3'
nucleotieds added
5'
no nucleotides added (grows from this end)
guanine pairs with
adenine
adenine pairs with
guanine
thymine pairs with
cytosin
cytosin pairs with
thymine
weaker nucleotide bonds
A-T
stronger nucleotide bonds
G-C
aDNA addresses questions of :
human evolution, disease and health of past populations, sex determination, kinship relationships , population movements and phylogenetic relationships, flora and fauna of past climates other arch and anth issues,
aDNA is used for forensic purposes
degraded DNA of human tissues/skeleton, trace tissues of endangered animals and plant species. wildlife conservation
aDNA is preserved in:
ancient remains such as archaeological bones, plant seeds, mummified tissues, fossils
aDNA versus Morphological
aDNA can be used to ID to species , population and individual, sex.
- exists in almost all tissues,
-has predictable inheritance patterns.
Morphological id is limited :
sex id can be inconclusive, other id not always possible
- fragmentary,
- burnt/damage
different types of DNA
nuclear, mitochondrial, chloroplast (plants only)
base base links of nucleotides broken by
enzymes , heat
chemical bonds
covalent bonds stronger than hydrogent bonds : sugar phospahte links tronger than base links
C-G Bonds are stronger
A-T bonds are weaker
Denature of DNA molecule
-DNA boiled in solution:
-bonds broken
-melts into single strand
-when cooled single strands collied and complimentary sequences will reassociate to double stranded (hydrogen bonds form)
Tm
temperature of melting
"temperature a whic 50% of DNA molecules are single stranded
-Tm is sequence dependant
Tm is greater the longer the sequence
Tm is greater the more c-G within fragment (less A-T)
Tm is less the shorter the sequence
Tm is less the mo
A-T
weaker bonds lower Tm
C-G
stronger bonds, greater Tm
Denature
modify by heat
DNA function
Must be able to...
1. replicate
2. make proteins by : 3 bases = codon : codes for 1 amino acid, amino acids form changes which create proteins
3. coordinate activities of proteins to produce bodies or have some way to translate the info it carries about m
central dogma
genetic information is coded in self-replicatingDNA and undergoes unidirectional transfer to messenger RNAs in transcription which act as templates for protein synthesis in translation
DNA sequence variation
if DNA sequence varies in a gene it can change the protein that is produced by the genetic code (but 1.) if is in a non-coding area will not make a difference 2.) several 3 letter codons can each produce the same protein
Why does DNA need to replicate itself ?
-reproduction of cells
-growth and maintenance
generating sperm and eggs fro reproduction of individuals/ species
chemical polymerization of DNA
Major Components
-fragment of DNA (template)
-DNA Polymerase
-mag nesium for polymerase catalyst
dNTP (precursor for nucleotides - raw material)
-optimal chemical condition (buffer)
coding and non-coding DNA sequences
Humans have 90% non coding sequences "junk " DNA
-10% coding seqenceds
A change in coding seqnece can mean
1.) a protein change
can be acted upon by natural selection
2.) no change if codon is for same protein
a change in non-coding sequence
no effect on
types of DNA
mitochondrial mtDNA chloroplast cDNA, nuclear nDNA
mitochondria mtDNA
-small oval shaped organelles
sites of aerobic respiration
generally major energy production centers in eukaryotes
animal mtDNA geneomes approc 16 kbp
relatively stable
chloroplasts cDNA
chloroplasts are in plants only
larger than mtDNA
sites of photosynthesis
-geneomes are approx 120-200k bp
nuclear DNA
DNA present within the nucleus of a cell. This form of DNA is inherited from both parents.
-chromosomes
-linear
-2 copies per cell (one from each parent)
-3 billion bp
-mendelian inheritance
-DNA recombination
-diploid
-lower mutation rate
mtDNA
-single DNA molecule
-circular
-thousands of copies per cell
-16k bp
-maternal inheritance
-no recombination
-haploid
-higher mutation rate
diploid
(genetics) an organism or cell having two sets of chromosomes or twice the haploid number
haploid
term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes
mendelian inheritance
-the basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment
-a mendelian trait is determined by 2 copies of the same gene, called alleles
chromosomes
A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information.
homozygous
describes an individual that has identical alleles for a trait on both homologous chromosomes, as opposed to heterozygous where each allele is different
heterozygous
having dissimilar alleles at corresponding chromosomal loci (expression of trait is determined by dominant allele)
loci
point on the chromosome where the gene is found
maternal inheritance
Genes that are inherited only from the mother, such as mitochondrial genes (all organelles come only from the ovum).
human genome project
An international effort to map the complete human genetic code. This effort was essentially completed in 2001, though analysis is ongoing.
gene databases
Genbank, EMBL, DDBJ - info is pooled and made available for free