DNA (Ch 7) DeoxyriboNucleic Acid The Blueprint of Life

DNA Structure nuclear DNA is found in the nucleus of cells in chromosomes nuclear DNA is found in the nucleus of cells in chromosomes

# of Chromosomes in human somatic cells, 46 chromosomes (23 pairs with one from mom, one from dad) in human somatic cells, 46 chromosomes (23 pairs with one from mom, one from dad) in human sex cells, only 23 chromosomes in human sex cells, only 23 chromosomes

DNA Structure mitochondrial DNA is a circular loop and ONLY inherited from mother mitochondrial DNA is a circular loop and ONLY inherited from mother

DNA Structure composed of smaller units called nucleotides - ph osphoric acid (phosphate) - deoxyribose sugar - nitrogenous base (Adenine, Thymine, Guanine or Cytosine)

DNA Structure shape: double helix (twisted ladder) side/rails: sugar-phosphate backbone steps/rungs: N bases

Watson & Cricks double helix

Nitrogenous Bases PURINES (big) and PYRIMIDINES (small) PURINES (big) and PYRIMIDINES (small) A & GC & T A & GC & T purines hydrogen bond with pyrimidines purines hydrogen bond with pyrimidines A = TC = G A = TC = G triple bonddouble bond triple bonddouble bond

Adenine bonds only to Thymine Cytosine bonds only to Guanine

Be able to find the complementary DNA strand given a DNA sequence: Be able to find the complementary DNA strand given a DNA sequence: 5 CCGATTACGGAA 3 5 CCGATTACGGAA 3 3 ? 3 ? ANS: GGCTAATGCCTT 5 ANS: GGCTAATGCCTT 5

Genes and Alleles alleles are alternative forms of a gene; one allele from mom, one from dad alleles are alternative forms of a gene; one allele from mom, one from dad human genome includes the total amount of DNA in a cell human genome includes the total amount of DNA in a cell only ~1.5% of the DNA is coding (makes proteins) – the rest is junk DNA only ~1.5% of the DNA is coding (makes proteins) – the rest is junk DNA

Function of DNA Hereditary instructions Chemical code for every trait Blueprint for making proteins

Chromosome DNA Code segments of DNA that code for a single trait Genes are segments of DNA that code for a single trait The code is in sets of 3 (triplicate) called CODONS Every codon = 1 amino acid in the protien Hair Color Eye Color Acid Sugar-T-A-Sugar Acid Sugar-G-C-Sugar Acid Sugar-C-G-Sugar

DNA code: DNA code: Ccc gga tta ggc Ccc gga tta ggc How many amino acids will this encode for? How many amino acids will this encode for? = 4 = 4

DNA Replication during mitosis – when the chromosomes double during late interphase 2N

DNA Replication 1. DNA unwinds 2. DNA unzips using DNA polymerase 3. Corresponding base pairs line up 4. DNA reforms 5. Zips back up and winds back up

DNA Identification differences in DNA sequences (lengths, sequences of bases): polymorphism differences in DNA sequences (lengths, sequences of bases): polymorphism use VTNR and STR in noncoding section to identify individuals use VTNR and STR in noncoding section to identify individuals Compare 13 regions to build a bank Compare 13 regions to build a bank Human differ <0.1% from each other Human differ <0.1% from each other

According to the Innocence project, about 200 people who have been jailed have been proven innocent and released from prison using DNA evidence According to the Innocence project, about 200 people who have been jailed have been proven innocent and released from prison using DNA evidence

DNA Identification Tissue Matching Tissue Matching - 2 samples with same pattern are same person (crime scene vs. suspect) Inheritance Matching Inheritance Matching - bands on a child must be present in one of the parents

DNA Typing portions of the DNA molecule contain sequences of bases that are repeated numerous times are known as VNTR portions of the DNA molecule contain sequences of bases that are repeated numerous times are known as VNTR to a forensic scientist, these tandem repeats offer a means of distinguishing one individual from another through DNA typing to a forensic scientist, these tandem repeats offer a means of distinguishing one individual from another through DNA typing

Restriction Enzymes can be thought of as highly specialized scissor that cuts a DNA molecule when it recognizes a specific sequence of bases. can be thought of as highly specialized scissor that cuts a DNA molecule when it recognizes a specific sequence of bases.

PCR Testing with the knowledge of how DNA replicates, forensic scientist are able to use PCR to take minute quantities of DNA and multiply it many millions of times to make a larger sample with the knowledge of how DNA replicates, forensic scientist are able to use PCR to take minute quantities of DNA and multiply it many millions of times to make a larger sample

Electrophoresis materials are forced to move across a gel- coated plate under the influence of an electrical current materials are forced to move across a gel- coated plate under the influence of an electrical current substances such as DNA can be separated and characterized substances such as DNA can be separated and characterized

bands and widths are significant in matching samples of DNA bands and widths are significant in matching samples of DNA DNA fingerprinting can (a) match crime scene DNA with a suspect, (b) determine maternity, paternity, or match to another relative, (c) eliminate a suspect, (d) free a falsely imprisoned individual, and (e) identify human remains. DNA fingerprinting can (a) match crime scene DNA with a suspect, (b) determine maternity, paternity, or match to another relative, (c) eliminate a suspect, (d) free a falsely imprisoned individual, and (e) identify human remains.

CODIS perhaps the most significant tool to arise from DNA typing is the ability to compare DNA types recovered from crime scene evidence to those of convicted criminals perhaps the most significant tool to arise from DNA typing is the ability to compare DNA types recovered from crime scene evidence to those of convicted criminals CODIS (COmbined Dna Index System) is a computer software program developed by the FBI that maintains local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and of missing persons CODIS (COmbined Dna Index System) is a computer software program developed by the FBI that maintains local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and of missing persons

DNA Sources saliva, blood, seminal fluid, skin, hair saliva, blood, seminal fluid, skin, hair INDIVIDUAL EVIDENCE INDIVIDUAL EVIDENCE

Pedigrees Dominant trait- a trait seen in every generation Distributed equally between males and females Recessive trait – seen rarely in a family

Sex-linked trait- seen more in males than females. At least three fold more males than females -Males inherit the gene from MOM -Girls inherit the gene from DAD -- gene found on the X chromosome -So girls have two alleles for the gene -Boys have one allele (NO CARRIERS) -*** Must be able to do pedigrees and calculate -Percent of genotype and phenotype possibilities