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DNA, Heredity, & Genetics

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Brian Jones

on 16 January 2018

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Transcript of DNA, Heredity, & Genetics

DNA, Heredity, & Genetics
Ch. 10, 11, 12, & 13
Main Concepts:
Transcription & Translation
Mutations & Mistakes
Simple to Complex Genetics & Heredity
Adv. Genetics & Gen. Tech.
- contains all the genetic information for proteins/enzymes--> for making organisms; located in the nucleus of every single eukaryotic cell
Structure- Double Helix; Made of Nucleotides (a nucleic acid polymer)
Anti-parallel- 3' or 5', stands run opposite
phosphate- backbone connecting adjacent nucleotides
deoxyribose- 5C sugar connects backbone to nitrogen base (less 1 Oxygen)
nitrogen bases- purines (2 C-ring; A&G) & pyrimidines (1 C-ring; T&C)
Complimentary Nitrogen Base Pairs- Adenine & Guanine; Thymine & Cytosine
A to T, C to G across the ladder

- contains the information for building proteins from the DNA code
Single Stranded; also made of Nucleotides (nucleic acid polymer)
phosphate- part of backbone connecting nucleotides
ribose (5C sugar has one more Oxygen the deoxyribose)
nitrogen base- Uracil not Thymine, U of RNA binds to A in DNA
Transcription - mRNA copy of DNA is made which carries the DNA message from the nucleus to the ribosome; RNA Splicing edits exon from intron RNA before the edited mRNA leaves the nucleus; exon mRNA exits the nucleus to be translated at the ribosome into an amino acid chain-


explained in depth
: Helicase unzips the DNA, upstream Promoter finds TATA Box which initiates, RNA polymerase pairs nucleotides, Termination signal stops; a 5' cap & poly A tail are added before RNA Splicing; exon mRNA leaves the nucleus moving to the ribosome complex
Mendelian Genetics - SMG
Genotype- the allele, or gene, combination; Phenotype- the physical appearance (expression)- what it looks like
S.M.G.- Phenotype for a trait comes from a single allele- Aa, AA, or aa; Capital letter= Dominant, lowercase= recessive
AA or
aa; Heterozygous Aa - (aka hybrids) The Dominate trait is
expressed, recessive can be passed down; can be easily modeled with Punnett Squares
Simple Recessive Disorders- overall rare traits but more prevalent in certain populations, can be potentially fatal, parents must be Carriers or Heterozygous (Aa) for the trait
 Sickle Cell Anemia and Resistance to Malaria (video below)
ex.- Cystic Fibrosis, Tay-Sachs, Phenylkentonuria
Simple Dominant Heredity & Disorders- more common, often "harmless" physical features- knuckle hair, attached earlobes, Hapsburg lip, tongue rolling
Others Very Harmful: Huntington's Disease- rare but fatal late onset Dominant disease.
Why would they be rare?
Would you want be tested for (incurable) hereditary diseases?
More Complex Heredity
Incomplete Dominance
- results in
ex.- snapdragons- white R1R1 + red RR = pink RR1
- Both alleles are expressed "equally" or together
= checkered, spotted or "roan" cattle,
Phenotypes resulting from Multiple Alleles or Genes
Multiple Allelic
- multiple expressions of a "single" 2 allele trait: pigeon colors, blood type (A, B, AB, O- A,B codominant, i recessive; ii=O)
Polygenic Inheritance
- one "trait", mult. genes: skin color, height (13 known "height" genes)= a standard distribution of phenotypes
Sex Determination & Inheritance
22 autosomes, 1 sex chromosome XX female or XY male; not the only way in nature but true for humans
(TedED Sex Det. video)
Sex Linked Traits-
are located only on the X or Y chromosome, trail usually expressed in males X1Y, while females are carriers X1X (ex. colorblindness, male pattern balding, hemophilia)
Thomas Hunt Morgan (discovered sex linkage) & Alfred Sturtevant (discovered
Linked Genes
& began
Gene Mapping
Environmental Influences (nature vs nurture)
Age, gender, hormone structure differs causing further variation
External- temperature, light, chemical, infection
Internal- horns, color (elaborate males), baldness pattern
Meiosis- production of haploid sex cells (gametes- eggs, sperm in humans)
Results in genetic recombination
sex & fertilization
P.M.A.T.x2- 2 phases- Meiosis I & Meiosis II
Differences from Mitosis- homologous chromosomes pair up forming tetrads (4 chromatids) in PI; crossing over and independent allele assortment & segregation occurs in Meiosis I make 2 new diploid cells ; Meiosis II results in 4 haploid cells (each containing only 1 unique chromatid for each chromosome)

Fertilization of gametes: egg + sperm = a zygote (mammals- morula, blastula, gastrula, fetus, infant...)
Biology Unit 4 Overview- Genetics
Advanced Genetics & Genetic Technology
Genetic Mistakes
Copying DNA for the purpose of cell division (mitosis or meiosis); occurs during S (synthesis) phase of Interphase
DNA Replication- Semiconservative Replication pg 333
Enzymes- Helicase unzips, an RNA primer starts, DNA polymerase copies/pairs; proceeds 5' to 3' directionally
Leading strand (one RNA primer, then DNA polymerase follows) vs Lagging strand (requires several RNA primers & DNA polymerases working backwards; DNA ligase links Okazaki Fragments together)
DNA Replication
Types of RNA
RNA is used in Transcription & Translation NOT DNA Replication
- "messenger" brings coded info from DNA in the nucleus to the ribosome; result of
 mRNA structure - long "unzipped" codon strips of transcribed DNA info that can travel to the ribosome; edited into exon mRNA during RNA splicing
- "transfer" translates mRNA chains by pairing codons with the tRNA anticodons & the their corresponding amino acid during
 tRNA structure- coiled up nucleotide with an anticodon & a specific amino acid attached at opposite ends
- "ribosomal" enzymes that assemble the amino acid chains from tRNA as they read the mRNA codons Ribosome structure- 2 part rRNA enzyme "blob" that feeds the mRNA strip through the blob allowing tRNAs to bring the amino acids that the rRNA attaches into an amino acid chain
Translation - three nitrogen bases of mRNA code copied from DNA into mRNA are known as a codon; tRNA anticodons pair with mRNA codons for a specific amino acid; rRNA from the ribosome complex binds the amino acids in correct order; the developing protein continues to fold & bend as the polypeptide chain grows
Protein Synthesis
- Any change in the DNA sequence that also changes the protein it codes for; often negative effects, sometimes minor, rarely positive or beneficial- a "positive" mutation may direct the evolution of a species
(ex. bacterial antibiotic resistance)
Mutations may be spontaneous replication/pairing errors or the result of mutagens/carcinogens; enzymes help proofread (3 billion nucleotide pairs= lots of opportunities for mistakes); Induced mutations from environmental chemical exposure (benzo-(a)pyrene)
Mitosis- an enzyme malfunction or DNA replication error/mistake often results in impaired cell function/metabolism or cancer (uncontrolled mitosis/cell cycle), this can spread to tissues & potentially organs but not to offspring; aging my be the accumulation of less functional DNA, genes, & enzymes over a lifetime of mutations (as well as shortened telomeres); increased mutagen exposure throughout lifetime plays a major role in your genetic health
Types of Mutations
Always depends on where (sense or nonsense strand) and what is being coded for; "important/vital" genes, higher levels genes, or in noncoding portions of DNA
Point mutations- miss-paired nucleotides; THE DOG BIT THE CA
; Example Sickle-cell anemia (P-S Lab 11-3 p. 305); Wet/Dry ear wax
Frameshift- nucleotide insertion or deletion, "shifts" the entire segment of code; THE DO
BIT THE CAR --> Deletion of
G becomes
is the improper separation of chromosomes or chromatids during meiosis; can be passed to the offspring; gamete/zygote rejected or dies or BDs & GDs
Chromosomal Mutations- deletion, insertion, inversion, translocation; chromosome can detach & reattach incorrectly or be completely lost
ex. Translocation- part of 1 chromosome breaks off and is add to chromosome 3
Polyploidy- any organisms with extra chromosomes (developing plant hybrids)
Ex.- trisomy, monosomy, triploly (ie. Downs Syndrome- Trisomy of C21)
Selective Breeding, Inbreeding/Backbreeding, Test Cross, Hybridization, Recombinant DNA, Transgenic Organisms, Restriction Enzymes, Vectors, Plasmid, DNA Sequencing, Gel Electrophoresis, Genome, Linkage Map, Gene Therapy, DNA Fingerprinting, Cloning, Polymerase Chain Reactions (PCR), Artificial Embryo Twining (AET), Somatic Cell Nuclear Transfer (SCNT)
(SNAP video: Genes & Cloning)
Goals: Gene Therapy, Disease Diagnosis & Prevention
- nature vs nurture; internal vs external environment on genes expression; DNA Methylation; Histone Acetylation; MicoRNA
- interaction of genes that are not alleles that can affect the expression or suppression of another gene; (color & albanism)- on/off switches- DNA Methylation, Histone Acetylation, Mirco RNA
X Inactivation
- Barr Bodies- Stem cell centers- cells with different activated X chromosomes; Mary Lyon- Lyonisation in female calico cats
Developmental Regulatory Genes & HOX Genes
- where, when , how to construct an organism from embryo to death; hierarchy of genes

Graphical evaluation of a "Blood Line"; Pedigrees do not imply that Genotype is always known; often used to track recessive disorders; or to encourage desired traits- dogs, cattle, pigs
Circle= female; Square= male
Fully Shaded= expressed homozygous recessive phenotype, or a dominant trait
Open= an unknown genotype or unexpressed phenotype- Homo or Hetero; may be an "unknown carrier"
 1/2 Shaded= known carrier, heterozygous
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