Genetics - part one

Simple Genetics (One Gene for One Trait)

n Mendel’s Pea Plants. – Tall or short. – Round or wrinkled. – Etc… n Dominant & recessive. n Purebred or Hybrid. n Simple Punnett Squares.

Gregor Mendel TEST 1 on SLIDES 1-19 1

n Gregor Mendel was a monk who worked with pea plants in the mid 1800’s. Today he is known as “Father of Genetics.” He was curious about the “factors” acting on inheritance.

Are there patterns?

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What is Genetics?

n Genetics is the branch of biology that deals with heredity.

n Heredity is the passing of traits from parents to offspring. – Parents à offspring

n Traits are characteristics of an organism. – Human examples: height, hair, eye color.

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1 Genetics - part one

n Gene: a section/piece of DNA on a chromosome that codes for a specific trait. § Alleles = alternate forms of a gene (Ex: Blood type A/B/O). § Genes tend to come in pairs (alleles).

n DOMINANT: an allele whose trait always shows up in the organism when the allele present. – (CAPITAL LETTER)

n recessive: an allele hidden by dominant. – (lower case letter)

n Genotype: genetic makeup; allele combinations. – (Ex: BB, Bb, bb)

n Phenotype: physical appearance of an organism (Ex: Brown hair)

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How to make a test cross (aka Punnett Square)

Parent #1 alleles

Offspring Offspring

Offspring Offspring Parent #2 alleles

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2 Genetics - part one

Diagrams & math can be used to predict the probability that a trait will pass from parent(s) to offspring.

Punnet Squares

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Complete this test cross between two purebred pea plants:

T T

t

t

T = tall stem

t = short stem 9

3 Genetics - part one

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Where are genes?

n Genes & chromosomes come in pairs. Most human cells have 23 pairs of chromosomes in the nucleus containing just under 30,000 genes.

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4 Genetics - part one

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CHROMOSOMES

n Half from each gamete (sperm and egg). n But what about asexual reproduction???

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Code Conservation

n All species on Earth use the same chemical code (GTCA). Biodiversity comes from SNP’s along a gene sequence.

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5 Genetics - part one

Must Know n Allele Challenge n Chromosome Terms n DNA (GTCA) n Central Dogma n Dominant n Co-dominance n Gene & Genetics n Dihybrid cross n Genotype n Diploid n Heterozygous n Haploid n Heredity n n Homozygous Histones n Hybrid n Gametes n Meiosis n Locus (Loci) n Mutation n Mutagen n Offspring n Pedigree chart n Phenotype n Purines (A & G) n Probability n Pyrimidines (T & C) n Punnett Square (Cross) n Purebred n Recessive 16 n Traits

Challenge Mendel’s Dihybrid cross

n We can look at two traits simultaneously using a dihybrid cross. n Consider shape & color in peas – R: round r: wrinkled – Y: yellow y: green – Cross two heterozygotes RrYy x RrYy – Try in your notes now!

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RY Ry ry rY

RY

Ry

ry

rY

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6 Genetics - part one

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GENETICS PART TWO -COMPLEX- NON-MENDELIAN

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DNA Structure understood 1953

Watson & Crick Rosalind Franklin21

7 Genetics - part one

DNA

*Human Genome mapped in 2003 22

Central Dogma DNA à mRNA à Protein

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The Limits of Mendel’s work

n Mendel’s experiments with pea plants looked at one gene for one trait. – This pattern of inheritance is called Mendelian.. § Some examples: Cheek dimples, face freckles & cleft chins § Tom Bradyà

n Few human traits actually obey this model

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8 Genetics - part one

Polygenic Traits

n Most human traits are polygenic, which means they are controlled by multiple genes. – This leads to a wide array of phenotypes. – Simple Punnett squares do NOT work for polygenic traits. § EX: Human height & eye color.

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Dynamic Development (GxE)

n Genes interact with their environment (GxE) – In other words, there is a relationship between your genetics & the way you live your life. § Nutrition, hormones, sensory input, physical and, etc…

n Epigenetics: Markers & tags (i.e. methyl groups), along with histones affect the epigenome of an organism. 26

Mutations

n Mutations are changes in the DNA bases. – G. T. C. A. – Change can be letter addition, substitution, deletion or inversion. n Mutations can be good, bad or indifferent to an organism. n Mutagens are agents capable of causing a mutation, such as UV light or certain chemicals.

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9 Genetics - part one

Mutations & Evolution

n Mutations drive evolution. – Since all living things use the same chemicals (G.T.C.A.) for their “code,” changes are necessary to give rise to new species. § A concept better known as genetic variation. – Observed at the taxonomic levels (D.K.P.C.O.F.G.s.) n Genetic Variation à Biodiversity.

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Glowing mutant mice, frog/duck genetic mutants.

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Drug resistant bacteria, mushroom mutant, lungfish, tomato mutations.

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Quotes:

n “It’s not that I’m so smart, it’s just that I stay with problems longer.” -Albert Einstein. n “I'm not out there sweating for three hours every day just to find out what it feels like to sweat.” -Michael Jordan. n “Some people want it to happen, some wish it would happen, and others make it happen.” -Michael Jordan.

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CALGENE 1994-1997 First GM Tomato approved by FDA

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11 Genetics - part one

Human Genome Project 1987-2003.

[~3.3 billion base pairs]

Faroe Islands (Denmark) ~ 50,000 People. Genome sequencing project for entire population (2013)

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