Genetics Notes Who is Gregor Mendel? Principle of _____________________– Inheritance of one trait has _________________on the inheritance of another trait “___________________”

Traits Genetics – study of how _________ are passed from __________ to ______________

Traits are determined by the __________on the ______________________. A gene is a segment of _________that determines a _______________.

Chromosomes come in _________________pairs, thus ____________come in pairs. Homologous pairs – _________________ genes – one from female parent and one from male parent Example: Humans have 46 chromosomes or ____ pairs. One set from dad – 23 in __________ One set from mom – 23 in _________

Gene for ________ ______ (blue eyes) Gene for ____________ (brown eyes) Homologous pair of chromosomes One pair of Homologous Chromosomes: _______– different _____(possibilities) for the same _____ – ex: blue eyes or brown eyes

Dominant and Recessive Genes Gene that ___________________the other gene from “showing” – ________________ Gene that _________________“show” even though it is ____________– _________________ Symbol – Dominant gene – ________case letter – ____ Recessive gene – ________case letter – ____ Dominant color Recessive color

Example: Straight thumb is ______________ to hitchhiker thumb___= straight thumb __= hitchhikers thumb (Always use the same letter for the same alleles— No S = straight, h = hitchhiker’s) Straight thumb = TT Straight thumb = Tt Hitchhikers thumb = tt * Must have __ recessive _______ for a recessive trait to “______”

Both genes of a pair are the same – ____________ or _______________ TT – homozygous _____________ tt – homozygous _____________ One dominant and one recessive gene – _________________or _________________ Tt – heterozygous BB – Black Bb – Black w/ white gene bb – White

Genotype and Phenotype Combination of genes an organism has (_____________ ____________) – ______________ Ex: TT, Tt, tt ___________________________resulting from gene make-up – _________________ Ex: hitchhiker’s thumb or straight thumb

White fur (b) Punnett Square and Probability Used to __________the _________ gene makeup of ____________– Punnett Square Example: Black fur (B) is dominant to white fur (b) in mice 1.Cross a ______________male with a ______________________ female. Black fur (B) White fur (b) Heterozygous male White fur (b) Homozygous recessive female

Bb bb Write the ratios in the following orders: Genotypic ratio homozygous : heterozygous : homozygous dominant recessive Phenotypic ratio dominant : recessive b b b B Possible offspring – 2N Male gametes - N (One gene in sperm) Female gametes – N (One gene in egg) Male = Bb X Female = bb Genotypic ratio = 2 Bb : 2 bb 50% Bb : 50% bb Phenotypic ratio = 2 black : 2 white 50% black : 50% white

BBBb bb Bb B Genotypic ratio = 1 BB : 2 Bb : 1 bb 25% BB : 50% Bb : 25% bb Phenotypic ratio = 3 black : 1 white 75% black : 25% white Cross 2 hybrid mice and give the genotypic ratio and phenotypic ratio. Bb X Bb b

BBBb bb B b B b Example: A man and woman, both with brown eyes (B) marry and have a blue eyed (b) child. What are the genotypes of the man, woman and child? Bb X Bb Man = Bb Woman = Bb

Sex Determination People – _______chromosomes or _____pairs 22 pairs are ___________________(look alike) – called _______________-– determine body traits 1 pair is the ______chromosomes – determines sex (male or female) Females – sex chromosomes are ___________(look alike) – label __ Males – sex chromosomes are different – label ____

XX XY X Y What is the probability of a couple having a boy? Or a girl? Chance of having female baby? 50% male baby? 50% Who determines the sex of the child? father X X

Incomplete dominance and Codominance When one allele is NOT completely _____________ over another (they _________) – _______________________ Example: In carnations the color red (R) is incompletely dominant over white (W). The ________ color is _________. Give the genotypic and phenotypic ratio from a cross between _____________________. RW X RW RRRW WW R W R W Genotypic = 1 RR : 2 RW : 1 WW Phenotypic = 1 red : 2 pink : 1 white

When _________ alleles are _______________– ____________________ Example: In certain chickens black feathers are codominant with white feathers. Heterozygous chickens have black and white speckled feathers.

Sex – linked Traits _________for these ______ are located _______ on the ___chromosome (NOT on the Y chromosome) X linked alleles __________ show up in _______ whether ___________ or _____________ because males have only _____ X chromosome

Examples of ________________sex-linked disorders: 1._____________________ – inability to distinguish between certain colors Color blindness is the inability to distinguish the differences between certain colors. The most common type is red-green color blindness, where red and green are seen as the same color. You should see 58 (upper left), 18 (upper right), E (lower left) and 17 (lower right).

2. ________________– blood won’t clot

XNXNXNXN XNXnXNXn XNYXNYXnYXnY XNXN XnXn XNXN Y Phenotype: 2 normal vision females 1 normal vision male 1 colorblind male Example: A female that has normal vision but is a ______ ______________ marries a male with ______________. Give the expected phenotypes of their children. N = normal vision n = colorblindness X N X n X X N Y

Multiple Alleles _____________________of the __________gene that code for a ____________trait In humans, ____________________is determined by 3 alleles – ___, ____, and _____ BUT each human can only _____________ alleles 1.Dominant – A and B (codominance) Recessive – O 2. Blood type – A = AA or AO B = BB or BO AB = AB O = OO

AB Example: What would be the possible blood types of children born to a female with type AB blood and a male with type O blood? AB X OO AOBO AOBO O O Children would be type A or B only

Mutations Mutation – sudden _____________________(change in _________ pair sequence of __________) Can be : _____________ mutations – organism ____________ to survive: genetic disorders, cancer, death ________mutations – allows organism to ____________ ______: provides _______________ __________ mutations – ________ harmful nor helpful to organism Mutations can occur in 2 ways: __________________ mutation or __________________ mutation

Chromosomal mutation: ________________________than a gene mutation more ________– affects entire ____________, so affects ___________________ rather than just one caused by failure of the _____________ chromosomes to _________________ normally during meiosis _________________no longer look the same – too few or too many genes, different shape

Examples: __________syndrome – (Trisomy 21) ___chromosomes, extra chromosome at pair _______

_________________syndrome – only ______ chromosomes, missing a ________ chromosome (X) _______ affected – short, slow growth, heart problems

_________________ syndrome – ____chromosomes, _______ chromosomes (XXY) _________________affected – low testosterone levels, underdeveloped muscles, sparse facial hair

Having an ____________of chromosomes is ________ in ____________, but in ___________ it makes them ___________and ______________. Hardier

Gene or Point Mutation _______________ and __________________ only _____________ is altered

Examples: Recessive gene mutations: _____________________– ____________________ are sickle shaped instead of round and cannot carry enough _____________ to the body tissues – heterozygous condition protects people from _____________

____________________– ______________ builds up in the _____________ ___________________________– deterioration of the ____________ ________________ – early death Mutated genes produce enzymes that are less effective than normal at breaking down fatty cell products known as gangliosides. As a result, gangliosides build up in the lysosomes and overload cells. Their buildup ultimately causes damage to nerve cells.

_____________________(PKU) – an __________________ common in ___________ cannot be broken down and as it builds up it causes ____________________ – newborns are tested for this Dominant gene mutations: _____________________– gradual _______________ of __________________, shows up in _____________and is _________ ___________________ – variety of _________________ abnormalities

Detecting Genetic Disorders picture of an individual’s chromosomes – ___________ amniotic fluid surrounding the embryo is removed for analysis – _________________________ Female with _______ syndrome