Mendel’s Laws of Mendel’s Laws of HeredityHeredity

Why we look the way Why we look the way we look...we look...

What is What is heredityheredity??

The The passing passing on of on of characteristics characteristics (traits)(traits) from parents to offspringfrom parents to offspring

GeneticsGenetics is the study of is the study of heredityheredity

Mendel used Mendel used peas...peas...

They reproduce They reproduce sexuallysexuallyThey have two distinct, They have two distinct,

malemale and and femalefemale, sex cells , sex cells called called gametesgametes

Their Their traitstraits are easy to are easy to isolateisolate

Egg cells

Sperm Cells

Mendel Mendel crossedcrossed them them

FertilizationFertilization - the uniting - the uniting of male and female of male and female gametesgametes

CrossCross - combining - combining gametes from parents gametes from parents with different traitswith different traits

Rule of Unit FactorsRule of Unit FactorsEach organism has two Each organism has two

alleles alleles for each for each traittrait–Alleles Alleles - different forms of - different forms of the same the same genegene

–Genes Genes - located on - located on chromosomes, they control chromosomes, they control how an organism developshow an organism develops

Rule of DominanceRule of Dominance

The trait that The trait that is observedis observed in the offspring is the in the offspring is the dominant trait dominant trait (uppercase)(uppercase)

The trait that The trait that disappears disappears in the offspring is the in the offspring is the recessive trait recessive trait (lowercase)(lowercase)

Law of SegregationLaw of Segregation

The two alleles for a trait The two alleles for a trait must separatemust separate when when gametes are formedgametes are formed

A parent randomly passesA parent randomly passes only oneonly one allele for each allele for each trait to each offspringtrait to each offspring

Law of Independent Law of Independent AssortmentAssortmentThe genes for different The genes for different

traits are traits are inherited inherited independentlyindependently of each of each other.other.

Phenotype & Phenotype & GenotypeGenotype

PhenotypePhenotype - the way an - the way an organism organism lookslooks

–red hair or brown hairred hair or brown hair

genotypegenotype - the - the gene gene combinationcombination of an organism of an organism

–AAAA or or Aa Aa oror aa aa

Heterozygous & Heterozygous & HomozygousHomozygous

HeterozygousHeterozygous - if the two - if the two alleles for a trait are alleles for a trait are different different ((AaAa))

Homozygous Homozygous - if the two - if the two alleles for a trait are the alleles for a trait are the same same ((AAAA or or aaaa))

Dihybrid vs Dihybrid vs MonohybridMonohybrid

Dihybrid CrossDihybrid Cross - crossing - crossing parents who differ in parents who differ in two two traits traits ((AAEEAAEE with with aaeeaaee))

Monohybrid CrossMonohybrid Cross - crossing - crossing parents who differ in only parents who differ in only one trait one trait ((AAAA with with aaaa))

Abnormalities of Chromosomes

Chromosome abnormalities fall into one of two categories: numerical or structural

Numerical abnormality, referred to as "aneuploidy", can be due to whole chromosome number change (having too many chromosomes or too few) or can be due to altered copy number of parts of chromosomes.

Structural changes are referred to as deletions (chromosomal material is missing), insertions (additional chromosomal material is present), inversions (a portion of the chromosome is 'backwards'), and translocations (chromosomal material has moved from one chromosome to another).

BackgroundBackground

Humans, like all other sexually reproducing organisms, receive one copy of each chromosome from each parent at conception (i.e. fertilization). Specifically, an egg contains 23 from the mother (chromosomes 1 through 22, and X), and a sperm contains 23 from the father (chromosomes 1 through 22, and either X or Y). When the egg and sperm fuse at conception, a new individual is created containing 46 chromosomes, the expected number for a human individual.

Abnormalities of Chromosome Number

CHILDREN W/ DOWN CHILDREN W/ DOWN SYNDROMESYNDROME

Trisomy is a type of anueploidy in which there are three copies of a particular chromosome instead of the regular two. Trisomy for most chromosomes is not compatible with life. The most common and recognized type of trisomy is trisomy 21, or Down syndrome.

Monsomy is another type of aneuploidy where there is one copy of a certain chromosome instead of the regular two copies. When this occurs it is almost always lethal. The only complete monosomy that is compatible with life is Turner syndrome, where there is only one X chromosome instead of the normal pair. Below is a depiction of a karyotype of a person with Turner syndrome:

WITH TURNER WITH TURNER SYNDROMESYNDROME

a "webbed" neck (extra folds of skin extending from the tops of the shoulders to the sides of the neck)a low hairline at the back of the neckdrooping of the eyelidsdifferently shaped ears that are set lower on the sides of the head than usualabnormal bone development (especially the bones of the hands and elbows)a larger than usual number of moles on the skinedema or extra fluid in the hands and feet

•DETERMINING YOUR GENES:

TONGUE ROLLING

ATTACHED EARLOBES

Widow's PeakWidow's Peak

AlbinismAlbinism(from albus, "white"; also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved melamin

IDENTICAL IDENTICAL TWINSTWINS

Identical -- Identical -- monozygoticmonozygotic (one zygote) -- (one zygote) -- twins form when a single fertilized egg twins form when a single fertilized egg splits into two genetically identical parts. splits into two genetically identical parts. The twins share the same DNA set, thus The twins share the same DNA set, thus they may share many similar attributes. they may share many similar attributes. However, since physical appearance is However, since physical appearance is influenced by environmental factors and influenced by environmental factors and not just genetics, identical twins can not just genetics, identical twins can actually look very different. Identical twins actually look very different. Identical twins are always same-sex sets. are always same-sex sets.

Fraternal TWINSFraternal TWINSFraternal -- or Fraternal -- or dizygoticdizygotic (two (two

zygotes) -- twins develop when zygotes) -- twins develop when two separate eggs are fertilized two separate eggs are fertilized and implant in the uterus. The and implant in the uterus. The genetic connection is no more or genetic connection is no more or less the same as siblings born at less the same as siblings born at separate times. They may look separate times. They may look alike, or they may not. alike, or they may not.

ENVIRONMENTAL ENVIRONMENTAL INFLUENCEINFLUENCE

SOCIALIZATIONSOCIALIZATION refers to the refers to the developmental period where the ideals developmental period where the ideals of morality and socially acceptable of morality and socially acceptable behavior are instilled in a childbehavior are instilled in a child

EDUCATIONEDUCATION have been determined to have been determined to be significant in the manifestation of be significant in the manifestation of criminal behavior.criminal behavior.

Human being is being Human being is being shape through heredity shape through heredity

and environmentand environment