Genetics - Details

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There’s “about” a __% chance of having a boy or a girl depending on which sex chromosome the father passes down.

Inherited or inheritable

Hereditary

The gene variation an individual possesses for a particular trait

Genotype

Different variations of the same gene trait represented as uppercase and lowercase letters; genotypes consist of two allele letters, one comes from and one from dad

Alleles

(uppercase letter) - hides the expression of the other allele’s trait

Dominant Allele

(lowercase letter) - hidden by the dominant allele’s trait

Recessive Allele

Same two uppercase or lowercase letters Also called “Purebred” Remember, the prefix “Hom” means same or similar

Homozygous Genotype

Different letters; one capital, one lowercase Also called “Hybrid” The prefix “Hetero” means different

Heterozygous Genotype

How the genotype is physically expressed; the physical appearance Ex: PP & Pp = Purple; pp = White Because the genotypes PP & Pp both have a dominant allele they both express the dominant purple phenotype Notice that individuals with the same phenotype do NOT have to have the same genotype

Phenotype

Father of Genetics

Gregor Mendel

An organism’s offspring will look like the parent due to its homozygous purebred genotype Ex: The puppies of two true-breeding purebred Golden Retrievers will be 100% Golden Retriever!

True breeding

Purple parent X White parent = All Purple F1 offspring

First Cross

Purple offspring X Purple offspring = F2 with 3 Purple and 1 White

Second Cross

Alleles separate during the formation of sex cell gametes

Law of Segregation

Predicts the outcome probability of genetic crosses Axes are parent’s genotypes; boxes are offsprings’ genotypes The number of boxes will give a ratio of the offspring’s genotypes and phenotypes Genotypic Ratio: 1 TT : 2 Tt : 1 tt Phenotypic Ratio: 3 Tall : 1 Short In ratios, the more dominant version comes first

Punnett Square

Two gene punnett square The two genes he crossed were pea texture, either dominant Round (RR, Rr) or recessive wrinkled (rr) and pea color, either dominant Yellow (YY, Yy) or recessive green (yy).

Dihybrid Cross

Genes can separate during the formation of sex cells gametes and do not have to be linked or inherited together

Law of Independent Assortment

Both alleles are equally as dominant so both are expressed side by side at the same time in a third phenotype Since one allele is not completely dominant over another we can no longer use just one uppercase or lowercase letter like with normal punnett squares. Instead, we have to use two different letters that are both capitalized to show equal dominance. Ex: Black chicken (BB) X White rooster (WW) = Black & White (BW)

Codominance

When one allele is not completely dominant over another resulting in a third mixed phenotype The heterozygous phenotype is a blended mix between the two homozygous phenotypes Ex: Red flower (RR) X White flower (WW) = Pink (RW)

Incomplete Dominance

Genes with more than two alleles resulting in more than just two phenotypes Ex: ABO Blood types Type A = AA or Ao Type B = BB or Bo Type AB = codominant AB Type O = recessive oo

Multiple Alleles

True or False Positive (+) and negative (-) blood type is not determined by multiple alleles. They are just carried on the blood type alleles. Positive blood types are dominant over negative blood types.

True

Traits controlled by two or more genes resulting in many phenotypes Ex: Skin, hair, eye color, etc. “Poly” means multiple or many

Polygenic Traits

The sex of an individual depends on the presence or absence of a Y chromosome. A male’s sex genotype is XY while a female’s is XX. There’s “about” a 50% chance of having a boy or a girl depending on which sex chromosome the father passes down.

Sex Chromosomes

Every other chromosome in your body because there’s only one pair of sex chromosomes per individual We’ve only been doing crosses using traits on autosomes up until this point.

Autosomes

Only located on the “X” sex chromosome Since males don’t have a second back up X they are more susceptible to expressing X-linked traits making these traits more common in men. Females, on the other hand, must have the recessive trait on both X chromosomes to express it. However, females can be heterozygous Carriers for a recessive X linked trait, but not males.

X-Linked Traits

What's an example of females being heterozygous carries for a recessive X linked trait, but not males

Color Blindness

A heterozygous individual carrying a hidden recessive trait who therefore remains unaffected by that trait

Carrier

Trace a family’s genotypes and phenotypes and therefore autosomal or X-linked traits

Pedigrees

Pedigree Key Symbol Circle

Female

Pedigree Key Symbol Square

Male

Pedigree Key Symbol Shaded

Expresses Trait

Pedigree Key Symbol Half-shaded

Carrier

Pedigree Key Symbol Crossed out

Deceased

Warning: Not all pedigrees will use half-filled in shapes to represent carriers because you may be expected to solve for the ___________ of the individuals in the pedigree.

Genotypes and phenotypes

How to Solve an Unknown Pedigree Trait !) Identify whether the trait is ___________ If every “affected” child in the pedigree has at least one parent who is also affected, then the trait is Dominant. If there are “affected” children where neither of their parents are also affected, then it’s Recessive.

Dominant or Recessive

How to Solve an Unknown Pedigree Trait Identify whether the trait is __________ Once you’ve determined if the trait is dominant or recessive, fill out the pedigree as if it’s an X-linked version of that trait and look for discrepancies. For example, if it doesn’t make sense for a child to be affected based on the parents info or vice versa, that’s a discrepancy, meaning it couldn’t possibly be X-linked, so instead it must be Autosomal. If there are no discrepancies, that it is X-linked.

Autosomal or X-linked

Diagrams used to diagnose chromosomal disorders in humans who should normally have no more and no less than 46 chromosomes in 23 pairs

Karyotypes

The 23rd pair are our Sex Chromosomes. Y chromosomes are shorter than X chromosomes because it only carries male developmental genes so a male’s karyotype will have two different sized chromosomes at pair 23 while females will have the same size.

Male/Female Karyotypes

The other 22 pairs of non-sex chromosome are called ________

Autosomes

Allows scientists to compare & identify an individual’s DNA pattern DNA sample will be cut into pieces and injected into the top of a gel slab inside a machine DNA will separate out into different sized pieces based on an individual’s unique DNA sequence The machine emits a charge at the bottom that causes the DNA pieces to move through the gel and form a unique pattern based on the size of the individual’s DNA pieces Smaller pieces move faster and travel further through the gel than large pieces

Gel Electrophoresis

To a certain extent, fingerprints are a unique combination of your parents’ fingerprints Every finger has a different print Ex: Your left thumb is not the same as your right and it’s not just a mirror image either

Fingerprinting

Cloning In 1996, ____ the sheep was the first clone of a mammal. ____ was engineered by taking a cell’s nucleus and DNA from ____ original clone and inserting it into an donor egg cell which was then stimulated to grow and develop into ____.

Dolly

Manipulating the genetic material of living organisms

Genetic Engineering

Bacteria that produce diesel fuel Cows that pass less gas Water filtering plants Pigs that absorb more phosphorus Banana vaccinators for cholera and hepatitis Onions that don’t make you cry Apples that don’t turn brown Web-spinning goat milk

Ex of Genetically Modified Organisms (GMO’S)

When a strand of DNA transforms because it has acquired and incorporated pieces of foreign DNA

DNA Transformation

Discovered when harmless bacteria transformed into harmful bacteria after being mixed with ___________

Dead Pneumonia bacteria

True or False DNA is living so it will breakdown as long as it’s exposed to the elements!

False

Combining a DNA plasmid from a bacterium with a gene of interest from a different organism to copy that gene and produce the protein associated with it so it came be inserted into an organism for engineering purposes

Recombinant DNA

Extra circular DNA in bacteria, that’s separate from its main DNA chromosome, because it contains genes that are only expressed under special conditions

Plasmids

True or False Warning: Not all pedigrees will use half-filled in shapes to represent carriers because you may be expected to solve for the genotypes and phenotypes of the individuals in the pedigree.

True

There’s “about” a __% chance of having a boy or a girl depending on which sex chromosome the father passes down.

Genetics

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