Aim: Aim: How do your How do your genetics play a role in genetics play a role in the person you are the person you are today?today? Do Now: Do Now: What similarities do you What similarities do you

have with your parents or have with your parents or siblings? siblings?

Homework:Textbook 126-132 #1-5 Homework:Textbook 126-132 #1-5

Human GeneticsHuman Genetics

What is Heredity?What is Heredity?

The transfer of characteristics from one The transfer of characteristics from one generation to the nextgeneration to the next

What are Traits?What are Traits? A characteristic that is determined by A characteristic that is determined by

your genesyour genes A pair of genes will determine the traitA pair of genes will determine the trait

Examples:Examples: Tongue rollingTongue rolling EarlobesEarlobes Widow’s PeakWidow’s Peak Hair WhorlHair Whorl DimplesDimples

What is genetics?What is genetics?

The science of how traits are inheritedThe science of how traits are inherited

How are traits determined?How are traits determined? Dominant GenesDominant Genes – the traits that will – the traits that will

usually appear in the individual usually appear in the individual (represented by an uppercase letter)(represented by an uppercase letter) If an organism has a gene for blue or If an organism has a gene for blue or

brown eyes, usually it will have brown brown eyes, usually it will have brown eyes because it is the dominant geneeyes because it is the dominant gene

Recessive GenesRecessive Genes – The gene hidden by – The gene hidden by the dominant gene the dominant gene (represented by a lowercase letter)(represented by a lowercase letter) Blue-eyed people need two recessive Blue-eyed people need two recessive

genes to show the blue-eyed traitgenes to show the blue-eyed trait

Who is Gregor Mendel?Who is Gregor Mendel?

““Father of Genetics”Father of Genetics” Studied pea plantsStudied pea plants He crossed pea plants with different He crossed pea plants with different

characteristics and studied their offspringcharacteristics and studied their offspring He was able to determine how He was able to determine how

traits get passed on from traits get passed on from

generation to generationgeneration to generation

What is a Punnett What is a Punnett Square?Square? A table that shows A table that shows

the possible results the possible results when the genes of when the genes of two parents are two parents are crossedcrossed

It shows the It shows the probability of a trait to probability of a trait to be expressed in the be expressed in the offspring offspring

BB BB

BB BBBB BBBB

bb BbBb BbBb

B – Brown Eyes

b – Blue Eyes

What is a genotype?What is a genotype?

The genetic code or make up of the The genetic code or make up of the individualindividual

Examples: Examples: BB, Bb, bbBB, Bb, bb

What is a genotype?What is a genotype?

Homozygous dominantHomozygous dominant

– – a pair of dominant genes (BB)a pair of dominant genes (BB) Homozygous recessiveHomozygous recessive

– – a pair of recessive genes (bb)a pair of recessive genes (bb) Heterozygous or hybridHeterozygous or hybrid

– – a mixed pair of one dominant gene and a mixed pair of one dominant gene and one recessive gene (Bb)one recessive gene (Bb)

What is a phenotype?What is a phenotype?

The way an organism looks or behavesThe way an organism looks or behaves Examples:Examples:

GenotypeGenotype PhenotypePhenotype

BBBB Brown HairBrown Hair

BbBb Brown HairBrown Hair

Lets try some Punnett Lets try some Punnett Squares!Squares!

Examples:Examples: BB x bbBB x bb Bb x bb Bb x bb Bb x BbBb x Bb bb x bbbb x bb BB x BBBB x BB BB x BbBB x Bb

B = Brown EyesB = Brown Eyes

b = Blue Eyesb = Blue Eyes

What we are looking for:What we are looking for:

1.1. GenotypesGenotypes

2.2. PhenotypesPhenotypes

3.3. Percentage Brown eyesPercentage Brown eyes

4.4. Percentage Blue EyesPercentage Blue Eyes

Pedigree ChartsPedigree Charts

Allow us to trace certain traits. Helpful for tracking genetic disorders passed down through generations. Ex: Colorblindness

DNA StructureDNA StructureA double helix made of a sugar-phosphate backbone bound in the middle by nucleotide base pairs-The backbone is made up of molecules that have phosphates and sugars – basically the sides of the ladder-The nucleotides,which come in pairs, make up each step of the ladder

NucleotidesNucleotidesEverything that determines what we look like, our likes, our dislikes, whether we’re a morning person or we like to sleep in is largely determined by four nucleotides that are repeated over and over again inside each and of one of our cells.

Adenine

Cytosine

Guanine

Thymine

These four molecules hold our DNA together by binding together in pairs. Adenine and Thymine will always be paired. Cytosine and Guanine will always be paired.

**Guanine will not pair with Adenine, nor Thymine with Cytosine!!!!

Protein BuildingProtein Building

So how does our DNA actually determine why we are made this way?

Earlier in the year, we learned about ribosomes – who synthesize proteins. They get their orders from the DNA.

How??How??The ribosomes will read sections of DNA, and every time it reads three nucleotides, it goes and gets an amino acid. Once it has a few amino acids lined up, it chains them together, forming a protein. That protein then goes out to do it’s job, building your body from the ground up!

Remember – proteins come in many different forms, think of them like tools – many shapes and sizes, all with very different jobs.

Protein BuildingProtein Building

ReplicationReplicationWhen DNA is copied, it is “unzipped”, separating the two strands of DNA.

Once separated, ribosomes work to create a complementary strand.

As the complementary strand is formed, the DNA and the new strand are “zipped” together, creating two separate strands of the same DNA.

Sometimes, errors occurs. These errors are called mutations

MutationMutationMutations can happen for a variety of reasons. Some are good, some are bad. Our DNA has methods built in to find and correct mutations, but not all of them are corrected in time.

If mutations are good, helping the organism to survive, there is a chance that they will be passed on to the offspring. This is a gradual change, that ultimately results in evolution over several generations of a species.

Restriction EnzymesRestriction Enzymes

Enzymes that cut DNA at specific Enzymes that cut DNA at specific locations.locations.

Genetically Engineered Genetically Engineered BacteriaBacteria

Genetically Engineered Genetically Engineered BacteriaBacteria

PlasmidPlasmid (loop of DNA) is (loop of DNA) is removed from bacterial removed from bacterial

cellcell A specific gene is removed A specific gene is removed

from an animal cellfrom an animal cell Animal gene is spliced into Animal gene is spliced into

plasmidplasmid Recombinant DNARecombinant DNA is inserted is inserted

into into bacterial cellbacterial cell Bacteria and it’s descendants will Bacteria and it’s descendants will

now produce an animal now produce an animal proteinprotein

DNA FingerprintingDNA Fingerprinting