Do Now 12/14/15

• Get out the “Genetic Traits” activity from Friday and work on that for about 10 minutes

• Homework: Finish Genetic Traits activity

Guinea Pig• Finalists were, in order

– Taco (23)– Oreo (20)– Plutonium (Pluto) (12)

DNA and Genetics

Who are you?This question can be answered many ways…

• Personality traits– Kindness– Vegetarian or

Carnivore– Competitiveness***Traits you can

control

Who are you?This question can be answered many ways…

• Physical Traits– Height– Eye color– Hair color and texture– Foot size– Bone strength

***Traits you can’t control

Who are you?• DNA controls your inherited traits• DNA is given to each new daughter cell in the cell

cycle to ensure that genetic information and traits are maintained.

DNA Structure

DNA double helix

DNA backbone Bases

• DNA has a structure we call a double helix

DNA Double Helix

Bases are Important!• There are four bases:

• The order of these bases along a strand of DNA codes for your genes.

Adenine A

Thymine T

Cytosine C

Guanine G

DNA is Picky• Just like a model wearing a suit jacket with suit pants, or a t-shirt with blue jeans, A only pairs with T and G only pairs with C.

• You put air (A) in your tires (T)• You put gas (G) in your car (C)

DNA Replication• DNA will unzip, and allow for 2 new

copies of DNA to be made. • How?

– Uses the base pairs to see what piece needs to be added to the DNA next

DNA Replication

• https://www.youtube.com/watch?v=zdDkiRw1PdU

Grasshoppers• Walter Sutton studied sex cells in grasshoppers

– Found 24 chromosomes in “body cells”– Found 12 chromosomes in “sex cells”– What???

Sex Cells• Humans have 46 chromosomes in body cells

• Where does your DNA come from?– Half from Mom, half from Dad

• How many chromosomes in sex cells?• 23

• Body cells have 23 pairs (46 total) of chromosomes– Why pairs?

Meiosis

• Process of creating sex cells from a body cell

• One cell will undergo division twice, creating 4 sex cells

After two cell divisions, four cells with23 chromosomes each are formed.

Do Now 12/15/15• Submit activity in the

box by the window• How do base pairs work

together to ensure that DNA is replicated properly?

• Homework: None

Twins• Identical twins are born with the same DNA

– Fertilized egg will split• Fraternal twins are born with separate DNA

– Two different eggs fertilized by two different sperm

– Much like regular brothers and sisters

Twins• Identical twins later in life do not have the same DNA

– How?• Studies found that certain things can change the DNA

over extended time– Diet and smoking are thought to change DNA– Mutations do change DNA

Genes

• Genes are found on chromosomes

• Genes have multiple alleles – Dominant and recessive

• Each body cell has about 35,000 genes

Protein synthesis• The order of the bases in DNA controls what protein

is to be made– DNA is the instructions for making proteins

• Need a messenger to carry the instructions!

Protein Synthesis

• mRNA is the messenger that carries the “code” to the _______________?– Ribosomes

Protein Synthesis• mRNA gives the ribosomes the instructions, and the

proteins are made from chains of amino acids!

• Video– https://www.youtube.com/watch?v=gG7uCskUOrA

Mutations• A mutation affects the way that proteins are made,

which changes a trait about a person– Substituting a base pair– Deleting a base pair– Adding a base pair

Mutations

Mutations• Mutations can be good and bad

– Mutation that turns a rabbit white• Help or hurt survival chances in a snowy area?• Help or hurt survival chances in a wooded area?

– Mutation that increases resistance to bacteria• Help or hurt survival chances?

Do Now 12/18/15

• Trace the order of steps in DNA replication

OR• Trace the order of steps

in mRNA production

• Finish “Discovering DNA Structure”

• Updated study guide

Additional Terms• Heredity

– The passing of traits from parent to offspring• Dominant

– Only one allele needs to be present for trait to appear

• Recessive– Two alleles need to be present for trait to appear

DNA Replication• DNA will unzip, and allow for 2 new

copies of DNA to be made. • How?

– Uses the base pairs to see what piece needs to be added to the DNA next

DNA Replication

• https://www.youtube.com/watch?v=zdDkiRw1PdU

Protein Synthesis

• mRNA is the messenger that carries the “code” to the _______________?– Ribosomes

Protein Synthesis• mRNA gives the ribosomes the instructions, and the

proteins are made from chains of amino acids!

• Video– https://www.youtube.com/watch?v=gG7uCskUOrA

DNA And mRNA Comparison• Both produce genetic material• Both read the existing base pairs to determine the

sequence of the new strand(s)• Both happen inside the nucleus

Contrast

• DNA Replication– Produces 2 new strands

(DNA)– Unzips the entire

molecule– DNA cannot leave the

nucleus

• mRNA Production– Produces 1 new strand

(RNA)– Only opens the molecule

at the bubble – RNA can leave the

nucleus

Mutation Ripple effect• change in order of bases in DNA → • change in order of bases in mRNA → • change in protein produced → • change in one of your traits