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 has a structure we
call a double helix
DNA
DNA
double backbone
helix
Bases
DNA Double Helix
Bases are Important!
• There are four bases:
Adenine
A
Thymine
T
Cytosine
C
Guanine
G
• The order of these bases along a strand of DNA
codes for your genes.
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.co
m/watch?v=zdDkiRw1Pd
U
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 with
23 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.co
m/watch?v=zdDkiRw1Pd
U
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