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What is DNA?
Where in the cell is DNA found?
Where does it come from?
What are Chromosomes
Copy questions leave 5 lines after each
one.
Discussion Questions
• What are some important discoveries in genetics?
• What is the structure and function of DNA?
• Where is DNA located?
• Why are some traits passed from parent to
offspring?
• What are the responsibilities of genes?
Preclass: Review Time. Answer in
complete sentences.
1. What structure connects chromatids together?
2. All living things rely on _____________to give
them the energy they need.
3. _________ is the stage of the cell cycle where
the nucleus divides.
4. ________ and ________ are products of
photosynthesis.
5. ________ and ________ are raw materials for
respiration.
6. What is the structure and function of DNA? How
do the nucleotides pair up (AGTC)?
7. • Where is DNA located?
Heredity Preclass
• Copy each term on page 75- using your glossary,
write out the definition for each word.
Heredity
Two ways organisms Reproduce
Sexual reproduction
– Offspring have
characteristics (traits)
from both parents
– These organisms have
two parents
• Female-egg cell
• Male-sperm cell
Asexual Reproduction
– Offspring look exactly
like their parent
– These organisms have
one parent
• Bacteria- binary fission
• Spores
• budding
Heredity- passing of traits
from parents to offspring
Traits are recorded on Genes
in the form of DNA
Making Sense of Genetic information:
Nucleotide Subunits + Sugar +Phosphate
DNA (instructions) Shape- double helix
Genes (heredity information)
Chromosomes (passed from parent to offspring)
Gregor Mendel
• An experiment was done with pea plants in 1800s
in Austria.
• The goal was to find out which traits are dominant
and which traits are recessive
– Dominant traits- always appears, uses a capital letter
as a symbol of the trait
– Recessive traits- recede into the background, uses a
lower case letter as a symbol of the trait
What else did he find out?
• There are different forms of the same gene
(allele)
– Ex. You have a gene for height but you may have
inherited two forms of height tall or short
• Many genes can influence a singe trait
– Ex. Your eyes have color and shape
• One gene can influence many traits
– Ex. tiger gene for fur color also controls eye color-
Answer in your journal
• Some people have brown eyes, some have blue,
some have green. Some people have earlobes
that are attached directly to their head, while
others have earlobes that hang loose. Where do
people get these traits? How are they passed
from one generation to the next?
• Collect Data
Ear Lobe Free
Widow's Peak Present or Absent
Interlocking Fingers Lf over rt Present
Tongue Roller
Hitch-hikers's Thumb
Bent Little Finger
Eye Color Not Blue
Index Finger Short
Dimples
Right Handed
Experiment Continued
• Analyze your data
– Use a sheet of graph paper to show your information
– WHAT ARE THE TRENDS YOU SEE
– ONLY TALK ABOUT YOUR DATA!
• Interpret your data- Draw conclusions
• Communicate your results
Draw Conclusions: Take a look Back at your
Experiment
– Which traits are dominant according to the
information you have. Explain how you know this.
– How could you find out whether or not a trait is
dominant or recessive in your family?
– What would you have done differently to figure out if
a trait is dominant or recessive?
DNA Structure
• The Shape of DNA is called Double Helix
• DNA has a sugar phosphate backbone
• DNA is made up of nucleotide subunits
–
–
–
–
Adenine
Thymine
Guanine
Cytosine
• Information can be organized using a Punnett
Square.
– Genotype- the inherited combination of alleles
• Homozygous (same) BB
• Heterozygous (different)Bb
– Phenotype- the expressed trait (what you see on the
outside)
HOW TO DO A PUNNETT SQUARE
• A Punnett square is a chart which
shows/predicts all possible gene combinations in
a cross of parents (whose genes are known).
Punnett squares are named for an English
geneticist, Reginald Punnett.
Sample Problem Step 1.
• Designate letters which will represent the
genes/traits. Capital letters represent dominant
traits, and lowercase letters represent recessive
traits. T = tall t = short
Step 2.
• Write down the genotypes (genes) of each
parent. These are often given to you or are
possible to determine. TT (tall) X tt (short) - both
homozygous (same) or purebred Step 3.
• List the genes that each parent can contribute.
– Parent 1
– Parent 2
• Step 4.
• Draw a Punnett square - 4 small squares in the
shape of a window. Write the possible gene(s) of
one parent across the top and the gene(s) of the
other parent along the side of the Punnett square.
Step 5.
• Fill in each box of the Punnett square by
transferring the letter above and in front of each
box into each appropriate box. As a general rule,
the capital letter goes first and a lowercase letter
follows.
•
• Step 6.
• List the possible genotypes and phenotypes of
the offspring for this cross.
Interpret your data…
• What are the possible genotype(s) of a tall
plant?
• What are the possible genotype(s) of a short
plant?
• What would be the phenotype of TT?
• What would be the phenotype of tt?
• Why is the phenotype of Tt tall and not
medium/average?
How do these traits get passed on
during sexual reproduction?
• Sperm Cells (male gametes)- contain half of the
genetic information for organisms
• Egg Cells (female gametes)- contain half of the
genetic information for organisms
• How many chromosomes do we have?
• How are these cells produced?
Meiosis
•
Haploid
Cells- half
the DNA
• Types of twins:
• Fraternal - two independent eggs are fertilized by
two independent sperm. Genetically, this type of
twins is the same as regular siblings that happen
to be born at the same time.
• Identical - one egg is fertilized by one sperm then
that zygote splits completely in half to become
two people with identical genes (they basically
started out as one person with one set of genes).
Making Sense of it all:
Nucleotide Subunits + Sugar +Phosphate
DNA (instructions)
Genes (heredity information)
Chromosomes (passed from parent to offspring
DNA Structure
• The Shape of DNA is called Double Helix
• DNA has a sugar phosphate backbone
• DNA is made up of nucleotide subunits
–
–
–
–
Adenine
Thymine
Guanine
Cytosine
DNA
• How does DNA determine what we look like?
– DNA provides the code for making RNA
• RNA is the ribonucleic acid that contains
instructions for making amino acids.
• Amino Acids go to the ribosomes to make
protiens.
– Proteins are made from amino acid
DNA Replication
• When the DNA is copied errors can happen
causing mutations
– Substitution- putting one nucleotide pair in the place
of another
– Insertion-adding in a nucleotide pair
– Deletion- removing on nucleotide pair
– Write an example for each one
– Remember: A-T, G-C
EXAMPLES
ORIGINAL
SUB
DELET.
INSERTION
Origin of Species
• Adaptations- changes a species undergoes to
enhance survival
• Mutations- permanent changes in DNA
• Natural Selection- the most “fit” survive
– Reproduction, finding food, shelter, etc.
Evolutionary Relationships
• Carolous Linnaeus- system of classification or
taxonomy