EQ: Where does an organism gets its unique characteristics?
1
Fri. 3/1/19 NB PG. 2
2
1. Turn to page 2 in your
notebook
2. Make a quick list of
the characteristics you
have of the choices on
the left.
TREE
OBJECTIVE:
Find the most and least common combination of three traits in our class!
PTC paper: In 1931, a chemist named Arthur Fox was pouring some powdered PTC into a bottle. When some of the powder accidentally blew into the air, a colleague standing nearby complained that the dust tasted bitter. Fox tasted nothing at all.
▪ Although PTC is not found in nature, the ability to taste it correlates strongly with the ability to taste other bitter substances that do occur naturally, many of which are toxins.
▪ Plants produce a variety of toxic compounds in order to protect themselves from being eaten. The ability to discern bitter tastes evolved as a mechanism to prevent early humans from eating poisonous plants. Humans have about 30 genes that code for bitter taste receptors. Each receptor can interact with several compounds, allowing people to taste a wide variety of bitter substances.
4
1. In your notebook:
2. Ask your partner to identify what characteristic they observe on you.
3. PTC paper will be given to you when you are done with the table and it is written in your notebook.
4. CUT OUT your leaf and write down your initials.
BOYS use dark green leaves and GIRLS use light green leaves.
5. Walk over to the tree and follow the branches. SEE INSTRUCTOR.
5
Trait YES NO
PTC PAPER
Attached earlobes
Tongue roller
Textbook page 263-266:
▪ Genetics
▪ Fertilization
▪ True-breeding
▪ Trait
▪ Hybrid
▪ Gene
▪ Allele
▪ Segregation
▪ Gamete
DUE BY Tomorow
Textbook page 267-269
•Probability
•Punnett square
•Homozygous
•Heterozygous
•Phenotype
•Genotype
For the following terms:- write & underline the term-define it-draw and color a picture that represents the term and definition, combined
7
EQ: How are different
forms of a gene
distributed to
offspring?
NB pg. 5
Title: "Mendel"
1. What did Gregor
Mendel discover in
the results of his first
experiment?
2. What did Mendel
discover in his
second experiment?
1 of 9
GREGOR MENDEL
Gregor Mendel as a Austrian monk who was born in 1822. He spent a great deal of time in the monastery garden where he was able to carry out experiments into inheritance. He chose to work with peas, which are small and easy to grow, and produce large number of offspring.
▪ Peas are a “model system.”
▪ •Started with “true breeding” plants
▪ •Trait: specific characteristic (e.g., seed color, plant height) of an individual
▪ •Hybrid: created from cross of true-breeding individuals
Mendel’s different groups of true-breeding plants would produce the same set of traits in each generation.
To figure out how traits were inherited from one generation to the next, Mendel crossed individuals from his true-breeding strains to produce hybrids.
8
2 of 9
▪ Mendel did not have our modern understanding of genes and alleles, he did understand that male parts of a flower produce male sex cells (sperm) and that female parts of a flower produce female sex cells (eggs), and that these cells join in the process fertilization.
▪ While offspring are produced from only one parent, each offspring forms from the fusion of male and female cells.
9
3 of 9 READ
▪ Mendel removed reproductive structuresfrom pea flowers so that only one set remained.
▪ Mendel was looking at seven characteristics in pea plants. His goal was to look for patterns in the traits across generations.
10
4 of 9
▪ Genes: passed from one generation to the next; determine an individual’s characteristics
▪ Alleles: the different forms of a gene
With your partner, complete the following sentences:
11
Characteristics such as seed color
are determined by ___________ .
Yellow and green seed colors are
determined by _______ .
The allele for yellow seeds is _______
to the allele for green.
WORD BANK:
Alleles
Dominant
Genes
5 of 9
PRINCIPLE OF DOMINANCE
▪ Some alleles are dominant, some recessive.
▪ An organism with at least one dominant allele will exhibit that trait.
▪ An organism with a recessive allele will exhibit the trait only in the absence of a dominant allele.
12
6 of 9
MENDEL’S F1 CROSSES
13
When Mendel
crossed plants with
contrasting traits, the
hybrid offspring
showed traits of
only one parent.
7 of 9 READ
▪ Segregation: separation of alleles during gamete formation
Why didn’t the allele for yellow color show in the F1 generation?
Was the recessive allele for yellow color lost in the F1 generation? How do you know?
14
8 of 9
THE FORMATION OF GAMETES
▪ during formation of gametes, or sex cells, alleles segregate from each other so that each gamete carries only a single copy of (one allele for) each gene.
Where are the eggs and sperm?
Where does fertilization occur?
SUMMARY: 15
9 of 9
16
NB Pg. 7
EQ: How can we use
probability to predict
traits?
Video Questions:
1. How many chromosomes
do we receive from EACH
parent?
2. What are Punnett squares
used for?
1 of 8
17
▪ In your notebook write the table below:
1. You and your partner will take turns flipping a coin. 10 times each.
2. Tally mark (/) the number of times out of ten, that the coin lands on either heads up or tails up on your table/ counter.
Heads Tails
Me
Partner
2 of 8 READ
PROBABILITY AND HEREDITY▪Probability: the likelihood an event will
occur. If you flip a coin, what is the
▪ probability of either outcome: ________
▪ Three coin tosses? _____________
▪ Each flip is an independent event.
18
3 of 8
GENOTYPE AND PHENOTYPE-DRAW A T-CHART
19
Two organisms may share the same __________
but have different ______________
4 of 8
HETEROZYGOUS AND HOMOZYGOUS
▪ Homozygous: has two identical alleles for a gene
▪ Heterozygous: has two different alleles for a gene
▪ Which are:
Homozygous? _______ heterozygous? ______
20
1 2 3 4
5 of 8
21
6 of 8 READ
22
The Two-
Factor Cross
7 of 8 READ
SUMMARY OF MENDEL’S PRINCIPLES▪ Inheritance is determined by units called __________ ,
which are passed from parents to offspring.
▪Where more than one form of a gene for a single trait exists, some alleles may be ______________ and others ______________ .
▪Each adult has two copies of each gene—one from each parent. These genes ____________ from each other when gametes are formed.
▪Alleles for different genes usually segregate ____________ of each other.
23
WORD BANK:
Dominant
Genes
Recessive
Independently
segregate
8 of 8
24
1. You will work with your
partner next to you.
2. Partner 1 will do 1 and
Partner 2 will do 2 and 4
3. CHECK each others
answers.
4. Be prepared to share
out.
If you do not finish
Spongebob WS, it will be
HW
EQ: How does the environment play a role in how genes determine traits?
Feather color in parakeets is controlled by multiple genes
25
1 of
▪Describe some of the exceptions to Mendel’s principles.
▪Explain the environment’s role in the way genes determine traits.
26
INCOMPLETE DOMINANCE
27
▪ Some alleles are neither dominant nor recessive.
▪ Incomplete dominance: One allele is not completely dominant over another.
▪ The phenotypes for both alleles are clearly expressed.
▪ Examples: chicken feather color, human protein controlling blood cholesterol levels
28
MULTIPLE ALLELES
▪ Many genes exist in more than two forms.
▪ Examples: human blood types, fur color in rabbits
29
POLYGENIC TRAITS
▪ •Many traits are produced by the interaction of several genes.
▪ • Examples: eye color in fruit flies, coat color in dogs
▪ • Traits typically show a wide variety of phenotypes.
30
▪ Environmental conditions can affect gene expression and influence genetically determined traits.
▪ The __________ of an organism is only partly
determined by its ___________________
31